LumberJocks

"Lumber core" plywood - be sure you know what you're getting

  • Advertise with us
Review by JJohnston posted 03-14-2010 10:56 PM 9532 views 0 times favorited 11 comments Add to Favorites Watch
"Lumber core" plywood - be sure  you know what you're getting "Lumber core" plywood - be sure  you know what you're getting No-picture-s Click the pictures to enlarge them

I thought I’d try a new (to me) product I found at my local “good” lumberyard – “lumber core plywood” – to build a few utility-grade shop projects. It’s made of solid lumber pieces laminated with thin face veneers. The core pieces are tongue-and-groove joined along their edges, which you can see in the first picture (if you can’t make out the part in focus, look below and to the right at the piece in the clamps. You can see the contrast between a light and a dark piece).

This seems great at first glance, but there’s a problem: only the pieces on the edges are the full length of the sheet. The interior pieces are of random lengths, and the ends are simply butted – there are even little gaps. See the second picture with a utility knife for scale. This edge is parallel to the long dimension of the sheet. The edge below it is the factory edge, which looks continuous and beautiful.

This construction method SERIOUSLY compromises the bending strength. The piece in the second picture was going to be a shelf, but with those two gaps, which are typical, I have serious reservations about using it – in fact, I’m not going to. Since the core pieces are of random lengths, and are edge-jointed, the problem isn’t so bad on a wide piece (more continuity), but it gets worse as you rip it narrower. About the only suitable application I can see for this material is as big pieces subject to edge-to-edge compression, like sides for a base cabinet or a cabinet-style bench.

There is one upside: it’s light, probably because it isn’t all soaked through with glue, like conventional plywood.

-- "Sometimes even now, when I'm feeling lonely and beat, I drift back in time, and I find my feet...Down on Main Street." - Bob Seger




View JJohnston's profile

JJohnston

1587 posts in 2012 days



11 comments so far

View live4ever's profile

live4ever

983 posts in 1730 days


#1 posted 03-14-2010 11:14 PM

Timely post. Lumbercore ply is making a comeback – all the orange BORGS in my area have started stocking it in 1/4 sheets. It is very light, and I suspect you may be right – it won’t be as high quality as the lumbercore ply of old, with possibly much less bending resistance.

And at $15 per 24×48” sheet, the borg version is not exactly cheap.

-- Optimists are usually disappointed. Pessimists are either right or pleasantly surprised. I tend to be a disappointed pessimist.

View JJohnston's profile

JJohnston

1587 posts in 2012 days


#2 posted 03-14-2010 11:57 PM

This was $40/sheet for 3/4”.

-- "Sometimes even now, when I'm feeling lonely and beat, I drift back in time, and I find my feet...Down on Main Street." - Bob Seger

View Dusty56's profile

Dusty56

11678 posts in 2408 days


#3 posted 03-15-2010 01:38 AM

It appears to be Pine used for the core from here , which might explain the light weight …Possibly Radiata Pine
I’ve seen some that also resembled Mahogany in color and texture as well. Back in the 80’s , the Lumber Core plywood that I handled was a hardwood ,fingerjointed core and at the very least they used Poplar. Either way , the plywood should have to meet strict codes and should have a stamp on it on the lesser face or the edge if it is finish grade plywood.

-- I'm absolutely positive that I couldn't be more uncertain!

View sdmref's profile

sdmref

15 posts in 1927 days


#4 posted 03-15-2010 01:45 AM

Did anyone notice that the manufacturer used wood with the pith included in the core? How dimensionally stable is that? They need to be called out on their processes. Its one thing not buy it, but another to let them know why we won’t buy it.

View Chris Wright's profile

Chris Wright

536 posts in 2202 days


#5 posted 03-15-2010 02:24 AM

The maple lumber core I’ve got in my shop is pretty good, and it’s pretty heavy. And a lot more expensive.

-- "At its best, life is completely unpredictable." - Christopher Walken

View araldite's profile

araldite

187 posts in 2124 days


#6 posted 03-15-2010 02:27 AM

Thanks for the education. I’ve never seen it before but now I’ll know what it is and avoid it when it pops up in my store.

-- Failure is the road to success if you learn to learn from your mistakes - Vince, Greenville, SC

View 489tad's profile

489tad

2445 posts in 1732 days


#7 posted 03-15-2010 03:07 PM

Thanks for the info. You’ll have to a strong edge with a groove to make that piece usefull.

-- Dan, Naperville IL, I.G.N.

View FunnelStudio's profile

FunnelStudio

30 posts in 2038 days


#8 posted 03-15-2010 09:49 PM

I thought the great thing about standard, multiply plywood was that it was fairly more sustainable, what are the benefits of this material?

-- -Shaun M. Baer, http://www.craftedphiladelphia.com

View 308Gap's profile

308Gap

332 posts in 1723 days


#9 posted 03-15-2010 10:34 PM

Whats the outside veneer like?
3/4 or 23/32 ?

-- Thank You Veterans!

View Dusty56's profile

Dusty56

11678 posts in 2408 days


#10 posted 03-16-2010 02:21 AM

FunnelStudio….You can put screws / hinges into/onto it on the edges for doors etc….And it is supposed to be more ridgid for shelving and panels etc..

-- I'm absolutely positive that I couldn't be more uncertain!

View JJohnston's profile

JJohnston

1587 posts in 2012 days


#11 posted 03-16-2010 04:07 AM

It’s more rigid only if all the core pieces run the full length of the sheet, and that’s the problem with this stuff. Each face has two thin veneer layers, one transverse and one longitudinal. It’s pine, grade B on both sides. It’s 23/32.

-- "Sometimes even now, when I'm feeling lonely and beat, I drift back in time, and I find my feet...Down on Main Street." - Bob Seger

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase