Acid, Aluminum, Oak, and Kiln Durability

The acids in Oak can attack aluminum kiln components. Here's advice on managing the problem. July 15, 2012

The aluminum walls, mandoors, and load doors of our oak kilns deteriorate much quicker than our other kilns (kilns that we predominately run cherry, maple, poplar, etc.). I am sure this is due to the acid present in the red oak. This becomes an issue when we are talking $20,000 to replace a load door.

Does anyone out there have a solution or a process in cleaning out/washing down your kilns (baking soda solution, etc.)? Also, how often do you do it? Just looking for something to prolong our kiln life and maximize our profitability.

Forum Responses
(Sawing and Drying Forum)
From contributor T:
I've read others have this issue also. Would a truck bed spray like Rhino Liner or Line X be durable to resist the acid long term?

From contributor R:
Do any of your kilns have a kiln coating on them? If not, it would be a good idea to look into it. Many kiln manufacturers recommend having a coating applied to the insides of the chambers, especially kilns targeted to dry oaks. There are numerous companies to purchase this product from and there are equally as many that provide the services to apply it.

From Gene Wengert, forum technical advisor:
Do you have kiln walls that are sealed well? Indeed, the acids in the oak can cause a problem. However, you can also get boiler water carryover in a spray line. Do you keep the steam spray turned off until equalizing and conditioning? If you have to run the spray line, then it is likely that you have poorly insulated doors. As suggested kiln coating can help if there is no other issue.

From Gene Wengert, forum technical advisor:
One popular product design for kilns rather than a generic tar coating is Pace Product's Silver Linier. Note that a key is to seal the joints in the door (and wall and roof, if coating them) as moisture can enter the wall through an unprotected joint and the water will then sit against the aluminum panel forever and lead to deterioration that seems to come from the inside of the wall.