I got a start on a large black walnut bowl this afternoon. A friend of mine was over to borrow my lathe for something else and he helped me get it mounted onto the lathe when he was done but before he left. The first view is from the rear.
This blank after it was prepared measured almost 18 by 20 inches. Obviously a bowl is round so the largest it could be is limited by the smaller dimension. The next view is one “end” of the blank. The wood had sat unsealed for a week since the blank was prepared, so there are small checks in the wood. These will turn out.
This is the other “end” of the blank.
The next pic is after about 4 minutes or so of turning, just trying to get the blank round and in balance.
After another few minutes – the blank is much more balanced, but is not yet round – still oblong.
After some more time, the bowl is now shaped. The bottom needs some work to be able to mount the bowl into a chuck to hollow the bowl.
The other side of the bowl showing a mix of the sapwood and heartwood. To be honest, the sap from the heartwood will bleed into the sapwood as it dries and turn it black/brown. There will be some contrast between the sapwood and heartwood when it is finished, but not as drastic as it appears in these photos.
Here is shown after a little more work. It’s difficult to see, but the right side of the bowl now has the “tenon” shaped up for the chuck to clamp on when I turn it around to hollow out the bowl.
I have the ability to “core” these large bowls. Instead of turning the complete inside of the bowl to shavings, this allows me to cut another bowl blank from inside the large one. I leave the thickness of the large bowl at approximately 10% of its diameter. As it dries down it will warp and go noticeably out-of-round. Hopefully this is thin enough to dry without cracking and thick enough to allow me bring the bowl back to roundness.
The picture below is after coring out the bowl but before I trim up the bowl with the bowl gouge. I was able to get an almost perfect core out of this bowl, which left me a second bowl of about 12 inches diameter and 3-1/2 inches deep inside. Unfortunately, as this walnut ages and dries, the differentiation in the grain will become less noticeable.
Here are the three bowls made from the large bowl blank – a 17-inch bowl, a 12-inch bowl and a 8-inch bowl. The white material is a sealer that slows the drying rate down and that will hopefully prevent the bowls from cracking as they dry.. It is applied liberally to the end grain of the bowl to try to force the moisture to exit through the cross grain which makes the wood dry evenly. Otherwise the moisture leaves the end grain portions of the bowl faster than the cross grain portions of the bowl and causes the bowl to crack.
All that’s left for now is to let them dry for a few months and then turn them to final thickness, I will likely add another coat of sealer in a week or so to add a little extra insurance against cracking as they dry. Oh, and I need to sweep up the shop. Again.