Darkroom Chemicals bad for pipes?

cjng · May 27, 2006

Hello,

I want to set up a simple darkroom in my new apartment, but have been told that some of the chemicals might corrode the plumbing. Is this true? I haven't moved into the new place yet, so I don't know if the pipes are lead, steel, or PVC.

I was planning to use steel wool to precipitate the metallic silver out of my spent fixer, so as not to pollute the environment with it. I'm hoping the the remaining liquid would be safe to pour down the drain, but perhaps one of you knowledgeable people could confirm/deny this? Thanks so much.

-CJ

Dave Parker · May 27, 2006

been doing it for years and have never had a problem with my pipes because of the chems, when I worked in the photo store, we used to extract the silver and then everything went down the sink, and the shop had been there for over 20 years with no problems....

R.

Roger Hicks · May 27, 2006

Unless you use some VERY weird chemicals indeed -- nothing that is likely to be used in anything resembling normal photography -- the risk to the pipes is zero. Nor need you worry about silver. Check the CDC site and you'll see that even they do not regard it as a particularly dangerous material.

Cheers,

Roger

jp80874 · May 27, 2006

cjng said:
Hello,

so I don't know if the pipes are lead, steel, or PVC.

-CJ

You probably don't want to drink the water coming out of any lead pipes.

John Powers

Claire Senft · May 27, 2006

You may find it much less messy to precipitate your silver on aluminum foil rather than steelwool. If you decant your spent fixer it will have added hardening qualities and may be suitable for reusing. I do not know how you feel about a hardening additive in your fixer.

PeterB · May 27, 2006

cjng said:
Hello,

I want to set up a simple darkroom in my new apartment, but have been told that some of the chemicals might corrode the plumbing. Is this true? I haven't moved into the new place yet, so I don't know if the pipes are lead, steel, or PVC.

I was planning to use steel wool to precipitate the metallic silver out of my spent fixer, so as not to pollute the environment with it. I'm hoping the the remaining liquid would be safe to pour down the drain, but perhaps one of you knowledgeable people could confirm/deny this? Thanks so much.

-CJ

Hi CJ,
I looked into this when I built my darkroom. In short, what you are suggesting is a good idea.

Personally I store my used fixer in old 3L P.E.T. plastic juice bottles and take them to my local chemical annual collection day run by our local government council. Silver is a biocide and especially in our area where the sewerage is recycled into grey water, it is not good to put chemicals into the sewer which would kill the bacteria that eat/decompose the sewerage.

My plumber told me not to put acid down the drain because it will eat the rubber joins used to join the PVC pipe. Up until now I wondered why this hasn't been mentioned as a problem. Well I did a bit of research and discovered that the problem is actually with strong acids, not weak acids like 20% acetic or citric (classified as organic acids). See this guide for a table showing the chemical resistance of rubber ring joints as used in plumbing.
http://www.vinidex.com.au/vinidex/live/me.get?Site.Sitesections.show&FFFF227 and also for the specific brand of rubber joiner (Fernco) as used for my plumbing. http://www.fernco.com/acid.asp part 1056-44 as shown in the attached photograph.

regards
Peter

timbo10ca · May 28, 2006

Claire Senft said:
You may find it much less messy to precipitate your silver on aluminum foil rather than steelwool. If you decant your spent fixer it will have added hardening qualities and may be suitable for reusing. I do not know how you feel about a hardening additive in your fixer.

How exactly do you do this?

Changeling1 · May 28, 2006

I found that Perma-Wash can be very corrosive to garbage disposals and chrome. Be sure to rinse well and wipe dry the surfaces that the hypo clear is in contact with. The wood bench I once used to hold my developing trays would build up an ugly sludge of dead fixer and stop-bath also which points to the wisdom of having a real live darkroom sink.

Having said that, the well-known photographer and author Andres Feininger says that anyone who prints and developes film that needs "a waterproof floor" is such a slob as to never become a good photographer! He wrote that in a chapter of his book, Feininger on Photography, where it describes how he could quickly turn his N.Y.C. office into a darkroom as needed with no one being the wiser. Floor space in the Big Apple was costly even in the 1940s. The point being is that with extra care you can develope and print without everyone knowing about it.

cjng · May 29, 2006

Thanks for all the good information, everyone. If I may add some bits:

How exactly do you do this?

Check out this thread: (there was a url link here which no longer exists)

I probably won't re-use my old fixer for prints, since I want to retain the option of selenium toning my prints. I've read that hardening agents greatly reduce the effects of toning. Hardening film sounds like a good idea, though.

I found that Perma-Wash can be very corrosive to garbage disposals and chrome. Be sure to rinse well and wipe dry the surfaces that the hypo clear is in contact with.

Thanks for this warning, but I'm planning to use a fixer from Photographers' Formulary called TF-4, which doesn't require hypo clear (according to their description).

Mark Layne · May 29, 2006

jp80874 said:
You probably don't want to drink the water coming out of any lead pipes.

John Powers

Then you would be unable to travel as much of the world still uses lead plumbing. However it develops a coating of calcification which seems to save most people

gainer · May 29, 2006

PeterB said:
Hi CJ,
I looked into this when I built my darkroom. In short, what you are suggesting is a good idea.

Personally I store my used fixer in old 3L P.E.T. plastic juice bottles and take them to my local chemical annual collection day run by our local government council. Silver is a biocide and especially in our area where the sewerage is recycled into grey water, it is not good to put chemicals into the sewer which would kill the bacteria that eat/decompose the sewerage.

My plumber told me not to put acid down the drain because it will eat the rubber joins used to join the PVC pipe. Up until now I wondered why this hasn't been mentioned as a problem. Well I did a bit of research and discovered that the problem is actually with strong acids, not weak acids like 20% acetic or citric (classified as organic acids). See this guide for a table showing the chemical resistance of rubber ring joints as used in plumbing.
http://www.vinidex.com.au/vinidex/live/me.get?Site.Sitesections.show&FFFF227 and also for the specific brand of rubber joiner (Fernco) as used for my plumbing. http://www.fernco.com/acid.asp part 1056-44 as shown in the attached photograph.

regards
Peter

I have done a good bit of plumbing in my own home and do not remember using any rubber (or even black plastic) join rings. I should think that flushing a copious amount of water down with the chemicals would keep the plastic or rubber from damage.

PeterB · May 29, 2006

gainer said:
I have done a good bit of plumbing in my own home and do not remember using any rubber (or even black plastic) join rings. I should think that flushing a copious amount of water down with the chemicals would keep the plastic or rubber from damage.

As shown in my previously attached photograph, the rubber rings tend to be used on larger diameter PVC pipes. Unless you dispose of low pH acids, the rubber should be able to cope OK.

regards
Peter

Dave Parker · May 29, 2006

I was a bit surprised to see the rubber rings as well, I have built my last three houses and never used rubber rings in any of the joints, I wonder if this is perhaps one of the little differences we see based on locations around the world.

R.

gainer · May 30, 2006

I'm still having a little trouble visualizing anything from my darkroom even coming in contact with the joint seals of my sewer pipes. The pipes are never full. The fluid in them should be flowing by at a rate such that simple slip joints would not leak. It is only when there is a stoppage somewhere in the line that one might have any concern, and even then, the solutions we wash down the drain are usually very well diluted. I fear that some of the remains of what I have eaten are more likely to eat holes in the seals, or the pipes too for that matter. Fortunately, the Creator designed us so that mearly everything we would think of eating either nourishes us or passes on through. Dogs are even better designed by that criterion.

wilsonneal · May 30, 2006

This thread is interesting to me as I've just hired a plumber who'll be installing my darkroom sink. He tells me that the length of the run for the drain will require a pump. The pumps come in two styles/prices: a cheaper one largely of plastic for around $300 and a more expensive one mostly of metal for around $600. He is urging the cheap one because either will, he states, deteriorate in a couple of years from the caustic chemicals I will use. I am not sure how he knows this, but he's proven to be an honest, reliable guy. I have to think that if I put enough water down the drain to dilute the chemicals and that I don't let the chemicals sit in the pump that this shouldn't be an issue.
Neal

gainer · May 30, 2006

wilsonneal said:
This thread is interesting to me as I've just hired a plumber who'll be installing my darkroom sink. He tells me that the length of the run for the drain will require a pump. The pumps come in two styles/prices: a cheaper one largely of plastic for around $300 and a more expensive one mostly of metal for around $600. He is urging the cheap one because either will, he states, deteriorate in a couple of years from the caustic chemicals I will use. I am not sure how he knows this, but he's proven to be an honest, reliable guy. I have to think that if I put enough water down the drain to dilute the chemicals and that I don't let the chemicals sit in the pump that this shouldn't be an issue.
Neal

How long a run is it? Is he talking about the slope of the run? Is your darkroom below grade, so that it has an uphill run? Just be sure he hasn't spotted you as an inexperienced person who can be convinced he needs a sewage pump for stuff that isn't even sewage. It seems he expects to be back in a couple of years to replace your cheap pump. I think I would get a second opinion and check up on city or county codes. Actually, I would probably do it myself and let them try to catch me.

psvensson · May 30, 2006

PeterB said:
Silver is a biocide and especially in our area where the sewerage is recycled into grey water, it is not good to put chemicals into the sewer which would kill the bacteria that eat/decompose the sewerage.

Any finely divided or dissolved silver that goes into sewage will quickly react with sulphur compounds to form a black sludge of silver sulfide, which is not a biocide and not biologically available. It's a naturally occuring form of silver. Unless you're pouring industrial quantities of silver down the drain, this reaction should be complete long before any silver reaches the water treatment station.

You can simulate this reaction by pouring Kodak Brown Toner into used fix.

wilsonneal · May 30, 2006

gainer said:
How long a run is it? Is he talking about the slope of the run? Is your darkroom below grade, so that it has an uphill run? Just be sure he hasn't spotted you as an inexperienced person who can be convinced he needs a sewage pump for stuff that isn't even sewage. It seems he expects to be back in a couple of years to replace your cheap pump. I think I would get a second opinion and check up on city or county codes. Actually, I would probably do it myself and let them try to catch me.

It's a 25 foot run and one 90 degree turn to the existing drainpipe. The downhill slope is just enough to meet code, but the issue was the venting. Code states that you must have a vent within a few feet of the drain. I did get a second opinion and that plumber wanted to skip the code requirement and install a 'check valve'. Interestingly, his quote was higher than the man who quoted it to code spec. At the end of the day, we thought it made sense to follow the code. The pump isn't for sewage. They call it a 'laundry tray pump'.

john_s · May 30, 2006

wilsonneal said:
............. a cheaper one largely of plastic for around $300 and a more expensive one mostly of metal for around $600. He is urging the cheap one because either will, he states, deteriorate in a couple of years from the caustic chemicals I will use............
Neal

$300 is still not really cheap. If the plastic one is designed for sewage my guess is that it will be reasonbly decent, and should last quite well. At the end of the day's use, you could consider flushing with relatively clean water (from your print washer maybe), so that the liquid that sits in the pump till the next session will be benign.

PeterB · May 31, 2006

Flexible Elastomeric Couplings and acid

gainer said:
I'm still having a little trouble visualizing anything from my darkroom even coming in contact with the joint seals of my sewer pipes. The pipes are never full. The fluid in them should be flowing by at a rate such that simple slip joints would not leak.

The joints shown in my plumbing photograph in a prior post aren't simple slip joints, the technical term for this type of joint is a "Flexible Elastomeric Coupling". They are used on larger diameter pipes which are buried in the ground. Under normal usage, the Slip joints shouldn't allow much of the liquid to contact the slip joint's rubber washer, so in your case it is OK.

A Flexible Elastomeric Coupling joint will ALWAYS have the rubber in contact with the liquid and there is an Australian Standard which specifies (amongst other things) how impervious such flexible joints should be to acid [1].

It is conceivable that undiluted urine could reach an Elastomeric Coupling joint and the lowest pH of urine is 4.5. That's nothing compared to the strength of the acid (Sulphuric (0.2N=0.1M)) as stipulated by the Standard for the tolerance of changes to the join's tensile strength or elongation when contacted by the acid. I'm not a chemist, so I don't know how low the pH of (undiluted) acids is likely to get in a darkroom.

Somewhere in the world where these elastomeric couplings are manufactured, it is possible that they aren't made to these standards and could be susceptible to weaker acids.

gainer said:
I fear that some of the remains of what I have eaten are more likely to eat holes in the seals, or the pipes too for that matter. Fortunately, the Creator designed us so that mearly everything we would think of eating either nourishes us or passes on through. Dogs are even better designed by that criterion.

What on earth do you include in your diet that would eat seals and pipes ?!

regards
Peter

[1] "AS/NZS 4327:1995 METAL-BANDED FLEXIBLE COUPLINGS FOR LOW-PRESSURE APPLICATIONS", contains the following text and table in APPENDIX B:

B9 FLUID IMMERSION When tested in accordance with AS 1683.23 [2], using Method (a) with the temperature and duration of immersion of 23 ±5°C and 168 ±2 h, respectively, the change in tensile strength or elongation shall not exceed the values given in Table B1 (attached) .

[2] "AS 1683.23-2000 Methods of test for elastomers Rubber - Vulcanized - Determination of resistance to liquids", in which methods are described to ascertain how a variety of properties (mass, volume, surface area, hardness, tensile stress/strain and extractable matter) of the elastomer change when contacted by liquids

Darkroom Chemicals bad for pipes?

cjng

Dave Parker

Roger Hicks

jp80874

Claire Senft

PeterB

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