Knife scales expanding?

A

AbLonewolf

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Jan 30, 2020
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Good Morning all.

Started making knives about 1 1/2 years ago as a retirement hobby, which I have became obsessed with...lol

About 10 months ago, I put Chechen scales on a knife. The wood was purchased, came as a board, which I cut into appropriate blocks. Then sliced a couple of pieces just over 1/4" thick. I decided to keep that one. The handle was subsequently finished using tung oil (3 coats- 24 hours apart). I had it stored in a small cardboard box since.

Yesterday, started putting my stuff together for the upcoming hunting season. I checked this knife and found the following issue:
The wood appeared to have "expanded". It has expanded enough that I can feel the rise with my fingers. Epoxy joints appear to be OK. No expansion where the brass pins were installed, just the outside edge of it.

What has happened here? Can many coats of finish cause this expansion?

Thank you in advance.
 
Changes in humidity level can cause this. If it was dry (like during winter) when you made the knife, but it's now humid, the scales can swell. That's why some makers use stabilized materials - less movement.
 
Ditto. Seems that even stabilized materials will expand or contract a little over time. Likely the only way to avoid this is to use a fully synthetic material
 
AR-Trvlr said:
Changes in humidity level can cause this. If it was dry (like during winter) when you made the knife, but it's now humid, the scales can swell. That's why some makers use stabilized materials - less movement.
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Thanx. I checked 2 more I made around the same time frame:
Bubinga: Swelled
Curly Maple: OK

I suppose the kind of wood will affect this more than others. Lesson learned...

So would my epoxy treatment be affected then? If not, I will sand the edges off. If so...will replace them.

Thanx
 
AbLonewolf said:
Thanx. I checked 2 more I made around the same time frame:
Bubinga: Swelled
Curly Maple: OK

I suppose the kind of wood will affect this more than others. Lesson learned...

So would my epoxy treatment be affected then? If not, I will sand the edges off. If so...will replace them.

Thanx
Click to expand...
It does not seem the scale to tang epoxy bond is affected by this (at least not in my old knives that have experienced this for years.

I guess you COULD sand the material to smooth now ... BUT, as AR-Tvlr said, the material will both expand and contract with the humidity changes of the seasons .... so if you sanded flat now, you might risk the material shrinking and producing the opposite problem in winter months..... :-(
 
If you leave it alone it will be back to normal this winter. If you sand it smooth now it will be a ridge this winter when they shrink back but now the steel will be a little higher than the wood. Wood moves. No way to avoid it using wood thats not stabilized, stabilized wood will do it much less than non-stabilized wood.
 
i am guessing two of the three woods were kiln dried, and like the others mentioned it swelled when it acclimated. i usually like to keep wood for over a year before using it. i also bought a wood moisture meter for $36 so i would not have the issue again. i had the opposite problem, the scales were too wet and then peeled away from the tang. 5-8% moisture content is usually optimum.
 
Will the epoxy integrity be affected with the wood movement?

All wood was purchased at the same place. I do not believe any were kiln dried.
 
Epoxy has some plasticity and will stretch/contract somewhat so you scales will probably be fine. The hardest woods absorve and release moisture more slowly than softer woods.
 
john april said:
i am guessing two of the three woods were kiln dried, and like the others mentioned it swelled when it acclimated. i usually like to keep wood for over a year before using it. i also bought a wood moisture meter for $36 so i would not have the issue again. i had the opposite problem, the scales were too wet and then peeled away from the tang. 5-8% moisture content is usually optimum.
Click to expand...
Couple things to note...proper moisture content is relative to the area you are in. Humid/wet pacific northwest "dry" is somewhere between 9-12% moisture content. Move to Arizona and it is closer to 5-8. Also, the wood will expand and contract according to the humidity in the area.

We have a carving knife in our kitchen that was made in the early 1960s from a bandsaw blade by my grandfather. I have always run my finger over the pins and the joint at the bolster since I was a teen (I'm 56 now) to see if the wood is beyond, below or even. Its always special when it is even because I know that it must have been "just like this" when gramps finished the knife 50+years ago.

Who knows....yours might move for that long too.
 
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Alright then. Thanx very much for all the valuable information guys. Very much appreciated and I will sleep better tonight...lol
 
yes, that is why i made sure to state "usually". there are extremes. that is why its important to have a moisture meter. especially if you are going to order scales and put them on a knife right away. i got the 5-8% from cabinetmaker forums, they do not like expansion/contraction either. i live in massachusetts, woods are normally around 5% moisture here once acclimated.
 
Lol ... I still get kind of a kick out of this topic. As Weo can attest, here in minnesota in the summer it can get really warm and very humid - wood expands. In the winter the air comes from the arctic tundra and is extremely dry. I see my knives cycling somewhat ... but I have at least two joints n wood floors that open up almost a quarter inch gap in the winter. Every once in a while you hear a loud spontaneous “crack” as something let’s loose as the weather gets colder and drier. Wood will do what it will with humidity ... just need to live with it I guess...
 
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