[OP]
Member
purebond void Nov 2011 001.JPG
I was wondering if anyone has had this experience with Columbia Forest Products Purebond Plywood. I keep running into places where they veneer over a knot hole. I had it happen last year and again this week. I would change brands but the alternitive would be Chinese plywood.
Member
Pretty sure that is what I use in my shop. I know it is Columbia brand. I haven't really run into that problem. I have found voids and complain constantly about $100 sheets with veneers that are .017" thick. But really never found any knots below the surface that impacted the work.
What is it that you are showing in the picture. Almost looks like you used a holesaw on that area.
Member
I've used it and found voids in the core but never in the layer just br
elow the veneer. What grade is it and what is your source ?
Contributor
I've had problems with Columbia C-2 maple plywood but with voids not with knots below the veener layer: when sprayed with water based primer the veener above the voids bubbled noticably. The affected areas were as large as my hand. Also, the Columbia we've purchased tends have significant mineral staining over the majority of the back surface (the "2" side). We've changed suppliers and buy Murphy plywood (Eugene, OR). Much better quality, no void problems thus far, and the gradings are very conservative.....some of their C-2 lots are near A grade in appearance.
Scott Vroom
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
Member
Columbia offers many different options as far as the core goes. We purchase Kay-core from a wholesale distributor, and have never had a sheet like the one you have. If you are getting your plywood from the depot, you are getting pretty much the cheapest core that columbia offers.
Member
That was my concern. The stuff at my local home center has no grade stamp, it simply says columbia pure bond and the shelf tag has some stick about its environmental friendliness and formaldehyde free aspect. But I'm pretty sure it's a pile of rejects that didn't make any other grade at the factory, or some lower spec. Unfortunately it's not inexpensive enough to compensate for the waste factor and e potential that you find the problem post assembly.Originally Posted by Zach Callum
[OP]
Member
The cabinets I'm building I'm using maple plywood for paint grade to keep from using Chinese plywood. I don't have a line bore machine and when I drilled the holes by hand I felt the drill drop through the veneer. That's when I looked closer to find it was hollow under the outer veneer and I just used a chisel to expose the knot. They had never made any attempt to fill the core veneer and just veneered over air.
Member
I use a fair amount of plywood all either US or Canadian products and all from wholesalers....never from the box store. I've found occasional defects just happen, sometimes a small void, sometimes a small spot that didn't get glue, and I once got a sheet of 1/4 mdf that blew in half when I cut it....(though I think that was most likely something caused by improper handling somewhere along the way?). The lines this stuff is made on process sheets so quick I think it's bound to happen on occasion. For major defects your supplier should credit you for the material, minor ones...?
Leo, what kind of material are you paying $100 a sheet for? Unless it's an exotic veneer, that's pretty steep. If your buying basics like maple and cherry on a veneer core as a business you should be paying a LOT less than $100 a sheet
good luck,
JeffD
Member
Well, I'm not. I don't buy lifts and usually only buying a few sheets at a time with the occasional 15-20 sheet order when doing kitchens. But unfortunately because of my buying record, that is how my pricing is set. A buddy of mine who does smaller quantities pays about 5% more than me for the same stuff.
90% of what I buy is A1 and it works out to about 2.90 sq. It has gone insane lately and I am now paying more for (white) maple then cherry.
Posting Permissions
Reply With Quote