Darkroom Sink Slope & Drain?

[Salmo22]

I'm preparing to build a sink for my darkroom. It will be 8'x30" and constructed out of 3/4" birch plywood.

I would appreciate comments about the amount of "slope" I should be designing into the floor/bottom of the sink so it can drain properly. I'd like to go with the minimum slope possible so my trays aren't cattywampus. I'm also wondering if you have your drain is "in sump". In other words, at the absolute low point of the sink so all liquids runs directly to the drain? In studying various plywood sinks online, I see where some drains are located in a corner. Some centered in the middle of the sink. Some are centered at on the end of the sink. Very few look like they are actually "in sump". It appears at least some water/chemistry needs to be squeegeed to the drain. While I realize the drain location is dictated by where the sewer pipes are in the wall, I am mainly interested in what works best. For my darkroom, the drain will be located at one end to facilitate connection to the existing plumbing system.

I'm not trying to overthink the room or make this too complicated, but birch plywood is expensive and I'd like to get this right on the first try.

All comments and suggestions are appreciated. Please share photos of your sink if reasonably possible.

[Richard Wasserman]

I've built several sinks and always used about 1/4 inch per foot slope with the drain in the lowest corner. They worked fine.

[Jim Jones]

Salmo -- Having the sink's drain near available plumbing is the logical way to go. As for the slope of the sink, rather than design that perfectly, just build it with the often recommended 1/4 inch slope, and adjust it later by shimming the sink if desired. Practical construction often beats tedious engineering.

[Tin Can]

I prefer 'in sump' aka lowest corner in back wall side at fixer end

I use 1.5" PVC and have connected 3 drains in 3 sinks in my 2 real DR all with 'traps'

I really like PEX for pressure water and use brass valves all over

I made a mistake by cheaping out with a bit of iron pipe fittings for the Hass Temp control

Then I bought the heavyduty PEX Crimper, it saves money

My pet peeve is too many 90's, I like to gently curve PEX

I have done a lot of industrial plumbing for 30 years

[Doremus Scudder]

Some random thoughts:

I built a 10-foot sink some years back. I used the 1/4-inch-per-foot rule and it works well. I placed my drain in the center rear of the sink so as not to have too much height difference from side-to-side. Make sure to slope the sink bottom not only from side-to-side, but also front-to-back. If you're placing the drain in a back corner, then that should be the lowest point. If in the center, then center back should be lower than center front.

I made an earlier sink that had a drain in the right front corner. That worked well too, but it was a smaller sink.

It's easier sloping a sink with the drain in one corner than in the center. Simply divide the height difference you need from one end to the other and subtract half of that from the leg under the drain and add the other half to the diagonally-opposite leg.

My present sink drains well, but when I'm not printing for a while, I'll squeegee it out and wipe it dry. I used marine plywood for the sink bottom and faired the corners with marine epoxy and sanded smooth, then primed and painted with marine topside paint. The advantage for me is that I can repaint small areas or the entire thing easily; just wet sand, dry, wipe down and paint. The marine paint levels out very nicely.

I made a double-thick front splash and rounded the top so now I have a comfortable place to rest my arms when processing (especially nice when shuffling film in trays in the dark - I found the right height for the front splash so I can rest my arms on it and reach the trays).

Had I had room, I'd have made a sink-size sump in one end of the larger sink with a dedicated faucet for dumping trays, clean-up, filling jugs, etc. Maybe that's something you wish to consider. As it is, I use a large funnel stuck in the sink drain to dump trays into (I hate just turning them over in the sink and then having to clean the entire 10-feet of sink later).

I made the sink splash guards all the same height. I then had a 10-foot x 42-inch countertop made, which I cut into sections, reinforced and shimmed so I can lay them out over the sink, resting on the tops of the splash guards to convert the sink to a 10-foot-long work area that I use for print mounting, framing, etc.

To that end, I have a separate 15-amp circuit (GFI, of course) with two sets of four outlets along the wall in back of the sink. I can use this for timers, etc., but use it mostly for my dry-mounting presses, tacking irons, etc., when mounting prints. I can also get my 72-inch mat cutter onto the counter and use the surface for cutting mats as well.

Hope this helps a little,

Doremus

[maltfalc]

if you want your trays and whatever else level, you could just add a little level strip around the sides of the sink to support wire mesh shelving or those plastic grids they put on ceiling light panels.

[awty]

I have my plywood sink flowing from front to back. Have a 4" trough at the back which is just a strip of ply fixed under the main ply so is the depth of the thicknes of ply. Install slats on the sink so trays aren't sitting directly on sink so moisture doesn't build up when trays are left sitting. Put a sink plug and waste at bottom end of trough. Paint the whole lot with pond paint.
Fall should be around 1:60 as previously mentioned.

[Eric Woodbury]

My sink is that size. I built mine flat and level and adjusted with blocks under the legs. It's about 1/8" per foot and it's plenty.

With a router, cut a relief for your drain flange so it is flush with the surface. Water seal before you place the drain stem and again with extra goop when you install it.

[Duolab123]

I have 2 lovely sinks that I have scrounged over the last 30 years. One is a Kreonite fiberglass litho sink 8 '. The neatest thing is a trough in the back to empty trays and tanks. Still has a drain for the main sink too, drains are in the center back. My other sink is Arkay SS 10' drain is in far right rear corner.

I always squeegee the SS sink dry. It drains quite well, just nice to squeegee, especially if you make a nice wood sink. Kodak had a formula for a stain for wood sinks and benches but modern coatings are bulletproof.

[Rick A]

Here's a little something to think about when building a sink. Sanitary sewer fall per run is figured to keep "solid waste" moving. Everyone thinks they must follow the 1/4 inch fall
per foot of run is necessary for their trough, not so, you can get away with as little as 1/16 inch per foot. Remember, you are not trying to flush a (you know what) down the drain.

[Conrad . Marvin]

I used an 8 1/2 foot sink that I made for about 17 years. I used a drop of a little less than 1/16” figuring that water flows off of level. I had the drain in the back corner even though the plumbing drain was below the center of the sink on the wall. I ran a drain pipe from the sink drain into a trap then into the main drain. The only place that I had any issues with dampness was in the corner where the drain was placed since the drain was round and the sink was not.

[Greg]

My sink measures 8' x 2'. Exterior plywood. Since the sink has multiple coats of paint I was advised by my friend (coincidently owner of a high end lumber yard) that I would be wasting $$ with getting marine plywood over exterior. 5 coats of RUST-OLEUM RESTORE 4X Deck Coat paint. Paint is four times thicker than ordinary paint. Re-coat the sink every summer without having to worry about the smell of Epoxy paint. The paint that I use is essentially odorless. Right angle corners are re-caulked every year before repainting. I'm sure this isn't needed to be done, but it takes so little time to do. Drain goes directly into a dry well. Pitch is 1/8" per foot. Heavy Duty Black Kodak Rubber Squeegee works great for pushing any "standing" water into the drain.

[Tin Can]

I never need to squeegee my ARKAY sink

I spray it down with water

When I got my 3 Arkay sinks nobody wanted them

I gave one away, sold the 10 ft, kept the 7 ft as I can move it by myself

Then I added 2 laundry tubs, one for 16X20 print washer and the other for my Gas Burst

Gave away a clean brown fiberglass DR sink

[ic-racer]

Over 20 years ago I designed my current darkroom without a large sink to hold the trays. Washing the trays in the little sink is not fun, but otherwise, I'd have almost no dry counter space between printing sessions for other projects.
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[Ulophot]

Ic-racer, interesting third photo. Is that for agitating the film?

[Duolab123]

I never need to squeegee my ARKAY sink

I spray it down with water

When I got my 3 Arkay sinks nobody wanted them

I gave one away, sold the 10 ft, kept the 7 ft as I can move it by myself

Then I added 2 laundry tubs, one for 16X20 print washer and the other for my Gas Burst

Gave away a clean brown fiberglass DR sink

I had a plastic Rubbermaid wash pan for a sink with a garden hose for the drain, luxurious corrugated cardboard walls. I had the sexiest darkroom of anyone else in 9th grade.

My Arkay sink was delivered to me for free, a professor here at the University of Iowa, he couldn't see it scrapped. I decided if it showed up in my driveway I would find a place for it. I moved some big shelves (I had installed about a year before) fit perfectly, I can't imagine how I got by without it.

I probably don't need to squeegee, but it minimizes water spots, and it makes for a drier darkroom.

[willwilson]

Working on a new sink myself, just moved and building a new space. I had thought 1/4" per foot but I am reconsidering based on this thread. Here is the design I am working off of. It has a pull out print washing drawer specd to hold a 11x14 and 20x24 washers. This DR is smaller than my previous but it is real living space so my goal is to make it super nice. I am designing to be able to print 20x30.

My old sink always stayed wet in spots. But it was free from someone on this forum (wish I could remember their name).

Will Wilson
www.willwilson.com

[esearing]

Alternative coating solution: Quick Seal - its a rubberized paint that is water proof. It also wipes down easily. I also fiberglassed my sink but I don't think that is really necessary if you use a good layer of epoxy to seal the wood before the final painted coats. Also not a bad idea to make the final end of the sink lower than the rest of the sink if that is where you will do most of your washing. |--------__|

[Luis-F-S]

I squegee my Elkay SS sink in order to keep it stainless! Luis

[Paul Ron]

Waste lines are 1/8" per foot, its a standard plumbing rule. Commercial SS sinks have sloped bottoms built in at 1/8" per foot.

I think at 1/4"/ft the water will drain pretty fast n take everything with it to the drain. print trays will have the chemicals off to one side and your developer tanks may also have a problem covering your film.

[Rick A]

Waste lines are 1/8" per foot, its a standard plumbing rule. Commercial SS sinks have sloped bottoms built in at 1/8" per foot.

I think at 1/4"/ft the water will drain pretty fast n take everything with it to the drain. print trays will have the chemicals off to one side and your developer tanks may also have a problem covering your film.

I don't know where you came up with your info, but the building codes in my area are specific,
Waste line slope-¼ inch to 3 inches per foot
Pipes must slope slightly downhill to drain properly. The standard slope is anywhere from ¼ inch to 3 inches per foot depending on the use. An accurate calculation is essential for properly functioning plumbing

It's not just about water in the lines, it's about keeping "solid waste" moving. Faster slope causes water to drain too fast leaving solids behind, and flatter slope doesn't have enough force to push solids down line.

[Paul Ron]

oh im sorry... the1/8" slope is for waste lines 3" or more... 1/4" is waste pipe smaller than 3"

but the op was asking about sinks, not waste lines.

long commercial ss sinks are designed with 1/8" slope built in the bottoms so no need to add to that. 1/4" slope on a sink is way too much.

https://up.codes/viewer/new_york_city/nyc-plumbing-code-2014/chapter/7/sanitary-drainage#704

[Tin Can]

Good data


I don't know where you came up with your info, but the building codes in my area are specific,
Waste line slope-¼ inch to 3 inches per foot
Pipes must slope slightly downhill to drain properly. The standard slope is anywhere from ¼ inch to 3 inches per foot depending on the use. An accurate calculation is essential for properly functioning plumbing

It's not just about water in the lines, it's about keeping "solid waste" moving. Faster slope causes water to drain too fast leaving solids behind, and flatter slope doesn't have enough force to push solids down line.

[Rick A]

oh im sorry... the1/8" slope is for waste lines 3" or more... 1/4" is waste pipe smaller than 3"

but the op was asking about sinks, not waste lines.

long commercial ss sinks are designed with 1/8" slope built in the bottoms so no need to add to that. 1/4" slope on a sink is way too much.

https://up.codes/viewer/new_york_city/nyc-plumbing-code-2014/chapter/7/sanitary-drainage#704

Again, wrong. You can get away with 1/8" per foot with small drain lines of 1.25" - 2" (sink drains) that carry water only, anything 3" and larger is used for solid waste.

[Tin Can]

Rick, you are giving good advice about things I didn't know

While I did all kinds of industrial plumbing, I was self taught, over 20 years, huge factory test lab

I was using large amounts of water for cooling engine Dynamometers, using big heat exchangers both plate and tube

But I never needed a normal household drain P trap

We had 6 test cells with open standing 4" pipe, which acted as https://www.amazon.com/hose-backflow-preventer/s?k=hose+backflow+preventer with a large air gap

[Rick A]

Rick, you are giving good advice about things I didn't know

While I did all kinds of industrial plumbing, I was self taught, over 20 years, huge factory test lab

I was using large amounts of water for cooling engine Dynamometers, using big heat exchangers both plate and tube

But I never needed a normal household drain P trap

We had 6 test cells with open standing 4" pipe, which acted as https://www.amazon.com/hose-backflow-preventer/s?k=hose+backflow+preventer with a large air gap

Impressive resume indeed!! I spent the last 25 years of my working career as a commercial construction super. and 10 years prior to that as a residential super, and have been in construction since working for my uncle's company since my childhood. I supported myself through college doing handyman work, and except for the five years I worked for Olan Mills as a photographer, that has been my entire career. I still do some occasional consulting work and even put on a tool belt when the need arises. I got my general contractors license in 1979 in Utah, had to endure three days of testing knowledge of all the related trades to pass.

[Paul Ron]

rick... first off, waste pipes, sinks and drains are 3 seperate subjects under different codes.

1... according to the nyc buildings code, pipes 3"diam and larger are sloped 1/8"/ft. pipes under 3" diam are sloped 1/4"/ft. that's nyc building code for waste lines... only the pipes!

2... commercial ss sinks like your darkroom sink are designed with 1/8"/ft sloped bottoms... thats only the sink, not the pipes, not the drain!

3... sink drain hookups are generally 1 1/4"-2" depending on volume, manufacture and the waste pipe its being hooked into via the trap. thats only the sink drain!

so what is your problem?

nyc building codes for plumbing, ch7 sanitary drainage codes

https://up.codes/viewer/new_york_city/nyc-plumbing-code-2014/chapter/7/sanitary-drainage#7

[esearing]

Just put adjustable feet on one end of your bench. If the water stands raise the height.