View Full Version : Plywood delamination
03-21-2003, 08:49 PM
I was sanding the cockpit seatbacks when I noticed a pronounced "bubble" in the plywood in one area. It's around 8" long and perhaps 3" high. It certainly feels like the plywood is delaminating (it was 5-layer meranti and I'll spare telling you where I bought it from but argh!!!). So anyway, my present idea is to drill a small hole into the bubble and pump (with a syringe?) in some epoxy. Then I'll find some clever way to brace across the other side of the cockpit and press the bubble out (and hope for the best. Does anyone have a better idea? Anyone have any expereince wtih this mess. What's the probability that the entire batch was bad and all my plywood is going to delaminate?
03-21-2003, 08:51 PM
Opps.. reading the previous post I realized I was ambiguous. The bubble is 8" x 3" in area and the bubble feels like it is about 1/8" high. A 3" high bubble would be quite a "boil" wouldn't it now!
03-21-2003, 09:06 PM
Scrap it. Chances are that it's not just in that one 8"x3" area that it's bad. You fix that area, and a few months down the road, that's the only area still laminated...
Dave, is this new plywood?
03-21-2003, 09:12 PM
yep... brand new plywood on a new boat. And cutting it out will be a royal pain in the rear... Could be done I supose but I fear it will be a huge mess.
Major bummer, Dave. I just picked up a few sheets of meranti last week for a little utility power boat. I got mine from Noah's in Toronto, Canada. Haven't started using it yet but looks like good ply on quick inspection.
03-22-2003, 05:56 AM
Obviously,the 100%solution would be to trash it.
The 10% experimental solution would be to do what you said.If it was to be finished bright,I would slit it with the grain on both sides of the bubble,squeeze glue in one side, let air out the other.Make sure it's dry in there first.
03-22-2003, 07:21 AM
Slit it and glue it. I've seen fir ply do this in isolated areas. If glueing does not work you can replace it later. No sense getting drastic if you don't need to.
03-22-2003, 12:02 PM
Thanks folks... The idea of slitting as opposed to drilling never occurred to me. I'll give it a shot. Wish me luck.
03-22-2003, 02:54 PM
If the original glue failed, it is not likely that additional glue will help since it only has the old glue to bond to. If the problem was a "holiday" in the applied glue, then adding glue through a small hole will solve the problem. If it were mine, I would probably make a slit large eonugh to determine if there is any glue in there. If there is old glue that just separated, then you might open up the void on three sides and clean it out before regluing.
If you just take your own advice and inject glue, at least you may not be any worse off than you are now.
I always (well, I should check it always) check plywood for delams before using it. At least I have always caught the problems before getting beyond the stage you are in. First quality plywood should not have this problem but the world is not full of either perfect workers or perfect professional engineers.
My two bits.
2 slits with the grain close to the edge of the void and as long as you can.
Then one careful slit across the grain to join the first two at one end or the other forming a U.
Warm up the wood gently with a iron or steam and very gently lift. If you see glue in the gap I think you may have a bad batch as mentioned above. If not then try to force glue in under all the edges and carefully lower the flap and clamp.
Voila a face lift for your boat.
03-23-2003, 09:19 AM
"What's the probability that the entire batch was bad and all my plywood is going to delaminate? "
It would certainly bother me.
If you have any scraps, you might want to stress them a bit. If they delaminate, replace it all. If they don't, just do a quick repair.
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