If you're wondering how those modelers get that incredible, three foot deep, slick as snake spit, luscious shine well wonder no more. There's no big secret to using it. There are a few things to make note of. It is a two part system and consists of the clear itself and a hardener. With the two part systems the hardener normally suffices for thinning.
Ratios differ with product.
I can't stress it any more. This stuff is dangerous and can cause serious respiratory damage if used improperly. Be smart and safe and use the respirator. Twenty bucks can save your lungs. Urethane is a little pricey.