What glue to use on wooden joints around a sink?
Here is the situation: The owners of an 80-year old cabin want me to install a section of wooden counterop immediately behind (and lapping 1/2″ over the back of) the old enamel undermount sink. They do NOT want a new sink or new countertops — the old stuff has sentimental value to them.
The countertop is 1″ thick solid wood painted with some sort of oil-based marine paint. The 24″ wide sink has been slung under the counter for years, with a 3.5″ gap behind it between the back of the sink & the wall. The cabin owners want the gap behind the sink to be filled. They have removed the old wall-mounted faucets; counter-mounted faucets are to be installed behind the sink once I have patched-in the space between the wall & the sink.
I am to close the gap behind the sink by installing a 1″ thick, 24″ long x 4″ wide bit of new painted wooden countertop behind the sink to support the faucets. I can support the board — my concern is the 4″ joint at each end, where it joints to the existing counter halves. This will be end-grain to end-grain, right behind the sink in an area which is doomed to get wet. The best idea I have come up to keep moisture out of the joint is to fill it with thickened epoxy or wood filler or glue, and then fair it out, sand it smooth, & then paint it along with the rest of the counter.
What would a boat-builder do?
What kind of “glue” would be best?
I do not like this situation, but that is what they want. I have spoken about moisture & expansion, and they are (presumably) aware of the risk of rot. But I want to minimize it if at all possible. The cabin owners do not want to add laminate or replace the wooden countertops with tile or anything else — they want to preserve the old parts, but add a filler strip & new faucets.
Does anybody have any advice about how to make this situation work?
Replies
A boat builder would probably use marine adhesive.
I'd use resorcinol glue, and scab pieces under the joints to span it and spread the stress.
And you might even consider oven-drying the replacement part a bit before final cutting, to shrink it up as much as possible.
My primary adhesive for wood kitchen countertops is epoxy, but the majority of the countertops I've made are exotics. Teak, etc. If you have epoxy on hand, it's a logical choice. I use West Systems, usually 105 resin with 205 or 206 hardner.
You can paint epoxy on the end grain. Let it cure a bit. Then recoat the end grain again and then set the fill piece in the gap. You can wipe the squeezout off the joint right away, or let it set up a bit and then shave the partially cured epoxy away with a chisel.
If the existing countertops are staying in place and you are simply inserting this new piece of wood into the gap, then there you go. If you are taking apart the old countertops, making repairs, and then will be resetting everything, then I'd also use biscuits on the end grain.
If you have access to the bottom of countertop where the insert will go, on the underside of the countertop you could also place a bridge support that will go under the length of the insert and extend under the two existing side coutertops. That'll tie the three pieces together and minimize tension on the epoxied end grain joints.
You can also use Titebond. TBII is water resistant, TBIII is water proof. TB is actually an excellent adhesive. With these tops being painted, TB might be easier than an expoy. I've used TB on "regular wood" countertops and it performs very well.
Thanks, All. Really good information there!
Epoxy wins. The original countertop was made of old-growth doug fir back in the 1930's -- they still had the really good stuff then. OG fir is incredibly stable & rot-resistant (witness the condition of the countertop after three generations of use!). So I made the insert out of the same stuff, salvaged from an old door. Ground it down so that it will drain really well, fitted it tight. It is now ready to seal with CPES (clear penetrating epoxy sealer). I could use West System epoxy to do the glue-up & make thickened epoxy fillets to keep moisture out of the inside corners.
Then the owners decided they did not like the sink after all. Go figure.
It all runs downhill & payday is on Friday?
A boat builder would cover the counter area with stainless steel. But that doesn't help you.
I would suggest you use the epoxy as Mongo outlined it. You probably have at least some experience with it since it was your own suggestion. You might also consider using some sort of synthetic wood product for that 1x4x24 piece. Since it will be a new piece anyway, its not historic. And a paintable synthetic will not only not rot, it will be visually indistinguishable from wood.
The deck mounted fixture is a mistake. If you can retain the wall mounted one, it will be much easier to keep that area of the counter dry. If you must use the deck mounted one, then seal it well with a product called LifeCaulk or LifeSeal. Both are paintable and are well regarded for mounting deck hardware onto boats. I like the LifeCaulk if the parts are not plastic.