# Filling a crack



## Guitar Maestro (Jun 18, 2011)

Hello, I'm new to this forum. My first post/question. I have a large plank of black walnut that has developed a crack down the center large enough that I want to fill it. I do not want to use a wood filler or putty; there is too much space and the color would never match. I have never used epoxy, but have heard it could be used to fill space this way. Any suggestions? The plank is around 2.5 inches thick; the crack is about 1/4 to 1/2 inch across and two feet long; the plank is 3.5 feet wide and 4 feet long. The crack is all the way through the wood, but it is at an angle, not straight.

Thanks in advance.


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## cabinetman (Jul 5, 2007)

Guitar Maestro said:


> Hello, I'm new to this forum. My first post/question. I have a large plank of black walnut that has developed a crack down the center large enough that I want to fill it. I do not want to use a wood filler or putty; there is too much space and the color would never match. I have never used epoxy, but have heard it could be used to fill space this way. Any suggestions? The plank is around 2.5 inches thick; the crack is about 1/4 to 1/2 inch across and two feet long; the plank is 3.5 feet wide and 4 feet long. The crack is all the waiece alomng the entire length of the cracky through the wood, but it is at an angle, not straight.
> 
> Thanks in advance.


I would cut the entire piece along the length of the crack. Then straight edge both pieces and glue and clamp back together.












 







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## Gene Howe (Feb 28, 2009)

Suggestion #2 Use a slow setting epoxy, mix a pancake like batter with walnut sawdust and pack it in the crack.
But, first, I'd insure the plank hasn't cupped.
C-man beat me to my first suggestion.


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## Brink (Nov 22, 2010)

do like C-man said, you can also flip the pieces around, see if there's a contrast that works well. Can even take pics of the front and back, print them, cut the pics at the crackline. You can then assemble them and see how it looks before doing any actual cutting.


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## Guitar Maestro (Jun 18, 2011)

Gene, the plank has cupped and that is another issue altogether. I succeeded in flattening out a small table top ((1/2)' x 1' x (1/4)" thick) by clamping it down. This plank is much larger and I've not tried to clamp it yet. A friend _volunteered_ to try and plane it down for me by hand (hard to find a 4' planer...). He planed for a very short time and gave it back to me, haha. Any suggestions on how to get the cup out? I sort of wanted to remove some material to flatten the surface because the plank is so heavy though. 

As for the crack, I was wanting to keep it clear instead of mixing the epoxy with sawdust. I intend to put a few butterflies across the crack for stability and structural integrity. Is there any issue with using the epoxy as-is? Again, I have no experience with epoxy.

The piece is not symmetric, which would mean cutting it in half and flipping the two sections would make the piece look strange. It also has the bark still on it, which would preclude applying too much clamping force which would damage the bark (I hope to keep the bark on for the end result.

Thanks for the posts so far.


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## Rick Mosher (Feb 26, 2009)

Rip a piece of matching walnut and epoxy that into the crack. If you have a commercial millwork shop or a large cabinet shop in your area ask them how much it would cost for them to run your plank through their wide belt sander. Usually doesn't cost a whole lot and it will be perfectly flat. Most shops I have worked at rent out the sander for a fixed hourly rate to use the sander and for their guy to sand it. (they won't let you do it for obvious reasons)


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## Brink (Nov 22, 2010)

Is this for a table?


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## Gene Howe (Feb 28, 2009)

The wide drum sander may be the only way to get it flat if you don't want to cut it. That may not work well if you want to retain the live edges. 
Straight epoxy will certainly work. Tape off the underside of the crack first. It's going to take a good amount of epoxy. I'd do it in about 3 pours.
You might consider tinting it, too.


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## woodnthings (Jan 24, 2009)

*As far as the crack/split*

This video may help: 




In your case the plank may be too large to fit in a standard bandsaw. You can look for a larger one or possibly use a quality sabre saw with a depth of cut of 2 1/2". 

The wood cracked/split/checked because it wanted to.
It was under stress from drying and other internal movements, so the best way is to follow the crack with the cut and relieve the stresses. Depending on the shape if the crack and it's curvature if any, a circular saw may be able to follow a gentle curve.
I can understand that you don't want to remove a section of wood and straighten/joint the surfaces and then glue it together, so a method like this will keep the grain continuity. 
A sawzall with an aggressive blade may also work to separate the piece along the crack, I donno? :blink: bill


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## Locodcdude (Oct 24, 2010)

Tell the plumber to pull up his pants.


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## Guitar Maestro (Jun 18, 2011)

Thanks for all the great ideas. Yes, this is for a table, probably a low-level coffee table of some sort.


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## woodnthings (Jan 24, 2009)

*another thought*

You can "stop a crack" by drilling a hole at the beginning to relieve the stress. A table with a split is not the end of the world, and has a natural feel, especially if you leave the bark on. That would be the easiest solution and I would not fill it, just leave it.  bill


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## Corbin3388 (Jan 22, 2011)

I love me some crack in a slab. Thought about filling it but decided it had too much character to epoxy.

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## Brink (Nov 22, 2010)

I'm really reading into this post. Correct me if I'm wrong, you want the live edge (bark) intact, and this will be a table top. 

My thought is filling the crack with epoxy will add an artificial element to a very natural piece. Why not use butterflies, like you mentioned, but don't alter the crack, use it as part of the character?


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## Hammer1 (Aug 1, 2010)

You can use polyester casting resin, similar to epoxy but without shrinking and air bubbles, looks like you filled it with liquid glass. You often see bugs and other things cast in it, joke ice cubes, etc. Find it at an artists supply.


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## Guitar Maestro (Jun 18, 2011)

Now that you mention it, I may consider just butterflying and leaving the crack open. Especially since this would be my first epoxy (or resin if I chose) project. I've attached a picture of the slab when it was first cut, the crack has since expanded greatly though I don't have an up-to-date picture on hand. The crack is along the area that looks wet.


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## Corbin3388 (Jan 22, 2011)

Slabs do tend to crack when drying out. It plagues us all. A nice butterfly would look fantastic.

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