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Hi all I'm new this is my first post, I recently made an a coffee table for a friend with an oak top and the cracks filled with epoxy resin. I had stored at mine for about a week after I had completed it, he picked it up 2 weeks ago and brought it back yesterday saying it had developed small crack on the top picture attached, any reason what might have caused it there are larger cracks and smaller ones filled with epoxy that are still all ok
 

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welcome to the forum, Tee.
can you post a photo of the whole table ??

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depending on many factors, (weather, humidity, atmospheric changes, etc)
a round "cookie" slab will crack like that for ever.
just accept that that is part of that style cut of wood.
repair it as it happens - don't fret over it. it is surely going to happen again.
(beautiful job on the table, BTW).

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I don't have a lot of experience with cookies that large. I will say that John Smith may well be correct and that you won't be able to predict when another crack will open up. In that case, your best bet would be a more matte, non-film finish (maybe my personal favorite, a tung oil friction finish?): That way, any new crack will be much less noticeable and will more easily be seen as just part of the table. (rather than an unsightly crack in an otherwise perfect, shiny surface).
 

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Thank you for the replies, I was thinking of filling it up with epoxy again and giving it a coat of varnish it's the first time I made a table with epoxy, if the epoxy did not sleep through would the table do that?
 

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if the epoxy did not seep through would the table do that?
it may or may not. we have no idea. but, just wait awhile, and another
crack will appear in another place. it is wood - that's what it does.

I have had good results with thick epoxy by putting a couple of layers
of an old cloth over the shop-vac hose end underneath the board (table)
and sort of sucking the thick epoxy down through the crack.
several factors play a role: thickness of epoxy, type of epoxy, temperature,
amount of suction applied to the bottom of the crack. (too little - too much).
you can find what works for you through experimentation.

Example:

Sensitive content, not recommended for those under 18 Show Content
Vacuum Epoxy.jpg

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Smart and Cool
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Many factors, was the cookie dried? Did you finish both sides of it?

I would say that it was not dry at a minimum, I have a 4' cookie in the shop that was kiln dried, it's been there for almost a year and has not developed any new cracks, and I don't expect it to.
 

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Well the guy who sold it to me said he had it drying for 2 years I had it stored by me for another 2 months before working on it, I used my router to plane it sanded and then filled cracks with epoxy and finished with coat of varnish, kept it for two weeks before my friend picked it up and according to him he went to bed and the nest day it had cracked..I have had it for 2 days since I there has been no change to the crack or more forming..
 

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There are three options that I see for you.

1: Keep doing what you're doing. Fill the crack, finish with another thin coat of varnish, and see what happens. Maybe it cracks, maybe it doesn't: If it does, fix it again.

2: Embrace the possibility of cracks and work around it. Refinish with an oil finish so that a new crack won't really mar the finish like it would mar a glossy finish. It'll just look like the crack was always there and may not require your attention to fix.

3: Do more to eliminate the possibility of cracks. Finish both the top and bottom of the slab with a thick coat of clear epoxy. This won't guarantee no cracks, but it will dramatically slow down the rate at which at the moisture content of the slab changes, which is what causes the cracks in the first place (I believe). With this option, you MAY prevent further cracks, but there's no guarantee, and fixing any cracks will likely be more time consuming.

I don't think there is a perfect option, because working with slabs like this is fundamentally tricky. In the end, you're going to have to take a leap of faith and be willing to fix it if necessary.
 

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all the above apply:

just for aesthetic purposes, put some contrasting color "butterfly" or "bowtie"
patches in. it will look jam up and jelly tight !!

1429207.jpg

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Well the guy who sold it to me said he had it drying for 2 years I had it stored by me for another 2 months before working on it, I used my router to plane it sanded and then filled cracks with epoxy and finished with coat of varnish, kept it for two weeks before my friend picked it up and according to him he went to bed and the nest day it had cracked..I have had it for 2 days since I there has been no change to the crack or more forming..
You haven't indicated how thick it is, but it's unlikely it was dry(as the crack has now told you).

There are a lot of folks out there cutting slabs and cookies, there are way fewer that are processing them correctly for use. A moisture meter would be a good investment if you continue working with slabs and cookies.
 

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Discussion Starter #16
Thank you all for the great advice a moisture meter is definitely on the way I'm going to keep the slab here for about a month till my friend moves into his new place I will monitor to see if anymore cracks appear.. what a great forum this is
 

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Adding to John's recommendation of bow-ties (I like), it will crack again, enhance these faults don't hide. Variations in humidity will continue to cause circumferential cracking in a cookie like this.
 
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