Raw chemical storage/separation

MarkL · 2026-01-26T09:57:24-0500

When I built my darkroom years ago, I went nuts and ordered lots of chemicals, ignorantly storing them together. I am now going to separate them. How does this scheme look? The ones at the end I’m not sure how to categorize.

Cabinet 1 – Acids
Hydrochloric Acid
Sulfuric Acid

Cabinet 2 – Bases
Sodium Hydroxide
Ammonium Hydroxide
Ammonium Carbonate
Sodium Carbonate

Cabinet 3 – Oxidizers & toxics
Potassium Dichromate
Potassium Ferricyanide
Selenium

Cabinet 4 – Developers & reducers
<Also packaged developers - Dektol etc.>
Metol
Hydroquinone
Amidol

Cabinet 5 – Fixers & salts
<Also packaged fixers>
Sodium Thiosulfate
Potassium Metabisulfite
Sodium Sulfite (Anhydrous)
Potassium Bromide
Potassium Iodide
Sodium Chloride
Copper Sulfate
Ammonium Thiocyanate

Cabinet X – Misc
<hypo clearing agent>
Sodium Sulfide
Benzatriazole
Thiocarbamide
Thiourea Dioxide

koraks · 2026-01-26T10:21:09-0500

I'm evidently the wrong person to talk to. Everything is right next to each other in my cabinet. As long as the containers are suited to the purpose, in good condition and properly capped/shut, there's no practical problem. What are the contingencies you are trying to manage for? Massive earthquake with everything toppling over? Home fire? Darkroom riddled with .50 cal. ammunition? How does the overall impact of these events relate to the potential mixing of the contents of the sodium carbonate jar with those of the acetic acid bottle?

retina_restoration · 2026-01-26T10:22:51-0500

I'm not sure what this plan is intended to mitigate for.

xkaes · 2026-01-26T10:32:38-0500

Looks fine to me if you have the space, but I've never had any problem storing chemicals together. I do sort them by their purposes however, like you listed. That makes them easier to find.

I make sure all containers are sealed after use.

The only problem I've had was a leaking plastic container once, but that was easily spotted by the darkening of the cardboard box it was in. So watch out for plastic containers with liquids!

And a few dry chemicals can expand with humidity -- ex., sodium hydroxide -- so make sure those containers are not over filled, and well sealed.

MarkL · 2026-01-26T10:45:57-0500

Thanks for the quick replies! A few years ago I noticed an increasing white powdery precipitate forming on all the containers, and some of their caps disintegrated. So I knew there was migration and potential fumes and/or cross contamination. So a couple years ago I got a stock of bottles (shown here), and once again a white residue formed on all the bottles, as well as the ink on some of printed bottle cap labels being destroyed! So in the interest of air quality I thought I'd separate them!

koraks · 2026-01-26T10:56:02-0500

You either have a problem with mold/moisture in that cupboard, or you're still using bottles/containers that don't seal properly.
The cap on that bottle looks dodgy to me, but I can't judge from a photo how well it seals.

If you're storing chemistry in bottles that don't seal well, then fix that. Separating the bottles into different parts of the cabinets isn't the solution. It's like having a flat tire on your car and using black paint to paint the tire nice and black again. It's a cosmetic 'fix' that doesn't fix anything in reality.

xkaes · 2026-01-26T11:25:42-0500

On ALL containers? Sounds like bad caps. Upstate NY can be pretty humid, but with good caps, you should be OK, and chemicals usually come in good containers.

Are the chemicals in these containers turning into hard chunks? Not good, for several reasons.

Kino · 2026-01-26T11:30:05-0500

I have found regular, clear canning jars with the sealing lids to work well for dry powders. Just place a layer of cling plastic between the sealing lid and screw it down tight.

No problems with clumping or moisture.

I then put them in a cardboard file box with butcher paper packing between the jars to cushion any sudden bumps. The lid assures a dark, dry storage environment and I place them on the floor on top of a sheet of Styrofoam to keep it from wicking any potential moisture. Storing them on the floor avoids my knocking them off a shelf, which I am known to do to things about waist high.

A list of what is inside is taped to the top for quick access.

I have 20+ year old Metol, Hydroquinone and other powders that are in perfect shape.

MCB18 · 2026-01-26T12:12:31-0500

I just have all my chems together in 1 place lol

MarkL · 2026-01-26T12:55:00-0500

Yeah lids must be the problem. Here are the specs when I bought the jars so I thought the lids were OK. I may try adding an additional liner. But I like the idea of the canning jars, especially being clear so I can see the contents.

Thanks everyone!

About this item

General-purpose glass bottle makes sampling and storage convenient
Features a PTFE foam-backed liner which resists most chemicals both liquid and solid contents
Design is for easy access to contents and for easy cleaning
Wide mouth amber glass bottle protects light or UV-sensitive solutions

xkaes · 2026-01-26T13:01:16-0500

I hope your chemicals are OK. If they have been exposed to high humidity for a long time, it might affect their function/usefulness to some degree -- but that depends on what it is.

Yezishu · 2026-01-26T13:01:38-0500

I’ve been through this. At that time, the plastic caps of the hydrochloric acid and ammonia bottles in the lab were all cracked, and there was white powder everywhere—which we assumed was ammonium chloride but didn't dare to investigate. Organic solvent bottles with cheap PVC caps also frequently leaked odors, and the latex stopper will expand and become sticky. The lesson we learned was to use glass or fluorinated polyethylene (FPE) bottles if possible, paired with good PE/PP caps and Silicone-PTFE gasket. Perhaps others have better suggestions on what kind of bottles are safest to use for reagents in North America. I've heard of wine bottles or wine bag?

Yezishu · 2026-01-26T13:14:24-0500

MarkL said:
Yeah lids must be the problem. Here are the specs when I bought the jars so I thought the lids were OK. I may try adding an additional liner. But I like the idea of the canning jars, especially being clear so I can see the contents.

Thanks everyone!

About this item

General-purpose glass bottle makes sampling and storage convenient

Features a PTFE foam-backed liner which resists most chemicals both liquid and solid contents

Design is for easy access to contents and for easy cleaning

Wide mouth amber glass bottle protects light or UV-sensitive solutions

I remember these reagent bottles have one small-mouth style, which makes them easier to seal and convenient for filling with liquids, looks like this:

Steve Goldstein · 2026-01-26T13:18:44-0500

Most of my chems are on a single shelf in their original bottles. Glycin and Catechol live in the freezer (Glycin because its room-temperature shelf life is short, and Catechol just because).

The only things I store far apart from each other (different rooms on different floors) are Potassium permanganate and Glycerine as these react very energetically if mixed.

xkaes · 2026-01-26T17:11:52-0500

I'm glad you straighten us out on the Catechol.

Brendan Quirk · 2026-01-26T19:28:31-0500

Separation like this is standard in research labs. Actually, the proposed scheme is better than typical. Also, fuels (paper, etc) are kept from oxidizers and acids and anything that might ignite.

I do think this scheme is way beyond most home darkrooms, but I am impressed with its professionalism.

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