Friend/customer has an expensive set of front doors, pair of 3-0x8-0 mahogany. They face mostly west with a short two-story porch overhang … maybe 6 ft. They were varnished for most of their life, but a couple of years ago she had the outside painted black … the insde is still varnished. The outside has been refinished about three times cuz the paint develops small bubbles and blisters. I did it the last time, using Sherwin Wms Duration.
I sanded the outside lightly, although inn some places the paint easily came off to bare wood, and applied 1-2-3 primer. This was done in June, I think, when it was very hot & dry. Now I notice that there are several small bubbles again. The house is always air conditioned or heated, so the humidity should be pretty stable. There is one crack in a panel joint, maybe 1/16″ x 3″, but the bubbles are in several places, even in the upper panel where there are no visible cracks.
Help. Any ideas why the bubble appear, and how to avoid them next time? Before you ask, the doors will always be black, so that’s not an option.
Whenever you are asked if you can do a job, tell’em “Certainly, I can!” Then get busy and find out how to do it. T. Roosevelt
Replies
Didn't we go through this once already?
The paint bubbles because it gets too hot.
There is no way to prevent it. If the customer insists on that material and that color in that location, the very best you can do is shorten the maintenance interval so you repaint it before it starts to bubble. If you've been doing every three years, try doing it every other year.
Edited 10/6/2004 8:54 am ET by Uncle Dunc
yes, we discussed these doors when I was doing the work. This is the first time I refinished them, they wewre done previously by other people.
Ok, maybe the heat is doing it. But why wouldn't it blister all over the door? There's maybe 10-12 aspirin sized blisters near the middle.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed - complete stab in the dark, but it's a thought. Varnish. Exterior. That means long oil. Soft squishy stuff. Latex over something with a high oil content.
Agree the heat doesn't help. But I'm having a hard time (not seeing it) swallowing that heat alone - unless it's trapped by a storm door, will do that. Maybe it will. To me, bubbles in a finish like you describe is telling me something behind the finish is popping it out. You see that kind of thing when wood that was damp gets painted. Gee, the paint doesn't stick, wonder why. Maybe the heat is enough to encourage off-gassing to some degree, even if the varnish is well aged.
As far fetched as it sounds, I've run into stuff that got oil furniture polish on it ten years ago and today you can't make some finishes stick to it. To cure that, I lean on vinyl sealer after washing the surface down. So far, nothing I've done that to has had a recurrance of bubbles. Ok. But have I put it on an exterior door. nope."If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." - Mark Twain
go to the source.. http://www.homesteadfinishing.com
"expectations are premeditated resentments"
Edited 10/10/2004 12:13 pm ET by the bear