19 Ways to Stop Green Wood from Cracking

I like working with green wood for my wood bowls, and also sell green bowl blanks on Etsy and eBay. One of my Etsy customers explained that they wanted to make a sculpture out of a 5 1/2″ thick by 12″ diameter green maple block I had sealed by dunking in a vat of hot paraffin. They didn’t specify how large the finished piece would be or what shape it would take, but here are some of the ideas I shared with them:

It is notoriously difficult to dry a small thick chunk of wood without getting bad checks and cracks.

The main problem is that there is a lot of end grain which lets moisture out of the piece relatively quickly.

Adding insult to injury, with a thick piece, it takes time for the moisture to migrate through the wood, so the surface will stay drier than the inside creating stresses on the wood.

Moreover, most woods shrink more in one direction than the other.

Since wood shrinks as it dries, checking and other drying defects are a common problem even in regular straight grained, dimensional lumber.

With my wood bowls, I “lose” about 10-20% of them to checks in spite of my best efforts.

Here are some thoughts that may or may not apply to your situation:

  1. One possibility is to leave the bowl blank just like it is, coated in paraffin, but stand it on edge so it gets air all around it and wait 5-10 years until it dries. It might or might not crack in that case. I didn’t look at it too close, but I’m thinking your blank stands about a 50-75% chance.
  2. Dunk your finished sculpture in a vat of hot paraffin (that is what I do with the bowl blanks).
  3. Cut out any knots that might be in the wood, or if you leave them in, try to sculpt it in such a way that the wood can move without cracking. (This is always risky, but in a bowl, that would likely take the shape of a thin, rounded side that was cut to an even thickness or sealed.)
  4. Use Anchorseal 2 Green Wood Sealer. (Not that different than paraffin, but will almost certainly require multiple coats.)
  5. Shape your piece in such a way that it is not more than 1/2″ thick, even in thickness and have some shape to allow for movement without cracking. With a bowl, that is fairly easy to do.
  6. If you are making a vessel such as a bowl, seal the outside with paraffin, packing tape, a plastic bag, or whatever so it dries from the inside.
  7. Use Pentacryl Wood Stabilizer. I have never used it, but understand it works pretty well for some things. That might be your best option.
  8. Dunk your sculpture in alcohol for a while to displace the moisture in the wood. It may or may not dry faster, but it should be less likely to crack. This is a common technique among wood turners.
  9. Boil/steam your sculpture in water. It may discolor the outer part of the wood, but you may be able to work the wood down, to say, within 1/2″ of finished thickness, carefully steam it, and then finish working it down to the finished thickness so as not to loose too much color.
  10. Put it in a plastic bag, seal it off for a day or two to let the moisture equalize, and then turn the bag inside out every day or two leaving the top open a bit so moisture doesn’t collect inside until it is dry. I do this with my bowls leaving the opening at the top of the bowl so it dries more from the inside than the outside.
  11. Some people have tried microwaving the wood. I haven’t tried it.
  12. Use Cyanoacrylate (Super Glue) to stabilize cracks.
  13. You my be able to cut away hairline cracks that might develop as you are working before they get too big.
  14. Use a temperature and humidity controlled kiln.
  15. Embrace the checks, cracks, warping, and other distressing as a feature.
  16. Soaking the piece in a vat of linseed oil while you are working may help. It is messy to work, but the wood, especially end grain areas should be easier to cut with hand tools. Tried & True Danish Oil doesn’t have VOCs or chemical driers.
  17. There may also be freeze drying methods, but I’m not familiar with them.
  18. Any finish may help some.
  19. Bury the finished piece in a pile of wet leaves, sawdust, or manure. This will tend to spalt the piece if there is enough moisture. To keep moisture levels high enough, you might put the whole mess in a plastic garbage bag, perhaps leaving the top open a bit and adding moisture if it gets too dry. After you get it dry, make the final cuts.

The key to all these methods is to stop cracks before they start. Once you have a hairline crack, it is hard to stop. When you are working the piece, if the process you are using is a slow one, such as hand carving, you will likely have to use methods such as putting it in a plastic bag between sessions, or sealing part of it you aren’t working on to stop hairline cracks from developing while you are working.

How do you handle green wood?

-Luke Townsley

About Luke Townsley