Chemistry 101

[Gerald C Koch]

It is strange to have to post this on a site devoted to photography. I always thought photography was about taking pictures. (Yes, I know that there are those that still seek to find the grail.)

As a former graduate student and someone who has taught chemistry I have seen the results of some rather horrific accidents. The first thing that a person learns in chemistry 101 is never mix together two chemicals unless you know what is going to happen. Remember that plain water is also a chemical. Just because you can buy something in a local store does not means that it is safe. Such chemicals as lye (sodium hydroxide) can cause serious physical injury. Milder alkalis such as washing soda (sodium carbonate) can cause blindness. Then there are the strong acids; acetic acid 28% can cause burns. Oxidants like potassium dichromate or potassium permanganate can cause fires or even explosions. Solvents such as glycols and TEA are dangerous when heated (toxic vapors and fire hazard).

If you insist on experimenting at the very least read the Material Safety Data Sheets (MSDS) for everything you will be using. If you don't understand what you have read then seek advice. Invest in a pair of safety googles. A face shield would be even better. If you have no knowledge of chemistry then please just take pictures. I'm not saying this to be dramatic but I cringe when I read some of the posts.

[jnanian]

If you insist on experimenting at the very least read the Material Safety Data Sheets (MSDS) for everything you will be using. If you don't understand what you have read then seek advice. Invest in a pair of safety googles. A face shield would be even better. If you have no knowledge of chemistry then please just take pictures. I'm not saying this to be dramatic but I cringe when I read some of the posts.

i agree 100% jerry !

[Monito]

+1

Never pour water into acid when diluting. Pour acid into water, carefully in no hurry. Reason: the dilution is exothermic (gives out heat) and it is worse to have hot slightly diluted acid boiling up than to have hot slightly acidic water boiling up.

[Photo Engineer]

Right on Jerry!

PE

[Klainmeister]

Yes, this is important, and maybe we should devote some time for a sticky with basic info regarding the most common photo chemical components and what they do.

[michaelbsc]

Here is the trick I always used to remember to pour the acid into the water.

A sub's battery needs to be topped off regularly. And a sub is in the ocean - big pond of water. You can pour the acid into the ocean, but you cannot pour the ocean into the acid.

It's easier to remember the trick than do the thermal analysis of the reaction. Of course if you don't have my experiences that memory trick might not mean much to you.

[ChristopherCoy]

In a basic darkroom, what is the danger level? What could possibly happen?

For instance, I've got three chemicals - Dektol, Kodak indicator stop bath, and Fixer. How harmful are those chemicals really? (other than ingestion or eye splashes?)

Is Dektol going to eat through the skin? Countertop? Will the combo of Fixer and Dektol create a toxic gas?

Its awesome that you put out a public warning as a chemistry teacher, but for those of use who are absolutely NOT interested in studying chemistry, WHY is safety important? What kinds of accidents are possible with basic chemicals?

[Monito]

Here is the trick I always used to remember to pour the acid into the water.

It's even easier than that. Remember, hot/boiling water is less dangerous than hot/boiling acid.

[MattKing]

In a basic darkroom, what is the danger level? What could possibly happen?

For instance, I've got three chemicals - Dektol, Kodak indicator stop bath, and Fixer. How harmful are those chemicals really? (other than ingestion or eye splashes?)

Is Dektol going to eat through the skin? Countertop? Will the combo of Fixer and Dektol create a toxic gas?

Its awesome that you put out a public warning as a chemistry teacher, but for those of use who are absolutely NOT interested in studying chemistry, WHY is safety important? What kinds of accidents are possible with basic chemicals?

With working strength solutions:

Don't drink any of them, don't get any in your eyes and if you spill any of them, clean them up.

Dektol might lead to problems for some people in terms of contact allergies - it is never unwise to minimize contact with the skin. I say that despite the fact that I have essentially ignored my own good advice on this subject for 40+ years, without problem.

If you spill fixer on your clothes, it sometimes doesn't wash out well

Dektol, stop bath and fixer aren't going to interact in any potentially harmful way.

Concentrated stop bath is fairly strongly acidic, so a bit extra care is required with it. It is a bad idea to carelessly pour developer into it.

[Toffle]

Its awesome that you put out a public warning as a chemistry teacher, but for those of use who are absolutely NOT interested in studying chemistry, WHY is safety important?

Because you use chemistry in your darkroom. It is not necessary to have a full knowledge of chemical processes, but safety is always important. MSDS sheets are readily available and actually make for interesting reading. Short of a chemistry class, they are perhaps the quickest way to learn the safe use and disposal of darkroom chemicals.

Start here... they're not that bad.