Stabilizing Questions

[jrc]

After 15 years of turning pens I'm thinking about stabilizing my best woods, I only use local Vermont hardwoods. What woods works best and is there woods you can not stabilize? I know you can not with dense woods like rosewood.

I have a piece of sugar maple that was cut a week ago and cut it into 7/8" X 7/8" strips and very wet. Normally I let them set for a couple months and then cut them blank size and let them set another few weeks. I check them by drilling for the tube and wait a week to see if the tube slides easy. If it does the wood is ready to use.

I would like to know if anyone here has put fresh cut wood in a vacuum to pull out some of the moisture to speed up the drying process?

 

[KenV]

Jim - I have not done it, but did research the technology a couple of years ago including going through the Forest Products Labratory publications on the topics, as well as pricing out the equipment needed to handle the volatile products that come with the moisture. The volatile byproduct are a challenge because they are not desirable to run through the vacuum pumps.

Those research suggested 26-28 inches hg vacuum. When I ran the numbers, for the small scale operation, the costs were outside practical.

My comparison was against small scale kiln systems.

The advantage went there in a hurry because case hardening is managed in most pen blanks with a tube to be inserted.

I have since set up a cactus juice stabilization system that has process requirements of oven heat at 170 until "bone dry".

If you go with an oven, have good temperature controls and sticker the blanks for air circulation.

 

[Sabaharr]

Better to wrap in a paper towel and put them in the microwave for 2 minutes on high for a few times. It will boil out the water and the paper towel will prevent it from soaking back in, mostly. I would only stabilize dry wood as any excessive moisture might contaminate the resin and certainly would not allow it to saturate into the wood. As a drying method vacuum would probably accomplish very little as the way it works is to remove air by expanding it. Water does not expand and flow freely until heated to steam. Call Curtis at Turn Tex (Google it) and he can explain the process in detail and answer any questions you might have, and he will enjoy doing it. He is a moderator on here.

 

[KenV]

Jim- you did not provide info on how many blanks you were planning to run. The smaller the numbers the higher the unit cost.

For a thousand a month, the costs per blank are a lot higher than for ten thousand a month.

For a few dozen a month the cost might pencil out for exhibition grade blanks with high retail value, but kiln processes would be a fraction of the costs.

 

[jrc]

I might stabilize a few dozen a month, mainly cherry burl that would not hold together turning. It would double or triple what I could get from some cherry burls. Can you stabilize pre drilled blanks? How many blanks can you stabilize with a gallon of C J?

 

[jrc]

I've dried blanks in a microwave before and just remembered why I stopped. I did it in the winter and had a strong unpleasant smell in my house for a day, the next batch I did crab apple and the smell was like I microwaved a baby's dirty diaper. Turning and sanding crab apple smells the same to me but not as strong.

 

[KenV]

Jim, be aware that cactus juice will fill small spaces between cells and tiny voids in punky wood. It will not fill voids and inclusions. It fills tiny tight cracks. It runs out of larger openings.

You may be looking at "worthless wood" processes to reinforce burl pieces with resins.


Sounds like a big dehydrator may be your target for a few dozen blanks a month.

Cactus juice consumption varies with the density of the wood.

 

[jrc]

Thanks for all the info. What's a good setup that's around $250. There is so many on eBay not sure how good they are.

 

[Sabaharr]

Turn Tex also sells the vacuum chambers in addition to the Cactus Juice resin. Curtis can set you up and answer any questions you may have. The customer service is top notch. You can get a vacuum pump anywhere. I am operating with a Harbor Freight pump now and it has worked fine for the last few years I have had it and they are on sale now too. AC supply houses will also have them. When it comes down to it the chamber is just a container that will hold the wood and resin with a sealable top and a valve to allow the air to be sucked out with a vent to open atmosphere. I built my own for $20.

 

[MesquiteMan]

I have since set up a cactus juice stabilization system that has process requirements of oven heat at 170 until "bone dry".

Ken, the temp requirement to get the wood bone dry is 217° F according to ASTM D4442. You have to exceed the boiling point of water to get all of the water out of the wood.

As a drying method vacuum would probably accomplish very little as the way it works is to remove air by expanding it. Water does not expand and flow freely until heated to steam.

Sabaharr, vacuum will indeed remove water. This is because water boils at 6° F (water temp) under a 29.87" Hg (quite achievable) vacuum. So, at full vacuum, you are turning the water into steam. Boiling requires different levels of heat at different pressures and is simply the point where the water vapor pressure is equal to the pressure surrounding it. If you were able to achieve a perfect vacuum (not achievable even in a lab), water would boil at any temp. Here is a chart that shows the boiling point at different vacuum levels. Water Boiling Temperature vs Pressure in Vacuum Table Chart | Engineers Edge

The problem with using vacuum to dry the wood is that it takes quite a while, typically 30 or more hours for pen blanks with the pump running the entire time. You also will most likely have to stop part of the way through to drain and replace the oil due to the water condensing in the oil.

The question of what can be stabilized...any wood or porous material that is not oily can be stabilized including antler and even rocks and minerals. Hard, dense woods will not pick up a lot of resin but can be properly and thoroughly stabilized. However, for pen making, a hard, dense wood does not benefit from being stabilized much, IMO. It depends on your objective for stabilizing. In pen making, we typically stabilize to make the wood harder and easier to turn. If you are wanting to stabilize to make the wood more resistant to changes in moisture, then even the densest stuff will benefit. However, as pen makers, our pens are typically not subject to harsh environments such as what knife makers deal with and we are able to apply a good finish that will seal the wood.

A typical pen blank will take somewhere between 1 to 1.5 ounces of resin on average. As mentioned, it highly variable though due to density of the wood being done.

 

[Sabaharr]

See, I told you he could answer your question. Curtis, do I get a free bottle of Cactus Juice for the commercial? Yeah, didn't think so.