Help With Splits and Checks In Oak...

[Derek Arita]

Well, I'm down putting the last coats of Arm R Seal on an oak rocker and much to my dismay, I'm finding splits and cracks that I never saw before. I thought I had checked the parts pretty well, but these things seemed to appear out of nowhere. Anyways, one of the cracks is on a corner and goes right out to the edge, making it impossible for me to not do something about. I had to cut the "splinter" at about 1/2" long and I'm going to simply epoxy it back on, then sand, stain and poly over it. I will probably show, but the natural grain should help hide it pretty well. What can I do about the rest of the cracks that are mid-board? Should I just leave them? Is this normal with oak, to move and crack like this after machining or just poor observation on my part to begin with?

[william watts]

I had small checks appear in white oak after I left the lumber stock in a my hot garage, 100 F.+ for a few days. I used the stock anyway and just polyed over it, these were small narrow cracks, it looked ok if not looking close. Some time later it occured to me that grain filler would have not only filled the pores but these checks as well. If these are narrow cracks, or checks that is what I would try.

[Derek Arita]

Grain filler...never thought of that. Good suggestion.

[Peter Quinn]

White oak? It checks notoriously. Trim it. Wait a day. It checks. Trim it again, sit and watch it a while, get up to go to the bathroom....it checks when you aren't looking...or when you are staring at it. It checks if it looses moisture or gains it, or doesn't. Its not just you. I've used epoxy in various forms, 5 minute for small cosmetic problems, west systems or similar wet formula for deeper things that you want to stabilize, grain filler seems a good call for cosmetic issues, flooring guys have that down to a science. Just be carful and don't spread the grain filler around if you haven't grain filled everything, it looks like a weird flat spot in a glancing light. DAMHIK

[John TenEyck]

White oak has high shrinkage during drying and it's expansion/contraction even after drying is still quite high, right up there with beech. But after it's dry, I've never had a problem with it cracking/checking when working it. However, I never work wood until it has come close to the EMC of my shop. So, Derek, did you buy the wood for your chair, bring it home, and then start working it right away? If so, I'll wager that the wood was at a significantly different MC than the EMC of your shop, and those cracks are the result of it gaining or losing moisture. I think chair parts would be especially susceptible to cracking/checking because of the varying cross sections.

You can probably fill the cracks with colored epoxy, but I'd wait for all of them to show up first. Even after repair, I wouldn't be surprised if the cracks that extend out to an edge crack show up again sometime in the future.

John

[Derek Arita]

Thanks. At least now I know. I had the wood in my garage for about a week before I began working it. I've never really worked with white oak before, so it was all new to me. Anyhow, lesson learned. Thanks again.

[Jason White]

Only a week? Next time try several weeks (or months) and invest in a moisture meter.

Don't take it personally; we've all made the same mistake. ;)

[Richard Coers]

Those cracks and checks were in the wood when you bought it. Some of it from air drying before the kiln, maybe some from the kiln. It's not going to surface check from sitting around in your shop. Here's a good reference from Purdue. http://www.extension.purdue.edu/extmedia/FNR/FNR-133.pdf
Repairing after the finish is not very good. Most fillers and glues are made for raw wood.