Anyone have any tips on doing a rough or textured finish with a spray gun and thunderbird. I Just can't seem to get what I'm looking for.

I painted BLACK on many Ornamental fence, gates, ect. over the years.
when your paint is to thick it would spray(spit) larger droplets of paint. my paint was quick dry also.
So I would stop and add more thinner, then the paint would lay down and be smooth

I would mix up 3 batches with less and less thinner.
if it's slow dry it may not do any good

there are textured paint's out there,          clear? I don't know

You are going to have to experiment with less or more thinner, you may need more air pressure with the thicker?

That's all I got.
Good luck

Shellac is a quick dry
I bet it allmost dry before it hit's the floor

I've never used thunderbird or a spray gun.

I have used spray can poly many times.
I get a textured finish by finishing the bow smooth..normally with wipe on poly. Then once the bow is sealed and would be just fine with the smooth finish if I wanted it that way, I take a can of poly and spray it from waaay back..like around 2 1/2 foot away. I hold the can far enough away so the spray is just sorta floating/rolling it's way onto the bow. I do 3-4 of these coats till the finish has the texture I'm looking for.

Not sure if this helps..but it's all the info I have for ya.

I may be wrong, but I thought you had to have a special nozzle for your spray gun to do that.

Drop your pressure to about 10lbs and open up the thru put of your gun. Back up the gun from the bow and just mist the final coat. That will give the splatter/texture finish.

Thanks for the help I will give it another go when it warms up here again.

That's what I do-drop the pressure a little and move a little further from the bow. Sometimes the flat gets milky though. Here's what mine looks like:

 

Looks good I think I was running to much pressure. I need to get a bit of free time and give it a try.

When I was texturing my bows, I was using 1 Part A, 1 Part B, to 1/2 part thinner, dropping the air pressure below 10 lbs and opening up the nozzle. It can be a little finicky, particularly if you get the air pressure too low and the nozzle too far open, you'll be really big splatters. Practice on a piece of cardboard or paper before you turn loose on your bow. Too fine a mist and it just looks like an orange peel finish. I quite spraying the texture when I got a new batch of finish and inexplicably all of the texture dots remained glossy after they dried. Scratched my head, pulled out my hair, then just went back to a smooth finish.

Terry Folts and South are correct that is is the best way to get it done!!!