What else is in Hetchel's tent

Hint 1 of 4:

Have you looked at the flask of dye?

Hint 2 of 4:

It can teach you the EMPTYING draft, if you listen closely.

Hint 3 of 4:

Be sure to also check the boiling pot.

Hint 4 of 4:

It will teach you the DYEING draft.