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I'm just about finished building my darkroom sink. I'm basing my design on one I found in an old darkroom book. Basically, it is made of plywood then, waterproofed with epoxy paint.
I've got the sink built, and am ready to caulk the seams again just to be safe, before applying the epoxy paint.
Has anyone built a similar sink and have any tips or suggestions? The joints already have caulk in them, and the instructions call for more caulk to be applied prior to the painting. You paint it, then apply caulk again just in case. Sounds pretty straightforward, and so far everything has gone pretty well.
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When I built mine I caulked the inside edges then I painted it with boat paint, which I think is epoxy.
I did about two coats of paint and that was it. I've had it for three years and it works fine.
Make sure you you have an angled towads the drain, and you should be fine. Remember it's not a bathtub, it only has to direct the water towards the drain and out.
Michael McBlane
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when i worked on mine - i didn't use calk, but i used fiberglass resin and cloth instead. i put 2-3 coats of the resin on, and looked forward to fixing it( pardon the pun) every few years :)
good luck & don't forget to ventilate <g>
-john
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Blansky-Did you caulk again after painting? I think that is the direction this book gives, but I'm wondering if that is something that you would want to do when or if you see cracks since this caulk would be the only item outside of this epoxy shell you create.
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David:
I've built a couple of these over the last few years and I think I caulked the first one and painted afterwards and on the second one the other way around. No particular reason.
I really don't think you need to get too anal over this as the combination of the paint and the caulk will stop the water from getting to the wood. Just make sure you caulk sufficiently and get a couple of good coats of paint on the wood and you should be just fine.
I used about 3/4 inch plywood so there is no flex in it, and as I said, it only has to channel the water to the drain.
Remember we're not going over Niagara Falls in it.
Michael McBlane
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I build a sink from MDF (fiberboard). It's cheaper than 3/4" ply and just as sturdy if you support it enough with the sink frame. I agonized over which epoxy paint to use..you can spend 100USD per gallon if you want to. I settled for a product used to paint garage floors (Valspar Epoxy Floor Paint from Home Depot or other home store). I caulked the raw seams first, then used drywall putty to form a smooth curve wherever the walls met the bottom. Let that dry, then applied two coats of paint. Nothing fancy. The trick is getting a rigid frame for the sink so it won't move when you lean on it/ against it. Oh, the floor paint cost about 50USD per gallon and I'm going to get about 4 more coats from what I have left.
Be careful installing the drain. If you recess the bottom so the drain sits below level, be sure to coat the recess, the sides of the drain hole, and the underside of the bottom with epoxy paint. Any water that creeps between the drain and the drain hole will swell the wood and it means doing it again.
Hope this helps / adds something
Jim
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I've bought some epoxy paint from Home Depot that says it is used to recoat bathtubs etc. for around 15 USD. It is in two parts much live I've read in posts and books. Hopefully this is the right stuff. It came in 1 quart which the book I'm going from recommends and it is in two parts. I guess I'll wait to see how thick it looks when I'm done to see if I think recaulking the seams will be required. The joints I have now are perfect.
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I want to warn people from using MDF, particle board or even OSB instead of plywood for making sinks. A little leakage in plywood causes a little problem but a little leakage in MDF causes massive swelling which cracks the finish causing more leaking causing more swelling etc. etc.
I hope it works out for jstewart but the odds are not in your favor.
Bob
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You're absolutely right Bob. MDF swells badly when it gets wet. The trick is to make sure it doesn't get wet by giving is a good coating. I made shutters for my outdoor shed over 4 years ago using MDF. I took care to paint them well and haven't had a single problem yet, and no recoating since. So long as the seams are well sealed, using MDF shouldn't be a problem. I used it because it's (1) cheap, and (2) easy to work with, (probably more stable than ply (i.e., no movement due to changing humidity), and (4) I knew it worked well for outdoor use !
Jim Stewart
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Your lucky Jim. MDF, particle board, OSB etc. are all very bad news when moisture is present. Plywood is a hands down safe bet. You're right though, if no water gets to it there is no issue, but for the extra cost, it's not worth the risk.
I just had a dishwasher leak in my house. The underlayment (particle board) swelled up like a sponge and was ruined. The subfloor (plywood) simply needed to be dried out. We use plywood at all our sink countertops (I'm an architect) or at a minimum we use industrial glued particle board.
