Replies

1. 
   StanleyNiemiec | Jul 17, 2002 02:17am | #1

   Just having a "kiln" will not necessarily guarantee that you will be able to dry wood successfully.   What is necessary is capacity to develop appropriate schedules that are within the limits of your equipment.

   The Dry Kiln Operator's Manual (DKOM) from the USDA Forest Service is a necessary reference.  I likewise recommend you get another FS publication entitled "Dry Kiln Schedules for Commercial Woods (USDA FS Forest Products Lab - General Technical Report FPL-GTR-57).  Somehow you will have to learn how to take an existing established schedule and be able to modify it within the appropriate temperature range of your kiln.

   Additionally you will have to understand the concepts of conditioning and equalization.  These are the last two steps in a kiln schedule and are necessary to relieve drying stresses and to balance the MC of the kiln charge (load).  This requires adding moisture and you will need to have capacity for doing this.  If you don't then you are likely to get a fair amount of case-hardened wood that will be very prone to warp during and after machining.

   I would recommend that you build in capacity to use the chamber for sterilization.  Off the top of my head, I seem to recall that the FPL recommends a minimum internal wood temperature of 125 degrees F held for 48 hours.

   Do not underestimate the importance of air velocity and your ability to control it.  Temperature and humidity will establish the gradient but it is the moving air that does the work.  If you have insufficient air flow, you will incubate bacteria, molds and mildews; too much air flow will accelerate drying beyond acceptable limits and will cause checking, splitting, honeycomb and collapse.  In the best of all possible worlds, the fans should be reversible so that you do not favor one side of the charge over another.

   I have not seen the article you are referring to but from what I know about most small dehumidifiers (eg Sear's units) the humidistatic controls are not sufficiently wide.  You will likely need to control humidity between 98% and 15% and as such will need to locate a better control.

   Forget about light bulbs and find some other way to generate heat.  I would recommend some enclosed heating element.