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Want to know if a process has been discovered for removing pigment from old paint?

Question asked by Denise Summerhays on Dec 1, 2014

I am an aid at a high school. Working on developing a 'green business', specifically researching recycling old paint into a usable product to cover graffiti, etc.

I would like to know if it is possible to remove the color/pigment from the paint?

This would be incredibly helpful for obvious reasons.

I now recognize this is far more complicated than I imagined, and possibly a slam-dunk for a chemist.  I tried to research a bit and found the following;

When preparing to dry out the pigment and get it into a 'packed' cake form (before adding it to the paint) they use a flocculating agent (What is this?) that causes the tiny particles to aggregate and then agglomerate all together so it can be efficiently filtrated, washed and dried.  Then when they want to add it to the paint, they use wetting and dispersion agents on the pigment so it can be 'deflocculated'.   Simpleton that I am, I'm thinkin', it was flocculated once, let's just add some of that there flocculating agent in again and filter the pigment back out.  Right?!?  Ha, Ha!

I do recognize they have a huge variety of wetting and dispersing agents (and there are organic and inorganic pigments) and they adhere along with the binding agent to the pigments differently.  Does this process chemically alter the pigment so it can't be flocculated and/or removed, in other words, does the addition of these materials make the removal process impossible?  Clearly, I ain't no chemist. 

Thank you so much for your kind and thoughtful response.  I look forward to input on the matter!