What would be the shelf life of stored powdered chemistry at 80F?

[What About Bob]

I have my containers of powdered chemistry stored inside of a filing cabinet, all closed up. Some containers haven't been opened yet. The inside of my apartment is 20 degree hotter than outside. The inside room temperature reads 82F on the PECO thermostat, it is 62F outside. My thermometer reads 80F inside of the filing cabinet. Bathroom reads 79.5F. This place is one big heat trap. Turning on a fan and aiming it out the window does nothing. Each room has only one window, bathrooms have no windows. I opened up a few of the containers and the contents look the same as they did before the temperature change. What are the temperature limits when it comes to powdered chemistry?

The apartment's AC will not be turned on until either the middle of May or June.

 

[Mick Fagan]

I wouldn't worry one bit. My own raw chemicals, with which I mix up my photographic chemistry, have, in some cases, been enduring temperatures up to 47ºC over the last 33 years.

I mixed some fresh D76 last week from some of them, works as well as 33 years ago.

 

[What About Bob]

I wouldn't worry one bit. My own raw chemicals, with which I mix up my photographic chemistry, have, in some cases, been enduring temperatures up to 47ºC over the last 33 years.

I mixed some fresh D76 last week from some of them, works as well as 33 years ago.

Thanks, Mick.

It's good to know that these chemicals can take the heat. I started buying raw chemistry last year and have been hooked ever since. D-76 will be the next one to make up. Haven't used D-76 in a long time.

 

[loccdor]

I agree with Mick.

But for your personal comfort, if you're able to create a draft between two windows on opposite sides of the apartment, with one fan blowing out and the other blowing in, it really helps. I do that in my house without central cooling - I usually start the fans around 5PM when it's getting really hot, and close the windows when I wake up around 6-7AM to trap in the night's cold air.

 

[What About Bob]

I agree with Mick.

But for your personal comfort, if you're able to create a draft between two windows on opposite sides of the apartment, with one fan blowing out and the other blowing in, it really goes a long way toward personal comfort. I do that in my house without central cooling - I usually start the fans around 5PM when it's getting really hot, and close the windows when I wake up around 6-7AM to trap in the night's cold air.

Unfortunately there are no opposite windows in any of the rooms. Having opposite windows or even an opened door would really help with air flow better. Summer time sucks here if the AC isn't turned on. When it turns on it is on for about three months, until September 15th then it goes back to heat. The switching of heat to AC and back is determined by the BOH and not the apartment management.

Residents cannot buy their own AC units, get the permissions and then have maintenance install them like they used to do. Having them hang out from the window was decided as a liability and the management outlawed it some years ago. Actually this law applies to all housing in town and probably other places as well.

Each bedroom has only one window. The living room has a sliding door window with the kitchen on the opposite side with the main door next to the kitchen and all bathrooms have no windows at all. The way that this complex should have been designed; they should have flip-flopped the bathrooms to be at the end where the windows are at. I live in a five floor complex. Bottom floor is the main lobby, mail room, community room and management office. I am on the fourth floor.

Also we have people who do not live in this complex, going in and out of it, and we recently had security hired by management to take care of this. Been like this for a few years.

 

[What About Bob]

This is one reason why I like Barry Thornton's two bath. It is panthermic to a point and I can get great results within a decent temperature range..

 

[John Wiegerink]

This is one reason why I like Barry Thornton's two bath. It is panthermic to a point and I can get great results within a decent temperature range..

Yes, your chems should be just fine. You do have to watch some chems like Sodium Hydroxide since if they aren't seal properly they will take on H2O.
I think some folks here poo-poo BT2B simply because it's to damn easy and works great. Nobody should get good negatives that easy! They use the old exercise line, " no pain, no gain". My wife's favorite line and the one I finally learned to follow is, "work smarter, not harder".

 

[Sirius Glass]

Temperature is not your problem. Just keep your powder dry.

 

[David Lyga]

Temperature is not your problem. Just keep your powder dry.

Exactly, temp has nothing to do with it.

But a very good tip is to keep the powder which is from open packages, including raw powders, in easily obtainable PET plastic bottles. These range in size from 50 - 100 mL (liquor) to 400 - 1000 mL. Reason? With the cap on they do not allow air in which could bring moisture. Also, they make things neat and organized. - David Lyga

 

[Ian C]

The range of ambient temperatures in a home isn’t a problem for storing dry chemicals. It is water vapor in the air that can enter the package and begin the reactions that spoil the chemicals.

Sealed packets of dry chemicals from the maker often turn out to be imperfectly sealed. I use canning jars with good lids and the jars inspected for smooth surfaced mouths where these meet the flexible gasket of the lid. New lids can be bought to replace old lids whose gaskets might have deteriorated.

If there’s room in the jar, you can place a silica gel packet atop the chemical to absorb any humidity trapped inside during the transfer.

Note: Some plastic containers are not truly vaporproof. Either the plastic is somewhat gas-permeable, or the lid is ineffective in forming a seal. There is no such problem with glass canning jars and gasketed lids.

 

[runswithsizzers]

About those silica gel gel packets...

First verify that the dessicant packets say "silica gel" and not something else. There are several other chemicals which are also used as desiccants other than silica gel (which is a form of silicon dioxide).

Each silica gel packet has a limited capacity to absorb moisture. Any packets that have been laying about in humid air will have already adsorbed all the mositure they are capable of in that environment. Some packets indicate when they are saturated by turning from blue to pink or from orange to green -- but the white ones stay white, so you can't tell if they are still useful just by looking at them.

When saturated, the packets can no longer adsorb moisture, and they will need to be reactivated (dried out) by heating them in an oven at 200-250°F (93-121°C) for 1-1/2 to 2 hours. As soon as they cool to room temp, store the regenerated packets in an airtight container until needed.

Larger storage containers, higher storage temperatures, and higher relative humidity will require more silica gel to control moisture. Calculating exactly how much silica gel is needed in a given environment is complex, but several websites suggest, as a general rule, use 1 gram silica gel per 1 liter volume. In hot humid conditions, more might be better, and using too much is safer than not enough.

BTW, I second the recommendation made by @Ian C to use canning jars for storage. I use them for coffee beans, cannabis (legal in my state), and other items when I want to preserve freshness.

 

[Sirius Glass]

Exactly, temp has nothing to do with it.

But a very good tip is to keep the powder which is from open packages, including raw powders, in easily obtainable PET plastic bottles. These range in size from 50 - 100 mL (liquor) to 400 - 1000 mL. Reason? With the cap on they do not allow air in which could bring moisture. Also, they make things neat and organized. - David Lyga

How about only opening the package when all the contents will be mixed for a full batch of chemical? No PET plastic waste bottles. It is good for for the environment.

 

[mshchem]

You're fine. I imagine you refrain from baking this time of year

 

[ags2mikon]

I buy glass jars from Amazon or Ebay and re label them to store my dry chemicals in. I have some chemicals that are 20 years old and still good. Storing dry chemicals before mixed is much more stable that when mixed. Kodak did some fancy things to enable long term storage of developers and other products in cans that worked real good but that was long ago. Some of my chemicals I use a lot of like sodium sulfite I put up in amber canning jars with gasketed lids. I keep extra lids and replace them before they deteriorate.

 

[What About Bob]

Thanks everyone for the information and suggestions.

I believe I have seen those canning type jars at the local dollar store not long ago, though not amber. I do have an unopened container of sodium hydroxide that was bought recently. It may be one of those chemicals that will not be used as much but when needed it will be there.

 

[Agulliver]

I work in a school where I'm responsible for 15 laboratories and two chemical stores. Most powdered chemicals are very stable, with a few exceptions that aren't generally used in photochemistry. We have some powders which date back to the 1960s that are still as good as new. As someone said upthread, keeping them dry is probably more important than the temperature though heat will accelerate decomposition.

I'm currently using fixer that I made up from chemicals at work....sodium thiosulphate which was delivered in 2008, sodium metabisulphite likely from the early 70s and sodium sulphite from the 1990s. Works at least as well as any commercial fixer I've ever used, and after making up the solution it lasts at least five months. The actual chemicals themselves are all "old" by most standards.

Developers and chemicals used to make developers would be more critical, so I'd suggest keeping tabs on the ages of all your chemicals and doing a quick test when you make up a solution...that way you know if everything is full strength. Chances are they will, and will remain good for years/decades to come. I have no doubts that the sodium metabisulphite in the school chemical store will still be in use long after I've departed this world.

 

[John Wiegerink]

Thanks everyone for the information and suggestions.

I believe I have seen those canning type jars at the local dollar store not long ago, though not amber. I do have an unopened container of sodium hydroxide that was bought recently. It may be one of those chemicals that will not be used as much but when needed it will be there.

You really don't need amber jars if you keep your chems in the dark. I keep mine in a dark cabinet as it serves the same purpose as an amber jar or bottle. Clear, well sealed plain glass works just as well.