Building a PVC sink: another approach

[bob carnie]

Bob, one of the problem with Sintra or ABS is that certain mold release compounds have been used, or plasticizer might have been incorporated into anything vinyl-based. It's important to scrub down any components with vinegar or alcohol before developing or washing anything photographic in these. Don't use any kind of strong solvent like acetone because it will attack these kinds of materials, including acrylic. Poplypropylene would be hell to fabricate into anything as complex as a slot washer, since it can't be glued.

The main problem with a huge slot washer versus just an oversized tray for 30X40's is going to be the sheer weight of the thing not only empty, but especially when filled. Not only will it need to be especially well made, but your floor and stand will probably have to be reinforced unless it's concrete to begin with. Vinyls are going to bow outward due to all that pressure. It makes a lot more sense for the outer housing to be welded from stainless steel, and only the dividers and siphon system be plastic. How much does your 20X24 washer weigh filled? A realistically built 30X40 washer of equal print capacity might be ten times heavier when full.

Textured acrylics are available, but prismatic would seem to be a little risky in terms of scratching print emulsions. What I use are tiny little self-adhesive pure silicone hemispherical bumpers (not the vinyl kind). They'll last for decades. Beware of styrene as a substitute for acrylic; it's relatively brittle, especially over time. Sintra can be obtained textured, and will be far more affordable than acrylic for dividers, but will warp a bit in warm water, so it's a good idea if dividers are not too close together, and are also individually removable if needed.

Hi Drew
the floor is solid and I would make it to sit about 3 inches off the floor so the drain is usable I need to make sure this is legal with the floor drain. I think the material that I have my sinks made out of would be strong enough I only need 6 slots or 5 slots. I think the inserts could be 3/4 or even 1 inch to stop bowing no matter how warm the water.

[bob carnie]

Bob, one of the problem with Sintra or ABS is that certain mold release compounds have been used, or plasticizer might have been incorporated into anything vinyl-based. It's important to scrub down any components with vinegar or alcohol before developing or washing anything photographic in these. Don't use any kind of strong solvent like acetone because it will attack these kinds of materials, including acrylic. Poplypropylene would be hell to fabricate into anything as complex as a slot washer, since it can't be glued.

The main problem with a huge slot washer versus just an oversized tray for 30X40's is going to be the sheer weight of the thing not only empty, but especially when filled. Not only will it need to be especially well made, but your floor and stand will probably have to be reinforced unless it's concrete to begin with. Vinyls are going to bow outward due to all that pressure. It makes a lot more sense for the outer housing to be welded from stainless steel, and only the dividers and siphon system be plastic. How much does your 20X24 washer weigh filled? A realistically built 30X40 washer of equal print capacity might be ten times heavier when full.

Textured acrylics are available, but prismatic would seem to be a little risky in terms of scratching print emulsions. What I use are tiny little self-adhesive pure silicone hemispherical bumpers (not the vinyl kind). They'll last for decades. Beware of styrene as a substitute for acrylic; it's relatively brittle, especially over time. Sintra can be obtained textured, and will be far more affordable than acrylic for dividers, but will warp a bit in warm water, so it's a good idea if dividers are not too close together, and are also individually removable if needed.

Hi Drew
the floor is solid and I would make it to sit about 3 inches off the floor so the drain is usable I need to make sure this is legal with the floor drain. I think the material that I have my sinks made out of would be strong enough I only need 6 slots or 5 slots. I think the inserts could be 3/4 or even 1 inch to stop bowing no matter how warm the water. As you can see this is the grey plastic I have had success with in past

[Drew Wiley]

Sounds good. Once the sheets are acquired, just as afternoon fabrication job for anyone properly equipped, though I like to see the solvent welds thoroughly cured for about 48 hrs before moving anything like that. Not too hard for two people to handle if the dividers are removable during transport, or even for one person with a handtruck.

[Michael Rosenberg]

Chuck,

Were you refering the article on the LF home page for making a PVC sink? I wrote that up some years ago. My sink is now 21 years old, and still going strong. Never had a leak.

The gray PVC is a chemical resistant material, not like sintra at all.

Regards,

Mike

[Drew Wiley]

All PVC is aromatic solvent susceptible; otherwise, it would be impossible to glue or solvent weld in the first place. But it will be resistant to alcohol and mild acids, and most typical darkroom chemicals. So it differs from poly plastics like polyethylene or polypropylene which have a far greater range of solvent resistance, and which must be either thermoformed or heat welded. After all, that's why most glue is sold in polyethylene containers, and not any kind of vinyl.

Ordinary PVC sheet is Grade 1; the stiffer and more resistant gray version, Grade 2. But you don't want to spill full strength glacial acetic acid onto even the gray product; it will handle common stop bath dilutions fine.

Sintra is expanded vinyl, so not as dense, but fine for many darkroom applications like liners where lower cost is a priority, at the expense of better rigidity. It's main usage is for signage.

[Chuck S.]

Mike,

Yes. And as I wrote, just "differences in details", and some ideas & suggestions that might interest forum members. Not expecting anyone to follow my example to the letter.

Chuck