Wondering about plywood

[Ed62]

I hope this is the right forum for the question. I don't really have a project going, but I'm wondering about plywood. It's been said many times that plywood from the Borg is prone to warping, twisting, or whatever. My question is "What causes it to be more unstable than better ply?"

Ed

[MikeMcCoy]

I saw some discussion over at Woodweb the other day ... I'll see if I can find it real quick. Here it is:

http://www.woodweb.com/knowledge_bas...ith_Bowed.html
From Gene Wengert, forum technical advisor:
Each sheet of veneer in a piece of plywood has a slope of grain (SOG). (This slope is the direction of the fibers. A split will follow the grain.) When the moisture content changes and there is slope of grain, the piece of plywood will warp, often twisting. If the moisture never changed, the piece would never warp (unless made in a warped shape initially). Certainly, some veneer mills have more SOG than other mills.
Assuming that the SOG is close to zero, a sheet of plywood (or any wood, for that matter), if exposed to one humidity on one face and to another humidity on the other face (that is, the moisture in the wood is different from face to face), moisture changes will cause size changes and warp can result, usually crowning, up or down. (As a rule of thumb, a 4% MC change results in a 1% size change across the grain. Further, wood does not change size along the grain.)

If, when manufacturing plywood with a decorative veneer face, the MC of the decorative veneer is not matched to the rest of the plywood, then again, as the moisture evens out, there will be shrinkage (or attempted shrinkage) that will cause warp. In this case, it would be common to see all the pieces warp in the same direction (such as toward the decorative veneer) rather than randomly.

A key point: Wood does not change its size or shape unless its moisture changes. The only exception is warp that occurs immediately when machining or cutting the piece of wood, or size changes that occur over many years when a piece of wood is under load (such as a loaded bookshelf).



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[Slik Geek]

The problem is not just warping

My experience with BORG plywood is that the instability with their Chinese plywood goes well beyond moisture content problems. I have found incredibly large voids in the veneers, resulting in "rubber plywood" after cutting sheets down to project sizes. It was like I had cut kerfs into theplywood to bend it, they flopped around that badly.

I made a large set of two bookcases and a large entertainment center cabinet using BORG plywood. When I cut the sheets into strips, I often exposed significant voids (multiple inches long, and multiple inches deep). In some cases, I was able to salvage portions. In the worst case, I returned half a sheet to BORG (it flopped around like rubber after I cut the other properly veneered section away) and demanded a refund.

I was able to use the BORG plywood for my project, but with a greater amount of waste. I had to be careful regarding structural integrity in my selection of how I used various pieces.

It also seems like the inner veneers of their plywood are not as strong as U.S. or Canadian plywood that I have used previously. This is a perception, however, and I cannot substantiate it like the plywood void problems that I indicated above.

Needless to say, I don't purchase plywood from BORG anymore.

On subsequent projects, I purchased my plywood from Menards (which are in your area, Ed). Their plywood is sourced from North America (at least it was the last time I bought some). They also have, at some stores, 4x8 sheets of baltic birch which I have never tried, but looks decent.

[cabinetman]

There are factors other than moisture that can cause warping, twisting, cupping, and delamination. Variations in the laminating process, veneers, pressures, and/or glue factors can produce sheets that aren't flat, not consistent in thickness, or delaminate. IOW, quality control problems with the manufacturing process. Or, how sheets are stacked and stored can also be a contributor.
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[Ed62]

I was pretty sure it had to do with moisture content, and I did consider that the voids might have something to do with it. I was wondering if the other materials used in making plywood had something to do with moisture problems.

I never considered slope of grain (Thanks, Mike), but I did think there was a difference in the way moisture is picked up between Borg plywood and better grades. I thought it might be because of different products being used, or voids.

edit: C-Man, you posted just as I was writing my response. Quality control problems would surely affect quality.

Ed

[BobSch]

On subsequent projects, I purchased my plywood from Menards (which are in your area, Ed). Their plywood is sourced from North America (at least it was the last time I bought some). They also have, at some stores, 4x8 sheets of baltic birch which I have never tried, but looks decent.

I looked at Menard's plywood and found some big voids in their 3/4" Birch ply. Since then, I've stuck to material from a local commercial lumber yard. (Youngblood Lumber, for those of you in the Mpls/St. Paul area.)

[rcp612]

What I saw with Borg's oak ply was inner plys (plies??) that were overlapped. I decided that the pressure used to create a flat sheet out of over-lapping veneers caused my cut pieces to curl up like potatoe (potato??) chips.
I've not had any similar experiances with Lowes though.

[jackellis]

I've been using a Chilean-made softwood plywood that's sold at Lowes (among other places) under the brand name Arauco. It tends to twist and warp slightly in the thicker sizes but not enough to make me use something more expensive for shop drawers and cabinets. The 1/4" ply tends to warp a lot and it can be difficult to use for drawer bottoms and backs. I've been getting mine at Lowes and will start buying it at a local lumber yard in Tahoe City when we move.

Arauco has no voids that I've found. The plies are of consistent thickness with alternating light and dark bands that look pretty nice "in the raw" with no edge banding. My only real complaint is that it tends to fuzz when routed.

[cabinetman]

I've been using a Chilean-made softwood plywood that's sold at Lowes (among other places) under the brand name Arauco. It tends to twist and warp slightly in the thicker sizes but not enough to make me use something more expensive for shop drawers and cabinets. The 1/4" ply tends to warp a lot and it can be difficult to use for drawer bottoms and backs. I've been getting mine at Lowes and will start buying it at a local lumber yard in Tahoe City when we move.

Arauco has no voids that I've found. The plies are of consistent thickness with alternating light and dark bands that look pretty nice "in the raw" with no edge banding. My only real complaint is that it tends to fuzz when routed.

The price for a veneer core plywood will definitely vary according to location. It is a pine sourced plywood, that is supposed to be void free, and no overlapping veneers. It carries a construction type grading like fir plywood. Could be very suitable for cabinet construction or as a substrate for veneer or mica (high pressure laminate).
.

[BasementDweller]

What I saw with Borg's oak ply was inner plys (plies??) that were overlapped. I decided that the pressure used to create a flat sheet out of over-lapping veneers caused my cut pieces to curl up like potatoe (potato??) chips.
I've not had any similar experiances with Lowes though.

I couldn't agree more. If I see any over-lapping along the sides of a sheet of plywood I'm looking at I keep looking. I know this is against the normal advise... but I like sheets with LESS layers. I like plywood with maybe 5 layers inside the face veneer. I was at BORG today and their stuff had 9! 9 very thin highly overlapping layers. I just doesn't work for me. I'll take the 5 thick layers anytime.

But what do I know...

[scmhogg]

I bought my last [ever] plywood from HD this year. The birch veneer was paper thin on a very poor base, with overlaps and voids. I actually sanded through the surface veneer with two passes with 220 on a soft sanding block.

My other experience, this year was more my fault, but a shocker anyway. I painted one side of a 4 X 8' sheet with a water based vinyl. The next morning, their was at least a 6" bow in the 8' length. It did come mostly back when I painted the other side.

Steve

[chopnhack]

Same with me, never again on BORG or Blue BORG crappy ply. There cab grade is a farce. Overlapping plies, crappy glue, glue line separations, extremely thin veneer, veneer that delaminates and the fact that the stuff is structurally more alive than a living tree!

[drumpriest]

I have never understood everyone's bad experiences with the HD ply until this year. I dunno if we didn't get the real junk until now, but the last several sheets have been TERRIBLE. I usually used the oak ply, which seems much nicer than the birch. My main issues are with just BAD BAD BAD glue bonds, delamination of the show veneer mostly, though I've had to patch up some places structurally.

Steve though, I've not had a piece with the veneer so thin that it came off with hand sanding, I can't imagine that. I don't use my power sanders on any veneered ply, as it's risky business regardless. I was able to go through the veneer on a sheet of 120$ cherry ply at one point with my Bosch ROS, so it's all about hand sanding for me with plywood.

I've used a lot of their birch this year for shop cabinets and for kitchen cabinet carcasses, where you are not going to see it, and it's really not great. They used to sell 30$ sheets and 45$ sheets, and the difference was huge. Seems as though they've ditched the old 45$ stuff and repriced the 30$ stuff at 45$....

I have not tried their oak in a couple of years, and their price on it here now (55$/sheet), I won't use it, it's no cheaper than buying it from the local cabinet shops, and the cabinet shop ply is much better. Thicker core veneers, and better adhesives for the face veneer.

I've had major chip out issues with the last birch that I've bought from HD, and it's not that the TS blade chipped it out, it's that the top veneer just peels off in chunks. It's as though the glue wasn't spread out over the substrate.

[Gator95]

Well, I guess I'll go against the grain here. Home Depot plywood can be fine, but with some qualifications- and it depends on where your local HD is sourcing ply from.

For the last project I did, I used a sheet of Maple plywood from HD because (1) I had a gift card, and (2) I was really really eager to get a project started day after thanksgiving and didn't want to wait until Monday for my usual lumberyard (Peachstate) to open. I've used Maple Plywood from Peachstate before, so I'm using their B-2, 11-ply 3/4" as a comparison. List price is something like $75 a sheet.

I bought a sheet of 3/4 Maple 5-ply plywood manufactured by Columbia Forest Products, was $55 or so. Had to sort through the top 5 sheets to find one that I thought was close to a B/C grade. One or two pieces were basically shop-grade. Fortunately someone there at HD helped me lift and sort and replace, and he agreed that a couple sheets didn't look that great- his exact words were (and this tells a lot) "gee... yeah if I'm going to spend over $50 for a piece of plywood I'd want it to look better than that too". His emphasis on the "$50" made it sound like he could not image spending more than that for a piece of plywood, ever.

Working with the material, I found the plywood to be dimensionally stable, and cut cleanly with an 80T blade and ZCI - pretty much zero tearout. Slightly more fuzz on dados cut with a 3/4" router bit than with the B-2 11-ply plywood I've gotten from Peachstate. Veneer was thick enough for mechanical sanding with a ROS. Veneer quality for finishing (Minwax polyurethane, 50/50 mineral spirits cut, wiped on) was only slightly below that of the B-2 Maple sheets I've gotten from Peachstate, but slightly below still means noticeably worse on close inspection by me and angled lighting- a casual observer would never see a difference.

Overall, I think the Columbia 5-ply plywood at HD is fine for most projects. Still feel a vague feeling of guilt for buying somewhere other than Peachstate, great folks there and I want to support them, so I don't know if I'd use the maple HD plywood again. But if for some reason I had to, I'd not be too concerned about the quality provided I could hand-pick the sheet.

[SARGE..g-47]

You ran into an exception at HD, Gator. What has been at HD in the past several years in our Atlanta area is Chinese plywood. Columbia is not Chinese ply and it it not made in Columbia. It is made in both the U.S. and Canada and is "Green" which means they garantee they are not using formaldehyde or other toxics in the glue.

With that said.. I don't know if Columibia is making a cheaper grade under their name for HD but... when I do buy ply I intentionally look for Columbia but I won't bother at HD as they are just too high. I purchase down the road from Peach State at Suwanee Lumber. Their prices are much lower than HD or Peach State for that matter from my experience and they are only 13 miles from me with Peach State about 35-40 from L'ville.

So... maybe HD has dumped the Chinese source (I know Lowe's still uses the Chinese)... maybe Columbia is making to their specs on a contract deal... I really can't say? Suwanee has Chinese ply for any interested (but few are) and domestic. Every stack is clearly marked IMPORT or DOMESTIC and blow the Box prices out of the water as I purchase at Contractor price.

The Chines stuff has micro thin top veneer... numerable voids... low grade backs.. twist and warp from what I have seen and very well may contain formaldehye in the glues as they don't have to conform to any specs. I simply won't purchase it at any price even though I use only a few sheets a year for drawer bottoms and dust backs on chest.