Which Black and White chemicals deteriorate through Oxidisation?

RobC · May 19, 2016

doesn't matter whether the storage container is clear plastic, black plastic, clear glass or brown glass providing you store them in a closed cupboard with no light in it. The chemicals are oblivious to what colour the container is. Light has a bad effect on chemicals over time. You just need to be sure that any plastic is the right sort. i.e. it must be chemical resistant and impervious to air.

Julie McLeod · May 19, 2016

RobC said:
doesn't matter whether the storage container is clear plastic, black plastic, clear glass or brown glass providing you store them in a closed cupboard with no light in it. The chemicals are oblivious to what colour the container is. Light has a bad effect on chemicals over time. You just need to be sure that any plastic is the right sort. i.e. it must be chemical resistant and impervious to air.

Thanks. So glass (any color) has no advantage over PET plastic?

RobC · May 19, 2016

No I don't think so. The exception is that glass is easier to clean than the plastic (PET) compression bottles and being clear you can see if there is any staining/residue left in glass bottles. And you can scrub inside bottles with a suitable flexible brush which isn't so easy with a black PET bottle you can't see through. But apart from that there is really no difference.

You can use a squirt of tetenal protectan in stored glass bottles to help keep the air away from the chemical.

http://www.tetenaluk.com/protectan-spray-400ml-bogof.html

Mainecoonmaniac · May 19, 2016

I'm learning a lot about air making chemicals go bad. For working solutions, I try to top off the bottle. For unmixed concentrated chemicals, I used my old Beseler XDL spray. I think it's heavier than air.

Julie McLeod · May 19, 2016

RobC said:
No I don't think so. The exception is that glass is easier to clean than the plastic (PET) compression bottles and being clear you can see if there is any staining/residue left in glass bottles. And you can scrub inside bottles with a suitable flexible brush which isn't so easy with a black PET bottle you can't see through. But apart from that there is really no difference.

You can use a squirt of tetenal protectan in stored glass bottles to help keep the air away from the chemical.

http://www.tetenaluk.com/protectan-spray-400ml-bogof.html

Thanks, Rob. I'll look for a supplier for the protectan spray.

RPC · May 19, 2016

Glass is probably less costly than PET. I use glass canning jars to store my chemistry in. They are available at grocery stores and hardware stores, have wide mouths for easy cleaning and lids with a rubber seal that seals very tightly. Very economical if you buy several in a package. I find them in sizes of half-pint, pint, quart and half gallon making it easier to keep them filled.

RobC · May 19, 2016

another major thing to consider in keeping life of stock solutions is ambient temperature. If you have a dedicated darkroom then consider installing a fridge and keep stock solutions in it. The cold temp will make it keep for a lot longer.
Storing chemicals where they will get warm will reduce their life far more quickly.

Julie McLeod · May 19, 2016

RobC said:
another major thing to consider in keeping life of stock solutions is ambient temperature. If you have a dedicated darkroom then consider installing a fridge and keep stock solutions in it. The cold temp will make it keep for a lot longer.
Storing chemicals where they will get warm will reduce their life far more quickly.

Thanks for that additional tip. I don't have a darkroom but could certainly keep my chemicals in a colder location in the house than I am now.

MattKing · May 19, 2016

RobC said:
another major thing to consider in keeping life of stock solutions is ambient temperature. If you have a dedicated darkroom then consider installing a fridge and keep stock solutions in it. The cold temp will make it keep for a lot longer.
Storing chemicals where they will get warm will reduce their life far more quickly.

Temperature control is a really good idea, but if you plan to use a refrigerator, be sure it is one that has good control itself.

Freezing will damage some chemicals, so you need a refrigerator that keeps things above the freezing point.

A room that stays cool is a great choice as well.

Julie McLeod · May 19, 2016

MattKing said:
Temperature control is a really good idea, but if you plan to use a refrigerator, be sure it is one that has good control itself.

Freezing will damage some chemicals, so you need a refrigerator that keeps things above the freezing point.

A room that stays cool is a great choice as well.

Thanks, Matt. It'll have to go in a cool spot in the basement.

By the way, do you know of a Canadian source for the Tetenal Protectan Spray (or something similar)? I did a quick search and didn't come up with any place to order that.

Photo Engineer · May 19, 2016

RobC said:
doesn't matter whether the storage container is clear plastic, black plastic, clear glass or brown glass providing you store them in a closed cupboard with no light in it. The chemicals are oblivious to what colour the container is. Light has a bad effect on chemicals over time. You just need to be sure that any plastic is the right sort. i.e. it must be chemical resistant and impervious to air.

Glass is always better than plastic (all else being equal). Light has no significant effect on solutions except a very mild one on developers exposed to daylight. The small amount of tungsten light in most darkrooms or storage areas is insignificant. If you store the chemicals in bright daylight all the time, then the heating effect of the sunlight might be more important in deterioration.

PE

RobC · May 19, 2016

tungsten bulbs give out UV which is why good enlargers using tungsten bulbs have built in UV filters. I thought UV is quite damaging. And sunlight gives out a lot of UV. Best keep checmicals out of light when stored.

RobC · May 19, 2016

Julie McLeod said:
By the way, do you know of a Canadian source for the Tetenal Protectan Spray (or something similar)? I did a quick search and didn't come up with any place to order that.

They are a German company with some regional offices in Europe. Not sure about North America/Canada.

Try emailing this address and ask for list of suppliers in your region. I'm guessing they they must have some dealers on your side of the pond as they say they are in 100 countries or have distributors in them.

salesoverseas@tetenal.com

Photo Engineer · May 19, 2016

Tungsten bulbs do not give out much UV at all, which is why alternate photography people have to use sunlight for exposing and why Azo paper is so slow when using (trying to use) tungsten light.

Is your darkroom subject to direct sunlight? Does it have fluorescent bulbs? If not, you are safe. We stored most mixed chemicals in 1 or 2 gallon clear glass bottles with cork stoppers.

PE

RobC · May 19, 2016

I repeat, quality enlargers using tungsten bulbs have built in UV filters. Its no wonder you can't expose when using a paper which requires UV light. You would need to remove the UV filter or not use an enlarger and use bare bulb.

But you are confirming what I said. A no light or low light storage place doesn't casue a problem whereas somewhere with daylight may affect your developer. I think thats what I was suggesting in the first place and you've confirmed that tungsten bulbs do give UV light which is what I said. So I fail to see what you're trying to argue about.

Photo Engineer · May 19, 2016

To be clelar, the UV that tungsten bulbs give out is so low it has little effect on solutions. We stored things in brightly lit areas even with fluorescent lights and there was no degradation of ANY solution over normal keeping times. The brown bottles were basically useless unless your storage area is brightly lit. Even then UV has no effect except on developers. And again, the effect of UV on any solution is rather insignificant compared to that of oxygen and carbon dioxide.

I do not use colored bottles!!! We didn't at KRL!!! To be clear, there were a few brown bottles left over from the dark ages that were kept in use but it was not a purposeful effort.

PE

RobC · May 19, 2016

see last section "Ultaviolet from Halogen Lamps" of following but the first section gives some background.
Dead Link Removed

Photo Engineer · May 19, 2016

Your source:

A traditional incandescent bulb produces white light from a tungsten filament heated by an electric current. The light from these bulbs has a very broad spectrum, a very small part of which is ultraviolet. Generally, the hotter the filament, the more UV it produces, although most incandescent light bulbs are designed to minimize UV.

My source: http://classroom.synonym.com/light-bulbs-not-emit-uv-radiation-15925.html

There is some common concern about the ultraviolet output of halogen bulbs, since they operate at high filament temperatures and the bulbs are made of quartz instead of glass. However, the filament temperature of halogen bulbs rated to last 2,000 hours or more is only slightly greater than that of standard incandescent lamps, and the UV output is only slightly higher. Halogen fixtures typically have a glass or plastic shield to confine any possible bulb explosions, and these shields absorb the small traces of shortwave and mediumwave UV that gets through the quartz bulb.

So, Rob, you have brought in halogen lamps. Just for comparison, tungsten minimizes UV and halogen gives only a bit more than tungsten. I agree, but this is not enough to expose a cyanotype or many other alternate (UV sensitive) processes let alone damage developers. Fixers are immune to UV but not air.

You can argue all you want, but we did not find any significant correlation between lighting in darkrooms and keeping. Air was more of a problem and even that can be minimized. Old fables die hard don't they?

I repeat: In the average darkroom or chemical storage area, tinted glass is not needed for storage! It is nice, as it IDs the developer, but otherwise no big deal.

PE

ME Super · May 19, 2016

Technically, mathematically, any thing above 0K (absolute zero) emits black body radiation (with the exception of black holes, which absorb any radiation the singularity at their center might emit, but I digress). Even the inside of your deep freezer, which is around 255K, technically emits black body radiation, including visible and UV radiation. But the amount emitted is so incredibly small that your eyes cannot detect the visible portion of it. The cooler something is, the less black body radiation it emits, and therefore the less UV it emits.

A tungsten bulb is a black body radiator. Most of its radiation is in the IR and red regions of the EM spectrum, with a little bit in the UV. A halogen bulb, because it is hotter, emits a bit more UV. But the amount of UV emitted is quite low.

Fluorescent bulbs require UV to work, and emit more UV than a tungsten bulb, even though they are cooler, because they are not pure black body radiators - they are discrete spectrum radiators superimposed on black body radiation, and it's the discrete spectrum from these (the blue and UV) that is down-converted by the phosphors coating the tube into visible light.

I wouldn't worry about tungsten or halogen bulbs emitting too much UV to affect your chemistry.

RobC · May 19, 2016

I think you missed the point of the link I provided or didn't read it. Its the temp of the filament which makes the difference and domestic tungsten/halogen bulbs are not much hotter than a standard light bulb. BUT projection bulbs as found in enlargers are much hotter and do emit more UV, potentially dangerous UV. Read the contents of the link.

[edit]
My durst L1200 uses a 240 watt tungsten-halogen bulb. Few if any house lights would be anywhere near that wattage and heat. That is where the misunderstanding lies. Going off on a tangent about UV printing with low wattage fluorescent tubes designed for purpose doesn't help.

Photo Engineer · May 19, 2016

Rob, the reason I did not comment on the enlarger example is that I could not imagine how an enlarger lamp could affect solutions. This is for 3 reasons. One, it is focused on the easel and two, it is surrounded by a housing. The third is most important. The light is dimmed by the stop on the lens and the exposure times are very short. So, it did not apply to the keeping of chemicals in bottles!

As for UV filters in enlargers, even though the amount of UV is low, it can affect the exposure of some VC papers by bypassing the contrast filters and it can also change the color balance for color printing in unexpected ways. So, why throw in another variable. Just get rid of the tiny amount that is there.

I did not digress into UV printing with low wattage fluorescent tubes. I did mention that enlargers could not be used for printing alternate photographic products due to low UV and contact print papers. This should indicate how low UV output is from an enlarger.

PE

RobC · May 19, 2016

I said that UV light is not good. I also said that sunlight has UV. I also said keep chemicals out of light when stored. Thats all. But you claimed that enlargers don't give out UV. Why? Oviously if developer is stored its not going to get exposure from enlarger. But no you wanted to argue the point about enlargers not giving out UV. So now you have not very cleverly chosen to omit the part of the link I gave which says YES THEY DO and its a lot of UV which has to be carefully managed. So just for everyone else here's the bit you didn't want anyone else to see:

Higher temperature photographic and projection bulbs are different. The much higher filament temperature of shorter life bulbs results in possibly significant hazardous UV. For maximum safety, use these bulbs in fixtures or equipment designed to take these bulbs, and in a manner consistent with the fixture or equipment instructions.

These are the bulbs in enlargers. Now do you want to admit that you were wrong to say enlargers don't give out much UV light or do you want people to think they are perfectly safe. Your enlarger should have a UV filter if its using a tungsten-halogen bulb otherwise it is potentially dangerous depending on the bulb wattage.

All I've said in this topic is:

Chemicals are best stored out of light which you have confirmed but want to argue about it.
UV light is damaging which you agree with but said there is little. But I have shown reference to say you are wrong and you want to hide and argue about it.

So you are back on my ignore list becasue you want to pick pointless arguments. Good bye

Photo Engineer · May 19, 2016

Poor Rob. Hiding from a problem does not solve it.

I don't ignore anyone as everyone can teach me.

That said, his rant does not make sense. I am trying to convince APUG member that storage away from oxygen is more important that storage away from light! He seems to not understand.

PE

Gerald C Koch · May 19, 2016

RobC said:
tungsten bulbs give out UV which is why good enlargers using tungsten bulbs have built in UV filters. I thought UV is quite damaging. And sunlight gives out a lot of UV. Best keep checmicals out of light when stored.

The average tungsten bulb emits little or no UV. This is why practitioners of certain alternative photographic methods like cyanotype must either use daylight or use UV emiting bulbs, the so called grow bulbs. In addition glass absorbs all but the longest UV wavelengths. UV spectrometers use special containers made of fused silica. As far as brown glass is concerned it is often used because it is cheaper to make than white glass or other colors. It has nothing to do with shielding the material inside from light. Finally there are few chemicals that are actually light sensitive. There are the typical silver compounds but little else. The main problem is that we live surrounded by oxygen, a very reactive element. It DOES attack many chemicals.

Look sat the following article in particular the graph entitled "Spectral Power Distribution of a 25 W Incandescent Light Bulb." The UV contribution is so small it doesn't even appear in the graph. Grow bulbs, enlarger bulbs and photoflood bulbs are all designed to have hotter filaments to increase the amount of UV light that they output. But these are not your common household variety of incandescent bulbs.

https://en.wikipedia.org/wiki/Incandescent_light_bulb

tedr1 · May 20, 2016

Gerald C Koch said:
Grow bulbs, enlarger bulbs and photoflood bulbs are all designed to have hotter filaments to increase the amount of UV light that they output.

Halogen enlarger lamps are a convenient form of high intensity compact lamp the UV output is not relevant. Photofloods operate at higher temperatures to shift the color temperature closer to "white light" any change in the output at UV wavelengths is incidental.

Which Black and White chemicals deteriorate through Oxidisation?

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