OK, the last post talked about PPG 2021, Omni, and PPG Duracryl 468. Which are urethane? Are all urethanes catalized?

Duh, Ward-O   

Randy, some misinformation may have been presented to you. Not many basecoats are actually Urethane, well not in the sense you think of them as urethane. In my experience, all URETHANE materials are catalyzed before spraying. Now that being said, there are some basecoat systems that react to the catalyst in the clear when you spray it, so they are in a form Urethane.
as for clears, Yes all Urethane clears are by definition catalysed, this is because to become Urethane,k thy need to cross link when they cure, However some of them are catalyzed by chemicals other than something you add to them. This is to say that there are Urethanes that are single pack in a spray can and they catalyze by something present in the air as I understand it. I dont have a lot of experience with those, for our purposes, I would say that any clear Urethane will be mixed with a catalyst before spraying.

Mark,

The guy at the paint shop told me that all color coats in a base coat/ clear coat system are urethane. The binder or carrier of the toners is urethane. It's one of the reasons that when I have the paint shop mix up colors for me, I tell them to leave out the binder (so I can use butyrate lacquer as a binder). This clear binder is urethane. I also have to be careful that any additives like pearls or metallic or whatever are in dry form and not in a liquid as this is almost always a urethane carrier. And they are not catalyzed, though I hadn't realized (or really considered) that when you spray the topcoat, the catalyst in the clear would catalyze the underlying color coat. This would certainly explain why urethane color coats tend to be so fragile.

I also hadn't considered that rattle can urethane like you get at Home Depot or whatever are also catalyzed. By the air if nothing else. Interesting.

And PPG 2021, Omni, and PPG Duracryl 468 are all catalyzed products.

Terry,

That's interesting. I know all the Omni colors use a urethane binder (told to my by the paint shop guys). I also know that Duracryl is going to a water based color coat, but has used a urethane carrier.

Doesn't really matter to me. I have the auto paint guys mix up colors for me and leave the binder out. I mix in clear lacquer for a binder.