Chemgineer - 22-3-2025 at 13:11
I took 200ml of 30% formaldehyde solution (Koi Carp treatment) and added ammonia hydroxide solution (says 10% on the bottle but I suspect it is 30%)
slowly until I had an excess of ammonia (confirmed by smell).
I then boiled this down and dried it in an oven at 170 deg C.
At some point the liquid turned from clear to yellow as it got to a small volume and then my final hexamine ended up being yellow when wet and light
brown when fully dry.
It burns cleanly as it should do but I am wondering if I have contamination or if I have over heated the product and caused the discoloration?
RustyShackleford - 23-3-2025 at 04:26
Probably due to overheating. You can purify it by dissolving it in minimum amount of water and adding acetone to crash it out. acetone should
hopefully keep whatever the colored crap is in solution.
Chemgineer - 23-3-2025 at 13:14
I'm putting a sample of bought hexamine in the same oven at the same temperature to see if it discolors it. If it doesn't then it must be some
contaminant in the formaldehyde.