Unstabilized hardwood and humidity

[R.C.Reichert]

An annoying little thing I've noticed with my hardwood scales...

I use mostly figured maple for my full tang scales. I use it unstabilized because I was always under the impression that maple doesm't need to be stabilized and ideally I would prefer to not use stabilized woods because my knives are historical based. When I finish up the handles everything is nice and smooth and you can''t feel where the scales meet the tang, but get them exposed to a different environment with different levels of humidity then you can feel the tang sticking out ever so slightly if you rub your fingers along the back of the handle. Is there a way to prevent this or minimize it?

One other question... Can this expansion and contraction movement of the scales cause an epoxy joint to fail? I peen my handle pins in place, but was considering just gluing them in with epoxy.

 

[milkbaby]

You can minimize the movement by minimizing the change in relative humidity the knife undergoes LOL

I've made full tang knives with natural hardwoods (like black walnut, padauk, wenge, etcetera, tho not maple) that were just epoxied with pins and they've been sent from me in humid Florida to the pacific northwest and points inbetween without incident. All kitchen knives, so they're probably washed a bunch and still held up. I'm sure the users could feel the small amount of movement due to seasonal changes in humidity tho.

Not sure there's any way around the natural movement of natural wood. I like to make sure any wood sits around my shop at least a year if not two or more years so they're dried and equilibrated to the humidity here before they're used. Not sure you'd want to consider it, but it possibly could help if you did a cyanoacrylate glue finish or epoxy finish over the handle scales when done? Somebody smarter than I should chime in on that tho...

I think Don Hanson makes some beautiful knives with natural black walnut that isn't stabilized.

 

[FredyCro]

Do you soak the handles after finishing? 50:50 natural terpentine and tung or lineseed oil. I would like too think that this helps with movement since the wood is saturated with finish. Closing the pores with wet sanding with pure oil after the soaking and multiple pure oil treatments for the finish with drying in between might also help. It would be nice for more experienced makers to chime in, but I think there is only as much one can do, will probably depend on the wood as well. Oily and proper hard wood will move less or not at IMHO. I also read of an old stabilising method by boiling wood in lineseed oil (take care of oil flash point).

 

[Cushing H.]

I am not sure that anything at all will be able to help this. I have knives with diamondwood handles (thin wood layers laminated with resin - even more "stabilized" than "stabilized wood" can get), and here in MN with very dry environment in non-summer months, the handle material has shrunk to the point you can easily feel (and see) the non-smoothness between handle and bolster/pin material. I am sure the other (i.e. swelling) will occur in going to a very humid environment. I thin the only way to avoid this would be to use a fully synthetic material (like G10).

 

[Rhinoknives1]

An annoying little thing I've noticed with my hardwood scales...

I use mostly figured maple for my full tang scales. I use it unstabilized because I was always under the impression that maple doesm't need to be stabilized and ideally I would prefer to not use stabilized woods because my knives are historical based. When I finish up the handles everything is nice and smooth and you can''t feel where the scales meet the tang, but get them exposed to a different environment with different levels of humidity then you can feel the tang sticking out ever so slightly if you rub your fingers along the back of the handle. Is there a way to prevent this or minimize it?

One other question... Can this expansion and contraction movement of the scales cause an epoxy joint to fail? I peen my handle pins in place, but was considering just gluing them in with epoxy.

All woods & natural materials can move due to ambient moisture .. even my Stabilized Maple handles will to a small extent .. if you want to stay historic. Use Linseed, Lacquer & other wood finishes of the era.. Most important is to , “as mentioned” let your woods sit around for at least a year or two and get a moisture tester and make sure the block is at 10% or less before using ..

 

[Fallbrook Forge]

There’s absolutely a way to minimize this, stabilize the wood.

barring that? Using a synthetic liner.

if you’re making strict reproductions, handle material movement is part and parcel.

 

[John mc c]

I've just finished a tester knife with bog oak which is very liable to shrink,that I vacuum treated with pentacryl which gets into the woods cells and coats them to stop movement
Hopefully it holds up well and I can use it as a first layer of protection on raw wood before oil and beeswax without the wood losing its wood feeling
Next I'll try it on a very shifty movable wood
I'd love to use raw wood that doesn't move

 

[Randydb]

Mple is a wood that moves quite a lot with changes in humidity. A buddy of mine makes slab live edged tables and he says he is more likely to get maple tables back because they moved than any other species he works with. I have a 6 foot maple burl table that cups about 3/4 of an inch corner to corner in the winter and is dead flat for about 6 months of the year. I think any wood has some movement when the relative humidity changes. Less so if it is stabilized.

 

[Cushing H.]

. I think any wood has some movement when the relative humidity changes. Less so if it is stabilized.

Just to be clear about words used here and the expectations they give rise to: stabilized wood reduces the swelling/shrinkage issue - but does not eliminate it. That “perfectly smooth” feel at the joint will likely not be so when the humidity changes a lot...