Tuesday, November 8, 2016

Steak Knives Part 2 - Testing Finishes 1

Since I've embarked on the adventure of making knife handles, I realized that applying a finish to a knife handle poses different challenges than I'm used to. First off, I hit up The Dusty Life for some suggestions.

A knife handle is different from something like a table top in a couple big practical ways.

1. It's going to be *handled* as in, subjected to both being in a hand (so needs to feel good there) as well as the wear, tear, and natural oils that are present on a human hand.
2. It's going to be near food and also will get wet when you wash it.

This means I needed to do a little more research.

One of the coolest things about people who create is that, for the most part, they are incredibly generous with their knowledge. Find someone who knows more about a craft than you, ask them a question, and odds are you'll get an answer.

Case in point, I asked this guy how he finishes his knife handles and he told me:
Seriously, check out this dude's work. He clearly knows what he's doing.

I was initially skeptical of the durability of a beeswax/mineral oil paste finish. A quick note about oil-finishes:

I asked:
Different finishes protect in different ways. For example, shellac is a protective finish dissolved in denatured alcohol. Spread the shellac on the surface, the alcohol evaporates, and leaves behind a layer of the finish. That's an evaporative finish. Some oil finishes are "drying oils" (namely linseed and tung oil) but despite the name "drying," they don't dry; the oil molecules react with oxygen and polymerize as they cure. In plain English that means that when exposed to oxygen the oil changes in a way that causes the molecules to grip together so that when the reaction is done you have a layer of protective coating. Some oils are not "drying oils" because they don't undergo the reaction with oxygen that causes polymerization. Mineral oil is one oil that doesn't polymerize and beeswax (well, it's a wax, not an oil but still) doesn't polymerize either.

Okay, so I reached the conclusion that given what I'm trying to accomplish with what I'm making, I should aim for a slightly more durable finish than mineral oil/beeswax.

I asked another knife maker on twitter, who responded "all our handles are first sealed, then oiled. Several times w/each. Each knife hand-sanded to 3000 grit!" but then he deleted the tweet, so I haven't credited him in case he got in trouble with his boss or something.

The Dusty Life Guys suggested that I look up Bad Axe Tool Works and see if they would be willing to share the finishing technique for the handles of their saws. After poking around their website, I found this: "The handles are then carefully contoured and sanded with a variety of hand and power tools, followed by a thorough soaking in a high-end oil treatment. Afterwards, the handles are buffed out with carnauba wax before assembly onto a saw." That makes me think of this video I saw of somebody submerging a knife handle in boiled linseed oil:

I've also read a good deal of people using Birchwood Casey Tru - Oil Gun Stock Finish,

Toth suggested a tung oil varnish, like Formby's.

Lastly, due to the fact that oils polymerize by way of a chemical reaction, some exotic woods (paduak for example) actually have natural oils that interfere with the chemical reaction. That means that oil finishes won't "dry" or cure properly. Toth suggested that I use a de-waxed shellac as a basecoat, which would seal in the natural oils of the wood, and prevent them from interfering with the curing process. The saying goes "Shellac sticks to everything, and everything sticks to shellac."

So, the way I see it, that sets up a few options:

1a. Tru-Oil
1b. Tru-Oil over dewaxed shellac
2a. Formby's Tung Oil Finish
2b. Formby's Tung Oil Finish over dewaxed shellac
3a. Soaked in Linseed Oil
3b. Buffed with carnauba wax

Luckily, I have a bunch of scrap left over from cutting knife handles, so I set up an experimental procedure:

I sanded scrap of the species to 800 grit. Then I finished each with my options and compared.

For organizational purposes, and because this post has already run pretty long, I'll put the results in a new post.

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