I've got a bunch of scales from a great guy in New Brunswick, Canada. They are mostly maple burl, but some cherry and birch as well. I am okay with using them 'as-is' with coat of Beechwood-Casey Tru-Oil, but I'd like something more deeply set into the wood and by nature more durable. One option is to send them out for stabilizing. As of this posting date, there doesn't seem to be anyone offering this as a service in Canada. Many are selling stabilized scales, but none want to do other people's scales.
This started as a research project and now it's become a full-blown obsession.
Wood Stabilization OverviewThe general process is to place the scales into some kind of vacuum chamber with a stabilizing resin and the air is evacuated from the wood. The resin is then allowed to penetrate the wood. Once the wood is saturated, it is removed and the resin is allowed to cure, often with the aid of heat.
VacuumIn the home stabilizing field, anything from a hand operated vacuum pump, (for bleeding automotive brake systems) to a air conditioning service vacuum pump. The objective here is to create a vacuum of around 25" of mercury or more, ideally 30".
ChamberFor the most part, home stabilizing is done in sealed jars, such as a pickle jar. The resin and pieces of wood are place into the jar (aka chamber), the lid is secured and a vacuum pump is attached.
ResinThe magic is in the resin! I've learned of people using anything from Minwax Wood Hardener to polyurethane to methyl methacrylate. Everyone is super secretive about their recipes, so we won't find it easy to compare apples to apples. A popular choice is Minwax High Performance Wood Hardener, but this may be more due to availability than effectiveness.
- Cactus Juice Stabilizing Resin
- Stick Fast Stabilizing Resin
- Resinol 90
The bulk of these resins are acrylic. Some of these other solutions I have encountered are:
- Plexiglas (acrylic) dissolved in acetone
- Oil Based Polyurethane
- Oil Based Polyurethane thinned with paint thinner
- Polyurethane thinned with Acetone
- Water Based Polyurethane
The MSDS for Minwax High Performance Wood Hardener states that it is 72% acetone, which leads me to believe some kind of acrylic is dissolved in the acetone.
My First ExperimentMy first experiment is to try some pentacryl in the vacuum chamber and observe the results. I have some nice maple and piece of birch from my mate in New Brunswick.
My vacuum chamber, err...jar. Good old quart pickle jar with a 1/4" (1/8" ID) barbed hose fitting attached to the lid. This can be sealed however you like. I found a roofing washer (Aztec washer) and an NPT fitting. Make sure you use a tapered (NPT) thread if you are using regular brass to barbed fitting.
I have a Princess Auto 'Power Fist' brand brake bleeding vacuum pump kit.
These are the three sets that I am going to stabilize. On the left we have some spalted maple, int he middle there some maple burl and on the right some yellow birch.
Pulling about 15" and this is foaming heartily.
You may have to let the bubbles settle before adding more vacuum.
After the bubbles slowed down I worked the vacuum pump every 10 minutes or so to maintain the vacuum at about 24". I then let these sit overnight at room temperature.
The next morning the level of pentacryl had dropped in the jar. It looks like about 100 ml was absorbed.
I will add more photos when I get to working up these scales into handles. I am curious to see how the pentacryl works and how deep it goes in under vacuum.
UPDATE: October 7, 2014
I made another batch this time with heat cured acrylic that shows under UV light so we can check the penetration into the wood. A bunch of pieces were treated at the same time using the same vacuum pump and jar idea.
The stabilizing liquid is called Stick Fast and I have a gallon to play with. So far the treatment seems superior to pentacryl as it's "more plasticy." When I cut into some pieces I hope to show how the scale interiors are impacted by the product.
About an hour at 88°C (200°F). You can see the acrylic has hardened.
Update: This knife was made with the above shown scales stabilized with Stick Fast.