Re: What causes this in polyurathane varnish?
Interesting thoughts. The coats have been thick, admittedly, On the bits ive had good results with I have applied thickly and its left a lovely smooth finish. I've been giving them a long time to cure before recoating. Before doing this final coat, it must have been about 2 weeks , and I did sand it quite heavily with wet 600 grit paper.
I wonder if environmental issues could be a factor. My shed is quite warm, and potentially a bit humid in this weather. Its insulated quite well, but later in the day the sun seems to have baked through it enough to heat the room up.
Perhaps some moisture has been left from my wet sanding too, I wiped it dry but maybe that wasn't enough.
Im going to do an experiment this time. Im wet sanding it as before, but will leave the piece overnight to make sure its free of moisture. I'll also run my dehumidifier on full overnight, and when I do the next coat, apply it in the morning or evening when the weather is cooler.
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