hobby thinner is used to thin your paint, for hand brush or air brush. However, one drawback of thinner is it dries or vaporise fast. hence it might create some problem: eg, spider web in air brush, or obvious brush stroke in hand paint etc.

To counter that, retarder mild comes into picture. basically retarder mild serve almost the same purpose. u can use it to thin your paint, or mix it togther with thinner n paint to thin the paint. Retarder has a longer drying time, hence the paint you mixed n thinned takes longer to dry. As a result, u have more time before the paint got too thick for air brush, or a longer time where the paint can settle before it turns solid, hence less obvious brush strokes.

I hope that answer your question, which u asked in a not-so-polite way.
Now, please say "Thank you", OK.

is this beam saber custom made? or ordered? any tips on doing it?