Veneering 101

[jteneyck]

If you've been frustrated by the poor quality of today's hardwood plywood, you're not alone.  I got so disappointed with it that 15 years ago I decided to make my own for important projects.  As it turns out, it's not that hard, although I will say a good bandsaw and especially a drum sander make it a lot easier.  So here's a quick tour of how to add veneer to a substrate.  In this case, I'm using Baltic birch because the edges will be left unfinished, but I typically use Sande Ply or poplar plywood for lesser projects and BB only for high end work.  I really like MDF for non-structural work, too. 

Of course, the most important thing is the veneer.  I've shown how I slice veneer before, but here are a couple of photos from the recent dining room table job to show the process.  I'm using a 5 HP bandsaw now, but I used to slice veneer on my 1.5 HP 14" Delta, a lot slower of course, and only after careful setup, but it can be done, and I cut a lot of veneer with it.  Regardless of the saw, it needs to cut straight and parallel with the fence, and you need some sort of tall featherboard to hold the stock against the fence.  The one I use is a copy from John Lanciani's design.  It works great and has the added and too me critical feature of keeping my hands away from the blade.  



For most interior work I slice the veneer to about 0.010" and then drum sand it to 0.065", which usually takes about 3 passes/side.  That gives me slices that are dead smooth on both sides.  Some folks don't sand at all until after the veneer is glued down, but I prefer to have it flat and smooth so I can decide the best layout of how to use the veneer.  





OK, you have a bunch of veneer, now what?  In most cases you now have to seam them into a panel wide enough for the panel you want to veneer.  To do that you need to get the edges of the adjacent slices to fit together really, really well.  Surprisingly, if you joint the board really well before slicing the veneer, the slices often will fit together really well.  If not, I start by ganging them all together with a backer on the outboard side and run them over my jointer.  That usually does it, but sometimes I have to joint one or two of them separately, too.  With really cantankerous veneer, I have resorted to sanding the edges between cauls.  Whatever it takes, those joints have to be really good or you'll see it after it's glued down.  Shop sawn veneer handles more like lumber than commercially sliced veneer, one of the reasons I prefer to make my own.  It's also thicker and more durable than commercial veneer, and there are no crepe checks in it.  

For the simple project I'm working on now, I started with a 10/4 piece of hard maple left over from the dining table project and sliced 12 pieces from it, then ran it through the drum sander.  I seamed 5 of them to make a panel using small pieces of veneer tape top, middle, and bottom of each joint.  I used to add a piece of veneer tape the full length of the seam but found it's unnecessary if the veneer is nice and flat.  I just add a few pieces of blue tape and make sure to handle the panel very carefully.  Removing the veneer tape after the panel is pressed is a bit of a pain, and sometimes leaves a shadow which is hard to get rid of, so that's why I try to minimize how much I use.  But I still use it because it pulls the joints together when you iron it on.  And that's reason enough to use it the full length of a seam if you're having trouble getting a tight joint.  



The hard work is done now.  All that's left is to glue it to the substrate.  The panel I'm making is 32 x 32" so I made the veneer panels 32-1/4 x 32-1/4. It's hard to see in the photo but I used a slip match pattern for the panels.  I think it gives a more modern look than book matching, and this panel is for a mid century modern piece.    

My veneering setup is pretty simple.  I use a shop made vacuum bag; 30 mil vinyl and a Gast vacuum pump with no controls.  It just runs continuously for the 2 hours it takes for the glue to set up enough that I can remove the panel.  



Below the work is a 3/4" platen.  On top of that I place a piece of window screen, and sometimes a piece of 4 or 6 mil plastic sheeting on top of that, under the bottom layer of veneer.  Today I forgot the plastic.  It's unnecessary if you are careful applying the glue.  OK, the bottom sheet of veneer is placed good face down on the window screen/plastic.  The substrate is placed beside it.  Next I apply Titebond II with a plastic Bondo spreader into which I cut 1/8" deep slits about 1/8 apart using a pull saw.  This gives a nice spread with TB II and also epoxy.  I used to use Plastic Resin Glue and Unibond 800 but found that TB II works just as well for interior applications.  It's cheap and readily available, so that's what I now use. 



I pour some glue directly onto the plywood and spread it uniformly with the spreader.  You want a wet coat, but not a thick one.  And if you've never used veneer, never, under almost all circumstances, apply glue to the veneer.  It will curl up almost immediately.  I pull excess glue off the substrate onto a scrap board or plastic container.  



With the glue spread, I pick up the substrate and place it glue side down onto the veneer.  Then I spread glue on the top surface of the substate and slide the top sheet of veneer in place.  I make sure to check that the veneer on both the top and bottom overhang the substrate uniformly and then add blue tape in the four corners to hold everything in place.  Then I place another layer of window screen on top of the assembly and then slide all of it, including the lower platen, into the vacuum bag.  I have found no benefit of using a top platen as long as the veneer doesn't overhang the substrate more than 1/8" or so. I roll the open end of the bag around a piece of wood and turn on the pump.  It's large enough to pull a vacuum in just a few seconds, after which I clamp another piece wood to the first one to minimize leakage.  



I get about 20" Hg with this setup, which is less than what many claim, but I've never had a bonding issue even with curved work so clearly it's enough.  



After 2 hours or so the glue is setup enough to remove the piece from the vacuum bag.  When it comes out of the bag I remove the blue tape from both sides and then stand up the piece so that air can circulate uniformly on both sides to dry.  After 24 hours, it's ready to use.  You can see the slip matched pattern in this photo. 



That's it.  It's a simple process that is easily done by anyone who wants to use something better than commercial hardwood plywood for furniture and cabinet projects.  You might want to give it try. 

John

[GaryMc]

If you've been frustrated by the poor quality of today's hardwood plywood, you're not alone.  I got so disappointed with it that 15 years ago I decided to make my own for important projects.  As it turns out, it's not that hard, although I will say a good bandsaw and especially a drum sander make it a lot easier.  So here's a quick tour of how to add veneer to a substrate.  In this case, I'm using Baltic birch because the edges will be left unfinished, but I typically use Sande Ply or poplar plywood for lesser projects and BB only for high end work.  I really like MDF for non-structural work, too. 

Of course, the most important thing is the veneer.  I've shown how I slice veneer before, but here are a couple of photos from the recent dining room table job to show the process.  I'm using a 5 HP bandsaw now, but I used to slice veneer on my 1.5 HP 14" Delta, a lot slower of course, and only after careful setup, but it can be done, and I cut a lot of veneer with it.  Regardless of the saw, it needs to cut straight and parallel with the fence, and you need some sort of tall featherboard to hold the stock against the fence.  The one I use is a copy from John Lanciani's design.  It works great and has the added and too me critical feature of keeping my hands away from the blade.  



For most interior work I slice the veneer to about 0.010" and then drum sand it to 0.065", which usually takes about 3 passes/side.  That gives me slices that are dead smooth on both sides.  Some folks don't sand at all until after the veneer is glued down, but I prefer to have it flat and smooth so I can decide the best layout of how to use the veneer.  





OK, you have a bunch of veneer, now what?  In most cases you now have to seam them into a panel wide enough for the panel you want to veneer.  To do that you need to get the edges of the adjacent slices to fit together really, really well.  Surprisingly, if you joint the board really well before slicing the veneer, the slices often will fit together really well.  If not, I start by ganging them all together with a backer on the outboard side and run them over my jointer.  That usually does it, but sometimes I have to joint one or two of them separately, too.  With really cantankerous veneer, I have resorted to sanding the edges between cauls.  Whatever it takes, those joints have to be really good or you'll see it after it's glued down.  Shop sawn veneer handles more like lumber than commercially sliced veneer, one of the reasons I prefer to make my own.  It's also thicker and more durable than commercial veneer, and there are no crepe checks in it.  

For the simple project I'm working on now, I started with a 10/4 piece of hard maple left over from the dining table project and sliced 12 pieces from it, then ran it through the drum sander.  I seamed 5 of them to make a panel using small pieces of veneer tape top, middle, and bottom of each joint.  I used to add a piece of veneer tape the full length of the seam but found it's unnecessary if the veneer is nice and flat.  I just add a few pieces of blue tape and make sure to handle the panel very carefully.  Removing the veneer tape after the panel is pressed is a bit of a pain, and sometimes leaves a shadow which is hard to get rid of, so that's why I try to minimize how much I use.  But I still use it because it pulls the joints together when you iron it on.  And that's reason enough to use it the full length of a seam if you're having trouble getting a tight joint.  



The hard work is done now.  All that's left is to glue it to the substrate.  The panel I'm making is 32 x 32" so I made the veneer panels 32-1/4 x 32-1/4. It's hard to see in the photo but I used a slip match pattern for the panels.  I think it gives a more modern look than book matching, and this panel is for a mid century modern piece.    

My veneering setup is pretty simple.  I use a shop made vacuum bag; 30 mil vinyl and a Gast vacuum pump with no controls.  It just runs continuously for the 2 hours it takes for the glue to set up enough that I can remove the panel.  



Below the work is a 3/4" platen.  On top of that I place a piece of window screen, and sometimes a piece of 4 or 6 mil plastic sheeting on top of that, under the bottom layer of veneer.  Today I forgot the plastic.  It's unnecessary if you are careful applying the glue.  OK, the bottom sheet of veneer is placed good face down on the window screen/plastic.  The substrate is placed beside it.  Next I apply Titebond II with a plastic Bondo spreader into which I cut 1/8" deep slits about 1/8 apart using a pull saw.  This gives a nice spread with TB II and also epoxy.  I used to use Plastic Resin Glue and Unibond 800 but found that TB II works just as well for interior applications.  It's cheap and readily available, so that's what I now use. 



I pour some glue directly onto the plywood and spread it uniformly with the spreader.  You want a wet coat, but not a thick one.  And if you've never used veneer, never, under almost all circumstances, apply glue to the veneer.  It will curl up almost immediately.  I pull excess glue off the substrate onto a scrap board or plastic container.  



With the glue spread, I pick up the substrate and place it glue side down onto the veneer.  Then I spread glue on the top surface of the substate and slide the top sheet of veneer in place.  I make sure to check that the veneer on both the top and bottom overhang the substrate uniformly and then add blue tape in the four corners to hold everything in place.  Then I place another layer of window screen on top of the assembly and then slide all of it, including the lower platen, into the vacuum bag.  I have found no benefit of using a top platen as long as the veneer doesn't overhang the substrate more than 1/8" or so. I roll the open end of the bag around a piece of wood and turn on the pump.  It's large enough to pull a vacuum in just a few seconds, after which I clamp another piece wood to the first one to minimize leakage.  



I get about 20" Hg with this setup, which is less than what many claim, but I've never had a bonding issue even with curved work so clearly it's enough.  



After 2 hours or so the glue is setup enough to remove the piece from the vacuum bag.  When it comes out of the bag I remove the blue tape from both sides and then stand up the piece so that air can circulate uniformly on both sides to dry.  After 24 hours, it's ready to use.  You can see the slip matched pattern in this photo. 



That's it.  It's a simple process that is easily done by anyone who wants to use something better than commercial hardwood plywood for furniture and cabinet projects.  You might want to give it try. 

John

Great description and suggestions as usual!  BTW, I don't know how you fashioned the vac bag but I have used the lower bags for my Penn State 2hp DC with great success.  Takes 24+in. wide (maybe 30) X 36" long very well.  And I use a venturi vac adapter to the sink faucet, pulls more than 20" with ease.

Gary

[jteneyck]

Great description and suggestions as usual!  BTW, I don't know how you fashioned the vac bag but I have used the lower bags for my Penn State 2hp DC with great success.  Takes 24+in. wide (maybe 30) X 36" long very well.  And I use a venturi vac adapter to the sink faucet, pulls more than 20" with ease.

Gary

That's a clever solution to use a venturi vac.  I used those back in my lab days. 

It's easy to make your own vacuum bag from sheet vinyl.  I bought it at a local place that makes wheelhouse covers with "windows" for boats.  I used 30 mil for the bag in the photo, and 20 mil for another I made.  McMaster Carr sells sheet vinyl, too. I rolled it into a tube and sealed the edge with standard plastic pipe cement, without first using the cleaner, clamping it securely until the glue curesd  Then I sealed one end the same way.  Joe Woodworker makes penetrations for vinyl, but I wasn't aware of him when I made the bag in the photos, so I fabricated a penetration from two pieces of PVC glued inside and out and tapped for a pipe fitting.  Your approach sounds even easier for parts up to the size it can handle.  People spend a lot of money for urethane bags, but you can make your own from vinyl for far less and they are plenty durable.  The bag in the photo is the first one I made, now well over 25 years old with hundreds of pressings.  One pin hole in all that time, easily patched.  

John

[PossumDog]

Thank you for the nice write up. I am interested but think it's a bit in the future for me.

Do you always veneer both sides, even if the second side will not be visible?

[jteneyck]

Thank you for the nice write up. I am interested but think it's a bit in the future for me.

Do you always veneer both sides, even if the second side will not be visible?

Generally, yes.  Veneering both sides maintains stability in the panel, both while the glue dries/cures and during seasonal humidity changes.  But there are some cases where it's OK to veneer just one side.  If you are going to attach the panel to another substrate, and do it soon after making it, you don't need to veneer the hidden side.  I've seen commercial furniture made with MDF, or something similar, also veneered only on the show surface, and they were still flat after 50 years even though the MDF side was exposed to air.  If I were contemplating that, however, I would use epoxy or some other glue with no water in it to glue down the veneer.  

You can't go wrong by veneering both sides.  If it's not going to show, the stuff on the bottom can be some other species, what people often refer to as backer veneer.  I usually use the lower quality slices from the boards I've sawn into veneer for the non-show side.  

John

[jteneyck]

I sanded the panel this morning.  The 80 and 100 grit sandpaper I use in my double drum sander leaves surprisingly deep scratches in the wood, so I begin sanding with 60 grit on my ROS.  Seems shocking, doesn't it, but it's the best way I've found to get rid of those scratches in a reasonable amount of time with hard woods like maple.  With softer woods like mahogany the scratches aren't as deep to begin with and 80 or 100 grit works fine to begin the ROSing.  Once the scratches are gone, I can move up through the grits pretty quickly.  

I've found the best way to sand large panels is to first start 90 deg cross grain, then 45 deg, first in one direction, then the other, and finally with the grain, just like you would do flattening a panel with a hand plane.  I do that with the 60 - 100 grits.  It gets rid of any variations in thickness, whether it's a glued-up panel of boards, or a veneered panel like this, and gives you a very flat surface.  After that I just sand with the grain.  I sanded this panel up to 150 grit.  The customer can do the final sanding.  






John

[BAdams]

Thanks for the explanation of how you make plywood.  I recently picked up a drum sander, and already have a vacuum pump for chucking on my lathe.  My bandsaw's only 1-1/2HP, so wide resawing is pretty slow, but possible.  I just need a vacuum bag to start messing around with veneering panels.  Sounds like fun.

[jteneyck]

Thanks for the explanation of how you make plywood.  I recently picked up a drum sander, and already have a vacuum pump for chucking on my lathe.  My bandsaw's only 1-1/2HP, so wide resawing is pretty slow, but possible.  I just need a vacuum bag to start messing around with veneering panels.  Sounds like fun.

I used my 14" Delta with riser and a 1-1/2 HP motor for a long time before I bought the big saw.  As you said, it's slow, but it works with a 1/2" x 3 tpi blade that's set up well.





Your saw will do the job.

John