Wood recover problems

[RickHuf]

Hello everyone.

I have had a lot of fun recovering a handful of knives this year. Three of them, though, have decided to expand or contract.

Here is an example. I just found this one today (haven't used it in a while) This is a Klein knife that was recovered in purpleheart. Please disregard my awful looking stainless pivot pin.



When I had finished, this wood was completely flush everywhere. Now it's overhanging the liners and bolsters.


This happened to a fixed blade that I covered in ebony as well. The wood overhangs even more on it than the one shown above.

A third was covered in locust and it actually shrunk a wee bit! This I had blamed on not drying out my wood enough, but I don't know. I baked it for a few 8 hour shifts at 180f.

All three of these seemed to appear this way over a month or two later. The wood covers are epoxied to the liners/tang before shaping and finishing. They are all oiled with linseed and polished a couple weeks later.

What am I doing wrong here? Does anyone have any ideas? I know wood expands and contracts, but it's getting to the cold season and this stuff shouldn't be expanding at this point. It's all super hard wood, too.

Do I dare sand these and refinish them only to find the wood has shrunk again at a later point?

Thanks for any consideration!

 

[catspa]

Wood expands and contracts with temp and humidity, as you know. If you glue it to metal with a much lower COE, it still expands and contracts.

One solution is to stabilize it, i. e. inject it with resin or something to fill the cellular spaces. Another idea is to maintain a constant set of storage conditions, avoiding temp and humidity changes.

Or you can attach it mechanically, with pins or rivets, and live with it moving.

Age old problem.

Parker

 

[RickHuf]

Thanks Parker, at least I'm not going crazy.

It's just odd that some have done this, some not... And factory manufactured knives seem to not do this at all.

My next one is cross cut spalted maple, I'll be certain to stabilize it first. I was going to soak it in thinned varnish but I guess I'll actually get some wood hardener.

Thank you very much for the reply.

 

[catspa]

You can also send dry wood to outfits like K&G (or others) to vacuum stabilize for you. When I last did that I sent some 4” thick maple and the resin got all the way to the center.

Parker

 

[garry3]

You can also send dry wood to outfits like K&G (or others) to vacuum stabilize for you. When I last did that I sent some 4” thick maple and the resin got all the way to the center.

Parker

Could the same thing be done at home when the wife was out using a a vacuum sealer with a container and what product?

 

[Old Biker]

Could the same thing be done at home when the wife was out using a a vacuum sealer with a container and what product?

It's unlikely that a vacuum sealer will be able to draw enough vacuum. You need a vacuum pump capable of achieving a minimum of 29” Hg at sea level or 100 microns or less. Do a search for Cactus Juice stabilizing resin. You should be able to find plenty of information on the process and what is needed.

O.B.

 

[catspa]

I’ve also read good things about the Cactus Juice system, although I have not tried it. My needs for stabilized woods were insufficient in volume to justify the investment when I looked into it a couple years ago.

I did attempt a couple of hillbilly stabilizing ideas (neither of which featured a vacuum packer), but didn’t get results that pleased me.

Parker

 

[sickpuppy1]

If you know anyone who does HVAC work, they may have a vacuum pump you could borrow
If it’s been properly maintained, it will get at least 500 microns or better.
They have hoses with threaded fittings so you’d have to make a box or something to use with a male fitting. Sealing it could be an issue.