This question was asked by Mike:
I plan on building a small box for my daughter’s birthday, and I want to use a veneered panel for the lid. I plan also to use PVA, and a press as the lid will be small (5×8) and I don’t think it needs any more. When watching you make Nicole’s frame, I noticed that you veneered both sides of the frame even though only one would show. Is this to ensure that the moisture balance in the piece stays equal, or was it just pride in craftsmanship? Also, if you’re veneering plywood or MDF, is this necessary considering that these materials are dimensionally stable?
As always, keep up the good work – you’re definitely my reason for trying my hand at fine wood working. Thanks!
And this was my response:
Hey Mike. In most woodworking circles, it is believed that you should always veneer both sides of a panel. By adding a layer of glue and a thin sheet of wood, one side of the panel will absorb and lose moisture at a different rate than the other. This lack of “balance” could lead to warping. If you ever have a sheet of commercial veneer laying around, you can see exactly how this works by applying a little water to one side of the veneer. It will curl up like Pringles chip (pic 1)! The side that receives the moisture expands, and the other side does not, resulting in a severe curl. Wet the other side (pic 2) and the sheet relaxes once again (pic3).
When we’re talking about veneer on a substrate under normal conditions, this effect is not nearly as great. Furthermore, I have seen the rule of thumb broken a number of times with no detrimental effect. But with my projects, most times, I don’t take the chance. I like to play it safe and usually veneer both sides. And again, this is really a “better safe than sorry” type of thing. Perhaps one day I’ll do a bunch of test panels and see what really happens. Good luck Mike!
So what about you folks? Any bad experiences from veneering only one side of a panel? If so, tell us about it by commenting.
26 Responses to “Veneer Both Sides of a Panel?”
You really do need to veneer both sides of any panel. Like Marc said, it’s due to balancing the rate of moisture absorption but also wood movement comes into play here. Even though commercial veneer is 1/42″ thin, it still moves with changing humidity. If you veneer both sides of the panel you get a more equalized movement on each side.
Also, plywood and MDF, while more stable than lumber, still move. Yes, even MDF. It can soak moisture like a sponge in the right conditions. So definitely veneer both sides. Plus it does look better, too!
Good luck.
I still haven’t done any veneering, but will soon on some drawer fronts – and in which case, this might be a good question -since the drawer front’s back side is glued to the drawer itself, in which case would it really make much of a difference to veneer it’s back side (I think not, since something “else” will be glued there anyways).
But with my lack of experience with veneering – this does sound a lot like the question that arises – should one finish both sides of a panel equally? and the typical answer these days would be YES, finish all sides of a piece equally for balanced moisture absorption. but a good point that was raised on several forums is that if you’ll look at all antique pieces – only the top of the panels is finished, whereas the underside is not. so who’s to know what is fact, and what is legend these days without some hard proof tests? play it safe is good, but only to a certain extend, at some point it becomes wasteful. I like to be on the safe side, but don’t want to get lost in it. I think in terms of finishing – it’s a safe bet to seal both sides, but only apply the finish to the visible side for protection. in terms of veneer? I think the concept would be similar… but with lack of experience – I’m really eager to read what other’s experience has been like, and thoughts are.
For the drawer, I definitely would not worry about the back face. And you have definitely pinpointed the ambiguity of the issue. I don’t really know for sure exactly what the effect would be. We all know its better to finish all sides equally. But that’s not to say your project is going to fold up or fall apart if you don’t. As you say, most antiques have unfinished parts. In general, it becomes more acceptable to finish only one side or veneer only one side when there is something securing the panel in place. The panels on a dresser, for instance, are going to be locked in place. If the panel starts to warp, it has to take the frame with it. The frame is locked to the legs or the front, which is locked to something else….and so on. So the movement would have to be pretty severe before we see a real problem. But if you are not a gambler, you just finish the inside and veneer both sides anyway. As Adam mentioned, it just looks better.
And FYI, I usually do put some finish on the inside of my projects, although typically I put on few coats.
Hi Mark,
First off, love the site, you are doing a great job.
Last week you were doing the week of workbenches, but I was wondering about your workbench. How long ago did you build it and how and of what did you make it of? I am getting ready to build myself a “proper” bench and was looking for some input on how you came about yours.
Keep up the great work and thanks again,
Charlie
Thanks Charlie! My bench was made about 4 years ago and is good old hard maple. Now a word of caution…..don’t be charmed by its good looks. Its a piece of crap on legs! lol. The bench is flawed in a number of ways. The worst issue is actually the base. I will never do a two-legged design again. If you do, you need a good wide stance and a lot of timber to get enough weight to stop the bench from moving around. And after reading Schwarz’s book on workbenches, I realized how important it is to have the base and bench front flush with one another. These are things that I will improve on in my next bench. If you haven’t read it yet, you should pick up a copy. At the very least it will help you plan an appropriate bench for your personal work style.
I think this issue is somewhat similar to the debate over whether you should finish both sides of a table top, using the same premise. Many people finish the bottoms of table tops to ensure moisture is exchanged at the same rate to avoid warping. However, I’ve read in several places that this is not necessary, and the difference in moisture exchange is so minimal it has no effect. So I wonder if this is a similar case, where your intuition would tell you that you should veneer both sides, but in reality or in practice the differential is so minimal it won’t make any difference. This could be a good “mythbusters” series Marc could start.
Would Marc be Adam or Jamie?
I am really hoping we’ll hear some disaster stories from one-side finishers or one-side “veneerers”. :) The fact that I never really hear any first-hand experiences makes me question how much movement potential there is. To muddy the water further, even wood and panels that have been constructed and finishes according to the rules have twisted and cupped. So how would we know it wasn’t just the bad luck that we normally have to deal with??
I made a standard box out of MDF for my son to store his video games and veneered the outside to practice. While movement hasn’t really been too much of an issue the thing that really bothers me is that it looks pretty good when closed and a cheap piece of crap that could have been purchased at the 99 cent store when it’s opened. Veneer both sides, that’s why we make it ourselves.
I make reproduction picture frame mouldings for a living including maple veneered. All my frames are veneered on the face side only. As long as the molding is quite thick and properly dried there should be no problems. My finished moldings are tollerenced to 1mm bend in any axis over 1.2M. Also for years I’ve restored antique frames including many over 200 years old and almost all of these are veneered on the face side only. The 17th,18th and early 19th century frames have thick hand cut veneers 1/32″+ If these cant bend a molding then modern veneer wont.
That said for a box lid I would usualy veneer both sides as lids tend to be thiner and a lot wider than frame mouldings.
Good answer… this has been my unsubstantiated belief and you’ve confirmed it. Just handling modern commercial veneers (1/42″ thick) cracks them.. so tell me they can bend even 1/2″ Baltic birch ply.. Ditto for moisture; the finish will have more to say about moisture transfer than 1/42″ veneer. I’ve also seen too many examples where only one side is finished to believe it’s the cataclysmic mistake I see in postings.
While I haven’t read it anywhere, I have decided that when I start veneering, I’d rather use a non-water based glue since saturating one side with moisture is likely the culprit. That said, I’m curious which glue you think they used on those antique frames.
Most of the antique frames used hide glue. Great stuff, if you make a mistake gluing you can heat it up and try again. Als hide glue is great to mix with sawdust to use as a filler.
There is an old english saying:-
if your joints they do not fit fill them up with glue and s… :-)
In similar vein. I’ve heard the finish both sides of whatever. But then many folk say they don’t finish the inside of a case (due to odor issues) or finish it with some thin cut shellac, while giving the outside top many coats of preferred finish. Any thoughts on this issue?
I just replied to a similar question above Tom. Check it out.
Mike,
If you want to see how dimensionally unstable sheet goods can be, do something to only one side. While I’ve always veneered both sides, I have done things like put a series of saw kerfs on one side and not the other (for a drying rack for some artwork), or set some plywood down so only one side was exposed, in an environment with changing humidity. Thngs like that can make plywood and MDF warp significantly. Maybe you can get away with veneering only one side if the edges are solidly captured in a frame, but I wouldn’t try it it otherwise.
I always use a balance sheet. My sample boards to demonstrate veneers made of particle board and MDF always seem to bow at least a bit, not severely though. Based on that experience I use the balance sheet. It does not have to be the same species, just the same thickness and type, that is paper backed or non-paper backed.
I try to eliminate every opportunity for my projects to fail. A redo could be financially devastating with some of the projects that I have done.
I have a couple of mottos.
1. Do it right or don’t do it at all. (Mom taught me that, but I could never seem to get out of washing the dishes by doing a crappy job.)
2. Call backs don’t make money. This is a business principle that I follow and I rarely ever have call backs and it is amazing what it does for reputation.
I am in process of building a built-in computer desk and was thinking of veneering walnut (3/32″) onto 1″ MDF for the desktop. Because the top will be anchored down to the bottom cases, do you think it necessary to veneer the bottom?
Thanks all for the great responses.
Paul,
My current router table top is the older Rockler top, which is 1″ MDF with laminate on the top side only. Since the humidty in my shop in the winter get get quite high, the underside absorbed more moisture than the top, and bowed quite a bit.
If your desk is going somewhere where the humidty is relatively constant, you may get away with just doing one side. I’d thought I would pass along that data point, though.
Like I said, I am pretty much always going to veneer both sides because of my fear of disaster. But at the same time I did want to present a bit of a counter-argument with this post. In my opinion, if a 1″ sheet of MDF decides it wants to do something funky (especially if humidity swings like Barry described are present), I’m not sure the frame of the desk would be enough to stop it. My vote: do both sides.
hi, Mark. like you for box lids ect.. I always veneered both sides, but this thread has got me thinking when I was an antique furniture restorer, good quality boxes were always veneered on both sides so were folding card tables these very often would be bent, in the trade ther is an expresion that the table is smilling at you (one of the more difficult faults to remedy). on the other hand case goods (and picture frames) would normaly be veneered on one side only (panels and styles) these usualy have little warping, maybe sometimes the substrate will have dryed out and the panel and veneer split, if the panel had got wet the veneer would seperate from the panel(not bend it).
The point im trying to make is that as a restorer the problems I saw (long term 1-2 hundread years) were with the pieces veneered both sides.
Also do you think it matters how the grain of the veneer is orientated in relation to the grain of the subsrate:-))?
Hey Marc:
This isn’t a veneer story but it’s the same principle. I was building my first router table and wanted to make the top thicker to support the Porter Cable 5 speed router. So I took a piece of ¾ MDF and glued it to a ¾ piece of Burch veneer plywood using standard yellow glue. Both pieces were cut a bit over size but they are both very flat. When I took the top out of the clamps the next day all looked good. The following week I started to trim the top down to the right size and sure enough it was so warped I couldn’t use it. I really believe that had I glued two sheets of ½ veneered ply, one to each side of the MDF I wouldn’t have had a problem. Since then I’ve never veneered/glued one side of the substrate.
I did just finish up building the 21st century workbench. I know that you probably have more workbenches than you need but if you want me to submit the one I built I would be happy to do so! You’re a true inspiration Marc!!! Thank you for all your hard work!
Tom
Send it on in Tom. It might take a while for us to post it but eventually we’ll get it up on the site.
sure have had the problem, the thicker the veneer the more prone to you are to have the problem. Cutting my own veneer, lyptus by species, that was bout 3/32 thick I had it pull MDF substrate apart. It was to be a shelf, 32 x 14 inches and with my limited clamps and working alone I thought I’ll do one side then the other. Things happen and so I didn’t get back to do the other side for about 4 days; the MDF was destroyed, pulled apart. Should have taken pictures but I didn’t.
I had terrible warping after I glued 1/16″ (approx 6″ x 12″) shop sawn ash veneer to 1/4″ plywood. I used TiteBond 3. It came out of the press flat, but after two days, it was warped at least 1/2″ on the long axis. It also warped a piece of 1/2″ plywood using the same process. I tried to wet the non-glue side of the veneer, but that didn’t help. My next veneering attempt will for sure be double sided.
I suspect it also depends on the glue you use. Ive practiced on 3/4″ MDF on one side only using hide glue and it really curled after a while I’ve also veneered 1/8″ ply one side only using contact adhesive with no distortion at all 5 years later!
Ok, so looks like I’ll veneer both sides. However, should both sides have the same thickness veneer? Also, should they be similar species?