Potassium Bromide pebbles

dpurdy · Feb 10, 2017

Maybe a stupid question but I just received 1000 grams of Potassium Bromide and it isn't a powder, it is all little rocks about 1 inch long and half in thick. Anyone have a great idea for getting it into a rough powder that I can measure small amounts from. I tried using a coffee grinder and it didn't work because it grinds unevenly and too fine. Do I sit on the floor with a hammer and a paper bag?
thanks
Dennis

pdeeh · Feb 10, 2017

Pestle and mortar

Photo Engineer · Feb 10, 2017

Just don't use teaspoons or tablespoons!

This is a perfect example of proving one should not use volumetric measure on solids. Michael_r has the best solution. A mortar and pestle is second best due to the difficulty of using it.

I should add that your coffee grinder is probably shot. Also, I would not want to use it for coffee anyhow unless it is very thoroughly cleaned.

PE

John Wiegerink · Feb 10, 2017

How long is the shelf life of potassium bromide? I found some that I was given about 30 years ago and the guy that owned it probably had it for 30 years prior to giving it to me. It's still in its Kodak brown glass jar. The top is a little rusty, but not bad. It is caked hard, but can be broken up with my jackknife. Just curious?

removed account4 · Feb 10, 2017

hi dennis

last time i used KBr i used the bottom of a pan and crushed it.
before that i just waited for it to dissolve..
i have since bought a mortar and pestle

have fun !
john

Photo Engineer · Feb 10, 2017

John, I have a bottle of Kodak KBr that is about 50 years old. It is still filled with little cubes of KBr that are about 1/8" on a side and some still flow free. It is perfectly fine!

PE

John Wiegerink · Feb 10, 2017

Thanks PE! I won't let it go to waste, but I have a feeling that when I "kick the bucket" there's still going to be a nearly full bottle that's going to probably end up tossed. There are certain cameras and things I'd like to take along in my casket for the "Big Photo Shoot in the Sky", but Potassium Bromide isn't one of them.

Photo Engineer · Feb 10, 2017

There is no luggage rack on a hearse!

PE

mshchem · Feb 10, 2017

I bought some Ebay Na thiosulfate. Nice uniform crystals. But nothing like my old bottles of Kodak chemicals. That is something else that went with the collapse of Kodak was nice bulk chemicals. It seems like You can buy AR grade lab stuff that is astronomically expensive. Or you get something that's pretty good but still not as nice as what was available in the good old days. I have nice old Ohaus mechanical balances. I can go from a milligram up to 50 kg. I got a beautiful solution balance that you can weigh liquids, has a big tare poise for your bucket. I have been gifted enough sodium sulfite to last me for many years. I don't take anything nasty though.

A kilo of KBr, that's going to last quite a while
Mike

Photo Engineer · Feb 10, 2017

Your Sulfite might not last quite a while though!

PE

dpurdy · Feb 11, 2017

Apparently sodium sulfite exposed to oxygen becomes sulfate. I never knew that and I have bought large quantities a few times from swimming spool supply houses and used it out of the bag and never noticed the difference.

The Potassium bromide, I guess I will get a whittling knife and scrape the stuff onto my scale... not such a big deal really.

darkroommike · Feb 11, 2017

michael_r said:
Besides grinding it up, you could also make up a stock solution with a larger amount (say 100g/l) which keeps a long time.

This is the approach I use with KBr, the last bottle I got was rather "chunky", large irregular crystals. I just weigh out 'x' and then make it into a 10% solution wt/vol adding warm water to make.

keenmaster486 · Feb 11, 2017

Photo Engineer said:
There is no luggage rack on a hearse!

PE

Yes, but I like to think that God probably has a stash of refrigerated Kodachrome and his own personal K-Lab...

Photo Engineer · Feb 11, 2017

I doubt that. He can probably see the entire electromagnetic spectrum and thus any film would be drab!

PE

keenmaster486 · Feb 11, 2017

Ha, yeah, you're probably right

Gerald C Koch · Feb 11, 2017

Many moons ago the local photo store stopped processing color. I was able to buy some large containers of Kodak chemicals like 5# of hydroquinone and a 25# fiber drum of sodium sulfite. I immediately transferred the sulfite to large glass canning jars. They're cheap and readily available at least during canning season.

Denverdad · Feb 11, 2017

I'll chime in with the others who suggested that mixing up a larger quantity of solution ahead of time is really the way to go - it's just so much more convenient to dispense liquid from a pre-mixed jar of solution than it is to deal with grinding up and measuring the very tiny amounts of solid each time. I put a note on the jar of 10% solution I created to remind me that 10ml of solution corresponds to 1 gram of KBr. Since the volume of solution required is still typically small, another tip is that a baby syringe can be a very useful tool for measuring and dispensing the liquid.

John Wiegerink · Feb 11, 2017

Photo Engineer said:
I doubt that. He can probably see the entire electromagnetic spectrum and thus any film would be drab!

PE

Hmm, how do you know He is a he? My wife says He is a she. I have a standing order at the local florist and candy shop for roses and chocolates to be stuffed in my casket when I die just in case she's right. Want to make a good first impression you know. I guess I'll have to leave my Hasselblad behind since there won't be room in the casket.

keenmaster486 · Feb 11, 2017

John Wiegerink said:
My wife says He is a she

Are we gonna get started on this? Cause I'd be happy to oblige

John Wiegerink · Feb 12, 2017

keenmaster486 said:
Are we gonna get started on this? Cause I'd be happy to oblige

Nah, I think we'll let sleeping dogs lie.

juan · Feb 12, 2017

I second the use of canning (Mason) jars. As they are clear, keep them in a dark cabinet.

silveror0 · Feb 12, 2017

John Wiegerink said:
...I guess I'll have to leave my Hasselblad behind since there won't be room in the casket.

No room for the Hassy? Sounds like the threat of claustrophobia would be present during a fit-check!

Photo Engineer · Feb 12, 2017

Be careful, the thin brass lids will corrode with some chemicals. The heavier glass lined ones are more resistant.

PE

darkroommike · Feb 12, 2017

You could also place a layer of plastic wrap under the lid since we aren't "canning" anything.

Photo Engineer · Feb 12, 2017

Good idea.

Potassium Bromide pebbles

Privacy & Transparency

Privacy & Transparency