How I Reduce Cracking - There Are Things You Can Do!
Try to turn the logs as soon as you can after they are cut. If you are not able to turn them immediately, seal the ends with Anchorseal. There are other brands but I’ve always used Anchorseal. I buy it in 5 gallon containers because I turn lots of bowls but it is available in smaller containers at a higher unit cost. If you are protecting an investment in quality logs, use a quality sealer. The longer you wait to seal and turn, the more likely that small, fine cracks will occur. By the time you discover the fine cracks in a green bowl, you already have a lot of time invested and the greater the loss.
Turn green bowls with very even rim, wall and bottom thicknesses. Slight variations in thickness increase the likelihood of cracking. I use calipers to make sure the wall thickness is even rim to bowl bottom. The last step is to round over the outside and inside of the rim. The picture below shows the rim rounded over. This portion of the rim will be lost anyway when you true up the dry bowl blank.
Beech bowl with rounded over edges on the rim.
I soak the green bowls for three days in denatured alcohol. Soaking them in alcohol does three things. It slows the initial drying because the wood is completely saturated again. If you’ve ever turned a green (freshly cut) bowl you’ve been drenched by the water that is spun out during the turning process. Soaking it in alcohol re-saturates the green bowl. Denatured alcohol also kills bugs. It’s not good to get a call from a customer about little piles of dust on the table under the bowl they purchased. Ambrosia maple often has living ambrosia beetles in the log. The third reason to soak in alcohol is reduced drying time. A typical green turned bowl with a one inch wall thickness takes one year to dry. That same bowl soaked in denatured alcohol take six months or less.
Wax the bowl after removing it from the alcohol. Many woodturners only wax the end grain. I wax the entire bowl. You use more wax (Anchorseal) but you insure even drying.
Wrap the entire bowl in brown paper or put it in a paper bag if it will fit. I usually leave it in paper for three months.
After three months remove the paper or remove from the bag. Place the bowl on a shelf in an area of the shop out of contact with direct drafts. If I stack bowls on the shelf I put sticks of wood between the bowls so air can circulate. Bowls do shrink at different rates. If you stack them without sticks between them they can get stuck together.
If you do everything right, cross your fingers and toes and turn around three times with your eyes closed your bowls will dry without cracking. If you’re really lucky they will turn out like this:
