Replies

1. 
   Jamie_Buxton | Sep 01, 2005 09:23pm | #1

   For bent lamination, I use urea-formaldehyde.   Epoxy would work too, but it costs about three times as much.   PVA, while it is useful for most woodworking, has a reputation for creep which is worrisome for bent lamination.

   You can buy urea-formaldehyde at a good price by the gallon from http://www.vacupress.com/.    Or you can use DAP Weldwood Plastic Resin, which is also a urea-formaldehyde.  

1. 
   giraffe | Sep 01, 2005 10:33pm | #2

   thanks, especially for the URL, very helpful

2. 
   Elcoholic | Sep 02, 2005 02:56am | #3

   I've used plastic resin, epoxy and polyurethane with good results.  I think plastic resin is probably the easiest and best for indoor work.  Epoxy has the advantage of variable open time and pot life for a large lamination.  You can slow down epoxy by using a slow hardener and dumping it out on a large cookie sheet or a paint pan.  For the utimate applicator (IMHO) find a Virutex dimpled roller.  Unlike paint or foam rollers they give a very even film thickness without a lot of squeeze out.

   John O'Connell - JKO Handcrafted Woodworking

   The more things change ...

   We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized.  I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.

   Petronious Arbiter, 210 BC

3. 
   jack | Sep 02, 2005 08:54am | #4

   I've done quite a few bent laminations using plastic resin and have had excellent results. Be sure to wear a respirator when mixing and later when sanding since the dust is nasty stuff. I also apply masking tape to the outer surfaces of the two outer strips to make clean up easier. "The Complete Manual of Wood Bending by Lon Schleining (Linden Publishing) is an excellent reference. Also note that the manufacturer rates the glue for a 1 year shelf life so be sure to check the date code. I've seen it on shelves over 5 years old.

4. 
   Ozzy | Sep 02, 2005 03:01pm | #5

   Hi, Giraffe

   I have a little experience of this, and used a urea-formaldehyde glue - it's called Cascamite or Extramite here in England.

   As mentioned by another respondent, it is good in that creep is pretty well negligible - unlike PVA.  The down side is that excess glue dries very hard, and is very tough on tools trying to clean it off. Try to use tungsten tipped tools, would be my advice.

   Take care,

   Ozzy

1. 
   WillGeorge | Sep 03, 2005 06:50am | #12

   lamination adhesives Grollias glue!

5. 
   theo | Sep 02, 2005 08:25pm | #6

   I have had great success with 24 hour epoxy-- west systems or industrial formulators. The long assembly time makes it very easy to do up a large lamination. I opted for epoxy for my workbench for this reason. Epoxy is more expensive but you can keep the cost down by not mixing too much at once. With the 24 hour stuff you could mix a pot big enough for half the job in your guestimation, then mix a bit more for whatever is left. I have often mixed up a pot and found I needed less than I thought, then hunted around the shop for some boards to laminate for later use on the lathe or similar.

   If you go with epoxy, note that the long setting time and greasy nature of the curing adhesive can allow the parts to slowly shift before everything sets up. I have found I need a few more clamps, screws or small bolts to hold things in position with epoxy.

   If you have enough material and you use one of the glues that is hard on tools, try to build your lamination so that you can cut off the squeeze out rather than cutting through the squeeze out.

   Have fun!

   Theo

6. 
   GHR | Sep 02, 2005 08:47pm | #7

   PVA works well.

   You should note that there is no shear on the glue surfaces in a bent lamination - a liquid, the glue, will not support shear. Once the glue is cured the only forces in the glue are tensile. PVA is stronger than wood in that regard.

   You may need to let the PVA cure for an extended amount of time - 8 hours is the longest I have had to keep wood clamped.

1. 
   giraffe | Sep 02, 2005 08:57pm | #8

   the advice I have gotten so far has been to avoid PVA because of creep. Your thoughts on that?

1. 
   SgianDubh | Sep 02, 2005 10:08pm | #10

   PVA does indeed tend to creep giraffe. It's one of the well known creepers and laminated components made with PVA tend to straighten out over time which is why it's somewhat less popular for this job than some other glue types.

   The tightness of the bend in the laminated part and the parts application can help determine if PVA is a decent choice, or not. If the laminated component is restrained at either end that can prevent it straightening out it can work very well. If the bend is slight then PVA might be a good choice.

   I've even seen PVA laminated parts creep across the glue line width, which is quite rare, leading to failure. An example I can cite were laminated rails for the seat frame of a sofa with typical tanged webbing where the tangs fitted into a groove worked in the top edge of the seat rail.

   Over time the weight of the sitters caused the rail laminates to slide past each other due to the stress on the PVA leading to the groove deforming into something more like a rebate. The problem was only discovered when a sitter fell through the sofa framework and landed on the floor.

   Generally it's pretty safe to use non-creepers like urea formaldehyde, urea resocinol, hide, or epoxy type glues, and even sometimes polyurethane glues, and sometimes PVA glues are adequate enough, but obviously not in certain circumstances such as the one I cited. Slainte.Richard Jones Furniture

1. 
   TomT226 | Sep 04, 2005 03:17pm | #15

   I've not had a PVA creep problem on the many bent lam cauls I make for edgebanding ply.  These are 4/4 oak ripped to 1/4" (1" total) and clamped to a form with varying deflection from 2-3-1/2" (depending on length), and used for years without a failure.  One reason is that the strips aren't completely smooth, but are glued up right off the saw.  The tooth may prevent the creep.

2. 
   GHR | Sep 03, 2005 04:14pm | #13

   PVA does not creep if you do your engineering correctly.

1. 
   dirtstirrer | Sep 03, 2005 10:28pm | #14

   I've had really good luck with Better Bond, as sold on http://www.veneersupplies.com . I think it is a propritary mix, I know it is a PVA filled with pecan shells.  It won't bleed through veneer, and I have never seen any evidence of creep.  I give it a workout too.  It works great in a vacuum press, although it dries a little faster then I like if the temp is above 90 and no humidity.  The owner of veneersupplies.com is a nice guy too, and customer service is phenomenal.

    Steve

7. 
   douglas2cats | Sep 02, 2005 09:39pm | #9

   I've had good results with the U-F glue that Highland Hdwr sells. http://www.tools-for-woodworking.com/index.asp?PageAction=VIEWPROD&ProdID=1659

   You didn't mention what kind of wood you're going to laminate. If it's a medium or darker colored hardwood, the U-F glues should work fine, but if it's a light colored wood you'll probably want to use epoxy as the U-F glue lines wood be too visible if the laminate edge can be seen.

   Waddaya mean it wont fit through the door?

   
   

   ---

   Edited 9/2/2005 2:40 pm ET by douglas2cats

8. 
   USANigel | Sep 02, 2005 11:59pm | #11

   Make the laminations thin and regular wood glue is fine, but it sets up quick so giddy up!