Need advice on how to deal with small cracks in bowl

[Izzy Charo]

Hello,
As the pandemic has confined us to our homes, I've been doing a bit of turning....but I'm still a novice. I had a nice piece of walnut that had "lived" for years in an unheated shed, and cut a bowl blank out of it. Started turning and as you can (I hope) see in the picture, noticed several small cracks in what will be the rim, and I'm not sure how to deal with these. I can try to turn them out and make the bowl smaller....but is there any hope of filling them now with a black epoxy and continuing on? I realize this may all become a moot point if cracks continue to appear as I remove more wood...but I would love to hear what some of you experienced turners think....
Many Thanks,
Izzy
bowl with crack rim.jpg

[Richard Coers]

My opinion on this isn't very popular these days, but if it's cracked, it's firewood. Turners these days don't seem to mind throwing $30 of resin on a free cracked up bowl blank to make a $50 bowl. I haven't paid for wood blanks in decades and I don't cry over throwing one away. I can just turn another one tomorrow at no additional cost. I don't see my glass artist or pottery friends selling cracked work, I don't either. Like I said, I'm pretty much a singular voice with this opinion so take it as you will.

[Brice Rogers]

Izzy, sure you can epoxy a crack. You can add a dye or colorant if you wish. I sometimes will mix epoxy with used dried fine ground coffee grounds. Comes out a very nice dark brown and goes well with a dark wood like walnut.

If the crack is too narrow, the epoxy may not go in very well. I've thinned epoxy with acetone and that works but it may take a week to cure. Another alternative is to drip thin on medium CA (superglue) into the crack.

It is not uncommon for CA or epoxy to stain the wood as it soaks in. So I'd advise coating the area to be glued with something like shellac to act as a sealer before applying the CA.

[John Keeton]

Richard, you are not the lone voice! Galleries and buyers do not like cracks in turnings. They are signs of instability and usually worsen over time. I enjoy turning, but the Lord has given me a limited amount of time on this earth and I don’t want to waste it on inferior wood that will produce an inferior result. I will add that cracks are different than inclusions, voids, etc., all of which can enhance work in the right piece.

[John K Jordan]

Izzy,

Your blank has the pith right in the middle. Radial cracks are common and even expected around the pith in most wood species due to the stability difference in the juvenile wood. The best thing to do when cutting blanks from green wood is remove the pith along with as much wood near the pith as you can stand. Then if not turning immediately, seal the wood well. Before turning, I inspect the blank for additional cracks and either cut them away, cut the blank up into smaller blanks for other uses, or toss it out.

While many people leave such cracks in turnings, sometimes filling them with epoxy and things like coffee ground and turquoise or metal powders to accent them, I don't. Beside the appearance, which I personally don't like, there is also a more serious issue - depending on the position and extent of the cracks, the type of wood, and the wall thickness, there is a danger of an injury from the wood coming apart while turning.

I do make an exception for certain defects, like voids or bark inclusions, when I am confident the strength of the wood isn't compromised for the design I plan. Even then, I stay well out of the "line of fire" while turning. Face turning wood with obvious pith cracks - never.

If that blank were mine and I didn't have any better, I'd probably remove it from the lathe, chainsaw away the pith and all existing cracks, then remount and turn a shallow dish.

I mostly turn dry wood and process a LOT of green into blanks to dry. The only time I leave even minor cracks in a blank is if they are on one end of an end grain blank intended for spindles or things like lidded boxes. In this case, I evaluate the blank after it's dry and may decide to use by holding the cracked end tightly in a chuck. That is safe to turn and that end of the wood is waste anyway.

Note also that some species are more stable and don't tend to crack as much around the pith and knots, especially when turned green and with a thin wall.

There is another way to leave the pith in the wood while turning - turn with the grain running along the axis of the lathe, in "spindle" orientation as apposed to "face" orientation. People often turn things like goblets, vases, and other vessels from green wood with the pith right in the center. For example, cut a limb from a tree, turn a tenon and mount one end in a chuck, then shape the outside and hollow the inside. If turned green and the limb isn't too large, the piece may survive with no pith cracks. If pith cracks do develop, at least the wood won't come apart while turning.

If new to turning, I recommend the book "Understanding Wood" by R. Bruce Hoadley. Hoadley is both a wood expert and craftsman and provides practical education on the structure and behavior of wood. https://www.amazon.com/Understanding.../dp/1561583588

JKJ

[William C Rogers]

That crack is significant and there would be no good way to save it as a bowl. However I would salvage the good wood to be used as a lidded box, ornament, contrasting wood, but not including the branch pith. I do try to turn out cracks if possible, but the branch pith will likely crack to the bottom.

[Izzy Charo]

Many Thanks for all of the thoughtful and comprehensive advice! Much appreciated! I will abandon the bowl...no loss, and look for some stable bowl blanks to work out techniques on. Again, thanks for the solid advice!
Izzy

[Dave Mount]

I would turn the pith away rather than fill the crack, but I wouldn't conclude that the pith crack means you should pitch the piece. It looks to me like there's plenty of bulk below the pith to salvage a reasonable bowl if you just turn away material until you remove the pitch, at or a little below where the step is in the picture, unless the pith comes out a lot lower on the other side of the blank. Don't evaluate it based on what you have to remove, evaluate what you'll have left to decide if it's worth saving. Walnut is pretty forgiving about the pith, you can be put the rim pretty close to the pith without problems. In other woods, I might stay an inch or more away. I don't mean to take away from sound advice that you need to be concerned about how cracks are going to affect safety, but a pith crack like that isn't going to cause the blank to fly apart while you're turning some of the depth away to remove the pith after the outside is done and you reverse the piece.

Best,

Dave