Leaving pith in bottom of bowl

[Bernie Kopfer]

I’ve seen pictures of bowls where the pith was left centered in the bottom without the usual cracks. Are there certain woods that have less tendency to crack when this is done? Or is there a special drying technique assuming green wood is being used?

[Robert Hayward]

Soaking the pith with CA works a lot of the time for me. Any small cracks that still show up are easily filled with a colored epoxy.

[John Keeton]

I have never understood leaving pith in any wood used for any purpose with the exception of a crotch piece with highly figured areas. Folks talk about ways to hopefully prevent the cracks, ways to repair them, etc. I prefer to have my work remain intact and my time spent enjoying turning good wood.

[Richard Coers]

Thin wall thickness and same thin bottom thickness is the biggest help. If you can stay around 1/8 thickness, the success rate goes up dramatically. I turned a large thin wall red oak vessel with the pith going through parallel to the base. It became a football when it dried. Very minimal cracking at the pith.

[Edward Weber]

I'm with John K on this

[David Walser]

Yes, Bernie, some woods are less prone to cracking than others. And, leaving the pith in is more likely to cause problems with some types of woods than others. Turning thin and/or using some method to stabilize the pith (CA, Cactus Juice, Minwax Wood Hardener, etc.) can reduce the chance of cracking. However, like the handsome and talented Mr. Keeton, I believe avoiding leaving the pith in is the best policy.

[Russell Neyman]

I’ve seen pictures of bowls where the pith was left centered in the bottom without the usual cracks.

Those are the exceptions, not the rule. It's quite likely those pictures were taken immediately after the bowl was completed and before the cracking took place. Leaving the pith in is very likely to leave you with a broken bowl and a broken heart. Simply put: it's a very bad idea.

Look, all wood shrinks when it dries, most dramatically around the perimeter. That causes stress that must be relieved in some fashion, usually in the form of radial cracking. Yes you can slow down the drying/shrinking process to a degree with sealers and epoxies, but eventually it will occur. Adding resins to those cracks isn't stopping the shrinking process; it's merely slowing it down. That method is a patch, not a repair. Don't waste your time trying to include the center of the tree.

[Bernie Kopfer]

I fully agree with the sentiments expressed about including the pith. But I was looking for information if someone has done so with some success and how they did it.

[Richard Coers]

I'll try and get a couple of pictures of my hollow forms. People love them because of the wood distortion.

[alan weinberg]

with Norfolk Island pine, bowls are often turned end grain with the pith in place. I’ve had variable luck keeping and stabilizing it. I’ve used CA to keep it and I’ve replaced a lost pith w sawdust and glue.

[Kevin Jenness]

I have read of someone parting off a pith section from a blank, drying the (small diameter) section very slowly with or without a ca infusion, turning a vessel from the rest of the blank with the pith drilled out and reuniting the parts when all is dry, using a drill and plug cutter and perhaps disguising the glue joint with a small cove. A lot of work, but perhaps worth it for a special piece.

David Ellsworth has said that no-one is surprised to see a crack in a fieldstone so why not accept it in a turned piece. It's a matter of perspective. Certain turning styles work with warping and other "defects", others not so much.