reclaimed fir – laminate to what for countertop?
I’m remaking a bathroom countertop, and wanted something rustic. I just found a bunch of reclaimed vertical grain fir that’s really nice, but it’s only 3/4 thick. If I make a double layer or stand the pieces on edge, I could laminate a nice counter, butcher-block style, but that seems like excessive use of the beautiful material.
So, I’m wondering what would happen if I laid it up in a single layer on top of something like MDF. I know people glue down pine floors all the time, but it worries me a bit. Would it tolerate the wood movement? Is there some better approach that still conserves material?
I’m not too worried about water penetration to the substrate, because this is not a heavy-use room, and I’ll be filling all the voids with black epoxy.
Any thoughts much appreciated.
Replies
Well you can eliminate the idea of gluing a top with the 3/4 inch edges turned upwards because then the vertical/quatersawn face would not show.
I should think that a 3/4 inch top thickness would be enough for a small countertop. But if you want it more substantial you could either simply double the thickness or slot screw it to a substrate. I'd go for the substrate and I'd use plywood not mdf. Because I don't like to work with mdf and mdf doesn't like moisture rich environments.
The front edge of the fir can easily be thickened by ripping off a bit from the last board and using that strip as the thickener. Then the edge grain will look appropriate. You may or may not want to invert that last strip. Play with it.
In no case should you glue your top to an stable substrate like ply or mdf. That will insure cracking or buckling depending on moisture contents.
Edit to add: You might investigate using cpes as a sealer. Smith's makes one that I've used. http://www.smithandcompany.org/CPES/
A Safe Method
A safe method is to resaw the 3/4" wood to make pieces that are 1/4" or less in thickness. Edge glue for width, then glue it down onto both sides of 3/4" MDF. I like the handy dandy vacuum press for this, but clamps and cauls will do also.
By reducing the thickness to 1/4" or less, you can get the stuff to behave more like veneer and quite acting like a solid board. Just make a balanced construction (same wood/thickenss/mobiture content on bothe sides), use low moisture glue - urethane would be my first choice for laminating, TB1 for the edges, and you're there.
A real bonus of this is if you manage to get 2 or 3 plies out of each board, then you doubled or tripled the square footage of a nice material.
But if you do this at 3/4", just one side or even both sides onto MDF, the wood will eventually crack, and will bow and cup before that.
A hybrid method would be to laminate the resawn plies to another wood substrate - both sides for balance, and then join those wood laminations together for width. This would be a solid wood assembly, and would move like solid wood. Make sure both Fir and core woods are the same moisture content, and the core should also be quartered or rift, yo match the Fir. Piner would be a good core to use.
More than one way to skin that cat. Or board.
Also a good idea, with the added bonus of justifying a bandsaw and vacuum press.
Not sure why I mentioned MDF actually - I hate the stuff and it seems like a sin to bond reclaimed lumber to it. I do have some nice pine that's been in the same environment for a while ...
I know that shop sawn veneer thickness is a volitile point of debate. I'm in the camp that limits the thickness to 3/32" before it starts acting like a board and not veneer. I did a large dining table once with 1/8 veneer for a client. Then I redid it using thinner stock. That was an expensive lesson.
In any case, I would not use 1/4" veneer in any application where it was rigidly glued to a stable substrate. It will either shrink and crack or expand and buckle. My opinion.
Pushing the Limit
1/4"thick shop sawn veneer is the upper limit of what works, in my experience. When I do a large table - lotsa width - I drop down to 1/8" or even turn to thick veneer.
That said, I have several 1/4" thick laminated tops that look fine after many years. They have good barrier coats on them, and they are not over 24" in width..
One top - a coffee table at 42 x 42 - puckered at a few seams, but it is a distresed thing that was beat up to look old, so even though it is a 'failure', the context saved my butt. Dumb luck is better than no luck.
Corestock is the one thing that MDF excels at. The object, as far as I'm concerned, is to cover up that nasty stuff with good wood so you don't have to see or smell it.
Dave S
The first thing I'd do was glue up the fir edge to edge with dowels or biscuits, to the full width of the counter top. Make the edges two layers thick. If the individual boards aren't too wide this should be extremely stable. Then I'd install this over a plywood substrate using construction adhesive and screws from underneath.
FWIW, Medex is water resistant MDF and the only MDF I'd use for a countertop.
You do not need a solid substrate beneath the whole top.Rip 2 pieces of the same material 3" wide and glues to the bottom side of the front and back.Rip another piece 1.5" wide for the front edge to be glued vertically.Rip 2 pieces 3 inches wide to fit between the front and back on the ends and screw with screws in slots routed in them NO GLUE ON THESE Saves material and lets the woood move .