NetNews Usenet Archive 1993 #3

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Newsgroups: rec.pyrotechnics Path: sparky!uunet!charon.amdahl.com!amdahl!rtech!decwrl!ames!elroy.jpl.nasa.gov!usc!cs.utexas.edu!torn!nott!cunews!watpod72 From: watpod72@alfred.carleton.ca (George Bragg) Subject: more boom files (4) Message-ID: <watpod72.728165448@cunews> Sender: news@cunews.carleton.ca (News Administrator) Organization: Carleton University Date: Wed, 27 Jan 1993 20:10:48 GMT Lines: 995 PYRO4.TXT - Casings and General Construction, Part 1 This is part of a series of files on pyrotechnics and explosives. It's serious stuff, and can be really dangerous if you don't treat it seriously. For you kids out there who watch too many cartoons, remember that if a part of your body gets blown away in the REAL world, it STAYS blown away. If you can't treat this stuff with respect, don't screw around with it. Each file will start with a set of safety rules. Don't skip over them. Read 'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules that always apply. Then there will be some things that you HAVE TO KNOW about the materials you will be using and making this time. Read it thoroughly before starting anything. Pyrotechnic preparations and explosives are, by their very nature, unstable, and subject to ignition by explosion or heat, shock, or friction. A clear understanding of their dangerous properties and due care in the handling of ingredients or finished products is necessary if accidents are to be avoided. Always observe all possible precautions, particularly the following: 1. Mix only small batches at one time. This means a few grams, or at most, an ounce or so. Don't go for big mixes -- they only make for bigger accidents. The power of an explosive cubes itself with every ounce. (9 Ounces is 729 times as powerful as one ounce.) 2. When weighing chemicals, use a clean piece of paper on the scale pan for each item. Then discard the used paper into a bucket of water before weighing the next ingredient. 3. Be a safe worker. Dispose of any chemicals spilled on the workbench or equipment between weighings. Don't keep open containers of chemicals on your table, since accidental spillage or mixing may occur. When finished with a container, close it, and replace it on the storage shelf. Use only clean equipment. 4. Where chemicals are to be ground, grind them separately, NEVER TOGETHER. Thoroughly wash and clean equipment before grinding another ingredient. 5. Mixing of batches should be done outdoors, away from flammable structures, such as buildings, barns, garages, etc. Mixes should also be made in NON METALLIC containers to avoid sparks. Glass also should not be used since it will shatter in case of an accident. Handy small containers can be made by cutting off the top of a plastic bottle three or four inches from the bottom. Some mixes may most conveniently be made by placing the ingredients in a plastic bottle and rolling around until the mixture is uniform. In all cases, point the open end of the container away from yourself. Never hold your body or face over the container. Any stirring should be done with a wooden paddle or stick to avoid sparks or static. Powdered or ground materials may also be mixed by placing them on a large sheet of paper on a flat surface and then rolling them across the sheet by lifting the sides and corners one at a time. 6. Never ram or tamp mixes into paper or cardboard tubes. Pour the material in and gently tap or shake the tube to settle the contents down. 7. Store ingredients and finished mixes where they will not be a fire hazard away from heat and flame. Finished preparations may be stored in plastic bottles which will not shatter in case of an accident. Since many of the ingredients and mixes are poisonous, they should be stored out of reach of children or pets, preferably locked away. 8. Be sure threads of screw top containers and caps are thoroughly cleaned. This applies also to containers with stoppers of rubber or cork and to all other types of closures. Traces of mixture caught between the container and closure may be ignited by the friction of opening or closing the container. Throughout any procedure, WORK WITH CLEAN CONDITIONS. 9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES. Any careful worker does when handling dangerous materials. Be sure lenses and frames are not flammable. 10. Always wear a dust respirator when handling chemicals in dust form. These small particles gather in your lungs and stay there. They may cause serious illnesses later on in life. 11. Always wear gloves when working with chemicals. 12. Always wear a waterproof lab apron. 13. If you must work indoors, have a good ventilation system. 14. Never smoke anywhere near where you are working. 15. Make sure there are NO open flames present, and NO MOTORS (they produce sparks inside.) No hot water heaters, furnaces, or pilot lights in stoves!! Sparks have been known to very readily explode dust floating in the air. 16. ALWAYS work with someone. Two heads are better than one. 17. Have a source of water READILY available. (Fire extinguisher, hose, etc.) 18. Never, under any circumstances, use any metal to load chemicals or put chemicals in. Fireworks with metal casings are worse to handle than a live hand grenade. Never use any metal container or can. This includes the very dangerous CO2 cartridges. Many people have been KILLED because of flying fragments from metal casings. Again, please do not use metal in any circumstance. 19. Always be thoroughly familiar with the chemicals you are using. Some information will be included in each file, but look for whatever extra information you can. Materials that were once thought to be safe can later be found out to be dangerous stuff. 20. Wash your hands and face thoroughly after using chemicals. Don't forget to wash your EARS AND YOUR NOSE. 21. If any device you've built fails to work, leave it alone. After a half hour or so, you may try to bury it, but never try to unload or reuse any dud. 22. If dust particles start to form in the air, stop what you are doing and leave until it settles. 23. Read the entire file before trying to do anything. 24. NEVER strike any mixture containing Chlorates, Nitrates, Perchlorates, Permanganates, Bichromates, or powdered metals don't drop them, or even handle them roughly. These rules may all look like a lot of silly nonsense, but let's look at one example. When the move "The Wizard of OZ" was made, the actress who played the good witch was severely burned when one of the exploding special effects got out of hand. The actress who played the bad witch got really messed up by the green coloring used on her face, and the original actor who played the Tin Man got his lungs destroyed by the aluminum dust used to color his face. The actor we know of as the tin man was actually a replacement. The point is, these chemicals were being used under the direction of people a lot more knowlegable of chemicals than you are, and terrible accidents still happened. Don't take this stuff lightly. *********************************** One of the biggest complaints I hear about firework formulas goes something like, "This $@#!!* thing doesn't work! I wish someone would actually try the things out before they upload them and waste my time!" Sometimes, I agree. There are formulas for fireworks and explosives that have no chance of working, and others that are downright dangerous. Many were obviously thrown together by kids who never really tried them out, but thought they would look "big" in the eyes of their friends if they wrote some "anarchy" files. Others copy formulas from old manuals on pyrotechnics or explosives, or even old encyclopedias. These will often work, but many were written before anyone thought about safety, and were abandoned after enough people got blown away. Modern literature on pyrotechnics often warn against some of these old formulations, but they get copied anyway by people who either don't know or don't care that they're dangerous. These files can then get passed around the country by others who don't know of the danger. Let me make my feelings clear. People who write such trash are dangerous and should be treated the same as anyone who tried to slip you a computer virus or trojan horse. At least a trojan will just screw up your hard drive. That can be repaired, but you can't go buy a new set of eyes or fingers! If you don't thoroughly understand what you're doing, go learn some more, first. There are enough bad text files out there that taking the time to learn about dangerous materials and mixtures will be your only defense against getting seriously hurt. But a formula may be completely correct and as safe as a pyrotechnic mixture is expected to be, and you still may have trouble making it work. Often the reason is that the kids who wrote the text files don't know how to package the materials to get the proper results. Or they didn't know that it takes more than just mixing chemicals to make some of the compositions work. If you've ever mixed together the ingredients for gunpowder and watched its feeble fizzling compared that to the hard flash of commercial gunpowder, you've seen how important the proper processing can be. Sure, the first time you mixed a few chemicals together it was a real kick just to set fire to a small pile of it and watch it burn. But to make any kind of decent firework requires that a properly designed casing be used to hold your magic powders, and then those powders have to be made properly. A poorly designed casing or improperly processed composition will louse things up as much as any lousy formula. There don't seem to be any text files out there that discuss casings or processing, though I've personally downloaded hundreds that contain formulas for pyrotechnic mixtures. Now we can change all that. So what's the big deal about casings? Just a paper tube, right? No, not quite. A roman candle casing has to be able to handle repeated bursts so as to fire its stars like a rifle does bullets. But if all the burning materials inside change the inside diameter of the casing by too much, then the puffs of gas that fire the stars into the air will escape around them and not push them very high. Some of my early attempts didn't fire the stars out at all. A skyrocket casing has to be light, strong enough not to burst even though the pressures inside can be tremendous, and if it has a nozzle it has to grip it tightly enough that it doesn't get blown out of the casing. A firecracker on the other hand, has to be flimsy enough to burst yet strong enough to grip its end plugs rather than let them rip loose and fire off of the end of the casing. There are dozens of other examples, and if the casings aren't built right then you've just built a dud. So, learning all about various papers and glues isn't nearly as sexy as playing with chemicals, but until you do you may as well just go lighting up little piles of powder. You'll save a lot of money, and the results will be no less spectacular. But there's a lot more to this than we can cover in the size text file that's been typical of this series. We'll break this topic up into a group of files that are a bit larger than usual. This will just be part 1 of the discussion on casings and construction. So, now that I've shamed you into wanting to learn about paper and glue, let's get down to business. There are two kinds of paper tubes available. These are called spiral wound and parallel wound. If you've ever tried to wrap a sheet of paper around a dowel, pencil, or broomstick handle, you produced a crude parallel wound casing. We'll be sharpening our skills in this area. Spiral wound casings are made by wrapping thin strips around a round dowel form in a spiral pattern. Tubes used to hold wrapping paper, paper towels and toilet paper are made using this method, so check one of these if you have trouble picturing the method. Spiral wound casings are almost useless in fireworks as they have much less strength. Only firecrackers like M-80s use spiral wound casings, and that's because they're not supposed to be strong. So if you happen to come across some spiral wound tubes that are the right size to cut up for M-80s, you may be able to use them. Otherwise, they're probably not all that useful, even if they seem thick enough. Just so as not to worry anybody, you don't NEED a spiral wound tube for M-80s. A suitably thin parallel wound tube will do the job just fine. Spiral wound tubes are frequently used wherever possible because they're cheaper to make. Machines that handle thin strips of paper don't make as many wrinkled tubes as machines that have to handle wide sheets. Since we'll be doing our work by hand, this need not bother us. Glues The good news here is that the materials won't be nearly as hard to come by as some of the pyrotechnic mixtures mentioned in earlier installments. There are different types of glue formulas, most being variations of flour paste, which you can select, depending on what's convenient to you. If you don't feel like doing the slimy work needed to make this muck, I'll mention that I've had some success with commercial white glues, like Elmer's Glue All, though this tends to make a casing that doesn't accept certain types of end plugs very tightly. I wouldn't use it for rocket casings, and firecrackers have to be specially constructed. It's also going to cost a lot more than flour paste. You can experiment with it for small batches, if you like. It's also possible to get passable results with batches of white school paste, thinned down with enough water to make it flow. But if you're going to make a reasonable number of casings, you'll need larger batches of glue, and you can make it fairly cheaply and simply. A good, homemade glue that will make strong casings is made by adding 4 1/2 cups of flour to 3 cups of boiling water and then adding 1/8 ounce of alum (aluminum potassium sulfate). Stir this combination until it is consistent in blend. When it's cooled, it's ready to use. The flour is the actual glue. The alum helps fireproof the mess and helps act as a preservative. This is important, as wet flour will eventually spoil, and so this mess has to be used up fairly quickly. Don't count on saving it for more than a couple of days and especially don't try storing it in a jar or other closed space. The flour will spoil by fermenting, producing lots of gas, bursting your jar. But if spoilage is a real problem, can we let the flour spoil BEFORE we make the glue? This is not as silly a question as it sounds. By doing this, we make a slop that can be kept a month or so, if it's also kept in a reasonably cool, dark place. Just don't make it on a full stomach. Pour anywhere from a few cups to a few bucketfulls of flour into a container large enough to cover it with a good layer of water but still be only a third full. How much water you use doesn't matter too much right now, as most of it will be poured out later. Just make sure that you're making a batter, instead of a dough. Stir it up good, but don't worry too much about little lumps. That will be corrected later. Now for the revolting part. Let the stuff sit for 2-3 days in a warm (90 degrees F) place and check it after then. If it hasn't begun fermenting by then, drop in a few pinches of instant yeast. When the fermentation is finished and there are no more bubbles forming, the flour will have settled as a gooey layer at the bottom of a pool of revolting brownish liquid. Get rid of the brown slop and note how much batter is resting in the bottom of the container. Boil enough water so as to have a volume that's twice the size of the batter, and pour it in slowly, stirring the flour briskly. It'll start out being easy to stir, but will get thick in a hurry. If you're only making a few cups at a time, it won't be heavy enough to hold still while you're trying to stir it, so you might want to have the container clamped down solid. If you did it all right, you should have a batch of clear, smooth paste that's plenty sticky and fine for sticking your casings together. Since it's already a spoiled batch of flour, it can't go bad a second time and needs no preservatives. If you plan to use any Chlorates in your fireworks you should also add some potassium carbonate dissolved in water to your glue before using it to make any casings. I always put it in, no matter what I plan to do. The reason for this is that glue tends to deteriorate slightly, producing a slightly acidic material. Old paper used in the casings can also become acidic. Any Chlorate that comes in contact with an acid will produce tiny amounts of Chloric Acid, which can ignite if you do anything more vigorous than just thinking about it. Potassium Carbonate will counteract the effect of any acids, making your final masterpiece much safer than it would be otherwise. After that, it's still common practice to design fireworks so that no Chlorate bearing portions actually touch any glue. A super hard pyrotechnic cement can be made by mixing finely powdered Calcium Carbonate (powdered chalk) with Sodium Silicate solution. The proportions will vary depending on the amount of water in the Sodium Silicate, but you can make a few small test batches to check what works best for your materials. The Sodium Silicate should be thick enough to remind you of maple syrup, and can either be thinned with distilled water or allowed to thicken by evaporation, as needed. Stir in the Calcium Carbonate until you've got a thick, sticky mess. When this stuff hardens, you won't be able to clean it off of your utensils, so use items that you won't mind throwing away. This material makes nice end plugs in large firecrackers, and can be mixed with sawdust and a bit of red powdered tempra paint to make that nice, solid shell that coats cherry bombs. But this stuff is rock hard and turns into a shower of skin and eye piercing shrapnel once it bursts. Keep this in mind as you design your little gems. What Was That About Chlorates? Materials like Potassium Chlorate and Barium Chlorate are among those that you love and fear to use. Unlike the Perchlorates, which are much safer, Chlorates form Chloric Acid in the presence of moisture (like humidity) and any kind of acid material, and this can cause your mixtures to ignite on their own. If that igniting mixture is inside a salute that's piled in a box with other salutes, you can expect the whole thing to go up at once. Impressive to watch from a distance, but if it was in the trunk of your car, you should expect to have to answer a lot of questions to the authorities. And pay higher insurance. Yes, there's nothing like Chlorates to make fireworks so thoroughly spectacular. What to do? I normally avoid them, but have no problem with passing on formulas that use them, as long as you realize what you're getting into. While there are some places they should never be used, Chlorates are sometimes used in stars that get fired from a roman candle or aerial bomb, because the speed with which they get ejected can actually blow them out. Chlorate based mixtures just don't blow out. If you want to use them, use small amounts and don't try to store your creations over long periods of time. Keep them away from other fireworks. We can neutralize an acid by adding a base (a Hydroxide) but bases tend to absorb atmospheric moisture and screw up the burning of your mixture. A group of compounds that act much like bases (Carbonates) also can counteract small traces of acids. Make sure that your glue contains carbonates to counteract the effect of any acids that may form. If you want your eyes and fingers to last a lifetime, it's also a good idea to add some sort of Carbonate to the firework mixture. This will counteract any acid, but adds nothing at all to the performance of the powder. Furthermore, they can change the color that the powder burns. We've covered the elements that add color in an earlier file, and know, for example that Strontium salts give a red color. So adding Strontium Carbonate to the mixture can at least give us some coloring. Barium Carbonate can give a green color. While Sodium Carbonate might give us a yellow though, it also absorbs atmospheric moisture and will keep your mixture from burning properly. The use of carbonates is particularly important if your mixture contains both a Chlorate and Sulfur. Sulfur can form both traces of Sulfur Dioxide and Hydrogen Sulfide, and BOTH of these become acidic in water. One of the earlier files in this series showed how a mixture of just Potassium Chlorate and Sulfur will explode when you strike them. The trace amounts of acid that are always present in sulfur in the air can form enough Chloric Acid to explode when hit. Now, if you let it sit by itself for a long time, it may decide to ignite by itself. Then again, it may not. A potassium Chlorate-Sulfur bearing pyrotechnic mixture may behave properly the first 99 times you try it, and then bite you on the hundredth. If you want to experiment with Chlorate-Sulfur formulas, use small amounts only, add a carbonate before using them in any real fireworks, and absolutely avoid any of the ancient formulas that use Chlorates and Sulfur in firecrackers. For that matter, Chlorates mixed with anything in a firecracker are a bad idea. Commercial Safety Fuse This handy item consists of a string coated with gunpowder, which is in turn gwrapped with light twine, and finally coated with a red or green varnish. The varnish is apparently applied without a great deal of thinner in it, because it covers the twine layer without actually soaking into it. This waterproofs the fuse, and it can get quite moist for a long time and still work, provided that you don't crack the varnish layer by bending it too severely. If you do, the fuse will still work fine as long as it stays dry. This type of construction is built around its being made by machine. You wouldn't want to make it this way by hand, though we'll talk in a minute about a way to make a somewhat inferior waterproof fuse. The red and green varnishes are more than just decorative. They tell you something about how the fuse works. All fuses will spit a stream of burning crud from their ends as they burn. Sometimes people who are the first to describe things have no imagination, and it must have been the case here, because this property is known as end spit. Some fuses also spit sparks to the side, and not surprisingly, this is called side spit. Consider that a fuse that has little side spit may not light some of the more difficult to ignite mixtures until it burns to the very end of the fuse and fires its last spit out of the far end. Some of the very difficult to ignite mixtures may not ignite at all. Fuse with side spit will be blasting away at the mixture its inserted into through the entire length of its insertion. Unfortunately, the fuse with side spit isn't nearly as tough as the fuse that only has end spit. If you have a choice of fuse types, you can make your selection according to what you have available. Fuse with mostly end spit is colored red, while fuse with a good amount of side spit is colored green. (And I'll bet you thought it was just a decoration!) Black Match and Quick Match These items have nothing to do with the matches you strike to light your fireworks. In the jargon of pyrotechnics, match is a simple fuse made around a string core. Black match is used much like you would use ordinary fuse. That is, it gives a time delay before the firework actually goes off. You should want this to happen most of the time. Quick match is just the opposite. It burns from end to end very quickly. This is used where you want to start several fireworks at once, but light only a single fuse. This happens most often in commercial fireworks displays, where a large array of various colored flares (lances, in pyrotechnic lingo) must all be lit together to form a picture of some sort on a wooden framework set on the ground. You may not have much need for quick match, but it's interesting information, and if you know why it works you don't cause it to happen accidentally. To make black match, you start with cotton twine. Different thicknesses will give different results. Thicker twine will hold more powder and will burn better, but heavy cord is too much. Try as many kinds as you can. Avoid synthetic fibers; they can keep your match from working properly. If you aren't sure wether or not the twine is synthetic, try to burn a small length of it. Cotton will burn with a tiny flame and leave a very mundane ash. Synthetics will clearly melt as they burn. The prime ingredient of black match is meal powder. This is the name used in the pyrotechnic field for an unprocessed gunpowder mixture. You can just powder the ingredients by hand in a mortar and pestle (do each one separately!) and then just mix them in a plastic bowl. There's no need to use a powder mill, as will be described below. The black match formulation consists of 10 parts meal powder and one part of either gum arabic or dextrine. These are two different types of glues, and you should make your selection based on the humidity. Gum arabic is better in dry climates and dextrine is better in higher humidity. Add water and stir the mix until all the grains are wet. It will probably take a bit of work to get it spread all around, as the fine dust likes to form dry patches. After you think you've got it all damp, let it all sit for a few minutes so that any dry areas too small to see will have a chance for the moisture to soak in. After this, add lots more water and a bit of alcohol stir until you have a disgusting black mush. The amounts of liquid will be roughly a pint of water and an ounce of alcohol for every pound of meal powder, but you may need a bit more or less, depending on the thickness of the string you use. Don't take these proportions as an indication of the size of your first batch, though. Start small. Take a 2 or 3 foot length of the string and stir it up in the mush, squishing it in so as to get it completely soaked. Slowly draw it out, dust it with some dry meal powder and hang it to dry. Be careful while stirring, making sure that you don't wind the string into knots. If you do, discard the string and start again. Since this piece of garbage will become very flammable when it dries out, I'd suggest either burying it or cutting it into shorter lengths and flushing it down the can. Don't hang up these things anywhere there's an open flame or a chance of a spark. If one goes off, the sparks it spits off should have a reasonably good chance of setting off any others hanging nearby, and if you don't end up starting a fire, you'll at least lose a lot of hard work in a hurry. If you need longer lengths of this stuff, you'll have to modify your technique, but be assured it's been done by others, and you can too. As I've never needed more than a few feet at a time, I can't speak from experience, though. Just use your head and you'll surely work out a good technique. This material, when dry, is black match, and will burn as a crude fuse. If you try to bend it, the powder will crumble off, leaving spot where the fuse may go out. Obviously, you can't use this everywhere you'd use waterproof safety fuse, but there are times where it's useful. All right then, if this stuff is so fragile, why not enclose it in a sort of tube, to beef it up? That should protect it from crumbling, right? Well, it'll certainly protect it, but it will also act entirely different. The match will burn erratically, sometimes normally, sometimes in fast jumps. If the tube is wide enough, say, 3/16 to 1/4 inch inside, the sparks that the burning powder spits out will fly down the tube, igniting more powder, and causing the flame to flash from one end of the tube to the other in almost no time at all. This is called Quick Match and the tubes can be made by rolling a few layers of newspaper over a 1/4 inch steel rod and quickly pulling the tubes off to dry. You can then run a length of black match through the tube, and wherever you want to attatch a firework to the tube, just poke a small hole and insert a piece of black match. Don't try to wrap a tighter tube around a piece of black match to try to strengthen it. You won't be able to count on any sort of predictable behavior out of the thing, and if you were counting on having a little time to head for cover and the flame just flashes through the tube, well, that could abruptly change your plans for the next few months. Safety fuse isn't hard to get and it's not all that expensive. Use it where it's needed. If you absolutely can't get safety fuse, you can coat the black match with spray on plastic, available from handicraft stores, and when that's dry, brush on a layer of liquid rubber mold compound, which you can often get from the same place. One or more layers of the rubber will keep the powder from crackling off, but absolutely don't skip the spray on plastic, first. The plastic will put a temporary waterproof coating on the powder, which is needed since the liquid rubber is water based, and will wet the powder and then dry on the surface, sealing in the water. Such fuse would be very likely to go out at an inopportune time. Feel free to experiment with various brush on varnishes as a waterproofing, but the convenience of spray application has many advantages. Firecracker Fuse The tiny firecrackers that come in packs of 20 or more, all braided together, show the most unusual fuses. A thin tissue tube that has been somehow filled with the tiniest string of powder. Most texts on fuse give this item a quick mention as being difficult to make and suggest that their authors tried to do it and gave up. As it turns out, these are not all that difficult to make once you get the procedure right. We'll start out making a fuse that's about twice as thick as those tiny things, and as you develop the proper technique, you'll be able to scale it down to make something that looks and acts like the real thing. Most attemps fail when the individual starts out trying to make the fuse as thin as the commercial version, and eventually gives up. What you really need to do is first develop the basic skills on something larger. After that, it's easy to work your way down. To be honest, this kind of fuse is not widely useful considering the time needed to make it, but for those times when you do have a use for it, this knowlege can be very handy. It's very important to start with the right kind of paper. The paper used in the orient is not availabe here, but reasonable substitutes can be found. What's needed must be tissue-thin, yet fairly firm and strong. The papers used in facial tissues and toilet paper are far too flimsy. The real dedicated model airplane builders who work in balsa wood have used various tissues, and one material, called silkspan, can get reasonable results. But a perfectly adequate paper can be scrounged for free. That crackly kind of tissue paper that's used by stores to pack clothing into gift boxes so that it doesn't flop around in the box will work just fine. If you don't know what I'm talking about, it's time you graduated up from blue jeans and T-shirts. You'll have a difficult time of it if you don't start out by making or getting a few simple tools. The first item you'll need is a piece of bent sheet metal or a piece of metal angle. Angle is sturdier and is easier to use. The item should be about 8-10 inches long. If you use sheet metal, make it about 2 inches wide and bend it down the middle along its length. You should have a long trough with an angle of 90-100 degrees. Next, you'll need a cradle to hold the trough so that the bend can be at the lowest point. Two strips of wood, attatched to a base, will do the job. Finally, you'll need tiny, spoonlike tools for dispensing and spreading the powder. Some biological supply houses sell a stainless steel spatula that's ideal. It consists of a thin metal rod about the thickness of a coat hanger, with one end flattened out into a 1/4 inch wide paddle that's great for spooning out tiny amounts of powder. The other side has a more pointy paddle that makes it much easier to spread out the powder. Make a weak glue by dissolving a bit of dextrine in water. Find a SHARP pair of scissors and cut out some pieces of the crackly tissue about 3 inches long and 3/4 inch wide. Get pieces that have no wrinkles. The pieces should be quite straight, which you'll have trouble doing if the scissors are not really sharp. Fold the tissue along its length, as shown; |<----------------- 3 inches ------------------>| | | \/ ----------------------------------------------- ---------- | | 1/4 inch ---------- |-----------------------------------------------| ---------- /\ | / | /\ 1/2 inch | / | \/ | fold here | ---------- ----------------------------------------------- Unfold the sheet and set it down into the trough, as shown in the cross section. The picture is angled incorrectly, since typewritten characters give only a limited ability to show graphics. The trough should look like an "arrowhead" pointing downward. / / / / / / ... / / powder ------> .... / / ...... / / paper ---> _______________________________/ / sheet metal -----> __________________________________________/ <---- First or metal angle fold Use the wider of the spoon tools to put a crude line of freshly mixed meal powder along the length of the fold. Next use the pointier tool to try to spread the powder out evenly. A few properly placed taps should cause the powder to spread out uniformly. This works much better if the trough is made of angle instead of sheet metal. It's not likely to work at all if the meal powder is a day or more old, since any humidity will probably have started it to cake together. It's difficult to describe how much powder to put in, but it's easy to describe what it will look like when it's done. Lift the paper out of the trough and refold the tissue, holding in the powder. Once folded, the powder should fill the folded section about halfway. _________________________________________________________ | | | | | | | | | | | | |_________________________________________________________| | | | | Crease and | | <---- fold here | ******************************************************* | | ********************* powder ************************** | ----------------------------------------------------------- <--- First fold Next, crease the paper right above the powder and fold it upward, enclosing the powder in a second fold. This may take a little practice, but it's not as hard to do as it might first appear. _________________________________________________________ | | | | | | | | | | | | |_________________________________________________________| | ******************************************************* | <--- First | ********************* powder ************************** | fold ----------------------------------------------------------- <--- Second fold Next, roll the folded powder section up into the remaining paper. Don't worry if it's not perfectly smooth, but try the best you can. Give the slender tube you've made a gentle, rolling twist. Don't twist it too tight, or you'll rip it. When it's about as thin as it's going to get, dip your finger in the water/dextrine mix, and quickly run it along the length of the fuse. Be careful not to use too much. It should not be soaked, just dampened along one side. Leaving the fuse twisted, set it down with a small weight on each end to keep the twist in the fuse. The weights will flatten the ends, and when it's dry you'll want to cut off at least 1/4 inch from each side. These parts won't have enough powder. You can experiment with making longer lengths of fuse. Three inches is a reasonable size to learn on, and you'll probably be able to add another inch or two, though you may not find the extra effort to be worth it. It's better to practice making thinner fuse. What you've just made is probably about twice as thick as is found in commercial packs of firecrackers. Work your way down to papers only 1/2 inch wide, using a smaller amount of powder. You are now an expert fusemaker. Processing Gunpowder Gunpowder is one of those items that every budding pyro knows something about, but few really understand. The standard formula shows this to be 75% Potassium Nitrate, 15% Charcoal, and 10% sulfur. But just powdering and then mixing these ingredients makes a powder that's just a weak parody of real gunpowder. Real gunpowder is made using certain commercial processing methods that make it burn much more fiercely. While we can't copy these methods exactly, we can make a pretty decent approximation that can be used in place of gunpowder in most fireworks formulas. By the way, the unprocessed mixture that most people think of as gunpowder is known in the pyrotechnic trade as "meal powder". One secret of good gunpowder is in making the individual ingredients as finely powdered as possible. Just running them around in a mortar and pestle for a few minutes won't do it. The other secret of good powder is to mix the ingredients thoroughly. Both of these must be done better than can be done by hand. Simple mechanical means will be used. If you've ever looked at commercial gunpowder, you've noticed that it comes in rock-hard granules of various sizes. It looks nothing like the gray meal powder you're probably used to making. If the ingredients are properly ground and mixed, then a tiny amount of water can be added (just enough to moisten it all) and the wet mass is pressed into a cake about 1/2 inch thick to drive out any air that may remain. The cake is kept pressed until it's dried solid and is very hard. This may take several days to a week. During this time, the moisture in the mix has dissolved a tiny bit of the Potassium Nitrate, which is very soluble in water. When the particles are tiny enough and the air between the particles is driven out, the Potassium Nitrate will actually RECRYSTALLIZE AROUND the particles of Sulfur and Charcoal, and will become very hard. It is then crushed with wooden tools (or brass or aluminum tools -- no iron or steel -- it can produce sparks!!!) and the particles are sorted by size by running them through various mesh sized screens. Mixing and powdering the ingredients requires you to make or buy a simple machine. Happily, the same machine can be used for both operations. The machine is a gemstone tumbler, and for small amounts of powder, a 3 lb. tumbler is about right. This will allow making 1/2 pound batches of powder. The reason a 3 lb. tumbler is being used for mere half pound loads, is that it will also contain about 2 pounds of brass pellets that you'll have to cut from half inch brass bar stock into 1/2 inch lengths. Don't cut the brass by hand with a hacksaw. If you have access to a power hacksaw, use that, otherwise, find a local machine shop that can do the job for you. You'll be glad you did, trust me. While bars of iron or steel are more readily available and cheaper, they will also make sparks and blow up your powder mill. Brass won't spark at all. Don't use anything else. After your pellets are cut, you'll want to smooth off the burrs on a belt sander or, shudder, by hand filing. This is all a lot of work, but you only have to do it once. If you want to try making your own tumbler, you'll want to be rolling a soft plastic bottle about a quart in volume. Don't even think of using metal, glass, or hard plastic. In either case, an explosion would send deadly shrapnel flying in all directions. While the hard plastic might not be quite as deadly as metal, it has the added disadvantage of not showing up in an X-Ray. Think about it. The bottle should roll at perhaps 10-12 RPM. The usual way to roll a bottle for mixing purposes is to have a roller attatched to a low speed motor, and another free rolling roller a couple of inches away. When the bottle is placed on top of, and parallel to the two rollers, all three will turn. Don't forget that electric motors make sparks and sparks can touch off powder. Make the shaft from the motor to the roller as long as you can, enclose the motor as best you can, and keep EVERYTHING as clean as you possibly can. If you buy a gemstone tumbler, make sure it has a solid rubber barrel. There are metal barrels available, but you should realize by now why you'd avoid that kind. Some cheap tumblers have plastic barrels. Again, you should avoid hard plastic. Once you have the proper equipment, put the brass pellets into the barrel and dump in the Potassium Nitrate. Now, run the mill for four (yes, I said four) hours. The Potassium Nitrate must be quite dry, or you'll be wasting a lot of effort for nothing. It's safe to warm it in a 300 degree oven for a few hours if it contains moisture, but you'll want to let it cool down in a closed container before you mix it with anything. Since the Potassium Nitrate will start caking on a humid day, you may wish to select a dry day before you begin. After you're done, remove the Potassium Nitrate and put it in a SEALED container. If you don't do this, the stuff will begin caking from any traces of humidity, and the final material will actually be less finely powdered than you want. Next, put in the charcoal, and run it for two hours. Once charcoal is powdered that finely, you'll make thoroughly nasty black dust clouds when you try to pour it, so don't take it out of the mill until everything's done. Next, add the Potassium Nitrate back in and the Sulfur, which normally comes finely powdered. Now all three ingredients will be in the mill and you should run it all for six (!!!) hours. These times are really minimum times if you want to make decent powder. You'll find that the powder will be much fiercer if you double all these mixing times, but the time needed will start becoming impractical. Once this is all done, you should take out the powder, add enough moisture to get it to cake together and press it into a flat cake. I've had some success with two heavy boards held together on one end with a wide hinge. These swing together leaving a half inch gap between them and are clamped together on their free ends with a metal C-Clamp. The boards should have several layers of waterproof varnish, otherwise they'll start warping, they'll leach out some of the dissolved Potassium Nitrate from your powder, and they'll probably become much more flammable than you'd like them to be. Let the thing sit in a dry, cool place for a couple of weeks. It should be away from any sparks or flames, including electric motors, and should be far enough away from other flammable materials that you won't have a fire on your hand if it accidentally ignites. After it's dry and hard, crush and screen it, and you're done. One final word on this. The extreme solubility of Potassium Nitrate allows all the recrystallization that makes good gunpowder possible. But recrystallization is a problem when it causes the Potassium Nitrate to cake in the container. If you get it in jars, you'll probably have to scrape or chip out the chunks you need. If you buy it in 100 lb sacks, you'll have to break pieces off with a sledge hammer. Don't forget that this unpleasant property also happens at the microscopic level, making tiny particles clump together into larger ones, as the clock ticks. Time is your enemy when you need to have your Potassium Nitrate in a fine powder. Use it as quickly as you can once you've powdered it. Don't powder it today for use tomorrow. Even if it looks okay the next day, you can be sure you've lost some of the work you've put into it, and that the performance of your final product will suffer. Rolling Casings This is one of those very important skills that always seem to be ignored in files that describe the pyrotechnic arts. Yet, the properly built casing will make the difference between sucess and failure of your creations. For most casings, brown Kraft paper will work very well. Everyone who's in any way involved with modern civilization is familiar with this stuff as the brown paper bags used by supermarkets, hardware stores, and many other businesses. It's tough and will absorb the glue, making a tough casing. While stores in many areas are switching to plastic bags, it should be possible to save enough bags to meet your needs. If not, you can buy the paper in large rolls from paper supply houses. While it comes in various thicknesses, choose something that's comparable to the paper bags, which seem to be well suited for our needs. While the simplest casings are just made by rolling a piece of paper over a rod, and then sliding it off and gluing the end closed, these are not of very much use. Most casings need to have glue between the layers of paper to make them hard, have to be cut to the proper length while they're still wet and mushy from the glue, and you have to use care not to glue the casing to the rod you're winding it on. You have two choices as to the type of rod to use to roll your casings. A metal bar will last longest, won't swelll from the moisture in the glue, and won't easily stick to a stray glue droplet, but is more expensive, takes more work to cut to size, and will quickly dull the knife blade that will be used to cut the casing. A wooden dowel is cheap, easy to cut to length, available in a wide variety of sizes. It will also have to be replaced more frequently if you cut your casings while they're on it, because the knife blade will quickly cut deep grooves into the wood. It also requires extra care to keep from gluing the casing to it. We'll describe the procedure for wrapping a casing around a wooden dowel. If you choose to use a metal rod, you can ignore the extra cautions that using wood will require. Start with a sheet of paper. One dimension will be about an inch and a half larger than the length of your casing. The other dimension will have to be learned from trial and error, and will have to do with how thick you want the casing wall to be. Wrap one and a half turns of the paper around the dowel and give the dowel a twist so that the paper is wrapped tightly with no slack or wrinkles. Unwrap about a quarter turn, enough so that it still remains tightly wrapped but just barely so. Next, put glue on the paper near the crack where the wrapped portion meets loose portion and start wrapping the paper by rolling the dowel over a flat surface. If you're using a bottle of white glue for this, the long line of glue will glob up and travel along as you roll the casing. Whenever an area runs low on glue, squirt some more in the depleted area. If you're using a liquid paste, you'll instead want to apply it with a brush. In either case, don't let the glue get any closer than a half inch from the ends of the tube. This is particularly important if you're using a wooden dowel, as any glue that runs out the end will make it difficult or impossible to remove the casing. Keep rolling and applying glue until the paper is all used up. If your casing isn't thick enough, it's easy to fix. Just glue on another piece, keep applying the glue, and keep rolling. Once you're done rolling, take a sharp knife and place it about 3/4 of an inch from one end, at right angles to the tube. Press down and roll back and forth, and you'll cut away the unglued end of the tube, along with a little of the glued portion. Slide the piece off and do the same to the other side. With a little practice, you can make the knife cut go around in a perfect circle rather than a slightly ragged spiral, and the end of the casing will be smooth. As quickly as you can, slide the tube off of the rod, and set it aside to dry. Besides the danger of gluing the tube to the rod, there is also the problem that the tube will shrink slightly as it dries, so don't leave it on the rod any longer than you have to. There are a few things to think about; the wetness in the glue will quickly dull the knife blade. Wipe it off immediately after cutting an end. It's not a bad idea to use an X-Acto knife, which uses cheap, disposable blades. You may also find that a whetstone is useful in extending the life of your blades. Another thing to consider is that even if no glue touches your dowel, it will still absorb traces of moisture and after you've wound a couple of casings, it will be much easier for you to accidentally glue the casing to the dowel. It's a good idea to have several dowels and use them in rotation so that each has time to dry off before it gets used again. After you've had some practice rolling casings, you'll find it fairly easy to roll your casings on one dowel, slide it off before you cut off the unglued ends, slide the end onto a second dowel that's been sanded down to make it just a bit smaller, and use that to cut the ends off. This way, you won't cut knife marks into your good rolling dowels, and when the ends of your cutting dowels get too ragged you can just cut them off and use the fresh end for cutting. You needn't put the cutting dowel more than an inch into the casing before cutting it. This will reduce the chances of getting it stuck. Salutes These are among the simplest pyrotechnic devices to make. There are many ways to make them, some more dangerous than others. When you get right down to it, there's no such thing as a safe salute; if one of these goes off in your hand, you'll lose fingers. But if you build them properly and use some common sense when firing them, there's little risk. There are several things to always avoid. First, only paper casings should be used. Metal, plastic or glass can send out lethal shrapnel, while hard paper will simply throw light shreds of paper while being just as loud. The second point is the end plugs used. Commercially made salutes used to use either a cast epoxy or the Sodium Silicate/Calcium Carbonate glue mentioned earlier. Either of these will send out eye piercing shrapnel. Wooden plugs, while easily cut from dowels, can also put an eye out. But good paper end plugs can be made that won't hurt anyone. The third danger point is the powder formulation. Some old books give compositions using Chlorates or even Chlorates with Sulfur. While these are the easiest and probably the cheapest, they're also very dangerous. Weingart's "Pyrotechnics", published in the 1930's, states that 90% of the injuries in fireworks factories involved Chlorate/Sulfur mixtures. Weingart's point was that you should be extra careful with these. It apparently never occurred to those folks that 90% of the accidents could then have been eliminated by using different formulations. Perchlorates and aluminum dust are the "modern" solution to this problem. They're not the cheapest, but they're just as good and are far safer. The fourth problem is the small wad of hard, black crud that's placed where the fuse meets the casing. It's referred to as priming, and while it serves as a glue to hold the fuse in place, it's mostly black powder and will flare up when the flame from the fuse reaches it. Rough treatment of the fuse will get it bent at that point, and that's where the fuse is most likely to go out. But if it does, it will first have lit the priming, and that's enough to relight the fuse. It kind of makes the salute more reliable. While it's more likely to go off properly when lit, it's also more likely to go off by accident. Any stray spark can set off the priming, and if one salute in a box goes off, it will easily light the priming on the others and set them off too. Priming would have been a good idea if it weren't so dangerous. But anyone with half a brain won't beat his salutes around so as to damage the fuse, and we can use ordinary glue instead of priming. Avoid using priming, or any salutes you find that use it. We'll look into making a salute that's just a little smaller than an M-80. It's fairly easy for a beginner and uses less powder, for those of you who can only get access to a limited supply, or are caniballizing powder out of packs of commercial firecrackers. It still makes a fairly respectable bang, and is fairly easily scaled up for those who want a really big boom. * fuse-> * * * glue * \ * /*\ casing ---> ==========*========== --. * .-- end | * | cap -----> | * | |.......*.......| |.......*.powder| --'...............`-- ==================== Start with a 7/16 inch dowel, about 8 inches long. Using the glueing techniques discussed above, take a 6 inch square sheet of kraft paper and roll it into a solid casing. Cut off the 3/4 inch pieces on the ends, or perhaps only 1/2 inch pieces, if your glueing skills are good enough. When in doubt, cut off more. If the ends don't contain sufficient glue they won't be strong enough to hold the end caps sturdily. Cut the remaining tube into pieces that are from 1 1/4 inches to 1 1/2 inches long. Take them off the dowel and set them aside to dry. Next, we'll make the end caps. Get a 5/16 inch dowel (whatever the inside diameter of the casing, this will always be about 1/8 inch less. This will allow it to be about 1/16 inch thick, as you'll see) and four squares of kraft paper. One square should be about 1 inch on a side, and the other three should be about 3/4 inch. Place the larger square flat on the tip of the dowel, centered as well as you can, and pull it down over the dowel to form a cap. Place a hefty drop of glue on the tip of this cap and rub one of the smaller squares over this drop. When one side of the square is fairly well covered, pull it down tightly over the first. Don't worry about keeping the corners alligned; they'll be cut off in a moment, anyway. Pull the last two squares down over the cap one at a time, smearing a drop of glue each time. Make sure that this cap is squeezed tightly. If you wish, you can make sure by momentarily wrapping a piece of heavy cord around it. The cord is always a good idea for larger end caps, but its optional here. Next, using the X Acto knife, use the same rolling motion we use for casings to cut off the ragged end, leaving a cap that's 3/16 to 1/4 inch high. It should be easy to slide this cap into the casing as shown in the picture, though the fit should be a bit snug. The first cap is best glued in while the casing is still wet. Make sure it's well glued, and then pinch the wet casing and end cap inward at 6 or 7 points around the circle with a pair of needle nosed pliers. With the end of the casing pinched in, it will be possible to put a slightly undersized dowel into the casing, and smash the pinched end down against a hard surface, causing the casing to curl around the end cap. When dry, this will never blow out. When the casing is dry, drill the fuse hole and insert a piece of safety fuse long enough to almost touch the opposite wall of the casing and to extend AT LEAST an inch from the casing. Glue it in place and let it dry. The casing should be filled no more than 1/3 full of loose powder. Any more and you'll actually get less of an explosion. I prefer to use 1 part dark pyro aluminum dust to 3 parts Potassium perchlorate. Most any flashpowder may be substituted here, but they tend to require metal in dust, not powdered, form. Gunpowder won't work at all here. Once the powder is in, a second end cap is liberally glued in and the ends pinched in as well as you can. Be extra careful, as attatching the second end cap turns the thing into an explosive device. Give it a day or two to dry completely. It should be pointed out that most of the explosive force of these things is dissipated within a couple of inches of the casing. This is why people often lose fingers or parts of their hands, but never their wrists. If you can make a wooden fixture to hold the salute while inserting the end plug with a wooden tool, you'll be safely distant from most of an accidental explosion. Safety glasses are also a good idea. If made properly, you'll get a decent bang, the casing will split along its length, usually through the fuse hole, and the second end cap will blow out. The first cap that got smashed in place never seems to come off. If only one cap blows out, it wasn't in tight enough, and the bang will be pretty lame. If you do your test firings in a little pit, 1 foot deep and no more than a foot wide, you'll usually be able to recover the fragments to determine how well you're doing. After mastering these you can try making larger ones. Since salutes with any respectable amount of powder are illegal in all 50 states, those you buy are made in clandestine factories, with little regard to safety. They're made cheap, fast and can contain all sorts of dangerous mixtures. Because factories can be found by tracing the purchases of certain chemicals, salutes often contain whatever garbage was available at the time. Besides Chlorate/Sulfur mixes, some have been found to contain Picrates, which can remove your hand by just shaking them. What's the point? Any large salutes you buy were probably made by people who wanted to make a fast buck and were cared more about evading the feds than assuring your safety. If you want to make a big bang, it's probably safer to make your own, where you know what you're playing with. It's strange, but true. Watch for part 5 of this series, where we'll carry on our discussions. ------------------------------------------------------------------------------ Neal's Note: No, sorry fans, I have not seen nor heard of any part 5. Good night, and please remember to switch off your sets. ------------------------------------------------------------------------------ Neal Miller | "Why not go mad?" | millernw@clutx.clarkson.edu Clarkson University | - Ford Prefect | millernw@clutx.bitnet ------------------------------------------------------------------------------ -- -------- "OCP pioneered cyborg technology; state-of-the-art destructive capability..." watpod72@alfred.carleton.ca