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Q: Tree log drying while in storage ( Answered ,   0 Comments )
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 Subject: Tree log drying while in storage Category: Science > Agriculture and Farming Asked by: hannsf-ga List Price: \$100.00 Posted: 22 Apr 2005 07:37 PDT Expires: 22 May 2005 07:37 PDT Question ID: 512675
 ```I need tables, or mathematical equations, that describe the drying rate (loss of moisture content over time) of logs while in log storage on land. Ideally this information is presented by tree species (major variable). Other variables may include log pile height, log length, log diameter, time of year (season/date).```
 ```Dear hannsf-ga; Thank you for allowing me to answer your interesting question. I?m afraid what you are looking for isn?t going to be nearly as easy as a single table that lists the drying rates of all species of logs. There are far too many variables to consider and one has to do some fancy elbow work to come to the most accurate conclusion. Hopefully what I have provided for you here will greatly decrease the amount of work you have to do on your own to calculate the drying rates. The equilibrium moisture content of living vs. non-living wood varies from one another as much as it does from one species to another. The type of cut, thickness, length, and circumference, etc. of the wood will also play a major factor. More importantly, the environment in which the wood is stored is a major factor as well, and will affect the drying rate calculations of any species, cut, thickness or viability (living vs. non-living) woods. The moisture content of wood is directly related to the humidity and temperature of the surrounding air so the drying time would depend on the environment as much (or possibly more) as any other factor. The best you can hope for in your search for a solution is an EMC (equilibrium moisture content) calculator, mathematical formula and shrinkage tables. Here is one such tool for non-living, (natural or cut) wood. It was created using information obtained from the U.S. Forest Products Laboratory: Wood Equilibrium Moisture Content Table And Calculator http://www.csgnetwork.com/emctablecalc.html (The mathematical formula is included) Here is another very similar one: WOODBIN: COMPUTING MOISTURE CONTENT OF WOOD http://www.woodbin.com/ref/wood/emc.htm The rate of drying is also known as ?moisture loss per day?. This is measured by ?shrinkage?. Here are some shrinkage tables in case they are of any use to you also. WOODBIN: SHRINKAGE CALCULATOR http://www.woodbin.com/calcs/shrinkulator.htm Domestic wood shrinkage values by species http://www.geocities.com/windyhilllogworks/shrinkagevalues0001.JPG Moisture content of green wood by species http://www.geocities.com/windyhilllogworks/Shrinkage10001.JPG You will also find some very interesting (and frankly, complicated) mathematical wood drying formulas in this document from the US Department of Agriculture. Also included are some very informative tables related to EMC at various times of the year and in various regions of the world: EQUILIBRIUM MOISTURE CONTENT OF WOOD IN OUTDOOR LOCATIONS IN THE UNITED STATES AND WORLDWIDE http://www.timberframe.org/fileuploads/Equilibrium_Moisture_Content.pdf Just when you think you might be on the right track to finding valuable information, my goodness, it becomes complicated indeed. Here are a number of tables that outline moisture contents by species, by electrical resistance along the grain, and other factors courtesy of Purdue University, Department of Forestry & Natural Resources. FORESTRY AND NATURAL RESOURCES http://www.ces.purdue.edu/extmedia/FNR/FNR-155.html I hope you find that my research exceeds your expectations. If you have any questions about my research please post a clarification request prior to rating the answer. Otherwise I welcome your rating and your final comments and I look forward to working with you again in the near future. Thank you for bringing your question to us. Best regards; Tutuzdad-ga ? Google Answers Researcher INFORMATION SOURCES Defined above SEARCH STRATEGY SEARCH ENGINE USED: Google ://www.google.com SEARCH TERMS USED: EQUILIBRIUM MOISTURE CONTENT DRYING LOGS WOOD SHRINKAGE FORMULA TABLE CALCULATOR``` Request for Answer Clarification by hannsf-ga on 22 Apr 2005 09:41 PDT ```Tutuzdad-ga: Thank you for your rapid response to my question. Thank you for the references and insight, however I note that your answer does not address the problem which is; The drying rate between Green moisture content and the Fibre Saturation Point and/or EMC. Your information is great for calculating what the EMC will become, but doesn't tell me the rate at which logs lose moisture from the green MC (sapwood can be from 75% to over 125% MC) through the Fibre Saturation Point (~30%MC) to finally achieve EMC. Sorry, I should have made my initial request clearer.``` Clarification of Answer by tutuzdad-ga on 22 Apr 2005 10:32 PDT ```Take a look at this document f rom the Oklahoma Cooperative Extension Service. There are two tables about midway down the page that show the average air drying time for various species (to achieve EMC) and a relative humidity EMC values chart. PRACTICALITIES IN DRYING LUMBER http://pearl.agcomm.okstate.edu/forestry/general/f-5042.html Let me know if this proves valuable to you. tutuzdad-ga``` Request for Answer Clarification by hannsf-ga on 22 Apr 2005 11:51 PDT ```Dear tutuzdad-ga: Thanks for this, however it deals with air drying of lumber which is quite different than logs, with bark on, in piles. Also, I'm not sure if it is a straight line decrease in MC/time (I suspect that loss of moisture is greater at start and then less as log approaches FSP). I notice that many of the measurements, in table 1, vary by an order of magnitude which doesn't help me much.``` Clarification of Answer by tutuzdad-ga on 22 Apr 2005 12:37 PDT ```Wow. It may be that what you are looking for doesn't exists in the broad spectrum. Maybe you can tell me what species and I will try and find the rate for that particular wood. tutuzdad-ga``` Clarification of Answer by tutuzdad-ga on 22 Apr 2005 12:43 PDT ```For example: ESTIMATING AIR DRYING TIMES OF SMALL-DIAMETER PONDEROSA PINE AND DOUGLAS-FIR LOGS. http://www.woodweb.com/knowledge_base/fpl_pdfs/fplrp613.pdf tutuzdad-ga``` Request for Answer Clarification by hannsf-ga on 22 Apr 2005 13:24 PDT ```Dear tutuzdad-ga: Your find on the air drying times of Ponderosa and Douglas-Fir logs is right on the mark. This would be suitable for a 2 star rating. If it is possible to find information, of the same type, on Aspen (I'm also looking for info on Lodgepole Pine, Balsam, Basswood, Birch and Tamarack = bonus) then I think this would be a 5 star answer, thanks!``` Clarification of Answer by tutuzdad-ga on 22 Apr 2005 13:51 PDT ```Ok. Please allow me a bit to see what I can come up with. Dad``` Clarification of Answer by tutuzdad-ga on 22 Apr 2005 18:24 PDT ```Because, I suspect, of the abundant technology, there just doesn?t seem to be a whole lot of information out there about air-drying nowadays when kilns, microwave and solar devices are becoming more popular. One of the best ones I can manage to find is probably more relative to lumber than poles, trees, or fresh felled timber, but it gives a great idea of the drying times of various species of wood. WOODWEB: ESTIMATES OF AIR DRYING TIMES -- FOR SEVERAL HARDWOODS AND SOFTWOODS http://www.woodweb.com/knowledge_base_images/zp/estimates_of_air_drying_times.pdf This one also pertains primarily to lumber but has some serious mathematical equations that may be of interest to you and applicable to timber. METHOD FOR ESTIMATING AIR DRYING TIMES OF LUMBER http://www.fpl.fs.fed.us/documnts/pdf2001/simps01c.pdf ( I found the article here: http://www.laymar-crafts.co.uk/linkr.htm ) Unfortunetly, search as I might, I have been unable to discover any other documents similar to the one I provided you with earlier. Having said that, I may have to accept whatever rating the information I have supplied will earn me, though I have tried diligently for hours now to find more satisfactory data. I do think that you may have some success by contacting the AMERICAN WOOD PRESERVERS ASSOCIATION as inquire with them about any published data they may have on the subject. I cannot be certain but I suspect that they may be able to help you further. AMERICAN WOOD PRESERVERS ASSOCIATION P.O. Box 388 Selma, AL 36702-0388 USA Telephone: 334-874-9800 Facsimile: 334-874-9008 Email: mailto:email@awpa.com Site: http://www.awpa.com/ I hope this earns a decent enough rating in spite of our mutual disappointment in the lack of data available on the subject. Regards; Tutuzdad-ga```
 hannsf-ga rated this answer: ```Although I didn't get my question fully answered, Tutuzdad did provide seveal useful further avenues of research to pursue and some good insights into the paucity of information available on my question.```