I actually had this happen quite by accident (as happens frequently). This is a scratch built structure in 1/87 out of styrene. I sprayed the structure with a Krylon red oxide primer that I decanted into an airbrush cup. Impatient as I am, I painted the structure by brush with an acrylic craft paint (Ceramicoat) in the linen white color apparently before the primer had a chance to completely dry. I'm not sure but I believe the different drying times made the top coat of acrylic paint crack as you see. I then coated it with a dullcoat to stabilize it since it looked like the cracked paint might peel off. It may be a bit much for the scale but might prove to be an interesting technique on something larger.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Ffarm1.static.flickr.com%2F136%2F393023706_21ed6c3f12_o.jpg&hash=a1ac6a7c3b192eb288dd28968e847ed1d5d27892)
Very cool chester. I think it definitely has some possibilities...especially in a larger scale, and if one goes back in and carefully/randomly flakes of smal chips an areas.
FWIW...I recently bought a "crackling" mixture from Vallejo made especally for models, but have not had the time to test it.
Marc