[stevehertz]

I remember Ronseal (?) used to talk about there being a critical time window between coats. Too soon and the new coat stops the one below from drying and causes interaction and surface rippling. Too much time lapse and the new coat starts to soften the old coat, again causing surface problems. Something like that. I think eight to 24 hours - something like that, is the recommendation. Don't quote me on it, but there is an optimum recommended window of time between coats. Maybe that's your problem. Plus coats being too thick, that would exacerbate the previously described scenario.