I've got a good deal of wood scraps from other projects laying about and am thinking of making a colored epoxy table, something like this:

enter image description here

Where the blocks are my scraps, the area between will be filled with epoxy, and the outside would be steel or iron (going for a modern industrial look).

I usually don't frame tables, but then again, this is the first one where I'd be filling it with epoxy as opposed to running full length boards. So, the question is: with this type of build, do I need to be concerned about wood expansion and the wood possibly bowing up?

Thanks!

  • 2
    "I usually don't frame tables" And as a rule, nobody should if working in solid wood. So +10 on @SaSSafraS1232's Answer, neither aspect of this design (the framing nor the epoxy fill) are feasible in wood. Also a reminder, it's not expansion only that needs to be factored in with solid wood, wood both expands and contracts and can become both narrower and wider than when built during the driest and most humid times of year (cycling between these two extremes each year). – Graphus Oct 9 at 11:47
  • @Graphus - I'm getting how the frame idea is going to be a problem; but can you expand on the epoxy fill not being feasible? I don't see how this design is very different from the plethora of epoxy-river tables? – Hueco Oct 9 at 18:09
  • 1
    In short, the wood is going to expand and contract and the epoxy won't be able to move to match. To expand a bit further, in epoxy-river tables the epoxy is along the long grain (hence the suggestion in the second paragraph of the Answer) with the wood set to move outwards from there. If wood moved along its length to any significant degree epoxy-river tables wouldn't be possible. – Graphus Oct 9 at 19:58
  • It's worth being aware that quarter-sawn wood contracts in the thickness as it dries rather than the length or width. Also, the main consideration with your design would be the expansion of the steel frame. But if your frame was made out of c section with a gap and then had a lip at the top to cover the gap, in theory you could make this work. – Robert Frost Oct 10 at 1:09
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    @RobertFrost, "quarter-sawn wood contracts in the thickness... rather than... width" QS wood expands less in width, but that's not to say not at all — radial movement is approximated as half that of tangential (it can be a little less but sometimes it's more, depending on species). See more in my Answer to this Q + follow-on links. Also, "the main consideration with your design would be the expansion of the steel frame" Thermal movement in metal at this scale is so small that it can be safely ignored. – Graphus 2 days ago

I would be quite concerned with wood movement in this design. You will be bonding epoxy (which doesn't move seasonally) directly to the end grain of wood. Since the wood will be expanding and contracting but the epoxy won't I would expect one or the other (or both) to crack or buckle.

I would suggest either redesigning the piece so that the epoxy is bonded to the sides of the boards instead of the ends or decoupling the center section from the boards (i.e. change it to a piece of glass resting on rabbets on the end of each board.)

Also, you will need to make sure that there is some mechanism for expansion of the wood in the metal frame. For example, the frame could be made of C-channel with the open side facing in and the boards float inside it with some room for expansion.

I've only done small scale surfaces like this, but if the epoxy completely surrounds the wood (i.e. put a layer of epoxy down first, then the wood, then fill over it with a gap between the frame and wood that the epoxy fills) I haven't seen any noticeable expansion/contraction because there is no change in humidity inside the wood.

Admittedly this is also for pieces that are inside, so temperature is a fairly constant 65-75 degrees year round.

I like the glass idea at the end of each piece with expansion gaps hidden by the frame as well - I'll have to steal that one myself.

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