Soap stone darkroom sink?

[Drew Wiley]

I got Formica countertops for free. But I know how to make my own too. There are chemical-resistant grades of these materials, even static-resistant if you want that.

[Ironage]

Thanks for the thoughts. I would be looking for a used one, and may have already found it, but I don't know it's dimensions yet. Stainless steel is also expensive and noisy, fiberglass is nasty stuff that I know would be a mess as soon as I start playing with it. (Think finger paint). ABS is to flimsy for me. This will be my final darkroom, it is time to settle down.

[Drew Wiley]

Be aware of a couple things if you need to resize a soapstone top. You need a special kind of distinctly expensive diamond blade because, ironically, being so soft and retaining heat so well, ordinary diamond blades tend to overheat and shed their rim (dangerous- wear a face visor, thick gloves, and thick coat). So if you must do it with a relatively ordinary hardware store or lumberyard diamond blade, go slowly and allow the blade to frequently cool, and use a stiff toothbrush to clear off any accumulated talc residue. Second, you want good control of the dust as well as wear a good dust mask because soapstone sometimes contains a bit of natural asbestos or other nasty minerals. Sizing this material is really best done by someone with the right kind of equipment and experience. Sanding corners etc is easy; but again, beware of the dust.

[John Layton]

I know this might not be helpful...but 3/4 inch birch ply screwed-n-glued together, three coats of low voc Rakka marine epoxy (with vents installed prior to application to ensure safety), and you have yourself a great sink which will last a long, long time.

[Drew Wiley]

I'm very familiar with marine epoxy. I sold more Smith epoxy than the plant store itself did. Drove right past the West System plant yesterday. Then there's Abatron. I'm not familiar with Rakka. Low VOC does not mean safe to breathe; it just pertains to whether the volatile solvents involved are considered smog-forming or not. Anything like this requires serious ventilation and chemical-resistant gloves. With plywood, the joints ideally needed to be supplemented with epoxy putty, and not just the same penetrating epoxy used for the wood. The achilles heel of epoxies is long-term UV exposure, which isn't going to be a problem in the darkroom.

[Paul Ron]

Be aware of a couple things if you need to resize a soapstone top. You need a special kind of distinctly expensive diamond blade because, ironically, being so soft and retaining heat so well, ordinary diamond blades tend to overheat and shed their rim (dangerous- wear a face visor, thick gloves, and thick coat). So if you must do it with a relatively ordinary hardware store or lumberyard diamond blade, go slowly and allow the blade to frequently cool, and use a stiff toothbrush to clear off any accumulated talc residue. Second, you want good control of the dust as well as wear a good dust mask because soapstone sometimes contains a bit of natural asbestos or other nasty minerals. Sizing this material is really best done by someone with the right kind of equipment and experience. Sanding corners etc is easy; but again, beware of the dust.

wet saw is the only right way to cut soapstone.

.

[Drew Wiley]

Yeah, wet saws. Well, for thick soapstone slabs, those are similar to a huge radial arm saw on an overhead rail. Damn fools would attach water hoses to ordinary Skilsaws and routers then hire some illegal day laborer to risk his own life. Ordinary wood carbide blades and router bits too. Whenever those particular machines came into our repair dept they were never ever returned to the person who brought them in. "Unrepairable", "your account is closed" was the standard answer. I kept all the diamond blades locked up and refused to sell them to anyone foolishly using them on a grinder or any saw not specifically engineered for wet use - and most of the real deal of those were actually tested after the engineering phase underwater in a special tank, yup, not kidding. The cheap Chinese clones were not and scared the heck out of me. There's a dumb stone age and a smart stone age, with the Darwin award fully applicable.

[John Layton]

as I said...ventilation installed prior to coating. Also...no putty (fillets) needed if joints are sound. Three coats of epoxy is more than enough to fill joints. Absolutely no leaks after five years and going strong! Nolo Problemo!

[Drew Wiley]

Five years is a quite small track record, and let me explain something else you haven't factored in. It depends on a several of things, John. Having the right quality plywood, and sealing the opposite sides with a least one coat of oil-based varnish or penetrating epoxy to prevent dimensional changes that could pop joints. Also good marine glue at all the seams and joints, supplemented by stainless screws. But here in earthquake country I do advise something additional like an epoxy putty along seams, though true moisture-cure polyurethane boat caulking could also be used after the epoxy has cured. I have indeed seen quite a few failed plywood sinks around here due to that very issue. It's inevitable, and a significant shake could happen a day later. Overbuilding things is not an option here; it's mandatory. And I dare say there are far more darkrooms and chem labs here on the Calif. coast than in Vermont. I really prefer seamless liners in such cases. At one time I sold liquid hypalon coatings that worked even for concentrated industrial acid vats - nasty, nasty stuff to apply, and now illegal. But now hypalon rubber can be purchased in safe roll form and be heat-welded in place; way more expensive than typical garage floor or truck bed liner products, but if someone wants the best, that's it. I already stated that I ordered a heat-welded polypropylene sheet sink for my own use; but that's a more difficult product to weld than hypalon roll material, which any pro torch-down roofer can manage. I coached all kinds of these situations, at the UCB with its many research facilities, in regard to both industrial and pharmaceutical mfg plants, many military applications, numerous commercial photo labs, etc. - got to hear and inspect a lot of horror stories about what failed. Geography counts too.

[Greg]

to prevent dimensional changes that could pop joints.

My experience with the sinks that I have constructed out of plywood, has been that the joints did indeed crack after a few months. Plywood was stored outside under cover in the lumber yard and exposed to the summer's high humidity. When it was delivered into my very low humidity basement/darkroom, I would immediately construct (one deck screw every 6"), paint, install, and use the sink. Resisted immediately caulking the joints, thick paint acted like caulk. After about 6 months the joints would show a hairline crack in them as I expected. Repainted the sink including a second coat over the joints.

Most flooring places tell you to store pre-finished flooring inside the house for a few days before installing. Our installer insisted on storing the flooring inside the house for 2 months before installing it. Think I read somewhere that Deardorff would store its "dried" wood for 2 years before using it to construct their cameras.