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Epoxy Table Help!!

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Forum topic by WhatDoIDo posted 05-06-2021 10:48 PM 285 views 0 times favorited 6 replies Add to Favorites Watch
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WhatDoIDo

2 posts in 44 days


05-06-2021 10:48 PM

Topic tags/keywords: question walnut finishing veneering

Hey all, long time listener, first time caller. As a (very) amateur wood worker, I have embarked on an ambitious project that’s testing my capabilities.

We had to cut down a dead walnut tree and the guy was kind enough to slice the trunks into cross-sections for me… but the cuts are very thick, making this table a bit of a challenge. As you can see, I have attached the cuts with construction screws—upside down, so it’s about as flat as it can be before I sand it. I’m almost ready to pour the epoxy, but I have a number of problems/questions:

- I plan to create a disposable frame using plywood and landscape edging (something like https://amzn.to/3unKQYq because it’s hard to otherwise create a rounded edge) covered in tuck tape. Any better ideas?

- I think I’m going to fill it with the table upside down, somehow shimming the table off the base of the tuck-taped frame by 1/4” or something. The bottom will be uneven and uncovered, otherwise it would take a TON of epoxy and be extraordinarily heavy. I would then just use some other sealant to cover the rest of the wood to preserve it. Is this stupid?

- What sort of epoxy resin should I use? I was thinking this 2:1 deep pour by Wise Bond https://bit.ly/3b2oYdC.

- Am I an idiot? Is this doomed to fail?

When the table has cured, I plan to rest it on top of the stumps pictured here and fasten it somehow. Any help would be GREATLY appreciated. Thanks!


6 replies so far

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AADavidBB

12 posts in 44 days


#1 posted 05-06-2021 10:52 PM

West System Epoxy, in Michigan, has great tech advisors who will help you choose a resin, catalyst, and any needed additives such as colorants, strengtheners, whatever. I’ve consulted them numerous times and always gotten great advice.

-- David Abbot

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Rich

6929 posts in 1709 days


#2 posted 05-06-2021 11:18 PM

You want to use a casting resin if you want it to be clear and colorless. Regular epoxy will have an amber tint. System Three makes RiverCast, but there are countless other products out there possibly for far less money.

I like your idea to pour it upside-down to save on resin. Be sure to affix the pieces to the base of the casting frame so they don’t float.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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CaptainKlutz

4549 posts in 2614 days


#3 posted 05-07-2021 01:34 AM

Here is what I learned about casting an epoxy table:

+1 must use casting epoxy. They are designed for thick sections, and to stay clear longer than conventional epoxy system.

- wood floats. Must fixture your mold to each and every piece to ensure the tops stay in same plane.

- Wood is porous. 100% pre-seal each and every round before casting. Can use shellac or poly, but best adhesion usually requires same casting epoxy used for pour. Failure to seal the wood, will create a never ending stream of bubbles that get trapped exactly where you do not want bubbles.

- Regardless of time/energy spent trying to level all the rounds, there will be uneven surface some where. The uneven surface will fill with resin. If you want exposed wood on surface, will need to machine/sand the surface to expose the wood. IME – Using rounds with random thickness complicates the molding fixture, and guarantees uneven surface.

- Do not want the back side to have uneven surface. The exposed wood will absorb moisture at different rate than embedded wood. This creates stress on the joints and will crack eventually. Suggest using an epoxy pour depth same as tallest round. If not same depth, then machine the back side flat so the panel moves at same rate with changes in temperature and humidity.

- Do not attempt to save money on epoxy by bonding a thin epoxy/wood filled slab to a support plate. Any mounting surfaces under the table, must allow the panel to move to allow expansion/contraction of the materials. Epoxy has CTE range of 35-60 ppm. Wood CTE is about 25-40 ppm perpendicular to gain, but only 3-5 PPM with grain. These differences can cause warping issues when the stress is captured on mounting plate.

- Casting epoxy is softer than most wood finishes. Epoxy can be challenging to polish the surface to high gloss, due softness and temp sensitivity. Will get a more uniform finish on the table applying a water white top coat on the epoxy cast table. Some casting resin mfg suggest use of a harder table top epoxy resin coating as top coat.

- Casting epoxy (or any room temp cure epoxy) takes long time for complete cure. Have wait month or more before attempting to polish slow cure casting resin, unless using an oven cure.

- Plan ahead, and test your entire process on some scraps. Large table can use many many gallons of epoxy, and with ave $100+ per gallon, practice first is best way to ensure desired results (without wasting a lot money).

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

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Aj2

3891 posts in 2917 days


#4 posted 05-07-2021 02:38 AM

Yes your a idiot.

-- Aj

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WhatDoIDo

2 posts in 44 days


#5 posted 05-07-2021 02:42 AM

*you’re


Yes your a idiot.

- Aj2


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Aj2

3891 posts in 2917 days


#6 posted 05-07-2021 01:07 PM


*you re

Yes your a idiot.

- Aj2

- WhatDoIDo

  • Or you are . :)

-- Aj

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