Problems gluing Argetine Lignum Vitae

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K37

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Aug 11, 2011
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I recently epoxied some Argentine Lignum Vitae scales to a Fallkniven F1 blank secured with T88 epoxy and corby bolts. After the glue cured and I sanded the scales back, I noticed a small gap the thickness of a paper shim (about .003") almost all the way around between the wood and the knife. Can anyone shed some light on why the joint would seem to be starved.

I prepped the knife by sanding with 80 grit sandpaper with a dremel until scuffed up pretty well. I measured the epoxy by volume and mixed it thoroughly. I prepped the wood by flattening with a hand plane then sanded with 80 grit sandpaper. I degreased the knife and the wood with lacquer thinner as per system three's instructions and let dry. Finally, I applied the epoxy in a thick layer to the wood, drove in a tube in the back and affixed two corby bolts. I tightened both bolts down hand tight being aware not to over tighten. I've used Titebond glues on wood and don't think I squeezed the joint dry when I tightened the corby bolts and I didn't use any clamps. I got a good amount of squeeze out though.

This is my first time using epoxy, gluing tropical hardwoods, and gluing wood to stainless steel. Any thoughts on the cause of this problem would be appreciated.

Kenrick
 
The reason is because of the wood.
It is like trying to glue a bar of soap to a piece of metal.
The wood will have a waxy or soap like feel because of all the oil in the wood so it will separate itself from the glue.
Lignum Vitae is/was used for bearings in sailing boats.
Works good for that because the wood is so dense and self lubricating when warm or under pressure.
If you use it for handle material it needs to be done where it is attached by mechanical means instead of glue or epoxy.
 
I'm glad I used corby bolts then. Is there any way that you know of to degrease the wood enough to take the epoxy?
 
K37 said:
I'm glad I used corby bolts then. Is there any way that you know of to degrease the wood enough to take the epoxy?
Click to expand...
The suggested way is with acetone.
That removes the surface oils, but seepage later can cause it to separate again.
Lignum doesn't move much (if it is old dry wood) so just mechanical means of fastening will usually work out ok.
For a surface finish I would use paste wax and hand buff with an old t-shirt. Like polishing a pair of shoes.
 
Years ago, I epoxied some lignum vitae unsuccessfully to some metal. The wood I had was a different variety than the argentine lignum vitae. I removed all the epoxy from both surfaces. Roughed up the metal with sand paper and gouged up the lignum vitae surface with a awl and dremel. When I reattached the pieces, I used JB weld instead of regular epoxy. This time it held.

Here's a link about argentine lignim vitae: http://www.wood-database.com/wood-articles/how-to-tell-genuine-lignum-vitae-from-argentine-lignum-vitae/

Ric
 
Hadn't thought to use JB Weld. I'm going to try to glue a couple scrap pieces after using acetone to degrease and gluing with epoxy then doing the same and using JB Weld.
 
This probably has nothing to do with wood and glue.
I would be willing to bet that it was either your sanding or over-tightening the bolts.

The tang and the scales have to both be dead flat. If they are both flat, then there will be no gaps. If you round the tang toward the edges any microscopic amount, that will show up as a tiny thin gap along the entire edge - as per:
".....I noticed a small gap the thickness of a paper shim (about .003") almost all the way around between the wood and the knife. ......"

Hand sanding with anything but a flat and hard block backing the paper will make the edges rounded...no matter how careful you try to sand it. The best method is to place the sandpaper on a flat surface ( granite surface plate being the best choice), and carefully sand the tang and scales against that .
If the sanded surface isn't a smooth set of parallel lines covering the entire surface from edge to edge, you still have sanding to do.

The other culprit in scales lifting ( usually at the ends), is torquing the Corby bolts down too hard ( and over clamping when using pins). There is no reason to do that, and a good reason not to. If you compress the wood in the center, it will cause it to lift in all directions from those pressure spots. The ends can lift quite a bit, and the sides can also lift some. The other reason not to over-clamp or tighten the scales is that it will squeeze out all the epoxy, and make a glue starved joint/seal. No glue equals no bonding, and no seal against moisture.
 
Lignum Vitae makes an excellent handle material for hidden tang knives. :D

Just sayin...
 
I sanded over my granite sharpening slab that is dead flat, but I did my dry fit before I scuffed up the wood and steel, so I may have rounded something. When I tightened the bolts, I tightened them until I could feel them seat which may have been an 1/8th of a turn too much.

I thought epoxy was supposed to fill gaps though? If that's so, and I had rounded the sides of either the wood or the steel and enough squeezed out all around, wouldn't the epoxy have filled the void?
 
Back several years there was a company that made epoxys for oily woods. They worked very well on lignam vitae and coco bolo as well as others. The company was called Industrial Formulators. I didn't try to google them. Frank
 
It sounds like you did everything right, but somewhere there became a problem with the flatness. If there wasn't a gap, there would not be any void for the epoxy to fill. The epoxy should fill the gap, but if it is wiped away with acetone before it cures, it may have been all removed from the gap.

On lignum vitae and other waxy/oily woods, I clean the wood with acetone before glue-up. This removes the surface oils to ally a better bond.
 
I've made some scales out of this and had good success. I think flatness is a key with any scale. I have a machined granite surfacing block that is perfect for doing this, I use spray adhesive and glue a sheet of wood sandpaper down on it and use figure 8 motions to get the scale flat. I think hand planing lignum vitae would be a nightmare! Also I wonder if you didn't round the edges on the wood and/or the knife tang when you went to sand them prior to gluing. When I am roughening the tang I make a point to stay away from the edges.

I used vulcanized fiber liners between the tang and scales. I epoxied the liners to the scales first. Of course I had to degrease the wood with acetone. When you degrease a wood like lignum it's not a simple wipe down, it takes multiple passes. You need to use plenty of solvent initially and flood the gluing surface so that it penetrates the wood a bit. I use a white cotton wiping cloth for this- as you wipe you will notice a residue on the cloth. That residue is the oil coming off the wood. Keep turning the cloth so that you expose clean portions of it, and keep wiping it down until stops leaving a residue. Then be ready to do the glue up immediately because if you let it sit the oils will creep back up to the surface.

The epoxy was just 60 minute epoxy from the hardware store, but it did a fine job adhering the liners to the wood. I did a lot of the shaping prior to attaching the scales to the tang, and the liner-scale bonds were stable through all of that. I also did a set of cocobolo scales at the same time and had success using the same techniques. Cocobolo is probably even worse than lignum in terms of oiliness.

Probably the liners helped a lot. A good metal to wood bond is not easy, even with non-oily wood. Anyways these knives were completed with corby bolts and so far I've had no issues with the glue joint for 8 months.
 
Thanks for all the detailed replies! I'm going to try all the recommendations on the next couple scales paying better attention to my flattening and solvent cleaning.
 
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