My current theory:
What I think makes the most sense isn't the Spraymax on TOP of the Createx. This seems to be fine. The above test really did not indicate anything really problematic between the two.
However, I am still having wrinking....mainly on my latest coats.
And I think that's the key.
Because I've been sealing each airbrush coat with Spraymax 1k, the layer or thickness of the Spraymax clear UNDERNEATH each progressive layer of sprayed Createx is getting slightly thicker.
What I think is happening is the 'sandwiched' Createx paints is caught between the bottom layer of Spraymax 1k and the top - as the top layer begins to interact with the bottom layer, the bottom layer expands with the 'heat' creating wrinkles. This is why I did not see it on my first few coats and now seems common as thicker layers of clear are underneath the Createx.
Here's my results (keep in mind that the standard process of sanding with 400 and wiping with naptha occurs between each of the below, but some of my attempts at heat-setting may have been too little):
1. CLEAR: Playfield lightly cleared with Spraymax 1k
2. YELLOW Createx/Wicked color-matched mix airbrushed. Multiple coats applied to cover black letters (yellow over black is a PAIN)
3. CLEAR: Light sealing coat of Spraymax 1k applied.
4, NO REACTIONS on Yellow. No wrinkles, lifting, etc... Perfect.
5. ORANGE Createx/Wicked color-matched mix airbrushed. Perhaps three thin coats to establish coverage.
6. CLEAR: Sealing coat of Spraymax 1k applied. I may have put it on a bit more heavier in some spots.
7. MINOR REACTION: First tiny wrinkles noticed in one of the thin orange arrows in upper playfield. Otherwise, everything is good. I proceed thinking this was due to too much clear.
8. INSERT FILLING: This should have been done in step 2, but I thought I could avoid it, and do it now. The dripped Spraymax 1k pulls up the yellow paint around two of the 10 inserts. Not great. Will need to fix. What happened?
9. BLUE: Createx-only color-matched paint air-brushed. Once dry, sanding and naptha wipe. Strangely...notice that naptha is actually pulling some of the blue paint off playfield! Huh? Poor adhesion for some reason. This is where my limited heat set time might have been an issue.
10. CLEAR: A coat of clear will lock it down and all will be okay.
11. REACTION: Significant wrinkling! Particularly in the blue areas on lower playfield (not so much at top). I spray from top to bottom (lengthwise) so the application amounts should be pretty close, but I may have given the lower playfield area with the worst adhesion some extra clear to 'lock it in'.
12. Starting over...blue mostly removed, yellow removed, and most orange on lower playfield removed (fixed cupped inserts, etc....)
13. WHITE: While I'm also taking this opportunity to properly fix the inserts (since reactions damage to the yellow are now irrelevant as I need to respray) I decide to shoot the white areas since I have little to loose and I want to test a disciplined application of thin coats, then heat set, then thin coat, then heat set. The white seems to go on nicely and adheres to the playfield well (Perhaps addressing my issue with the Blue in step 9?)
14. CLEAR: After 4 days (plenty of time to cure) and having gotten my inserts nice and flat, time for a coat of clear to seal some of the now exposed bare wood near the inserts and the white paint.
15. REACTION: The white wrinkles after just a few seconds of application. Once cured, the wrinkles do subside a bit, but are still somewhat noticeable.
The most logical answer for the wrinkling seems to me to be related to the increasingly thick layers of the bottom layers of clear reacting to the new top clear, causing the new Createx layer to wrinkle. I may try and test this out (do a better job than above)!