I have been spraying two part clear for several years and swear by it. Today I almost swore AT it. I use it on guitars and basses, and on my airplanes. I have trusted it to be fule PROOF, not just resistant, and it has proven to be just that.
I've sprayed it over just about everything you can think of for the stunters and instruments. I've even sprayed some other materials over it, all with no problems.
BUT - I'm finishing a guitar with tinted nitro cellulous lacquer to get a sunburst red followed, as usual, with two part.
I sanded through on an edge today, so went into the paint room and lightly shot some red tinted lacquer on the spot to touch it up. Now, before you jump all over me, I know you cannot spray nitrate over butyrate, etc. But this was going over death paint which supposedly will take anything. Not so.
The edges of the area where I shot the tiny little spritz of nitro cell bubbled up about 1/8 inch into the clear!
I tell you about this so you can be advised of the possibilities of this type of problem. I'm dealing with hard maple, and all I did was lightly sand the bubbled area down with dry sandpaper until it was smooth, then shot the entire back of the neck and the edge with a zillion coats of the two part. Problem solved.
But if this were to happen with balsa, repair would be much more troubling.
So, if you're doing an unusual task involving two part, I reccomend you do the old "try a sample first" trick.
It ain't cast iron like I thought.