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View Full Version : Polyurethane and humidity



John Timberlake
05-16-2006, 11:24 AM
I have always heard that polyurethane finishes don't dry well in humid conditions. During last week, it has been raining about 60 degrees, but I had to finish some bookcases. Figured putting the PU on under these conditions might take longer, but it would work. To my suprise, all the finishes dried to the touch in four hours. Only problem I had was the first coat over some Minwax stain seemed to take longer to dry. Just wondering what others have experienced.

Jim King
05-16-2006, 2:10 PM
John: I live in the upper Amazon river Basin of Peru and use nothing but polyurethane floor finish (high gloss). You are correct it will dry quite well in humidity, we have 90% every day. Try putting on your last coats and then let a peice set a month before you wet sand and polish it. You will be amazed and the better quality finish. This to me means that it continues to dry more than you think over time.

Allen Bookout
05-16-2006, 3:54 PM
Jim,

I will not try to hijack this thread but living in Iquitos, Peru really strikes me. I cannot imagine. May be you could write a short article in Off Topic. I would be interested in local woods, woodworking equipment available. electricity, where you are from, are you coming back (assuming you are not from there with a name like Jim King), is woodworking your job there and things like are you going to give presentations if you come to the United States and on and on.

You may be too busy for such things, but it sure would be interesting.

Thanks! Allen

Carl Eyman
05-16-2006, 5:34 PM
I think my first experience with Poly was in the early 1970's. A manufacturers' Rep came into the factory and demonstrated his poly floor finish. He etched the concrete, applied the poly, and then set up a fogger to humidify the air to make the poly cure better. Am I dreaming, or did this really happen?

Steve Schoene
05-16-2006, 10:31 PM
Certain poly's are moisture cured, just like polyurethane glue. But the cure is slowed by lower temperature, and I suspect by moisture in excess of that needed for optimal curing. But unless you are doing industrial coatings, its not likely that the manufacturers data sheet will give the full information.