How do I deal with small cracks in a burl?

I have a piece of Gmelia Burl from SE Asia that’s been sitting in the workshop for well over a year now. I’ve prepped it to make two small change bowls, about 4.5” dia by 1.25” high. My question is: How do I deal with all the small open cracks in it. I’d like to turn these bowls thin, about 1/16” at the rim, but I'm afraid that the wood won’t hold up. Before I do something I’ll regret and ruin an expensive chunk of wood, I wanted to get some advice on how to stabilize it. The current idea is to rough turn to about 3/8” and allow it to set for a few days, then work clear epoxy into the cracks and all over the surface. The wood is very hard and grey with light brown highlights. I think the epoxy will fill the cracks, provide strength, and the clear will hide better than a contrasting color. After the epoxy cures, finish turn the outside, adding epoxy if I expose new cracks. Then turn the inside close to final thickness, work more epoxy into the surface, and gently scrape down to the wood after it sets. Final finish would be Minwax AO. Does this sound like it will work? Is there a better way?

Thanks,
---Scott

Scott,

I recently turned a large Sweet Gum bowl from a section that had a lot of checks as an experiment. I made a mixture of sanding dust wet with DNA and mixed that with 5 minute epoxy. The resulting mix was much thinner than the straight epoxy and filled the checks/cracks easier and deeper than a mix of epoxy and dust or even straight epoxy. You could add some instant coffee or other colored powder to darken the mix if you want to make a better blend or contrast. The result is hard to detect in the marbled Sweet Gum. I liked the result as well or better than using shavings and CA to fill cracks. Somewhere there is a reference to using an Epoxy Manhattan (epoxy and DNA mix ) to fill cracks in old posts here at SMC.

I use the epoxy cocktail. I mix 5 minute epoxy and sanding dust. I then mix DNA in the mix so it is the consistancy of milk. If the cracks are all the way thru I will put some blue painters tape on the outside then fill the crack. I will sand on the roughed bowl to get some dust if I don't have any. It will work fine as I have used this method for 3 yrs now.

Hi
Would acetone work as the a substitute for the DNA in your epoxy cocktail's???

Denis

Thanks for the epoxy DNA cocktail idea and confirmation that this will work. I'll give it a test with and without sanding dust on the cutoffs. That way I should be able to see if I like the clear or the dust version before turning the real thing.

I'm working on an Oak Burl now with cracks in it. I'm using CA and saw dust from the bowl itself.So far it's working great. I will post pics when I get it finished.
Donny

Why fill them?

Unless they are large cracks they might not be a problem.

Toney

For years I have used sawdust and glue to fill places on flatwork, and I have done the same on bowls. However, I have just been using Titebond, with some fine dust. Seems to fill the cracks very well, and I don't get the shiny areas of filled grain around the crack as with CA. Those seem to be more difficult to sand out. Could be that I filled the cracks toward the end of my sanding cycle, too.

Interesting cocktail with the epoxy - may have to try that.

If your piece has any spalting or dark spots you can use charcoal rubbed in the crack then use thin CA over it. Sometimes shavings don't look that great to me for filling cracks. It looks like you put a peice of partacle board in the crack.

Sone people just leave the cracks.....but it's only really acceptible if it's burl.

This is how I deal with cracks, I buy some colorful gemstones like malochite or turquiose put them inbetween a few bags crush them to bits
use the finest crystals to initially fill the crack
then thin ca glue
then startpacking the bigger of the crushed pieces in
then thin ca glue
wait an hour then sand

not only does the common person not know it was a cover up, but they think it was some difficult inlay or something.

Brian,

Do the crystals sand at the same rate of the wood?

Quote:

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Originally Posted by Toney Robertson

Why fill them?

Unless they are large cracks they might not be a problem.

Toney

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There are lots of them. Some very narrow and short, others longer and wider. Nothing wider than a couple 1/100's of an inch. As a block, the wood is quite strong (and hard). But I want to turn this burl thin and am afraid that it will loose structural integrity resulting in spontaneous disassembly of the turning in progress. :mad:

Quote:

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Originally Posted by Ray Bell

Brian,

Do the crystals sand at the same rate of the wood?

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Different crystals vary, but all are MUCH harder than wood, so you might want to use those cylander round sanders and put it in your jacobs chuck, drill press, or drill, those cylander rubber sanding drums work well when you need to sand in a line.........the're almost perfect for it. Or a proxxon merlin would take care of it in a sec.....

or just crush up the stones to where they're so fine that there is little overflow, but with some, usually very colorful crystals, when you smash them very thin the color doesn't show thru as well as the slightly bigger pieces, so it's really about improvisation. turquoise shows up nicely finely crushed and craft supply sells 4 different crushed crystals in 1oz bags.......so you're paying alot more than if you just bought some stones off of ebay, or your local neighborhood Hippie, where you could get 5x that for $10.

I use fiberglass resin and coffee grounds or whatever to add some color and texture. I have been known to use chalk crushed up if I want some odd colors or multitude of colors added to the piece. Turquoise color chalk with a little deeper green really works well with wood. Let you imagination run wild with color options. Nice thin with the fiberglass resin is that it sands at the same rate as most woods that are medium to hard.