You can thin it out now. Most of the old timers and some of the new would have told you to start out with the dope thinned 50/50 so that it penetrates better and goes on smoother. So go ahead and thin it a bit. Use a good quality brush as well. It will dry a bit faster as well. You can stay with the thinned mixture until your satisfied with the fill. Lightly sand with 400 grit or finer sand paper then wipe to remove the fuzz. One thing to remember. Let the nitrate dope cure for at least 7 to 10 days or longer before you apply any other paint. Even Butyrate dope. Be careful what you apply clear butyrate over (i.e. your colored paint). Test it on a seperate test piece to see how it works. Good luck and have fun. [&:]