Ive thinned Hamerite with cellulose thinners to spray paint powerpacks , but I also used to add some xylene to the mix too , it slowed the drying time and let the hammer finish develop really well , but it also seemed to let the paint flatten too ,, so you got the best of both worlds ,,, dry in about 4 hours and smooth to touch with a hammered look ,,, but once the gun was used for it it was no use for anything else ever again ,,,