polly s

Some PollyS paints do need thinning, especially for fine work, in my experience.

Use only water to thin PollyS paints!

I have tested PollyS for compatibility with just about everything, using the methods used in the paint industry. It is incompatible with most common forms of alcohol. You can clean it very effectively with Windex or Simple Green, but I wouldn't use those as solvents.

Unless it has dried in the bottle it should already be thin as water and not need any thinning at all.  The only time I've ever had to thin it I did what it says on the label and used distilled water.