Frequently Asked Questions

Choose from the following topic areas or enter a keyword in the box below. You can post a question using our Ask the Expert form.
Drying wood (kiln schedules, solar or DH kilns, etc.)
Wood-moisture relations (shrink/swell, fungi, etc.)
Stain/discoloration (from mildew, fasteners, or during kiln-drying)
Wood preservation/durability (toxicity of chemicals, natural durability, decay, etc.)
Insects (powderpost beetles, risks of leaving bark on logs, etc.)
Biomass (BTU value, biofuels, estimates of available volumes, cogen, etc.)
Industry directory (finding log buyers, custom sawmillers, posting Classified Ads, etc.)
Grading (log and lumber)
All Topics

Recent Questions

Q: At what temperature does pitch in ponderosa pine get set? Can it be reliquefied after its been set? 

A: Setting pitch requires driving off the volatile compounds (turpentine, for example) that allow the pitch to liquefy. The pitch is 'set' to the highest temperature you reach; that is, if the wood gets hotter in-service than the hottest it got in the kiln cycle, the pitch will liquefy again. So in that case, the hotter the better. The USDA Dry Kiln Operators Manual recommends setting pitch early in the schedule with high temperature (though they do not specify any specific temperature). To minimize checking of course, you would want to use high humidity as well - so, steam injection may be required. The schedule should finish at at least 170° F.  
Q: I want to reproduce an old wood railroad brake stick which is about 48 inches long and looks like a baseball bat but is rectangular in cross section not round. They were used to turn the manual brake wheels on railroad cars. My brother is head mechanic at our local railroad museum and this is a present. My question is should I use tough ash, soft ash, or hickory or something else? Thanks so much. 

A: There’s an article in the May 1913 issue of Popular Mechanics that states that hickory was the species of choice for railroad brake clubs. They should be made of "straight-grained, split hickory, entirely free from knots, splits, and like imperfections." 
Q: I was reading about Promontory Summit and the Transcontinental Railroad and the tie that was used was California Laurel wood. What is the more common name for this species and where can I purchase some? 

A: This is one of those species that goes by at least a couple names – California-laurel as well as Oregon myrtle or Oregon myrtlewood (or simply myrtlewood). See our species page for some information on the species. You can find a list of firms that buy myrtlewood logs in our forestry industry directory under myrtlewood log buyers. While not all of these firms will produce lumber (some may just chip low quality logs for pulp), it’s at least a starting point. It’s a fairly small tree with a niche market; it’s more often used to make gift items than for lumber.  
Q: Can Rayon and more importantly, Lyocel/Tencel be made from wood? What\'s the state of research on fiber from wood? Feasible? China uses bamboo as raw material for Rayon and Lycel also.  

A: Yes indeed, rayon and lyocell/tencel are made from wood and as far as I know, wood was the original source for rayon. This is a special type of chemical pulp known as dissolving grade pulp. Tencel mentions the use of wood on their page at http://www.lenzing.com/en/fibers/tencel/applications/more/tencelr-technical-fiber.html There used to be a mill in Ketchikan producing pulp for rayon, but they closed years ago. And in general, it seemed like the US was shifting away from dissolving grade pulp – until recently. Recent news suggests that at least a mill or two are shifting back into that market. See: http://www.naylornetwork.com/PPI-OTW/articles/?aid=159198&issueID=22347 (Cloquet, MN) and a bit closer to home in the Pacific Northwest: http://www.oregonlive.com/business/index.ssf/2011/06/cosmopolis_pulp_mill_shipping.html (Cosmopolis, WA)  
Q: I have air dried white ash that is at 12% moisture. I plan on cutting to near finished size, then standing it vertically in a wood chamber with an electric heater on a timer placed at the bottom of the chamber. The chamber would be about two foot square by about 4 foot tall. Would this dry the lumber to about 6% over a 2-week period. 

A: Given that you are already at 12% and that the chamber is so small, I would expect it would get to 6% pretty quickly. Specifically how fast, will depend greatly on the thickness and width. Is this 4/4 material that is 4 inches to 6 inches wide and narrower? If so, I would expect 2-3 weeks under the conditions you describe. However if this is thick, wide stock, it could 6-8 weeks or longer. Also, do you have a fan to keep the air moving? Are the ends of the lumber coated to prevent splitting (though much of the checking likely to occur would have already happened – i.e., more from green to 12% than from 12% to 6%).