Building Sink Now

[David Ruby]

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.

 

[blansky]

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

 

[removed account4]

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

 

[David Ruby]

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.

 

[blansky]

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

 

[jstewart]

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

 

[David Ruby]

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.

 

[BobF]

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

 

[jstewart]

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

 

[David Ruby]

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.

 

[David Ruby]

Well, with 3 coats of this stuff it looks pretty good. The only problems areas are the little "boats" that they mill uses to fill imperfections (they look like ovals with sharp ends). Something about the glue used has caused the epoxy to avoid a very tiny area around the boat. I'm thinking about trying a 24 hour epoxy glue to seal these tiny areas.

Everywhere else looks great. In some areas it's almost like a bathtub. This stuff reaks though! Smelled up half the house and my furnace isn't even in the garage. It's starting to die down now though thankfully. Talk about off-gassing!

 

[Tim Budd]

I see you have all used epoxy paint for your sinks but over here in the UK I am having trouble getting epoxy paint. I can get garage floor paint but I don't think it is epoxy as it isn't a 2-part package. Does anybidy know where I could get some epoxy paint in the UK without much trouble or is there some other safe alternative I can use for my darkroom sink?

 

[GreyWolf]

Just a quick bit of info to share.

Most epoxy paint (the two part stuff) is simply a thin fiberglass resin. The only difference when you do fiberglass is that you add fiberglass cloth and then spread the resin on top. (of course there is a bit more skill required). The idea behind the cloth is that it adds strength to your project.

I used to work making houseboats and doing the fiberglass parts. The difference between that and a sink is mostly the smooth finish. A boat has to beautiful to sell where as a sink only has to be functional. I have recently (2 months ago) made a plywood/fiberglass sink for my darkroom and am just doing the plumbing changes over the next two weeks.

I suggest that anybody who wants to waterproof the sink obtain a beginner's book to fiberglassing from the library and read a bit. All that you really need to do is have fresh air, mix the epoxy resin /catalyst and lay the stuff down. (a bit simple but it actually works). The paint stuff that sells is usually more diluted (easier to spread) and sometimes they give you some grit to add so that it is not as "slick as grease" when it gets wet.

I would not place caulking under fiberglass resin. I would do all my resin first, let the resin cure and then if necessary do caulking.

In my sink I did not require any caulking, the resin sealed everything. Even though as mentioned it does not have to hold water like a bathtub I tested mine anyways. I filled it with water in the garage and left it to sit overnight.

Watertight and nary a leak.

Kind Regards,

 

[GreyWolf]

Hi Jdef,

I thought of doing the same thing, cove my inside corners. I also did 1/2 round on the top edges so that I could lean against the sink without the sharp corners.

Just had to be careful not to get air bubbles on the inside edges. I did a triple coat of epoxy (needed to use it up) on all of the inside seams. A bit crude for a boat show.... but only I will be looking.



Kind Regards,

 

[protar]

From out of the blue...
If you are a woodworker, you know that you don't need a diamond hone to make your tools sharp, good sandpaper will do and if you are working on the cheap for dark room stuff, try using beach coolers for water temperature control. It is hard to beat the price and time investment is small.

Cheers

PS, I made my "sink" (more so a splashway really) out of Luan subfloor material and 1x4 pine, coated with Polyester resin. $40, works fine!

 

[GreyWolf]

Hi Jdef,

I am not sure what exactly it is that you need for ULF film. I can share with you what I have built. (If you want I can take a couple of digital pics and post them or send them)

My sink is fairly large as I only wanted to do this once. I can fit 3 16x20 trays along the length (cross ways - sink is 32" across) and I still have the deep well at the end. My design criteria was to be able to do (4) 11x14 trays along the length and still have a 12" x 32" x 10" deep well at the end.

My sink slopes very gently from the top end to the deep well. The deep well then slopes from both sides towards the middle where I have made a fiberglass seat for placing the drain. (exact same drain as a standard kitchen sink). I wanted a deep well for washing up mostly and a place to dip my hands and rinse before going back top the dry side of the darkroom.

The "coupe to grace" is that I won on Ebay early this spring a brand new "unused" Noritsu temperature control board for less than $200. This thing is all premounted on a slab of white ABS like board, has both a cold and hot inlet cannister filters, a flow meter and of course the temperature control valve. Rather excited about getting this in place in the next couple of weeks before Xmas holidays.

I also wanted my sink to accommodate (3) 11x14 trays and the print washer at then end. (Versalab 11x14 courtesy of Bmac....thanks). I'll be placing the plumbing in place this weekend and working throughout the next week or two fine tuning all of the parts. When it is done I'll do a digital picture for you.

After blabbering away about this, I hope I did not leave the impression that the sink was a real work of art. On the contrary... anybody who can attach plywood together with glue and screws can build something like this. The fiberglassing is relatively easy once you understand what to do and what to watch out for.

Perhaps you can tell us what you are building for ULF?

Kind Regards,

 

[blansky]

jdef,

I have a right angle shaped sink that I process a lot of 20x24 prints in and what I did was to stack the trays with a wooden homemade shelf system. I have stacked, dev, stop, fix 1, fix 2, and permawash at the bottom. This leaves me room for a bleach tray (for sepia) a wash tray, a toning tray as well as a archival print washer. I am able to do the entire process at one time.

Some people don't like the stacking system but it is easy to get used to and the space savings are great.

Just and idea,


Michael McBlane

 

[magic823]

Take the built sink to one of these spray on truck bed lining places. It works great!

 

[wm_brant]

I'm a little late to the party, and it may have been mentioned above, but an excellent alternative to the expensive epoxy paint is PPG's Coal Tar Epoxy.

I put this on my sink when I built it (3/4 inch regular plywood) and have had zilch problems with it. It's *real* heavy-duty stuff that is used where you want to coat something ONCE and never have to do it again; I think I read somewhere it's used on the inside of septic tanks...

I used it because one of the 'how to build a darkroom' books I was using recommended it. I have not been sorry; it's held up very well and I cannot complain about the cost ($25/gallon?), which easily allowed two coats of my 7 foot by 2.5 foot sink. The paint was not available 'off the shelf' here in Des Moines, (it's an industrial, not a consumer product) but a nearby dealer ordered it for me and had it delivered to my door.

It comes only in black, it's thick (imagine what you would get if you mixed coal tar and exoxy together and you will not be far off the mark), but it works well.

If you're looking for a tough paint and don't want to spend a fortune, you might give it a try.

-- Bill