How Effective is End Coating Lumber?

Is end coating a worthwhile technique to reduce end checking in air drying oak lumber? We paint the ends of our kiln dried lumber when we package it for shipment but haven't tried end coating yet.

Gene Wengert (now of Univ. of Wisconsin Madison) and Fred Lamb of the Brooks Forest Products Center in Virginia did a study on the effectiveness of end coating that was paid for by U.C. Coatings of Buffalo. They found:

1. End Coating immediately after sawing reduces the average length of end checks by 2-1/8". On a 8 foot piece of lumber, this is a potential increase of 4 percent.

2. 62 percent of the pieces of lumber that were end coated immediately had end checks that were one inch or less in length. Only 4 percent of the uncoated pieces had end checks that were this short.

3. A delay of three of more days in coating the ends reduces the benefits of the coating by a significant amount. This applies whether the lumber was stickered or tight piled.

End coating is a well established practice to reduce end checking in lumber. This practice is occasionally used on high value logs as well. I know one small mill that harvests, saws and drys for the reatil market. He has his logging crew promptly end coat the logs after bucking. The result was lumber which appeared to have only a few short end checks an needed less trim allowance.

End coating gives the greatest benefits when used on thick, valuable, easily split (Oak and Ash) species, that is stacked in the sun during dry, windy, hot weather.

Other useful techniques to reduce end checking involve:

• Placing the stickers right at the end of the pile.

• Placing the lumber under a shed to get the boards out of the sun and rain. Pile covers are a cheap way to get some protection from the elements.

• Consider covering the windward side of the pile with burlap or an industrial textile designed for that purpose.

• Don't put valuable, easily check lumber on the edges of the yard or top of the pile, where too-rapid drying is likely to occur. The spacing between piles also can be used to get a little control over drying rates.

May of these techniques will also help prevent other surface checks.