Stop Bath.. How important?

Donald Qualls · Mar 23, 2023

Xylo said:
I also tend to stay away from chemicals that can melt my skin.

I've got lye, concentrated sulfuric acid, 75% acetic acid, potassium dichromate -- can't instantly think what all else that shouldn't ever contact my skin, but there's probably a couple other things. It's just part of being able to mix my own photo chemicals. Lye is an indispensable ingredient for Parodinal, potassium dichromate is used (in tiny quantities) in many alt-process sensitizers (or is the sensitizer in things like gum bichromate or carbon transfer) as well as being the premiere bleach for B&W reversal, sulfuric acid is also an ingredient for a couple different B&W reversal bleaches. I may pick up a jug of hydrochloric acid, too, to try copper sulfate bleach without having to add a chloride donor like table salt.

Of course, it's important to have respect for these and all chemicals, and understand how to use them safely -- but if you paid attention in a college level intro chemistry lab class (at least before 1990, maybe a bit later), you probably know (or knew, once) what you need to.

foc · Mar 23, 2023

Xylo said:
Personally, I also tend to stay away from chemicals that can melt my skin... I don't know, it's just a thing that I somehow care about.

Best to keep away from any of these.

Philippe-Georges · Mar 24, 2023

Nicholas Lindan said:
And for this you get to play with Lye and Glacial Acetic Acid???? If this is what's desired just use vinegar and baking soda.

I am used to work (not playing) with these chemicals as I needed them for fine tuning the pH value of the chromatic developer in the E-6 process (but instead acetic acid it was sulphuric acid), and I still have a few kilo's of NaOH left (I nought a bucket of 5kg long time ago).

Xylo · Mar 24, 2023

In that case you do know the proper safety procedures, so no problem there.

Xylo · Mar 24, 2023

Donald Qualls said:
but if you paid attention in a college level intro chemistry lab class (at least before 1990, maybe a bit later), you probably know (or knew, once) what you need to.

Back in College I was at the Administrative Sciences School... so no lab work for me.
But I still remember quite a bit from high school chemistry classes where some idiot decided to mix the acids in a test tube by shaking it with his thumb as a stopper... he never admitted to it but he probably had a numb thumb for a few days after that.

Donald Qualls · Mar 26, 2023

Xylo said:
some idiot decided to mix the acids in a test tube by shaking it with his thumb as a stopper

Fortunately for him, what I recall is that even in college Chem 101 Lab they gave us such weak chemical solutions it was hard to hurt yourself or someone else short of actually drinking the stuff. My high school chem lab (and the one at summer camp, the first place I took chemistry) had stronger chemicals, but they were reserved for instructor demonstrations (like pouring strong nitric acid on copper pot scrubber to show the brown nitrogen dioxide fumes evolved).

You'd most likely do your thumb no harm with 0.1 M solutions of nitric, hydrochloric, or sulfuric acid (okay, the nitric might make a yellow stain in the contact area). I wouldn't want to get even that on my face, but the skin on fingertips is pretty sturdy.

Xylo · Mar 27, 2023

Still, it's never a smart thing to do.

Donald Qualls · Mar 28, 2023

Xylo said:
Still, it's never a smart thing to do.

Oh, no argument. If his lab instructor saw him (or his video) he likely heard a few things about it...

Xylo · Mar 28, 2023

That was back in the late 80's... in that time people would get away with a lot of stupid stuff...
The same guy was also handling blocks of dry ice with his bare fingers... so I guess he never learned.

MattKing · Mar 28, 2023

During the early 1970s I was attending junior high school and there was a high school at the other end of the same road.
Apparently one day a few students there were playing around with stuff that they shouldn't have access to in the chemistry lab, an explosion ensued, and one of the students had to have a hand amputated due to his injuries.
The teacher with responsibility was fired - probably lost his/her teacher' certificate as well.
I expect a whole bunch of rules and protocols came into being as a result!

Donald Qualls · Mar 28, 2023

Xylo said:
handling blocks of dry ice with his bare fingers

I've done that without injury -- mind you, you need to be QUICK at it to avoid little frostbite spots (much like the burns you'd get from handling a block of aluminum straight out of a hot oven).

Anon Ymous · Mar 28, 2023

Donald Qualls said:
I've done that without injury -- mind you, you need to be QUICK at it to avoid little frostbite spots (much like the burns you'd get from handling a block of aluminum straight out of a hot oven).

You can get away with dipping your hand in liquid nitrogen if you do it fast.

Donald Qualls · Mar 28, 2023

Anon Ymous said:
You can get away with dipping your hand in liquid nitrogen if you do it fast.

Or splashing a stream of molten iron. Best if your skin is a little damp for that one (Leydenfrost is you friend in this situation).

Anon Ymous · Mar 28, 2023

Donald Qualls said:
(Leydenfrost is you friend in this situation).

Exactly

MattKing · Mar 28, 2023

Are we going to have to post safety warnings on Photrio posts!!??

Sirius Glass · Mar 28, 2023

Donald Qualls said:
I've done that without injury -- mind you, you need to be QUICK at it to avoid little frostbite spots (much like the burns you'd get from handling a block of aluminum straight out of a hot oven).

Anon Ymous said:
You can get away with dipping your hand in liquid nitrogen if you do it fast.

Donald Qualls said:
Or splashing a stream of molten iron. Best if your skin is a little damp for that one (Leydenfrost is you friend in this situation).

Do not try this at home!

Xylo · Mar 29, 2023

Donald Qualls said:
I've done that without injury -- mind you, you need to be QUICK at it to avoid little frostbite spots

Nah, he was just walking around holding the block and telling everybody that the teacher knew nothing when he told the rest of the kids not to do it.

Donald Qualls · Mar 29, 2023

You do know, do you not, that YouTube (at least, likely other platforms) have a "Report" button that includes "unsafe activities" and "misinformation" as reasons to report. If YouTube management agrees, they'll pull the video and issue a strike to the channel.

Xylo · Mar 30, 2023

Donald Qualls said:
You do know, do you not, that YouTube (at least, likely other platforms) have a "Report" button that includes "unsafe activities" and "misinformation" as reasons to report. If YouTube management agrees, they'll pull the video and issue a strike to the channel.

I know, I've done that plenty of times.
It's just that it's kinda hard to press the button when the guy doing the stupid stuff is just 5 feet away from you

Donald Qualls · Mar 30, 2023

Xylo said:
It's just that it's kinda hard to press the button when the guy doing the stupid stuff is just 5 feet away from you

Oh. That's a different button. Best pressed with a mallet, length of lumber, etc.

Xylo · Mar 30, 2023

Donald Qualls said:
Oh. That's a different button. Best pressed with a mallet, length of lumber, etc.

neilt3 · Apr 14, 2023

Xylo said:
Back in College I was at the Administrative Sciences School... so no lab work for me.
But I still remember quite a bit from high school chemistry classes where some idiot decided to mix the acids in a test tube by shaking it with his thumb as a stopper... he never admitted to it but he probably had a numb thumb for a few days after that.

Presumably he was a bit numb in the head to start with , so couldn't feel it anyway .

Xylo said:
That was back in the late 80's... in that time people would get away with a lot of stupid stuff...
The same guy was also handling blocks of dry ice with his bare fingers... so I guess he never learned.

Yep . Definitely sounds a bit numb in the head !

Donald Qualls said:
I've done that without injury -- mind you, you need to be QUICK at it to avoid little frostbite spots (much like the burns you'd get from handling a block of aluminum straight out of a hot oven).

Anon Ymous said:
You can get away with dipping your hand in liquid nitrogen if you do it fast.

I've always found if getting hot stuff out if an oven , oven gloves work well .
For small hot things , a pair of grips etc

YMMV

lpt10 · Apr 22, 2023

foc said:
Best to keep away from any of these.

View attachment 333485

Uranium toner might also have some detrimental effects to your health. Also, ensure there's no green/blue sensitive photo emulsions nearby when using. And if going outside on a summer night without washing your hands, beware of horny fireflies.
On a more serious note, there was indeed such a thing, Kodak T-9 Uranium Toner. See also Uranium by Robert W. Schramm

In regard to the original topic, i'll add that i also never used a stop bath ever, in over 30 years. All the negatives are fine so far as well. They're going to outlive me for sure.

faberryman · Apr 22, 2023

Are there any benefits to not using stop bath other than the nominal cost savings?

For film, how many water rinses do you use between developer and fixer?

For prints, how long do you leave the print in the water tray between developer and fixer?

GregY · Apr 22, 2023

faberryman said:
Are there any benefits to not using stop bath other than the nominal cost savings?

For film, how many water rinses do you use between developer and fixer?

For prints, how long do you leave the print in the water tray between developer and fixer?

With the staining developers i use, the benefit is not having an acid stop bath followed by an alkaline fixer.
After developer, i use one minute with agitation for roll film and 1-2 minutes for sheet film processing in trays

Stop Bath.. How important?

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