lAnother table top question....

made by the inexperienced

Bill Tindall, E.Tn.

Goes to show another example of not learning woodworking from Facebook. There is no need for the rods and in fact they may create problems.

But to answer your question, epoxy like all polymer films, is permeable by water molecules. The epoxy will slow the rate, more on the top than the bottom (see any problem here) but at equilibrium with the atmosphere the wood will be the same moisture content as if it had not been coated.

Re: lAnother table top question....

John McGaw

I learned, albeit too slowly, that gluing up multiple species of wood is dangerous. I made some really precise and, to my mind at least, beautiful stationary boxes as gifts when I first started out and lacking subtlety, mixed strips and panels of birdseye maple, ebony, purple heart, satin wood and anything else that came along. Needless to say, a couple of seasonal changes later the lids came apart.

If I was going for the look you describe I'd be going for something dead stable as a base (laminated MDF?) and lots of little squares of high-end veneers to make up the pattern. Fiddly but probably no more so than what you described.

Veneer is an arcane science

Jim Matthews

Jamie Robertson was kind enough to guide a through his studio back in 2014.

He makes large marquetry and veneer panels, exclusively with Cascamite.

Dunno how wood species are selected for his furniture, but the consistent results and lasting bond were why he insisted on the stuff.

https://www.artfulhome.com/product/Wood-Bed-Frame/Sunrise-Sunset-Bed/15533

question the diagnosis

Bill Tindall, E.Tn.

The differences in response to moisture changes between different species may not be any more than the differences within a species and within the range of grain orientation one might have. I suspect the glue failure was from a reason different than using different species. I see multi species cutting boards prepared by people earning a living making them. If using multispecies was a flaw these boards would not be successful.

Re: question the diagnosis

Barry Irby

I have made a number of cutting boards out of different species of wood using several types of glue and some of them are fifty years old. Never had a failure because of differing types of wood or glue. One slight exception might be one I tried many years ago using some sort of two part powdered glue and I was WAY below the minimum temp for the glue and it did not adhere at all.

I have made chess boards out of maple and walnut and in one case I resawed the strips and glued the whole thing to half inch plywood. The wood was about a 1/4" thick. When the wood dried further the board warped badly, probably had about 1/2" cup in it. This could conceivably apply to marquetry but since those pieces are glued on separately I doubt it.

The top I was asking about in the OP was glued up of strips that appeared to be about 1 x 2's like an edge grain cutting board and I was questioning the steel "rebars".

Re: question the diagnosis

Garthinsandiego

I think the steel rebar and epoxy approach may be a mis-applied technique derived from stone countertops. It is common to epoxy steel bars or rods in grooves to reinforce narrow sections prone to breakage. Doesn't really belong in woodworking.

That glue...

John in NM

Is called plastic resin glue - it's fantastic stuff.

Except when mixed too thin with water, that makes it weak, or as you found, when used below it's ambient temperature range, then it doesn't adhere well. I had the same problem as you describe once when using it below the recommended 70 F - but not that far below, in the low 60's as I recall. Powdery glue joints, but just at the edges of the veneer where the too low ambient temp had the greatest effect.

I think it's not intended as a consumer product, so the manufacturer did not put a "buffer factor" in the instructions. When they say do not use below 70 F, they really mean it! Same with the strict recommendation to weigh glue powder vs. water rather than attempt to mix by volume. It works much better when measured by weight.

All probably water under the bridge now, just wanted to confirm your speculation with my own similar experiences.