[barrel browner]

I have a metal finishing formula for gun barrels that I have used for many years, it is made up of acids, alcohol, and ferric chloride, in the last few months every time I mix the formula it goes off after 4 or 5 days and darkens, I realized I had started storing the ferric near a strip light so moved it and brought in fresh stock but the problem is still there, can anyone think of what is causing this? thanks in advance.

[MOTOBALL]

First thought is that you have recently changed your supplier of one or more ingredients.

Second thought is that maybe you are using ferric chloride from a very old batch; water vapour from the air may have caused some hydrolysis.

Question: does the darkening solution show any particulates, or is it just a coloration ? 

[barrel browner]

Hi Motoball, thanks for your reply, I have not changed supplier it was my thought that maybe I was buying old stock but I cannot seem to find a supplier of 50 % ferric chloride, the formula darkens slowly after about five days no particles just gets darker each day.