Paint cracking on ABS

[Kram]

Last year painted my bike fairing, ABS panel. I used autotek 1k plastic primer (rubbish), old metalic basecoat, old 1k clear coat, then 1k upol s2085 clear as I was out of the old stuff.

Where the panel has flexed, fitting headlight etc it has some crack lines appearing.
Im unsure it is the type of clearcoat, or the plastic which is quite flexible, or that I put too much on, or something else?

Now this panel doesnt matter too much, Im still very happy with it and it will get winter use, but I will be doing another one soon and I'd like to learn from it. I will use epoxy, primer, same basecoat, and 2k clear. Will I need a flexible additive for the clear? Ive only seen it for Mipa branded paint looking on ebay.

 

[Ianb]

I think most brands sell an additive to increase the flexibility of the clear/paint, although the Lesonal 420 clear I use states in the TDS that no flex additive is required for flexible substrates.

 

[richie00boy]

2k clear is much more flexible than 1k clear, I wouldn't put any flex in.
Also just go from epoxy primer to basecoat, the less material thickness and less different materials the better in this case.