I’m preparing to veneer a tabletop, 42″ x 60″, and both epoxy and plastic resin have been recommended. I’m considering West System epoxy or Unibond 800.
I’m using shop cut veneers that are about 1/8″ thick. They will be finish sanded to about 1/16″ after they have been applied to the MDF substrate.
As it stands now I plan to simply weight the top with several hundred pounds of 3/4″ hardwood plywood if I use the epoxy. Have been told that I need a vacuum bag if I go with the Unibond.
I don’t have tha vacuum system so the epoxy would be a real plus but I’ll get the vacuum if it is really necessary.
Anyone have experience with either system?
Replies
liquid hide glue. specifically, http://home.pacbell.net/ebeniste/gluepage.htm. take a look around on his site and see check out the veneering he does. you'll be pretty well convinced. plus, if you have a problem, you'll never, ever, get the epoxy or plastic resin off. hide glue is reversible.
Bruce
I don't think you can only use Unibond with a bag. It's just a modified urea resin which is what was commonly used in the past, often called Scotch or Plastic resin glue. You may want to use their blocker additive with it to prevent bleed through. Epoxy would not be my choice.
Beat it to fit / Paint it to match
Thanks, Hammer. It didn't make sense that plastic resin could only be used with a bag. Just out of curiosity, why wouldn't you use epoxy? Based on manufacturers data it looks like a reasonable choice.
Veneering has usually been used with high end furniture, cabinets, etc. It allows the maker to use burls and exotic grains that otherwise are not available at reasonable prices and some are only avaialable as veneers. All good furniture is assembled with the idea that the entire process is reversible making the piece easily repaired .
Today, veneers are found in everything from the most expensive pieces to knock off (and knock down!) pieces made in China. So you have to evaluate the level of product you are making and if repairability is a consideration. Epoxy is usable in most woodworking applications, but it is more expensive that "reguarly used" adhesives and you will need a veneer press to ensure proper adhesion without bubbles.
Typically I use either hide glue or for small areas, woodworking PVA glue when veneering. I'm not a fan of contact cement, but I woulod be more prone to using it than epoxy because I wouldn't have to worry about a veneer press or other clamping structures.
Jack, of all the adhesives I've used over the years, epoxy is one of the few that I have had failures with. I can't stand the smell. Conditions and mix have to be just right. Epoxy causes dermal reactions, it's just a matter of time before folks develop an allergy to it. For the most part I have used Behlens and West Systems. It's expensive and can take a week to fully cure, in the press. Other than in marine environments, I don't see where it does anything better than other products. It will bleed through the veneer. With your method of sanding afterwards, the epoxy could have an impact on the finish you use. Unibond has modified and addressed some of the problems with ordinary urea resin. The additive you can use with it will greatly reduce bleed through. It would be my choice for large flat panels in a press.Beat it to fit / Paint it to match
Wow, what a morass to wade through. Bubblegum and masking tape are looking better all the time. Or maybe a 1/8" thick tabletop. Or maybe just get a sheet of 3/4 doug fir plywood and a can of spray paint. At least it won't curl or have the veneers lift off. And no noxious glue or adhesive fumes to contend with. No bleed through either.
Seriously, though, is bleedthrough a major concern with epoxy? The veneers have quite a few cracks, small holes, and splits that will be filled with black epoxy. I've seen it done and it provides a striking contrast that is stunning. Won't any bleedthrough blend in with the cracks and holes?
As you know from my earlier post, I prefer epoxy for veneering. However, it is true that bleed-through is worse with epoxy. It is not limited to places with cracks or large voids. It seeps through the natural pores, especially in figured areas where the grain runs through the thickness of the veneer.
Even so, you are going to want to sand the front surface of the veneered piece anyway. Not to just remove the bleed-through, but to smooth the surface for finishing. In my experience, epoxy bleed-through is not really a problem. West system epoxy sands very nicely. Once the wood is smooth, you cannot tell where the bleed-through occurred and it does not obscure the figure of the finished piece. At this moment, I am finishing some drop-dead gorgeous curly walnut veneered drawer fronts. The epoxy bleed-through is undetectable.
Thanks, John. I'll give it a try on some scrap and see how it comes out.
I mostly use epoxy for veneering. Epoxy has several things going for it. It has great gap filling abilities so if you don't have a good pressing system, it is forgiving. It is not water based so you don't have to worry about curling the veneer. It has a long open time. It holds the veneer well and doesn't allow "creep".
I haven'y had positive experiences with urea resin products. The glue is very brittle when dry and does not have near as good gap filling abilities, so the pressing system has to be precise. Some ureas are water based and curl veneer. It is not that much cheaper than epoxy and I am not wild about the formaldehyde exposure, not that epoxy is benign.
I use liquid hide glue for veneering sometimes and I can't think of any advantages ureas have over it. Hide glue fills gaps very well and best of all it is repairable, which is a distinct advantage it has over any other glues I know of.
I'd go with the urea formaldeyde over epoxy....yes, you can use epoxy, but it's expensive, messy, has a shorter pot life, and that's a fairly substantial item you're pressing. Urea formaldehyde is the standard in the industry for a reason...... it works very well, and it's pretty easy to use an not expensive.....I realize that may not be the most important thing to you. The vast majority of people doing a lot of veneer use UF glue.
Urea glue can be cold pressed very successfully....you don't need a vacuum rig, but they are pretty neat; we're just starting to use our new one and I'm impressed so far. Now, we also have a big cold press here in this shop (and renting a little time on a press in a pro shop may be a good investment too), but we still use a homemade cold press we made here for a lot of work.....it's just four solid hardwood frames mortise and tenoned together......there are a couple of pieces that hold them in position, and a hardwood beam that is slung from the top (for 42" wide, you might need 2 beams). A big solid platen on the bottom, one on the top, and some car jacks I bought at the hardware store on sale that bear on the beams......very low tech, cheap, works great, and knocks apart for storage.
anyway, good luck wi=hichever way you go....the one thing I have found with UF glue is that it takes a while to get to full strength, especially if your shop is on the cool side.....you need to press it, then dead stack it for a while before you use it.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
Hello Jack,
I've used PVA, urea formaldehyde and epoxy on about a dozen glue-ups, each. Most were with a vacuum press. I had real bad luck with mechanical pressing; the pressure just wasn't uniform across the panel and the adhesive collected in spots, making bubbles. Enough of that, back to your question.
Both urea formaldehyde and epoxy have a long open time. I've read the specs for PVA open times and I don't get that in practice. Also PVA sets suddenly; it floats and floats and then grabs and you're stuck. UF and epoxy cure up in a gradual, continuous process; the increasing viscosity tells you where it is in its cure.
With urea formaldehyde, you need to weigh the liquid (more like honey) and the powder on a sensitive scale. It takes a lot of mixing to get the powder to dissolve. The resulting mixture is thick like cool honey and it is easy to lay too much on the substrate.
I prefer West System epoxy. The dispensing pumps make things neat and easy. One press of the plunger for each component. The components have the consistency of a good varnish. I use those cheap disposable paint rollers and trays. It is easy to keep rolling on more adhesive untile you get a layer about the thickness you like (I like it to be like a one-coat acrylic paint.) While you roll the adhesive on, you can judge how absorbent the substrate is and add more.
Just one more thing with epoxy; be sure to put a layer of waxed paper or polyethylene plastic between the veneer and the cauls. There will be some weep through of the adhesive. Epoxy adheres to most everything really well. It took me three hours to pry a glue-up from my favorite pair of cauls that had no problems with PVA or UF. The epoxy tore the faces of the cauls; they are ruined. Lesson learned.
You didn't ask .... but you really should do some test glue-ups with whatever system you choose. That's a big project; you don't want to be saying, "Aw shucks!
Thanks, everyone, for taking the time to share your experiences. As expected, there are varying opinions and many very good suggestions. I particularly value the pros and cons of the products. I had pretty well discounted pva for the reasons cited, and don't want to invest in a glue pot.
That leaves epoxy vs plastic resin, and when I weigh the points you have raised I think epoxy has a slight advantage for my application. I've used Weldwood plastic resin for bent laminations and while it works well it is highly toxic and contains water that can curl the veneer. I'll probably go with the vacuum bag since I simply don't have the space for a cold press, and most of you lean towards it anyway.
John, thanks for the tip about using plastic sheeting between the caul and veneer, I didn't think about that. And yes, I'll try a practice glue up before the real thing.
Glue pot's not necessary for hide glue. Plenty of threads around here, folks use hotplates, the warmer off a busted Mr Coffee, and plain old pots one inside another on the stove as a double boiler.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Thanks, John, I thought you needed a glue pot. I do have an old hot plate that might work. What kind of vessel do you recommend? Also, what is the pot life of heated, melted glue, and what is the open time? It's pretty common for me to go several hours between gluing operations so the glue would just sit idle in the pot most of the day. Is this a problem?
I really do like the idea of using a reversible glue, though, since I build furniture and most of it is fairly nice stuff that will certainly outlast me.
I'm at my depth already, Jack. Others here can definitely help you on those questions... good luck!My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Do a search for FSV glue,this is used on veneers. I have never used it ,or seen it. I use hot hide glue. I use a small crockpot with a coffee can inside, I put about 3 " of water in the crockpot if I will use a lot of glue that day. Put hide glue granules in the can ,add water.Read the instructions for the amount of water. The glue is ready at 135 °.Glue should appear like syrup.Not runny like water or too thick so it doesn't drip off the brush.
Apply the glue to the base evenly, brush or use a thin piece of wood.Make sure you have full coverage, but not overly thick.The glue can dry ,or the veneer can be put on while it is liquid. You'll have to iron it on ,use silk setting. If the veneer is not completely flat you will have to flatten it first.Dampen the face, place between mdf boards with wax paper on the damp surface.Weight the mdf down or clamp them.
You should veneer the bottom too with an inexpensive veneer such as poplar. I have skipped this in small projects and sealed the bottom with varnish instead. So far I haven't any problems,but most people will tell you to veneer the opposite side always, Use their advice,I do veneer the underside when the job is more than a couple of square feet.
First I would get info on the FSV glue,this may be the way to go.As far as epoxy, never used it for veneer,the plastic resin glue was difficult to clean up. Pva okay for small areas, not for any thing that has seams. Pva holds but creeps slightly.
If you go with hide glue ,the hot plate will work. Need a pot with water ,and a another vessel inside with glue.A candy thermometer is fine for determining the temperature. Use a scrap board for a lid,bore a 1/2" hole for the thermometer. I cut the lid in half, when I need glue I remove the half piece to access the glue.
mike
Thanks, Mike. Sounds like good advice. One other question, though. Can you turn the pot off at the end of the day and remelt it the next day?
Yes, but if you do not plan to use the glue for several days, refrigerate it after it cools. You will have to add water every so often to keep the consistency. The last batch I made I put the leftover glue in the freezer. Before I use it again I'll test it on scrap to make sure the glue is good. No way to tell if the glue is good after freezing for a long time.I tested one batch 3 years ago that sat in the freezer for 4 months, glue was still good.
If the shop is not real hot, and you are sure you will use it the next day,just turn the heat off and leane it covered.
mike
If you use liquid hide glue, as opposed to HOT hide glue, you don't need any special apparatus. It comes in a bottle, liquid form, doesn't need to be mixed or heated, has lots of open assembly time, requires no special preparation and is repairable.
bruce
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