Mixing own chemistry

Deleted member 88956 · Feb 13, 2020

Looking into mixing own B&W chemistry. Outside of lab quality volume measuring graduates/pipettes/etc , what type and max capacity of scale would you recommend (I see "precision" electronic scales are quite cheap, but cheap is not on my menu as reason to buy)
Have already a precision thermometer with very fast response, but what or any other measuring gear would be advisable?

koraks · Feb 13, 2020

I do virtually all my mixing with a scale that goes up to only 20g. I mix small batches only.
A pH meter is nice to have.

Anon Ymous · Feb 13, 2020

I use a 100g scale, with a 0,01g resolution. It's not very precise at very small quantities, anything below 0,1g is rather iffy. For such quantities, I make a solution of known concentration with a reasonably large quantity and measure the volume I'll need. I have some glass pipettes for this purpose, 2, 5 and 10ml and a bulb to use them. Of course, a syringe will for the most part work just as well. If you're simply going to mix specific formulae without making any modifications - substitutions, then a pH isn't essential, but if you do, or plan to mix any colour chemicals it will be. Lastly, I use borosilicate glass beakers, which I find very useful. The fact alone that they can be heated with an electric, or gas stove is a big plus IMHO.

drpsilver · Feb 13, 2020

12 Feb 2020

Witold:

I user a "triple beam balance" to measure out chemistry, but any kitchen scale with a capacity of several pounds would work as well. Most of these scales can be set to readout in grams. I would recommend purchasing some weighing papers for small quantities, and using larger cups (labeled for photo use only) for larger quantities. For liquids there are many graduates that are available from Freestyle Photographic (or like vendors). In a pinch you can use any kitchen graduates. Just DO NOT use it for food afterwards, i.e. it become a "photo graduate" and is labeled as such.

Regards,
Darwin

Mick Fagan · Feb 13, 2020

I've had really good electronic scales with a business I one had and I did use these, but I went back to my triple beam scales. They are accurate, require no batteries and if kept clean, will probably see you out. I have had mine for about 30 years and they are as good as the day I bought them.

This is similar to what I have, without the extra weights. The knob at the left end under the tray, is for zeroing your scales once you have placed a cup or paper for your chemistry.

https://www.google.com/search?q=tri...ECBEQAw&biw=1536&bih=710#imgrc=6icSJTphb4us6M

Mick.

AgX · Feb 13, 2020

I still use a beam balance with sliding counterweights, with a division of 0.01g , which I can repeatably readout down to 0.005g with some effort.

Deleted member 88956 · Feb 13, 2020

AgX said:
I still use a beam balance with sliding counterweights, with a division of 0.01g , which I can repeatably readout down to 0.005g with some effort.

So something like THIS?

M-88 · Feb 13, 2020

Working with a digital scale for "jewelry". Precision is around 0.01 grams and I'm unaware of how precise it is, but never had any problem, monochrome forgives a lot of mistakes.

AgX · Feb 13, 2020

Witold said:
So something like THIS?

Something of similar principle. One slider counterweight with mechanical-digital readout for the grams and a threaded weight for the decimals.
https://www.picclickimg.com/d/l400/pict/232529121591_/Bosch-Maphy-Präzisionswaage-mechanische-Waage-Schulwaage-für-Chemie.jpg (though wrongly set-up in photo)
It got a knife bearing and an Eddy-current damping.
It's fun.

Recently I found at a fleamarket a professional mechanical balance with an intriguing mechanism of adding and substracting counterweights, but I could not transport it, furthermore it had issues and I had no time for yet another project...
something similar to this: https://sammlungen.uni-goettingen.de/fullscreen/record_kuniweb_1109648/1/

But as meanwhile I use on rare occasions even a calliper with digital display instead of my loved vernier-type one, I guess I could use an electronic balance too by now... And I better should not become too nerdy...

guangong · Feb 13, 2020

About 10-15 yrs ago I bought a triple beam balance that works very well. Before that I used a simple balance with weights that was given to me for free by a man who operated a scientific instruments store when I was 12 yrs old. I would go shop with 25 cents to buy 5 test tubes and often walk out with two shopping bags of lab equipment. Now, I realize that these were probably returns. A baseball stadium occupies the location now. 70 yrs later I occasionally use this balance. He gave me a Bunsen burner more sophisticated than anything I encountered in high school or college.

removed account4 · Feb 13, 2020

get something like this
http://pocket-scales.com/toyo/pocket-mini-scales.html
it is overkill to get an over the lab quality scale. mixing photochemistry
is not like mixing something that requires something beyond 0.1g, if you look
at recipes for most developers, sensitizers, binders, fixers, stop baths, toners, cyanotype, and even emulsion formulas,
they require nothing more than an inexpensive digital scale like the one i linked to ( and own ).
you can probably get it on amazon for not much money.
15+ years ago david goldfarb ( moderator here ) recommended to me the one i am linked to, never had issue with anything i have measured
or made.
good luck!

RalphLambrecht · Feb 13, 2020

Witold said:
Looking into mixing own B&W chemistry. Outside of lab quality volume measuring graduates/pipettes/etc , what type and max capacity of scale would you recommend (I see "precision" electronic scales are quite cheap, but cheap is not on my menu as reason to buy)
Have already a precision thermometer with very fast response, but what or any other measuring gear would be advisable?

good question. It took me a frustrating while until I finally found the ideal set up and I'm working with a medical Tronic scam with a max capacity of 300 g It took me a frustrating while until I finally found the ideal set up and I'm working with a medical Tronic scam with a max capacity of 300 grams and the sensitivity of 0.01 g. For a few ingredients are use the scale with a max capacity of 10 g and the sensitivity of 0.001 g. This set up works well for all my formulae.

Rudeofus · Feb 13, 2020

There are extremely cheap scales to be found on ebay, coming directly from China. It usually takes several weeks for these scales to arrive in your mailbox, but so far it has always worked out for me. These scales offered there frequently look exactly like the jeweler's scales you get in my home town - for 5-10 times the price.

Deleted member 88956 · Feb 13, 2020

Good lord nobody recommends THIS

Thanks for all the input. I do like the triple beam and its "manuality", (especially THIS one) but here in Poland so far only new are popping up on screen and that is about $250, so may have to wait a bit as I see no reason to justify it.

Yet surely a digital scale is a convenience nice to have and for around $100-110 can get a 300 g capacity 0.001g resolution. Take $25 off that and 0.01g is in. Under $50 plethora of choices with 0.1g resolution. I purposely label them "resolution" as none are lab calibrated so would not bet my last camera on getting "accuracy" of that degree. Not that it matters, apparently. I still like to see digits beyond needed, so am leaning towards 0.001g display. There is one that not only gives that but also weighs about 1.5kg as a unit, and gives some sense of raw quality feel, like anything that can cause injury if dropped on the big toe.

How "popular" are ph meters in any of your set ups? I don't see it critical or even essential for B&W chemistry and color is rather nothing I plan doing any time soon. Just remembered Dr. Henry talking ph readings in his "Controls in Black and White Photography".

Rudeofus · Feb 13, 2020

Don't waste money on a scale that resolves 1mg and goes up to 300g. For less than 10$ you get scales of the 200g max with 10mg resolution. If you really really need 1mg resolution, then you can get a scale with that resolution and 20g or 50g max range for less than 15$. That's <25$ for two scales, which can serve as each other's backup in case of breakage. You certainly won't have to measure 30g with 1mg resolution in photography.

If you mix standard formulas, there's no need to have a pH meter. You may have to use one for color chemistry, or if you start experimenting with modified formulas. pH meters have limited life expectancy, so there's no point in buying one just in case.

wahiba · Feb 13, 2020

Just in to caffenol with some success so today ordered some bulk vitamin C and soda off Amazon. Thought I might try basic fixer as well so ordered some thiosulphate along with 200g scales for £7. Made the free postage with the Vit C. Generally a good day, even won £10 off a £2 scratch card.

Europan · Feb 13, 2020

I have worked with several commercial motion-picture film labs as developer, QC person, printer, packer-driver, and more. At my own commercial movie lab I prepared all baths myself with rubber gloves on, from ten liters up to 50. I would start with four or five liters of water in a large tub, a big surface and a shallow bath. I would accelerate dissolution with synthetic foam sponges.

I didn’t and still don’t use a scale but a Roberval balance. It has two brass pans. Besides it a set of weights. The important point is to always work in the same manner. That way the errors stay the same as well, you have consistency. Once a good workflow is established you can attack the deviations. Laboratory workers should be conservative workers. Also important is to keep a record of what you do, step by step. My carnet shows the date, the time, the formula, and everything extraordinary. The rest is my precisely followed standard and a secret. In addition I develop a pre-exposed wedge strip together with every film portion. That protects me from attempted blackmail by clients. Oh, yes, they exist.

Anon Ymous · Feb 13, 2020

Rudeofus said:
Don't waste money on a scale that resolves 1mg and goes up to 300g. For less than 10$ you get scales of the 200g max with 10mg resolution. If you really really need 1mg resolution, then you can get a scale with that resolution and 20g or 50g max range for less than 15$. That's <25$ for two scales, which can serve as each other's backup in case of breakage. You certainly won't have to measure 30g with 1mg resolution in photography.

If you mix standard formulas, there's no need to have a pH meter. You may have to use one for color chemistry, or if you start experimenting with modified formulas. pH meters have limited life expectancy, so there's no point in buying one just in case.

Spot on about scales and pH meter. I definitely second that.

Deleted member 88956 · Feb 13, 2020

Rudeofus said:
Don't waste money on a scale that resolves 1mg and goes up to 300g. For less than 10$ you get scales of the 200g max with 10mg resolution. If you really really need 1mg resolution, then you can get a scale with that resolution and 20g or 50g max range for less than 15$. That's <25$ for two scales, which can serve as each other's backup in case of breakage. You certainly won't have to measure 30g with 1mg resolution in photography.

If you mix standard formulas, there's no need to have a pH meter. You may have to use one for color chemistry, or if you start experimenting with modified formulas. pH meters have limited life expectancy, so there's no point in buying one just in case.

Well, I'm not buying $10 scale for sure. While it would work, and might last years, just as well it may not work on arrival or last a month or 6. I bought a wrist watch at WalMart in early 90's for $15, kept ticking within 5 seconds on a year and battery lasted over 5 years, superior performance to a $300 Seiko I was so excited about (it was better looking though). so you never know with cheap what it brings. Had a top of the line Sony Walkman at its peak of technological development, all metal, slightly larger than the cassette itself and cost over $100 in late 80's. A friend of mine bought same thing on same day. His lasted 3 months, mine only stopped auto reversing after many years and eventually I stopped using a Walkman.

So, if I do buy one it will need to have build quality, irrespective of what display resolution or capacity I choose. I mentioned the 300g capacity because the unit has some heft to it too, which is part of my considerations. By the time I pull the card out it might be an entirely different unit. At the same time I do like tray classic balance with weights or the triple-beam already spoken of. Just going through due diligence on this right now.

This is not a jab at your post, just they way I approach these things. At the same time I do like tray classic balance with weights or the triple-beam already spoken of.

Andrew O'Neill · Feb 13, 2020

I have a triple beam scale, and an electronic one. I prefer the triple beam. Battery not required...

Rudeofus · Feb 13, 2020

Witold said:
This is not a jab at your post, just they way I approach these things. At the same time I do like tray classic balance with weights or the triple-beam already spoken of.

I understand your approach, but don't share the conclusions. These cheap Chinese scales do work, in fact some are resold here locally, albeit with a hefty markup. The risk to your work is minuscule, since you have a two scale setup, which gives you some degree of redundancy. You can get four of these scale pairs for less than what you pay for this one scale you suggested. There are some risks involved with every technical purchase, but the numbers in this case definitely work out in favor of the cheap ones.

Deleted member 88956 · Feb 13, 2020

Rudeofus said:
I understand your approach, but don't share the conclusions. These cheap Chinese scales do work, in fact some are resold here locally, albeit with a hefty markup. The risk to your work is minuscule, since you have a two scale setup, which gives you some degree of redundancy. You can get four of these scale pairs for less than what you pay for this one scale you suggested. There are some risks involved with every technical purchase, but the numbers in this case definitely work out in favor of the cheap ones.

I'm not disagreeing, but I do like to sneeze sometimes and do not want that scale to move when I do

Anon Ymous · Feb 13, 2020

Witold said:
I'm not disagreeing, but I do like to sneeze sometimes and do not want that scale to move when I do

If you sneeze while weighing powders, an inaccurate reading would be the least of your concerns.

Doremus Scudder · Feb 13, 2020

How small your scale needs to resolve really has to do with the amounts you will be measuring. If you measure relatively large amounts of chemicals, say in the 5g and up range, you don't need a scale that reads down to 10mg even; an error of 1/10g with 5g is only 2%, well within tolerances for most darkroom chemicals. If you need to weigh very small quantities, then the resolution of your scale needs to be better. Figure out what and how much you are going to be weighing before making a decision on a scale.

Triple-beam balance scales are nice and quite accurate. They take up more room than digital scales, however. So, base your choice on available workspace.

FWIW, I have both triple-beam balance scales and a nice digital scale that reads down to .01g. I still mix my D-72 with measuring spoons...

Best,

Doremus

Luckless · Feb 13, 2020

Anon Ymous said:
If you sneeze while weighing powders, an inaccurate reading would be the least of your concerns.

Sneeze guards are useful for more than just salad bars...

While I've not gotten into doing lab work more involved than mixing pre-packaged photo chemistry in over a decade at this point, one thing that I found useful and important that is often overlooked is the value of a trustworthy set of reference masses.

I'm also rather on the fence for a digital scale vs old school triple beam balances. Digitals tend to be faster and have less faffing about involved, but a good triple beam balance is just lovely to work with.

Mixing own chemistry

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