Official Luthiers Forum!

Hello everyone- I'm having issues with glue bleeding through my veneer. Using sapele veneer, 1/42" thick and tightbond II. The glue is not just coming through pinholes, it is seeping through the veneer as if it were a sponge. Shall I try and thicken the glue? I tried sealing the "glue side" of the veneer first with both tru-oil and with urethane, they both seeped through. My supply of veneer is rapidly diminishing at the current rate. Anyone have any advice?

First of all I would use less glue ! You want just a little bleed through. Get a fine foam roller to apply the glue. With veneer that thin I would only apply glue to your substraight. I also wouldn't use titebond for gluing veneer. I would use Uni-bond the best of the urea-formaldehyde type glues. With either glue use a solid cardboard called news board. It is like the card board that backs pads of paper. (Not corrugated. ) You use it between the veneer and your caul. It gives just the right amount to apply even pressure over any irregularities and if there is a little piece of debris it will let the debris push into the card board and not your veneer. It also will absorbe glue that bleeds through. When you peel off the cardboard after a glue up there will be a lot of areas where the paper absorbed the glue and stuck to your veneer but the glue won't spread. It is easy to scrape or sand these little glue paper dots off. With the uni-bond it is much easier to sand these off. This is only one of the many ways Uni-bond is superior to yellow glue for veneering. This will not cause any finishing problems or be visable. Uni-bond can be had in dark, med, or light color. I have done many veneer glue ups with in some cases lots of bleed through (burl can be quite porus) and never had any issues when using Uni-bond.
With that being said yellow glue will work if you must but I wouldn't trust it if you have seams in your veneer. It can creep with time and seams will open or lift. With a one piece job it will work but it is not the best stuff for the job.
Also do not put oil, ureathane, or anything else on your glue surface !!!!!! You are asking for failure for sure.
So in summary if you use less glue and the cardboard you should be fine.
Link

_________________
Cut to size.....Beat to fit.....Paint to match.

Hi, Doug. When gluing the first burl veneer to my recently completed archtop, I ran into the same problem. I was using yellow glue, too. I can tell you what worked for me. I applied the glue to my substrate, as described above, using my little finger to spread it as evenly as I could. Just enough glue to get the whole surface wet. I have a 4-inch rubber roller that I then used to roll out the glue, back and forth, alternating directions across the headstock and then the length of the headstock. I just kept rolling until some of the water in the glue had evaporated, and the glue became pretty clear and started to get tacky. While it was tacky, but before it had dried anywhere, I quickly positioned the veneer, pad, caul, etc. It worked like a charm. Like everything else, it took a little practice. But once I got the hang of it, there were no further problems.
Patrick

OK, maybe a newbie error, but why not use contact cement to bond veneer with the base wood? That's the standard method in most wood working, why not on a guitar?

Thanks for the input folks! I seem to be doing much better now with a lot less glue and only gluing one of the surfaces.

Dont forget the original and best for laying veneers,Hot hide glue! Lots of bleed through, use a veneer hammer and lots of really hot water. In fine woodwork this is still the prefered technique.
Cheers Chopper

I would like to clear up a couple of things here.
First of all the contact cement is not the "standard" method of applying veneer unless your standards are very low. Contact cement is a inferior method for applying veneer. When it is done it is used with paper backed veneer, not raw veneer. It is never done on quality work.
Second, hammer veneering with hide glue is not the prefered technique or the best method. It is limited to very thin veneers and I don't know a single person who uses this technique. Way back before the forties hide glue was use with thicker veneers and they would have a thick zinc or steel plate that was heated and part of the mechanical press. This allowed larger panels to be veneered. The room and everything had to be very warm.
The prefered method now is to use a urea-formaldehyde glue and a vacumm press. A cold press glue is also used.
Industry uses a few other methods and variations on the above theme.
I am not saying you have to have a vacumm bag it is just what most of use us now. Clamps and cauls are fine for small things. Fine for big things too if you have a big enough press.
Link

_________________
Cut to size.....Beat to fit.....Paint to match.

Interesting, I always glue my veneer because I'm usually working with a piece that I'm fitting into a broken area. I'm also working with wood backed veneer, not paper backed. Like I said a newbie question...

Ok now a real newbie question!

I have been giving this a lot of thought for months and am curious what the result would be. First let me start by saying I have never built a guitar but it is something I want to do and especially now since I currently have 3 grandsons and a son in law wanting to learn to play.

Would there be a detrimental effect to the sound produced by an acoustic guitar if:
1. You applied a very thin 1/42 or thinner veener to the soundboard?
2. If you wanted the glue, epoxy in this case, to bleed thru to act as a partial finish, filling grain etc from the inside.

Now, again assuming, this was done, would it be necessary to reduce the thickness of the soundboard by an equal amount of the veneer? Actually the same questions apply to the sides and back as well?

Mike

Hi Mike,
Let me start with the question of sound of the guitar. This is where I am the least qualified to answer but let me say that if you look around here and talk to real experts you will find them talking about different finishes affecting the sound and different thicknesses of finish ! affecting the sound. What is a 1/42" layer of veneer plus glue going to do. My guess would be not great things.

I wonder why you would want to do this ? I am not sure what you are trying to achieve. What veneer could you use that could possibly be better than vertical grain 500 year old sika, engelman, adirondac, cedar, etc. I can't imagine anything better. And what wood could you get in veneers you couldn't get for the back and sides. Have you seen some of the guitars made here. I have seen water fall bubinga, brazilian rosewood, spaulted bay, on and on.

Ok, from purely a woodworking standpoint I see no advantage to epoxying the veneer down to try to bleed it through for a grain filler. You could glue it with a less messy easier to use glue as I have mentiond in the posts above and then use the epoxy to fill the grain if that was what you wanted to do. Solid wood is not the best substraight for veneering. Typically when you veneer over solid wood you use the same spieces and orient the grain the same. It is not done very much. Where you might see it is on a drawer front where you had some figured wood you wanted to show and needed to maximize your usage. You would then veneer it onto some wood of the same spieces but of lesser quality for the core. When you veneer it is best to have a "balanced" construction. That is if you veneer on one side of a panel or piece of wood you need to veneer the same on the opposite site. Usually the same spieces. The glue line, pull of the veneer and stresses will be equalized. One sided veneering can lead to warped wood.
Hope this answered some of your questions,
Link

_________________
Cut to size.....Beat to fit.....Paint to match.

From a guitar building point, as Link ask, WHY? If doing an acoustic, you have great top woods available. If not want to use spruce, cedar or other "norm" top wood, why not get a piece of mahogany, koa or whatever as a top. Thin it, brace it right and will work much better than putting a veneer on. I have no idea of what veneer using or what you want to accomplish with the veneer on top, so with that answer, I gues others can give you opinions as to what woods (same type veneer is) would be good tops. I have only done mahogany and koa as a top, and did fine. Sure others work well, but then need to get into how to thin, brace and voice for what you want.

Link sounds like an expert on the use of veneer and how to laminate it and glue it, so would listen to what he says. I don't use veneer except on headstock so have no idea on big stuff like tops, sides or backs.

Hi Link and Stan,

First let me thank you for you answers. The reason of course is the availability of beautiful wood that would not hold up to building a sound board from, such as a burl.

Link the reason for the epoxy is to use a very thin viscosity, and as I said, let it be at least the base for the finish. Second, I was curious that since the top is braced, that the veneer on the surface would not cause the typical problems.

Again, both of you please remember I am asking this in total ignorance, but have wondered about this for some time.

Mike

ps I have some birds eye maple veneer that has an eye about every 1/8"......can you imagine what that would look like as a top?

Mike, I really think this would kill the sound in the top. Epoxy is a pretty flexible glue and if you really did this you would be better off with a rigid type glue to avoid dampening or should I say at least limit this part of the dampening. Think about how if you saturate the veneer till it bleeds through you will have a layer of flexible damening epoxy 1/42" thick !
I also think that you should build a couple of guitars first to figure out how it all goes together and what it sounds like so you would know that what you did with the veneer to the top is what killed the sound and not something else.
What you are proposing could be done to the back and sides and still have a good sounding guitar. I like my seagull guitar which has a laminated back and sides. To do this well you will need forums and a vacuum bag and some woodworking acumen to pull it off. If we haven't dissuaded you and you are really determinded to do this P.M. me and I will tell you how to pull it off.

One other thing and this is IMO but wood does have it's limitations. Some woods are better suited for certain things than others. For example I don't use soft woods like redwood for table legs. They will get dented and look bad in a short time. I do like hicory for legs and in something like a leg it's unstable nature is not a drawback. So form follows function or wood follows function. It try to use the woods that naturaly lend themselves to particular uses and not force the wood to do things it doesn't want to do or do well. Some woods are acoustic. Guitar makers have discovered what these woods are. Guitars are instruments to make music and if they don't sound good then what is the point ? You might as well make a shape or sculpture that shows off your wood better. I would suguest you get some bear claw sika to satisfy your wood lust and wow desire and use it for a top. Learn to appreciate the subtle beauty of vertical grain old growth softwoods. (Actually a lot of bear claw is not subtle) You could still ritz up your back and sides and do your birdseye there and still end up with a good sounding guitar.
Link

_________________
Cut to size.....Beat to fit.....Paint to match.

Over a hundred years ago people were gluing brazilian rosewood and maple veneers to a softwood substrate to make the back and sides of high quality guitars. They used hide glue.
Modern makers have used plywood tops on guitars with mixed success. Veneering a solid wood soundboard could probably be done, but would probably adversely affect the volume some. If you are making an amplified acoustic this might noy be such a big deal.