Thermally Modified Wood for Interior Use

David Agnew

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Another finish question from the new guy...

I just picked up a few board feet from my local hardwood store. It's labeled "Cambia" and it's a very nice brown wood. Almost looks like Wenge. It was cheap at $4.99/bf. I came to find out that Cambia is actually a name-brand process for heat treating wood. It's designed as a no-chemical alternative to pressure treated wood. Meant for decks and outdoor furniture. The thermal process can be applied to many different hardwoods... poplar, oak, ash, etc. I think this particular piece may be poplar.

Anyway, I'm wondering if anybody here has used it for an indoor project, applied a furniture-grade finish, and can point me in the right direction for finishing. It's going into a cremains box for my soon-to-be-departed cat, so I want to apply a very nice gloss finish to it.

Thanks.
 
I have a friend who builds a lot of high end custom furniture from carmelized birch, which looks much like walnut after it is "carmelized." No issues working or finishing it. I will certainly try it when I have the opportunity. I expect the process is the same.
 
Charlie - Thank you. Using your keyword of "caramelized" I found a number of results. Apparently, "caramelized", "carbonized", "roasted", and "toasted" are other terms for this thermal process. Carbonized generally refers to bamboo, roasted/toasted to oak.

I found this thread on Sawmill referring to "Black Maple" including a picture. To sum it up, those guys say it's extremely dry, more brittle than un-roasted wood, and they didn't see the point in it. The topic of outdoor use didn't come up, which seems to be the current marketing angle on the product (affordable chemical free alternative to PT lumber)

http://www.sawmillcreek.org/showthread.php?120796-Black-Maple-Caramelized-Maple

Here are photos of my board:
W/ unfinished white oak, poplar, and QS Sycamore
di-KPXK.jpg


Close up #1
di-WBGP.jpg


Close up #2
di-RMID.jpg



The color was hard to capture. It's closer to brown than black. So more like cocobolo than wenge.

After handling it more and examining the grain, I'm almost certain the base wood is poplar. It has the exact same ultra smooth, almost suede-like feel as poplar and the few knots are very tight pins. The grain is muted.

I'll do a couple test pieces w/ BLO and Minwax oil gloss poly. I'm a rank finishing amateur, though....
 
David,

I own a "green" building supply center in Newark Delaware and have been selling Thermally modified lumber now for about a year. The piece you pictured does look like poplar. The most common species of lumber being thermally modified is Poplar, Ash, Gum and oak. Some companies are treating pine but in my opinion I would stay away from it due to it's high degree of sap. Your comments about being extremely dry and more brittle are correct. With that in mind, Thermally modified wood does not accept stain as well as non treated due to the collapsing of the cell structure which is part of the process that makes it more stable (less susceptible to moisture). It does glue up nicely but requires slightly longer clamp times - again due to it's non porous nature. If your going to be staining this piece I would suggest using a priming oil prior to the finish. I have had good success with OSMO Polyx hardwax as a finish. If your going to use a top coat finish like a poly than you should be fine with a sanded finish ready to coat. One of my favorite uses is interior 3/4" Ash hardwood floor that then was taken right outside as decking. It produced a very rich look. Hope this helps.
Reid




 

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That's some good info. Thanks for the pictures.

Well, I cut off some test pieces and am testing glue and poly. It cross cut and ripped very well. Even better than un-treated poplar. Very smooth, glue ready cuts with my blades that leave oak with a cut that needs a quick 120 grit clean-up. The smell was... interesting... almost like charcoal.

I'm a wipe-on poly guy, so I mixed up a bit of urethane with a smaller bit of mineral spirits, just like normal. Man, those other guys weren't joking about it sucking up finish. The fact grain sucked up the poly like it was end grain. Never seen anything like it. I wish I had a moisture meter so I could check out dry this stuff really is. It's quick dry poly, so I'll 220 it and add a second coat in about 4 hours.

I've also got 2 pieces cut at 45* sitting in a clamp. The Sawmill guys said it didn't take glue too well. They were right on that too. The end grain gluing was the opposite of the face grain sucking up poly. The glue didn't really sink in like I'd normally expect. I'll see how the glue holds up in the morning.
 
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