I have gotten several PMs and e-mails asking about polymers in coatings.

Here are a few comments classifying them.

First I must comment that no polymer that I know of can chill set so that a coating process involving polymers must be adjusted for this!

1. Polymers that don't harden: Polyvinyl alcohol, Polyvinyl chloride etc.... These are merely gelatin extenders if they mix with water + gelatin, otherwise they must be coated from a solvent. PVA helps bulk up gelatin.

2. Poylymers that harden: Well, they still don't chill set, but harden. Fish gelatin is among those of this class. They are OK but are hard to coat well.

3. Polymers with couplers attached: Well, I worked with these for a few years, and they are ok, but due to the fact that they don't chill set and are hard to coat at high speed, they are problematic.

So, with this summary, those asking may continue to ask and I will try to answer.