types of plywood

[Brad Wood]

LOML has started talking about me building an entertainment center. I've started thinking about, pondering, etc. Nothing really concrete yet.

Anyway, I'm thinking the overall construction will be plywood. I've started looking around at hardwood plywood and have discovered yet another area I know nothing about. At the big box, you buy what they have, and thats it...

Now that I am looking at ply from alternate sources than the big box, I am seeing descriptions like "The core choices are MDF, Veneer-core, Armor-core, and Particle board core"

First off, what core type would I be buying when I go buy a sheet from the big box? Secondly, what are the pros and cons of these choices I am suddenly faced with?

Thanks in advance

[Jose Kilpatrick]

http://www.taunton.com/finehomebuilding/how-to/articles/understanding-cabinet-plywood.aspx

Veneer core is made by layers of veneer (not face veneer) with the grains at 90 degree angles of each other. Thats what most plywood is at the big box store.

MDF core will be heavier and more uniform.

The pros and cons will depend primarily on the construction techniques used as well as they substrate desired.

MDF core is great for a glue up job, but doesn't handle screws as well as veneer core.

[Charlie Plesums]

First, avoid big box ply. I have wished I hadn't every time I weakened and tried them again. Locally it only costs a couple dollars more for oak ply from the lumber yard, and the quality is FAR better. Sometimes I actually get a full 3/4 inch from the lumber yard (19 mm), and as many as 11 plies, compared to 5 plies with lots of voids from the big box.

Quality rating for hardwood ply... the first side is ABCD, the second side is 1234, so the best is A1. I often get oak that is B2 and it is very good. Quarter inch walnut is typically A4 (only one good side)

MDF core ply is very smooth and flat.... just like MDF. Although some may disagree, I believe it sags more than ply core. And it is as heavy as MDF. I do not routinely use it.

Ply core is just like it sounds. Domestic ply core is generally formaldehyde free, and had thicker outer cores. It costs 5-10% more than imported ply core, which is generally sanded better - good thing because the veneer is so thin that you probably can't sand it. Normally I pay the premium and buy domestic ply core, sometimes listed as "green" plywood.

Lumber core has glued up lumber under the show ply. So why bother? You don't get the dimensional stability of plywood, but you have the thin veneer.

I can guess what particle board core is, but since I refuse to use particle board for anything else, I am not going to start here.

Around here there is a type called "combi-core" which is probably a slang expression and may be what you call Armor core. Under the show veneer on each side is a veneer of man-made material - looks and acts like the old non-tempered masonite. The lumber yards tell me that the cabinet shops love it, since the surface is smooth like MDF core, but the 5 or more normal ply cores give it the advantage of plywood. I have found that you cannot glue anything to the surface - no strength in the masonite layer - it has to be screwed into the core. If you bump the corner you will have a large wound of delamination. I even had a mystery bump appear on a flat panel after a twisting catch in the shop - I thought I had saved an accident, but when I was finishing could feel a bruise in the panel. At first my lumber yard thought I was crazy since everyone else loved the combi core, but eventually they found others complaining like me.

[Brad Wood]

Thanks guys

What exactly is it that is a problem with the stuff from Lowes/HD? If I recall it is birch - so, I think somewhere here there was a conversation that it doesn't take stains and such very well... is that the only reason, or are there other manufacturing/quality issues that would cause me to stay away?

The article from http://www.hardwoodlumberandmore.com/ on finishing poplar to look like cherry was very informative and I was wondering if the same technique can be applie to birch to get satisfactory results (I noticed a LOT of places sell birch, which puzzles me if it is so awful for finishing)

[Eric DeSilva]

I'm never buying ply from the borg again. First time I did it, I didn't really know better. The ply had a lot of voids in it and warped badly. The second time I did it, it was because I happened to see some Columbia ply there with a substantial number of plys--fart better than the average the borg carried. Only, it still sucked. I started making some shop cabinets with it, and I've got one shelf (11" x 22.5") with a 1/2" warp in it.

From now on, its baltic birch or good quality veneered plywood from a hardwood supplier...

[Kevin Groenke]

A few other plywood materials to consider are:

Baltic Birch(aka Finnish, Russian):
Imported from Eastern European and neighboring environs. Typically void free with birch outer veneers and (i think) alder inner veneers. Typically more layers of thinner inner veneers than domestic plywood. Metric sizes 6mm, 13mm, 19mm, others.
http://www.woodpeck.com/media/main_birch-boards.jpg


Some borgs sell a Chinese plywood that is similar to baltic birch but is often inferior. I have seen entire sheets delaminate when they're cut into. Then again, I have used this material for shop cabinets with some success. Hard to argue with $25/sht.
http://lh5.ggpht.com/_rHdeE-SI5cc/SWENXdZmD1I/AAAAAAAAAWw/p4Cz6_fc-U8/P1020428.JPG


ApplePly (tm): http://www.statesind.com/prod/ind_2a2.html
Domestic, similar to baltic birch, but better. Exterior veneers are hard maple, interior plys are birch and/or alder. 1/4"-1-1/4" thicknesses.
http://images.meredith.com/wood/images/p_477_3_3.gif


FinColorPly:http://www.fincolorply.com/
Comparable to ApplePly. Hard to find. Some pre-stained and pre-finished. Bright primary colors are real purdy. Some variety of FinColorPly are phenolic coated and exterior rated:very hard/tough and slippery surface, great for jigs.
Here's some at Woodcraft:http://www.woodcraft.com/product.aspx?ProductID=131170&FamilyID=3958

http://www.germes-online.com/direct/dbimage/50278237/Film_Face_Plywood.jpg


Dieboard: 100% solid, hard maple plywood. Used for steel rule die cutting.
http://www.ameriken.com/images/ads/banner08/banner08.php

MDO and HDO plywood:
with a resin-treated fiber overlay which is generally smooth and opaque. This allows for rapid, even paint and coating applications. waterproof adhesives . Typically used for concrete formwork and exterior signage.

Many of these have edges that can be left untreated in utility and "modern" casework and applications.

There's lots more, I'm going to post this and see how many beat me to the post.
-kg

[Drew Eckhardt]

Thanks guys

What exactly is it that is a problem with the stuff from Lowes/HD? If I recall it is birch - so, I think somewhere here there was a conversation that it doesn't take stains and such very well... is that the only reason, or are there other manufacturing/quality issues that would cause me to stay away?


Face veneers as thin as .010" which are nearly unsandable and get damaged if you look at them sideways versus .050" on real 13 ply 18mm Baltic birch, way more likely to warp, worse glue if you're cutting joints like lock miters, and with voids instead of without.

[Joe Chritz]

Look for consistant core thickness and thick face veneer. Preferably something that is graded by the HVPA (hardwood veneer plywood association). I happen to find all US produced Maple, Birch, Oak and occasionally cherry veneer core that meets all this at my local Menards. It is B2 grade but still pretty nice stuff.

Then you have different face veneer stuff, like rotary cut (peeled from a log), flat sawn (just like is sounds), 1/4 sawn, bookmatched, etc.

Armor core is plywood with hardboard outer skins then veneer. Very nice stuff but a bit expensive. I have never seen it locally around here.

I try to match the plywood to the hardwood. My entertainment center I am starting is 1/4 sawn white oak so the plywood will be also (to the tune of a buck forty a sheet :eek: ).

Joe

[Charlie Plesums]

...
Armor core is plywood with hardboard outer skins then veneer. Very nice stuff but a bit expensive. I have never seen it locally around here....
Joe
This is the stuff I have had trouble with (see my post earlier in this thread). It has become the "normal" plywood around here, at normal costs, loved by the cabinet shops that cut everything on a CNC with ample staff because of the smooth surface. As a solo woodworker, I have occasional bumps and twists which cause surprising damage, and have even had some glued-on trim pull off the surface veneer, since the hardboard layer (which may be strong in some directions) has almost no strength to pulling.

To add to the other comments about BORG plywood, the thickness is often inconsistent (A dado tight at one end may be loose in the middle). Birch plywood is popular as paint grade wood (construction plywood is not smooth enough to be painted) because it is the cheapest. The grain is somewhat similar to cherry, which is why it is sometimes stained to look like cherry.

[Bill White]

Thanks guys

What exactly is it that is a problem with the stuff from Lowes/HD? If I recall it is birch - so, I think somewhere here there was a conversation that it doesn't take stains and such very well... is that the only reason, or are there other manufacturing/quality issues that would cause me to stay away?

The article from http://www.hardwoodlumberandmore.com/ on finishing poplar to look like cherry was very informative and I was wondering if the same technique can be applie to birch to get satisfactory results (I noticed a LOT of places sell birch, which puzzles me if it is so awful for finishing)

I can only give you my opinion on borg ply.
It is for use by the general public which doesn't know from squat what ply is about. Last I bought there (see above statement) had a very wavey surface, a birch ply that was soooo thin ya could spit through it, and a 1/2 sheet cost $40.00. I HAD TO HAVE IT SO THERE.
The local lumber yards carry better stuff, but a cabinet shop supplier will always have the best stock.
Bill

[Joe Jensen]

One other consideration for hardwood veneered plywood. There are two main ways the veneer is laid up on the face. The less expensive is rotary cut veneer. When veneer is cut this way, the grain doesn't really match any solid lumber. The grain is much more open and there are no seams on the veneer. Some like this look, but I think it screams "I'm plywood". The other type is "Plain Sliced". In this style the veneer is sliced just like boards are cut. "Plain Sliced" can be laid up book matched or random. To my eye, nice plain sliced can look every bit as nice as glued up solid panels.

I never use rotary cut. Around here, plain sliced red oak 3/4" is $2 a sheet more than rotary.

Here is a link to a page that explains the differences and different layups of plain sliced veneers.

http://www.marshfielddoors.com/FaceOptions_WDMA_p2.html