Help with fixing a crackI'm not crazy about the look of clear glues

[Brian Brown]

I have a piece of black walnut that had a large crack from the outer edge to about 1/3 of the way in. The piece was too good looking to toss, or to cut into small pieces, so I decided to turn it, and find a way to fix the crack. I thought about not filling the crack, and finding a way to make the crack a feature after it is turned, but I am worried about the integrity while turning. I really don't want a schrapnell bomb just as I am finishing it. I usually wrap the outside with glass filament tape, or stretch banding while I turn the inside. This way if the piece comes apart, at least the pieces don't go flying. The problem here is that the form of this one is a shallow bowl/ deep platter style. There is nowhere to wrap tape or palette wrap. The options I have come up with are:

1. Fill with CA glue. The crack is huge and would take forever and need a lot of glue.
2. Fill with epoxy. I don't know how to get thick liquid into the narrowest part of the crack.
I'm not crazy about the look of clear glues in cracks, they just don't look right.
3. Fill with colored epoxy. Still don't know how to get it in the crack.
4. Mix stone or metal powder with glues. Even harder to get it in the crack.
5. Nothing in the crack, and leather stitching after turning. This is what I would really like to do, but talk about a sphincter tightener.
6. Your ideas here.

If this one survives, I think it can be an attractive piece, but I am stumped on how to make it work. Just for the record, the MC was 10%-12% when I started. The outside is turned, and I have started the inside, bit I am getting nervous. I have put a small amount of CA into the narrow end of the crack to provide the slightest amount of stabilization, but otherwise the crack is currently au natural. I am to the point where i am starting to get chatter on the outer edge of the rim, and that is only going to get worse. I am going to have to build a platter steady before I get much farther. Any other thoughts on how to proceed?

[Ken Fitzgerald]

Brian,

Denatured alcohol will thin epoxy.

I have had good success crushing instant coffee crystals, mixing with epoxy to color it and use it to fix cracks.

There is a several threads here about an epoxy cocktail where guys take thinned epoxy and use it to harden punky wood before turning.

Here's a link to making an epoxy manhattan... http://www.sawmillcreek.org/showthread.php?32083-Epoxy-Manhatten-bowl-results-pic!

[Doug Herzberg]

Not sure how big it is or what equipment you have available, but could you rip it, plane it and glue and clamp it with regular wood glue?

[Richard Coers]

Doug makes a good point, we need more info. How big is the turning? If it's 12" in diameter, and the crack goes in 1/3 of the turning, and it goes all the way through the blank, I say firewood. Once someone got killed on the lathe, I'm not taking chances. I've made it 60 years, I don't want to be taken out by a block of wood. Now if it is 4" in diameter, and the crack only goes through 1/2 the blank, maybe. I've also finally started listening to that inner voice about danger. If it scares me, I won't do it.

[John Keeton]

Brian, mix some Transtint dye in the DNA you will use to thin the epoxy. That should let you fill the crack with some color. However, make sure you understand that you will get some bleeding from the dye and should seal the surrounding wood with shellac prior to doing this - even down in the crack if you can as you will be turning away the surface wood and may expose stained wood.

[Thom Sturgill]

Get a large piece of something stable and turn a jamb chuck that fits snugly against the outside, rim AND back. That should stabilize it enough to finish turning the inside then make another to reverse it into. A lot of work, but if the piece is worth it...

[Jamie Donaldson]

Burn it, don't turn it! Even if you can seal the crack, the wood will always continue to move with humidity changes, and the filler will separate and open cracks because it doesn't move with the wood. Remember, life is too short to..............................

[jared herbert]

I have made several bowls with rather large cracks in them. Then I opened the crack up a little with a carving knife and laced it up with copper wire. People seem to really like that and they go first. I find it attractive, better than trying to fill the crack, because the crack always seems to move a little and whatever you fill it with will soon separate from the wood do to temperature or moisture movement. Jared

[Jeffrey J Smith]

I've turned a fair amount of bowls with cracks - small and large, and just last week filled a fairly large crack with colored epoxy for the first time. As the past owner of a vintage Chris Craft with issues, I've got a fair amount of time with epoxies under my belt, so I thought I'd give it a go. A good epoxy like System 3 or West mixed with a slow hardener will seek out the smallest of cracks. Just build some dams with masking tape and keep on pouring it in until it stops disappearing. Just make sure you've got any exit points covered with masking tape as well or it's all over the place.

I've also used hot melt glue on the finish-turned outside of a cracked bowl - covering the crack and out into solid wood on both sides - to hold all together while I turn the inside. The hot glue comes off with a little scraping and sanding. Big cracks can take a while to make the hot glue 'bridge', and a lot of glue, but it has worked pretty well so far.

[Thomas Canfield]

I like to spray shellac (rattle can) around the area of the crack to prevent the filler material from running and discoloring the ajacent wood. Gap filling to me depends on the size of the gap.
Small cracks - use thin CA first and then follow with a gap filling CA. Thin CA helps to wick in the thicker CA.

Medium cracks - pack with sanding dust and then apply thin CA to set the dust

Wider cracks & worm holes- mix fine wood shavings and coarse sanding dust with some instand coffee to get a darker fill material, then spray the mix with DNA to dampen the mix prior to mixing with 5 min epoxy. I have better luck getting a consistent mix this way than mixing DNA in with the epoxy prior to the wood mix. The resulting epoxy mix is thinner and will penetrate more, but thin cracks.

[Leo Van Der Loo]

Brian I have used plywood, if the top is flat glue a piece of plywood to the blank, turn right through the plywood and then just hollow the piece, just like in the picture :)

248348

and then you could stitch it like this

248352

[David E Keller]

You can always place butterfly patches or even use a plate joined to add contrasting splines for decoration and support. I've also glued pieces across the outer edge of the crack to support the piece while turning... Then remove them off the lathe. Leo's idea is appealing to me... I hadn't seen that approach.

[Brian Brown]

Richard,

The bowl is 12", and the crack is about 4" from outer edge toward the center. The crack goes all the way through the thickness of the blank. I am trying really hard to stay out of the line of fire with this one.

[Brian Brown]

Thom,

I really like this idea, but I turn on a 46-460, so a max of 12.5". I probably could use a modified form that can be glued to the outside for stability. I thought I might glue a bridge on the outside of the bowl, but I worried about the balance. The chatter will be enough of a problem already, so a modified jamb chuck may really fit the bill.

[Pat Scott]

I've used colored epoxy as well with good results. Several years later and so far no problems. I use Artists color (like toothpaste in a squeeze tube) to color the epoxy. I wouldn't use 5-minute epoxy, I only use the 24 hour kind. The 5-minute will start to set too quickly and not flow into all the little cracks and splits. You'll be surprised how small of crack the 24 hour epoxy will fill. Cover the bottom of the crack with tape and gently work and knead the epoxy into the gap using a needle or small spatula. Create a mound with excess epoxy, then come back an hour later and see if you need to add more. That's what's nice about the 24 hour kind, is if you come back an hour later and the epoxy has shrunk down into the crack, you can add more to top it off and the new will mix with the old.