Home-Built Dehumidification Kilns Here's a long discussion of small, inexpensive dehumidifier kiln design, including a consideration of the fire risks involved. September 17, 2012
Controlling Drying Conditions and Monitoring Progress Here's a lively, sometimes contentious, and very informative thread about how to ensure quality control when drying lumber in a variety of different kiln types with different control systems and instrumentation. July 16, 2012
"Intermediate Conditioning" in the Drying Kiln Is it a good idea to add moisture to a kiln for a period during the middle of the drying cycle, in order to relieve casehardening stress? June 13, 2014
Dry Kiln Information Resources A list of clubs, organizations, books and publications providing information about drying lumber for use in woodworking. 1998.
Blue-Stained Pine Pros and Cons Controversy simmers over whether blue stain is is a special value, a visual defect, or a mold liability risk. September 17, 2008
Developing Software to Calculate Wood Kiln Schedules The wood drying process is complex, and involves many inter-related variables. So creating software to determine drying schedules is a challenge. June 13, 2014
Kiln Drying Large Timbers An extended discussion of the technical issues involved in drying big beams for various uses. July 28, 2006
Why Insulate a Solar Kiln? A long discussion delving into the mechanics of how a solar kiln creates proper conditions for drying wood. January 28, 2014
Stickers and sticker shadow A discussion on synthetic and traditional stickers, and an explanation of reverse sticker shadow. May 30, 2001
Kiln Control Technology and Drying Parameters This mostly hypothetical discussion develops into a back-and-forth about whether wood stress should be used as a determining factor in kiln control systems. June 13, 2014
Choosing a Moisture Meter A well-informed discussion comparing the cost and characteristics of various pin and pinless moisture meters. October 11, 2012
Wet Pockets in Kiln-Dried Wood Bacterial infections can cause streaks of 30% moisture content in wood that is mostly at 7% MC. March 4, 2009
Monitoring Moisture Content During Kiln Drying At the critical early stages when wood moisture content is high, moisture meters are not accurate. Here are tips on keeping track of moisture throughout the drying process. May 17, 2011
Building a Small Drying Kiln A long discussion of the considerations involved in building and operating a small backyard or garage kiln. August 8, 2008
Wood and Water An excerpt from Gene Wengert's book, "Drying Oak Lumber." May 31, 2001
Is Kiln Drying to 7% Worth It? Why kiln dry wood to 7% moisture content when it will gain moisture in storage? Here's an informative thread about proper drying targets and storage based on the intended end use of the lumber. December 31, 2013
Troubleshooting Drying Stress Some general instruction about the causes of drying stress for the owner of a dehumidifier kiln. April 2, 2013
Mixed-Species Loads and Moisture Equalization Kiln-drying Spruce and Fir together creates difficulty, because they dry at radically different rates and because there is moisture transfer between boards. June 13, 2014
Over-Drying and Wood Quality Kiln operators discuss what happens to lumber when you overshoot your moisture content target. February 14, 2006
Hairline Cracks in Kiln-Drying Cherry Checking in Cherry appears as a fine crack, and is the result of too-fast air-drying, not kiln-drying. April 15, 2012
Solar Drying Kiln Q&A Basic questions and answers on vent sizing and temperature conditions in a solar kiln. January 18, 2011
Steaming, Drying, and Honeycomb in Walnut Bacterial infection as well as steamer and kiln settings may have caused reported honeycombing at one end of thick Walnut boards. June 18, 2009
Air Flow Meters for Kilns A discussion on the state of technology for monitoring airflow inside a kiln during drying, and about whether the data is useful in any case.June 13, 2014
Minimum Sticker Thickness How thin can stickers be in order to maximize kiln capacity without creating drying problems? May 11, 2005
Making a Drying Kiln from an Insulated Truck Body This conversation touches on the quantity of heat needed to dry a load of wood, the advantage of using a dehumidifier, and the possible issues with corrosion. April 18, 2015
Keeping lumber flat during drying Advice from Professor Gene Wengert on drying lumber in order to produce flat, true boards. December 12, 2000
Test for Honeycomb A method for testing dried lumber to detect honeycomb, with advice on how to prevent the checking that leads to honeycomb. June 13, 2014
Pricing for Kiln Drying Sawmillers share numbers on kiln-drying service charges. November 14, 2009
Finish Over Air-Dried Pine Soft resin and volatile natural solvents in softwoods will interfere with finishes unless the wood is kiln-dried at a high enough temperature to "set the pitch."August 17, 2009
Vacuum kiln drying How do vacuum kilns work and how effective are they? (From WOODWEB's Sawing and Drying Forum) January 21, 2003
Vacuum Kiln Principles Vacuum kilns cause evaporation at low temperatures, but they still require heat — and that heat is tricky to supply because of the vacuum. Here's an explanation. July 29, 2011
Drying Eucalyptus Eucalyptus is a fussy wood to air-dry or kiln-dry. Here are some clues about its character. October 14, 2006
Vacuum, Dehumidification, and Microwaves — in One Kiln? Here's a long, highly speculative, but informative discussion of the concept of using microwaves, vacuum, and dehumidification for drying wood in a prototype kiln. April 20, 2011
Drying Ash Flooring Kiln-drying is essential to kill bugs and achieve the proper low moisture content for stability in service. May 11, 2005
Acid Condensation Issues with Drying Kilns This discussion of drying Oak for iron-and-wood furniture purposes takes an interesting detour into a discussion of acidic conditions in wood and kilns. October 15, 2010
Fan Speed for Solar Kilns Advice on maintaining appropriate air flow over the stack in a solar drying kiln. March 26, 2013
Causes and cures for sticker stain The Wood Doctor weighs in with comprehensive information about the causes and prevention of sticker stain. 1998.
Using a Corn Drier as a Kiln Lumber drying is a controlled process, that an agricultural corn dryer probably cannot accomplish correctly. February 15, 2009
Using Outdoor Cold for Drying Dehumidification Unlike a powered dehumidifier, a cold kiln wall dumps heat to the outdoors, and so expends energy just as venting does. Here's a long discussion of alternatives to heat for kiln drying, and why they're mostly not practical. April 10, 2007
Is it Worth Kiln-Drying Firewood? Considering the cost of kiln construction and energy inputs versus the value of extra-dry firewood, it's hard to see how the dollars make sense. January 27, 2008
Air-drying oak Can a suitable MC for cabinet construction be reached? February 6, 2002
Sizing Up a Kiln This question about how to assess the worth of a used kiln leads to a discussion of kiln technology in general, including the different requirements for drying softwoods and hardwoods. October 17, 2012
Case Hardening Explained A semi-technical discussion about how the wood drying process can create stresses between interior and surface wood layers — and about how to reduce or prevent that situation. January 19, 2012
Double-Checking Moisture Content You can check your moisture meter by drying wood samples and weighing them, but the method has its own uncertainties and imprecisions. August 29, 2006
Drying Lodgepole Pine in Colorado Detailed advice on air-drying and kiln-drying lodgepole pine (some logged green and some killed by beetles). April 21, 2008
Monitoring Progress in a Dehumidifier Kiln Collecting and measuring the removed water is not a reliable way to gauge drying progress, especially when drying mixed thicknesses of wood. June 4, 2012
Tension Set and Lumber Conditioning Advice on remediating curved lumber after resawing, with a discussion of why "tension set" occurs and how the effect can be reversed. October 19, 2013
Dead Standing Douglas Fir: Is It Dry Already? A discussion about the useability of wood from dead standing tree logs without further drying, and a little bit of kiln-related history. April 27, 2007
Size effect on shrinkage Are traditional shrinkage values applicable to drying large cants? May 9, 2001
Checking in Oak A discussion of kiln conditions and other factors that can cause Oak to check while drying. October 29, 2008
Miniature Solar Kilns Very small solar kilns are indeed practicable, if you only need to dry small pieces of wood. December 31, 2012
Reconditioning of Collapsed/Washboard Timber Collapse of sawn lumber during drying is a rare event. Steaming may help prevent the problem, and to some extent cure it. January 12, 2015
Is Dehumidifier Kiln Wastewater Safe? Don't assume that it's safe to dump kiln water to the environment. There could be some contamination. March 10, 2008
Moisture Variations in Dried Lumber "Wet pockets" in kiln-dried lumber, or occasional wet pieces of wood in a load of dried lumber, are an unacceptable defect.June 13, 2014
Solar Kilns and Wood Sterilizing Solar kilns don't get hot enough to sterilize wood (for that you should have an artificially heated supplemental chamber).July 7, 2011
Shopping for a Dehumidifying Kiln If you consider getting a European-made dehumidifying kiln for use in the U.S., make sure it's compatible with U.S. power supply voltages. June 16, 2014
Understanding Drying Stress in Wood A complaint about cupping in mahogany door stiles after machining leads to a discussion of what causes drying stress and related movement in kiln-dried wood. June 23, 2006
Venting and Fans for a Solar Kiln A quick expert explanation from the Wood Doctor of how and why vents and fans are used in a solar wood drying kiln. April 20, 2011
Kiln Drying Color Change Experts and sawyers discuss the various reasons wood from the same batch might end up with slightly different colors. September 6, 2010
Reducing warp during kiln drying Weights? Restraints? What are the best methods for preventing warp in boards near the top of the drying stack? February 13, 2001
Spots revealed in dry, planed lumber Dr. Gene attempts to find the causes of discolored spots on dried lumber, revealed only when the stock has been planed. 1998.
Tips for drying butternut burls Butternut burls are dried much like regular lumber. Also, a source for further information on drying burls. 1998.
Stained oak from supplier There are solutions for stained, milled, not-yet-dried oak lumber, but first , one must determine the cause of the staining. 1998.
Phytosanitary Standards for Lumber Export A little information about heat-treating and labeling requirements for wood pallets and lumber destined for export overseas. July 26, 2010
Beetle Troubles Tips on dealing with lyctid (powderpost) beetles and the less troublesome anobiid beetle. April 27, 2007
A Small Kiln for Final Drying A woodworker needs to get his already kiln-dried stock down to lower moisture content to match indoor end-use conditions. Here's detailed advice for equipment choice and drying methods for a small-batch wood-shop drying chamber. May 9, 2007
Dehumidifier Kiln Advice Detailed conversation about building, equipping, and operating a dehumidifier kiln to dry lumber. September 10, 2007
Self Air-Drying Versus Kiln-Drying Carefully air-drying wood yourself may be preferable to trusting the load to a less-than-perfect kiln-drying operation. January 18, 2011
Warp in Drying Causes and cures for warpage when drying lumber. May 4, 2001
Eradicating an Insect Infestation A load of insect-infested reclaimed wood may have contaminated a whole operation. What to do? April 20, 2011
Temperature, Humidity, and Drying Some generic head-scratching over relative humidity and the heat required to dry wood under various conditions. April 10, 2007
Drying with Moderate Heat Here's info on how various types of wood will respond to conditions in a home-built drying room that doesn't get much warmer than 120°F. There's a useful lecture here on how case-hardening occurs. May 16, 2008
I've Got that Shrinking Feeling Specific information on lumber shrinkage during the drying process. Includes 'typical shrinkage' tables for red and white oak. 1998.
Water and Wood Some options for measuring moisture in lumber during the kiln-drying process. 1998.
Is Vacuum Dried Wood Stronger? With so many variables to control, it's hard to be sure whether any particular drying system gives better results in terms of wood properties. October 29, 2012
Drying Rewetted Kiln-Dried Lumber How to render kiln-dried lumber, which has been rewetted due to flooding or excessive humidity, useful once again. 1998.
Lumber Conditioning Advice Info on mixed loads, re-wetting dried lumber, and related topics. September 25, 2014
Treating Air-Dried Wood with Pesticides Surface-applied pesticides may be dangerous or even illegal, and will probably do no good. Instead, heat-treat wood to kill bugs. February 14, 2006
Managing Airflow in the Pre-Dryer Advice on using temporary baffles to keep air flowing through the remaining stacks as some wood is removed. June 13, 2014
Kiln Humidity Monitoring: In-Flow or Out-Flow? Standard practice is to monitor the characteristics of air before it enters the pile, but monitoring exiting air could work under some circumstances. July 29, 2012
Lowering Wood Moisture Content A woodworker has some lumber at 12% moisture content that he wants to dry down to 9%. Here are some quick and cheap ways to accomplish that. October 19, 2013
Troubleshooting a Dehumidifier Kiln A newly acquired (but secondhand) dehumidifier kiln has some performance issues, and the Sawing and Drying forum offers advice. March 26, 2013
Drying Time for 6/4 Red Oak Here's a quick technical look at the factors affecting kiln drying 6/4 Red Oak, including kiln type and initial moisture content. Air drying may be more cost-effective. July 16, 2012
Determining MC by weight Tools and techniques for measuring moisture content by weighing lumber cuttings. January 4, 2001
Drying Willow in a Solar Kiln Challenging scenario: a tricky wood to dry and a difficult kiln to control. February 14, 2010
Solar Kiln at Work Here's a look at a newly completed backyard solar wood drying kiln with its first load of lumber. March 28, 2012
Fans Size and Drying Kiln Dimensions Considerations regarding fan capacity, kiln size, and lumber pile size in a dehumidfying kiln. January 25, 2010
20 Steps to Drying Hard White Maple The Wood Doctor's 100 percent guaranteed, sure-fire, no-snake-oil method for successfully drying hard white maple. 1998.
Challenges of Drying Eucalyptus Many ways have been tried to prevent Eucalyptus wood's tendency to warp and check, but none have proven to be highly successful. February 29, 2012
Growth Stress End Checking Log characteristics can cause checks to open up, even when ends are coated and drying conditions are correct. February 19, 2006
Cause of Loose Knots in Pine Looseness or tightness of a knot in Pine is a characteristic that is formed during tree growth, not a product of the kiln process. June 13, 2014
Wood weight and highway transport How to accurately estimate the weight of a truckload of air-dried lumber to assure compliance with trucking regulations. Includes access info for resources. August 1, 2000
Kiln Drying in a Heat Wave When conditions are wrong, a solar kiln can easily be too hot for good results. Here are tips on controlling drying conditions during hot weather. May 15, 2012
Worm Holes in Mahogany Worm holes aren't always considered as a defect in Mahogany, but they do leave you wondering whether the critters will come back. July 30, 2007
Slippery kiln-dried wood What could make dried wood so slippery that it is difficult to machine? August 12, 2001
Adding Fans to a Dehumidifier Kiln Is it worth it to exceed the design air circulation in a dehumidifier kiln? By the numbers, probably not. May 15, 2012
Dark Core in Soft Maple A kiln operator finds that his maple boards develop a light surface and dark core. Others weigh in with thoughts and advice. August 31, 2005
Wet Pockets in Infected Wood Bacterial infections cause wet pockets to remain in kiln-dried wood. Bad smells and other characteristic symptoms are described here. July 28, 2006
Drying Horticultural Maple Specialty Maples used in landscaping dry like other Maple, but the wood tends to be twisty. June 16, 2014
Drying Loads with Mixed Moisture Content It's a balancing act — you have to watch out for the drier wood causing the wetter wood to dry too fast and check. October 4, 2011
Salvaging lumber from submerged wood The best chance for salvaging lumber from submerged wood lies in cutting it quickly, and drying it slowly. 1998.
Bowing in Pine Staves After Planing Here's a good explanation of why lumber may move after being planed — and why that is not easy to correct. January 20, 2010
Pricing for Kiln Drying Lumber Here are pictures of a drying kiln building under construction, with commentary on how to charge for drying wood with a dehumidifier kiln. December 8, 2012
How to Prevent Drying Stress A quick explanation from the Wood Doctor of what causes drying stress, and how to prevent or reduce it. August 15, 2011
Bug Control in Ash and Oak Details about the heat conditions required to kill insects in a load of lumber being kiln-dried. March 28, 2012
Holly Staining: Fungus or Pigment? Holly stains if it's not dried quickly and properly. But what's the real cause? A scientist weighs in on samples collected by a sawyer. July 12, 2005
Setting Pitch in Southern Yellow Pine You have to heat the wood to 160°F to set all the sap. Otherwise it will ooze out, even through shellac or other sealers. February 9, 2008
Cupping and Bowing in Resawn Stock Furnituremakers discuss drying issues such as casehardening that can cause lumber to move when ripped or re-sawn. April 18, 2015
Air-Drying and Kiln-Drying 8/4 Oak Experts and kiln owners discuss the proper drying schedule and the best equipment for drying thick Red Oak boards. August 13, 2014
Drying wood in a tent Recommendations on how to use the sun's rays and a plastic tent to dry lumber. November 7, 2001
Why is Walnut Purple Sometimes? The purple color of some Walnut boards is natural. Here's more background with comments and observations from woodworkers. February 16, 2014
Elevated Moisture Readings after Planing Wood that is not uniformly dry will read higher after planing; and the results vary between pin meters and pinless models. June 4, 2012
Running a Solar Kiln Advice from old hands on operating a solar kiln. August 22, 2005
Selecting Fans for a Solar Kiln Advice on picking fans that will move the right amount of air and not fail from overheating. February 8, 2008
Storing Maple in Partially Dried Condition A woodworker gets advice on the feasibility of maintaining wood at 25% moisture content for use in drying operations. January 8, 2010
Maple Color and Drying Conditions Maple can turn gray as it dries. If you want white wood, you have to carefully control the kiln conditions. July 30, 2007
Drying Schedule for Red Oak Advice for a kiln operator on drying rates and humidity and heat settings for drying Red Oak in a dehumidifier kiln. October 3, 2009
Sizing Up Dehumidifier Kilns Thoughts on the objective characteristics to consider when evaluating which dehumidifier kiln is right for you. April 11, 2008
Dehumidifier Kiln Drying and Insects Cooler temperatures in a DH kiln aren't a reliable way to kill all insects, but the dryness will get some of them. May 18, 2010
Drying Technique and Wood Hardness Those in the know describe the effects of case-hardening (a drying defect) and how to diagnose it, as opposed to hardness that would affect machinability of wood. July 30, 2007
How to Eliminate Beetles in a Finished Slab Heating in a kiln to 130 degrees Fahrenheit will destroy the finish, but it's the only sure, safe way to kill the bugs. June 18, 2010
Mold on Southern Pine The wood doctor explains why Southern Pine supposedly dried to 18% moisture content would still support mold after being stacked inside a dried-in house under construction. January 25, 2013
Mahogany Honeycombing Defect Honeycombing that appears after planing is typically a drying defect — similar to end checking, but different. April 17, 2009
Drying to ISPM 15 Specs Wood for foreign-bound pallets and crating needs to be heat-treated according to International Standards for Phytosanitary Measures (ISPM) criteria. There's a strict standard and a verification requirement, so it's not a casual undertaking. August 29, 2006
Checking of Dry Lumber Checking occurs when the wood is very wet. Checking that appears in lumber purchased as kiln-dried is a defect. December 8, 2012
DH kiln preferences A look at dehumidification kiln construction, and manufacturers of DH units. July 26, 2000
A good, cheap end sealant? A discussion of the pros and cons of various sealants used on ends of boards in primary lumber processing. April 22, 2000
Drying Logs for Cabin Construction Advice on drying logs for cabin building, including how long to expect air drying to take and how hot to heat logs to set the pitch. October 19, 2014
Kiln Baffle Material Canvas or carpet works well for directing air through the wood stack in a kiln. January 14, 2009
Variable Speed Fan Efficiency People do drive their kiln fans above rated capacity sometimes, but it's an inefficient use of energy. June 13, 2014
Wood Moisture Content and Equalization Understanding how to evaluate wood moisture content when conditions have created a moisture gradient within the wood. April 11, 2008
Thinner Sticks in the Lumber Drying Pile Reducing the thickness of spacer sticks in the lumber stack could reduce the drying effectiveness of the system and create quality issues. October 19, 2014
Moisture transfer in humid climes Do tropical and sub-tropical species re-absorb moisture when left in their humid, native lands? September 6, 2000
Wet bulb, dry bulb An explanation of the terms "wet bulb" and "dry bulb" in reference to temperature measurement, and their particular usefulness. March 6, 2000
Mixed Drying Loads Mixing wood of different moisture contents in the same kiln load causes big problems, but mixing different lumber species at the same moisture content can be okay. May 15, 2012
Heat Control in a Dehumidifier Kiln Understanding how supplemental heating and the compressor's heating effect interact in a dehumidifier kiln. February 15, 2009
Bugs in air-dried ash Can a stack of ash be saved from an infestation of powderpost beetles? June 20, 2000
Basement drying basics The Wood Doctor prescribes proper drying procedures for a small batch in a basement. June 21, 2000
Heat Treating Wood for Overseas Shipment The rules for heat-treating lumber for shipment overseas are impracticable because of the likely damage to both the lumber and the treating kiln. January 12, 2015
Peruvian Walnut Drying Defects Peruvian Walnut shows wide variability, which can create drying and machining difficulties. June 13, 2014
Preventing Sticker Stain Stickers should be kiln-dry, and quickly pre-drying boards on end can help. August 31, 2005
Bug Control: Pesticide, or a Salamander Heater? Warnings: Pesticides will likely not penetrate lumber and kill a particular pest, and heating wood with fuel combustion exhaust can cause discoloration. January 28, 2014
Pause button on kiln? Is lumber adversely affected if drying is suspended late in the kiln schedule? August 1, 2000
Boiling Wood Boiling wood before drying has various effects on the outcome. May 23, 2011
Kiln velocity and sticker thickness The necessary volume and velocity of air exchange, and sticker size, for a small dehumidification kiln are discussed. November 29, 2000
Mold on Green Lumber Quick drying should contain most mold problems encountered on freshly-sawn green lumber arriving at the kiln. June 13, 2014
Brainstorming About Vacuum Kilns Inquiring minds discuss why vacuum kilns are so expensive, how they work, and the possibilities of building your own — or even improving on the concept. July 30, 2007
Vacuum kilns Choosing between a vacuum and dehumidification kiln. July 24, 2001
Dehumidifier Kiln "Hanging Up" Dehumidifier kilns sometimes stall as moisture content readings get closer to the target. An extra shot of heat can help a lot. July 3, 2008
Moisture content for exterior doors Determining the appropriate MC for lumber that will be exposed to vastly different humidity levels. November 14, 2001
Wood Worms White worms in reclaimed lumber intended for furniture. What to do? April 20, 2011
Controlling Bugs in Finished Furniture Fumigation or spraying are ineffective and have drawbacks. Instead, here's a tip for heat-treating furniture. April 24, 2013
Redrying 4/4 Hard Maple Tips for re-drying a load of wood that got wetted by rain, without incurring damage. December 31, 2013
Promoting blue stain How to promote this visual effect in a stack of red pine. March 21, 2002
Protecting Fresh Wood from Bugs Chemical means have drawbacks and are not very effective. So good drying and careful hygeine in the the yard are your best methods for keeping wood bug-free. April 20, 2011
Pink Stain in White Ash Pink fungal staining is tough to bleach out, and may be allergenic. March 9, 2010
Managing Fungus on Cedar Advice on handling and cleaning a Cedar slab that wasn't properly dried and now harbors fungus. October 19, 2014
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