My apologies to all if this has been covered–I didn’t find it in archives.
Ansell Adams used a microwave to test “dry down” of blacks and greys on paper for paper exposure before doing a bunch of prints. The were silvers in the papers, but so limited that it didn’t cause a problem. Probably no more than the heavy metals in BLO.
Has anyone used a microwave on test finishes to assess the end results of a particular depth of saturation, look of multiple coats, etc?
I’m not talking high heat. Just enough to accelerate drying. more in the “clarifying butter range”— 15% to 25% power Not enough to ignite BLO or even enough to change the moisture content of the wood.
I’m in the Pacific Northwest, on the wet side (very high humidity) but even with a heated shop, it takes about a lot of additional time to dry finishes. I’m trying to find a simple solution as I do a lot of finish testing and it really consumes time.
—She says the microwave is one thing but putting them in the smoker is not an option 🙂
Thanks to all
John
Replies
Keep in mind that microwave ovens don't work like a normal heat source. Depending on their chemical make up, some things get hot, other things do not. The microwave frequency of a microwave oven is tuned to the absorption frequency of water, so that's what gets hot. Pure oils typically will not get that hot. Some plastics (e.g., melamine) get hot, others (e.g., polyethylene) do not.
All of the above is a long-winded way of saying that it might work, but it's probably not a good approximation to what will actually happen to the finish under "normal" conditions. You'll likely drive water out of the wood into the finish, with possibly unpleasant results.
-Steve
Thanks Steve,If the power were extremely low-just enough to exite the water molecules, would that not in turn heat the wood, in turn promote the reaction?
Just enough to slightly warm the wood. As I said, not enough to change the water %.
I'm thinking, this is just what happens over time (other than the water and the cells both warming or cooling together naturally)? I'm mostly thinking of depth of color with thinned BLO, or multiple BLO saturations or and a single very long BLO saturation.
I'm only thinking of testing, not doing.
If the results were close to ballpark, I would do normal application tests to fine tune as I would also do the actual finish.
Your input would be appreciated.Thanks again
John
On very low power, you'll probably be okay. And you're right, you'll mostly just raise the temperature a few degrees overall. But no guarantees. ;-)
-Steve
Steve,
Thanks for your input. If I can get a repeatable system going, I'll let you know the setup.John
Do you think a hair dryer might be a gentler, more controllable option?
Possibly gentler, and a good thought, but I'm not sure quite as repeatable given a microwave's repeatable power settings et all. Which begs a second question on BLO, that of when do you know it's absolutely dry and ready for recoat? When it's not tacky, when no bleed back oil is present? When it looks nice and no smell....When....Now you have me thinking of a controlled oven...Maybe the smoker wasn't such a bad idea. Straight time/temperature...
Thanks
John
I would think the issue is the material that is deeper in the pores of the wood. I would normally wipe it several times during the day and then let it go overnight to see if any more works its way to the surface. Since I am not on as tight a schedule as you mention that you are, I have no problem waiting. What to do in a production environment is beyond my experience. Sorry.
What about a de-humidifier in the shop?
Alan - planesaw
Maybe, but the humidity inside isn't that unreasonable. What I'm really trying to do is to set up a more rapid repeatable finish testing process independent of shop conditions. I don't mind how long the actual finishing in the shop will take. Whatever it takes it takes. The de-humidifier is a good idea though.Thanks for your thoughts
John
I do it with small pieces that are green. After I get them dry I finish them while they are still warm and sometimes put them back in for rewarming. For larger pieces my infrared lamp is great and even just a standard desk lamp is good for small parts. The car dash is pretty great (except in winter) for drying the walnut oil I use to finish my spoons (speeds things up about 10x to 12x).
had not thought of the infrared. This would be just for small parts.
might work
ThanksThe car is really highly innovative but I'm not sure It would work on the consistent requirements :)
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