Question
My understanding of the reason that veneers must be applied to both sides is because of the water in the glue evaporating and a balance being required during the drying process. I'm looking to veneer 1/4" thick shop cut veneers onto 1" MDO. If epoxy is used, would it still be necessary to do both sides?
Forum Responses
(Veneer Forum)
From contributor O:
1) Your understanding about why you need to veneer both sides of a panel is completely wrong. Veneered panels need to be balanced (unless restrained by framing) because veneer tries to expand and contract with seasonal humidity changes, and the panel will curl and warp unless those forces are balanced. This is a permanent requirement, not a temporary, assembly-related need.
2) 1/4" thick wood is not veneer. It's at least two or three times as thick as anything I'd call veneer. You're thinking of gluing a layer of unstable solid wood to a stable sheet good. Don't do it - not even on both sides.
Although odd numbers of plies is a handy rule of thumb, it's not really the number of plies that makes or breaks a system like this. The problem you're flirting with is that the forces of expansion and contraction, due to humidity changes, of the veneer on one side of the panel won't be balanced by similar forces on the other side of the panel unless there's a similar veneer, oriented with the same grain direction, on the other side of the panel. When the panel is balanced, the opposite veneers push and pull against each other and maintain an equilibrium that minimizes deformation of the panel.
Think of it like an arm wrestling match. A balanced panel is like two evenly matched opponents; huge forces may be at work, but the grasped hands barely move because the opponents are equally strong. An unbalanced panel is like a bodybuilder arm-wrestling a weakling; there's no real contest, and the grasped hands slam quickly to one side.
It may well be a failure but I'm going to glue up 2 and leave one in the shop for a couple of weeks on a shelf and the other in a mini skirt.
I have a stair book showing thick composite treads consisting of an inner lumber core and over-laid with two layers of wood. The first or sub-layer is applied cross-grain (or cross-banded) over the core and the exposed top face layer. The tread is completely wrapped. The layers are a minimum of 5 MM (a little less than 1/4").
I have replaced stairs in homes and public buildings that were over a hundred years old. The original solid oak treads were worn and hollowed out along the walking line by a half inch and more. These steps were unsightly but still serviceable. The risers all had deep dents and dings that would have punched through any veneer.
A glued-on nosing along the leading edge of a tread is another big no-no. There are tremendous forces applied at the nosing by just walking up the stair (let alone bounding up and down). A nosing piece that breaks off under the foot of a person bounding up the stair is going to be a serious issue!
Solid treads and risers should be the rule for professional stairbuilders. Engineered clad treads are mostly seen in modern riser-less designed stairs. These treads are often cantilevered or perhaps supported only by a single central beam. These laminated treads are often 4" thick and covered with a carpet mat along the walking line.
"Artisan craftsmen" often throw reason out the window for the sake of their art. My points are still valid but who cares? This is gorgeous woodwork!
There's a recent picture posted in the Project Gallery of a custom made hand plane. Check it out and decide if you would use it or put it on display? You get my point? Anyway, I get yours. I am sure whatever you do will turn out great, so don't pay any attention to naysayers like me.
I have been working on some flooring borders that use Tigerwood, and after milling a portion of the rough stock into blanks I realized I was going to run out due to excess wastage. There are many boards in the stack that I feel awfully guilty cutting up and I don't really want to order more stock due to my location, so I am doing a few mockup trials to test. I am using a 1/2" Baltic birch substrate, 1/4" wear surface and Unibond 800 in a vac press. I have applied a thin finish to replicate a worn out finish and am going to submerge the test into water for a few days in an attempt to replicate the effect of years of water abuse.
Around here (Seattle) a 100 year old house is considered old and the ones I've been in don't show a 1/4" of wear. I'm sure that's not the case everywhere and the homes I'm referring to started as upper end and were well maintained.
