# Wood Slab Table Cracking



## matt123 (Jun 21, 2013)

Hello,

I really could use some help!

I recently finished putting together a very simple wood slab table for stuff in my kitchen. However, it is starting to get cracks where the knots are and they are getting bigger. I really want to stop this from getting worse, I read to use epoxy to fill them, will this work? Also are the cinder blocks a bad idea, they have felt pads on them to stop any scratching; I am waiting for tree stumps from a friend to make legs. Are the cinder blocks too much weight? I was told the slab dried for 1 year, but its about 2.5 inches thick. Lastly, it has been hot in my apartment. I am open to suggestions. The slab was finished with 5 coats of arm r seal, and 1 base coat of dewaxed shellac.


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## matt123 (Jun 21, 2013)

My only guess is that not enough moisture has gotten out and the extra heat in my apartment is causing it to crack this quickly, I put it in like 3 weeks ago.


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## firefighterontheside (Apr 26, 2013)

It seems that the rule is to let something like that dry for one year per inch before you start making tables out of it. I made the same mistake with some pin oak. Now that its inside the drying has accelerated.


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## matt123 (Jun 21, 2013)

What if I put the tables back outside in the garage or something for anther year? I am not crazy about doing ti but it sounds better than huge cracks. Or can I use Epoxy to fill the cracks?


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## Mahdeew (Jul 24, 2013)

You have many options as it relates to the cracks; epoxy, gems mixed in epoxy, copper dust and different color wood that can be wedged at the bottom and hammered in.


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## Woodendeavor (Apr 7, 2011)

You need to control the drying or it will continue to crack. A slab 2" thick should air dry for 3 years in my woodshop. I would try and find someone with a moisture meter to check the MC of the slabs and would hold off on trying to fix the cracks untill you have the moisture content down to 8%


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## matt123 (Jun 21, 2013)

Hello,

I do not know anyone with a MC machine. Here in northern NJ, its a miracle I found a mill that sold slabs under 500 a piece. I am close to NYC. I ended up using a celluose based product called plastic wood, it was a putter type product and I filled the cracks with it.

I understand what you are saying about checking the content first as if it is too high it will just continue to find ways to crack. I panicked a little bit and put in that product as I read it will bond with the wood and help with the cracks. Honestly I would have needed a syringe to get the epoxy on the cracks as they were deep but slim.

I feel like my only option is to buy a Moisture checker and put the slabs back in my garage, or just leave it with the this product in it and see what happens.

I am open to suggestions at this point as well, I will pull the slabs if it is the best thing to do and try something else. TO be honest, I do not even know where to buy a moisture meter (amazon?), if so what brand and model.


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## richardwootton (Jan 17, 2013)

Harbor Freight, lowes and Home Depot all sell relatively inexpensive moisture meters.


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## matt123 (Jun 21, 2013)

Ok so, if I get a moisture meter and the content is over, what 10, 15%, then I should pull the slabs from my apartment and put them in my garage? Or in a basement?


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## firefighterontheside (Apr 26, 2013)

The odds are that no matter where you put them, theyre just going to crack more as they finish drying. I would just leave them where they are and either learn to love the cracks or do some sort of fix once they have stablized.


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## matt123 (Jun 21, 2013)

Thank you very much, for the help. I will reapply more of that DAP plastic wood or an Epoxy (if its bad) after it stabilizes, maybe another year.

Thank you all for the help, this website has great deal of wisdom.


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## Nomad62 (Apr 20, 2010)

99% of problems like these are moisture related alright, you're on the right track in letting it dry more completely. Once you get back to it, heat the epoxy filler up and it will get thin like water allowing it to get all the way to the bottom of the crack. Best of luck!


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## matt123 (Jun 21, 2013)

Hello,

has anyone used DAP plastic wood, I was told that while it is a putty type texture, it is a cellulose based product that can help with cracking, is this true or is epoxy the better alternative?


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## BacktotheWood (Feb 16, 2010)

I believe that epoxy would be better. It can seep into the wood on both sides of the crack before it hardens and help keep the crack from widening. The plastic wood will separate as the crack widens.


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## donwilwol (May 16, 2011)

The safest way to check the moisture content is check something that's been in your house for a while, and match it as close as you can.

I agree with some of the others, just let it dry now that its in the house.


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## rhett (May 11, 2008)

My preference for slab cracks are butterfly joints. The other option is epoxy. Mirror coat or bartop epoxy can be mixed and poured into the crack, completely filling the void. Press filling with putty is little more than a bandaid and will eventually flake out of the cracks.


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## matt123 (Jun 21, 2013)

So can I chip the DAP plastic wood out and try to pour in wood epoxy? The cracks do not seem to be getting any bigger, but a new crack is forming on the bottom slab.


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## thesoninlaw (Jul 6, 2013)

Butterfly keys. Sooner=better. They not only stabilize cracks, but they add character.


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## matt123 (Jun 21, 2013)

Thank you. the cracks are very thin, about 1/4 of inch wide, so perhaps epoxy would be better.

On a side note, I called DAP and they said that plastic wood filler is not meant to deal with cracks in wood slabs, basically what everyone here has been saying.

I am going to get the filler out as best I can today and apply epoxy.

I noticed that all the cracks are on the bottom slab, the upper slab has none, is the cracking also being sped up by the weight being placed on the slab?


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## Post_Oakie (Jul 3, 2012)

The advice to let the wood dry in place (give it another year). I've seen beautiful work done by mixing bronze powder or turquoise with the epoxy. The bronze powder makes the crack look like a mineral streak, and the turquoise sometimes looks like a river. Concrete blocks are no problem as long as they are lined up vertically so that the weight of each block gets transferred to the block below it, to the floor. Otherwise, the wood will eventually sag.

You can weigh the wood once a month or so. When it stops loosing weight, you will know that it has equalized out to the relative humidity of your house (equilibrium moisture content). You could also carefuly monitor the spreading of the cracks. When you can go all winter without the cracks growing, the stress will be pretty well relieved, and it will be ready for the epoxy filler. With the finish on it, this will happen very slowly


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## DaddyZ (Jan 28, 2010)

Nature of the Beast !!!

Butterfly or Epoxy, either way it adds Character…

+1 for letting it acclimate where it is


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## matt123 (Jun 21, 2013)

Hello,

So what you are saying is to not put the epoxy in yet and wait until after the winter? Or fill it now with epoxy to stop the cracks from progressing?

I bought some basic gorilla epoxy because the home depot does not carry the west systems. Please let me know if I should wait or fill it?


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## dbray45 (Oct 19, 2010)

First things first - let it dry. Around knots can always be an issue. You want the MC to be less than 8% MC. When I get my wood slabs, they are 8-10% MC. I put them in my basement (with a dehumidifier) until they are down to 5% or less - 3-6 months more - unfinished. Some of them are pretty warped, cupped and twisted. As they dry, they straighten and flatten out. I have found that once you get below the 8%, the wood gets more stable and moves less.

If I am doing a project for someone and I have to get the wood, it is my first stop - before drawing it up (I usually get 20-25% more than I will need. I spread them out in the basement for maximum exposure. I try to let them sit for a week after milling to get them as dry and acclimated as possible.

Wood moves and cracks. Slabs more than boards - learn to work with it because in fighting it - you will not win.


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## matt123 (Jun 21, 2013)

I am sorry if I sound like a parot, but just to be clear, do not fill the cracks and wait until the moisture content is below 8%, correct?

Just curious, that means that if the cracks get worse I just need to wait until its below 8%?

Also, should I leave it with all my kitchen stuff on it and the cinder blocks? will that make the cracks worse in any way? I only ask because the bottom slab (with more weight on it) is cracking more than the top one.


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## ClintSearl (Dec 8, 2011)

No filler will stop them from cracking more until they reach equilibrium with the environment. Wait a couple years and revisit the question.


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## matt123 (Jun 21, 2013)

Really? Wow, so when I see posts about people putting epoxy or butterflys into wood slabs, they are doing so after the moisture content has come done under 8%, assuming they are doing it the right way of course and waiting.

So, I am wondering, if someone puts epoxy in a crack before the moisture content drops, the slab will just continue to crack in that spot or another because the slab has to reach an equilibrium. I am also guessing that a butterfly joint could crack if put in to early due to the stress.


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## donwilwol (May 16, 2011)

The butterfly may stop the crack from opening more, but probably won't stop the cracking. Filler will do nothing but look awful.

Edit: so the crack may get longer, but not wider if that makes sense.


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## firefighterontheside (Apr 26, 2013)

I built my dining table from pin oak that apparently was not dried well enough even though it had sat in my shop for over a year. I did not allow well enough for wood shrinkage. My bread board ends were adhered too tightly. I could see the middle of the table bowing in. Finally one night there was a loud bang, I saw everything on the table jump and fall over. A joint between two slabs came apart violently. This was years ago before I learned about things like building to allow for shrinkage or how long something needed to dry before usage. I also learned recently that pin oak is notoriously difficult to dry. Point was there is a lot of force stored in the wood and not much is going to stop the wood when it wants to move. The epoxy is definitely not going to stop it. The butterfly may work for a while, but eventually the butterfly would fail and your microwave and flowers may be on the floor.


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## matt123 (Jun 21, 2013)

Thank you,

I noticed that the bottom slab has the cracks, the top one does not have that much. Is this a result from all the weight and moisture buildup on that bottom slab? Or is it just that some slabs crack more than others?


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## firefighterontheside (Apr 26, 2013)

I don't think it has anything to do with the weight. It's wood. One piece is different than the next.


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## donwilwol (May 16, 2011)

it also depends on how it was sawn. A piece closer to the bark and further from being quarter sawn will check and move more.


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## oldworld124 (Mar 2, 2008)

You can strip them and then soak them with Nelsonite. That will help stabilize the wood. Fill the cracks with epoxy and maybe butterfly joints. Nelsonite will normally not interfere with a later finish.


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## dbray45 (Oct 19, 2010)

Flat sawn wood moves side to side, quarter sawn wood up and down. Follow the grain lines, that is the direction of movement. Once dried, wood still moves, just not as much. Think about ice - as water freezes, it expands. Ice will move a house. Unless you heat treat the wood to 300+ degrees and crystalize the sugars, you are not going to stop the process - it is your job to work with it, and still make it look nice.

Good luck


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