Preparing little weight chemicals for mixing developer

Mustafa Umut Sarac · Oct 13, 2014

I am quite ready to mix my d23 developer. I have 1 kilogram sodium sulfite and 100 grams of metol. I want to mix 1 liter solution per mixing.

I have to measure 7.5 grams of metol and only solution is to use big , in raw and frequent used grocery digital weight finder.

They are big and everywhere and tradesmen are my friends. I can get help. Can I trust them for such a small weight ?

How do you measure such small weight ?

Umut

scheimfluger_77 · Oct 13, 2014

Umut,

Do you have access to anything like this?

http://www.ebay.com/sch/i.html?_fro...C2.A0.H0.Xfood+scale&_nkw=food+scale&_sacat=0

These are food scales that first one says it's accurate to 1.0 g. that's probably not good enough for what we do but some the others listed there might be.

Xmas · Oct 13, 2014

you can buy micro scales 0.01 gm resolution 200 gm max for about 35GBP or cheaper - ebay.

JW PHOTO · Oct 13, 2014

Mustafa,
Here is a way so you don't have to weigh out the chemicals. It will work just fine, but make sure you level the spoons and do it the same way for each batch. You'll have to test your development times anyway so it should work perfect for you. I'm sure they have measuring spoons in Turkey. Have fun. John W
1.Heat to 120 F, in a stainless steel or enamel pan, 1000 ml of distilled water.
2.Take a "pinch" of sodium sulfite, drop into the heated water, and stir until dissolved.
3.Stir in 2 1/2 teaspoons of metol (be sure the metol is completely dissolved before proceeding).
4.Stir in 4 tablespoons plus 1 teaspoon of sodium sulfite.
5.Pour into Pyrex cup, cool slightly, and then fill two 16 oz or four 8 oz glass bottles.

Bill Burk · Oct 13, 2014

Hi Umut

Find something small and of a uniform known weight such as coins. Setup a balance, a steel ruler 18 inches long for example a printer's "line gauge". Position a small bar, or pen shaft, under the ruler at a point which multiplies the weight by leverage, for example 100 of the coins balances a single coin.

Then remove the single coin from the balance and replace it with paper on which you shake the chemical to be measured.

Variations on the number of coins on the heavy side of the balance will give you a balanced measure for the 7.5 grams you need.

john_s · Oct 13, 2014

JW PHOTO said:
Mustafa,
Here is a way so you don't have to weigh out the chemicals. It will work just fine, but make sure you level the spoons and do it the same way for each batch. You'll have to test your development times anyway so it should work perfect for you. I'm sure they have measuring spoons in Turkey. Have fun. John W
1.Heat to 120 F, in a stainless steel or enamel pan, 1000 ml of distilled water.
2.Take a "pinch" of sodium sulfite, drop into the heated water, and stir until dissolved.
3.Stir in 2 1/2 teaspoons of metol (be sure the metol is completely dissolved before proceeding).
4.Stir in 4 tablespoons plus 1 teaspoon of sodium sulfite.
5.Pour into Pyrex cup, cool slightly, and then fill two 16 oz or four 8 oz glass bottles.

Please be aware that spoon measures are different in different countries!

JW PHOTO · Oct 13, 2014

john_s said:
Please be aware that spoon measures are different in different countries!

Was not aware there would be that much difference. Hmmm! John W

Gerald C Koch · Oct 13, 2014

The accuracy of a scale or balance is said to be 1/2 half of the smallest marked increment. I have a kitchen scale that I use for food which weighs in even increments, that is 0, 2, 4, 6, 8, ... grams. Therefore its accuracy is ± 1 g. For mixing developers I use scale where the smallest designated increment is 0.01 g. There is a bar with a rider and the bar is marked in 0.01 g increments. Therefor its accuracy is 0.01/2 or ± 0.005 g.

So to weight out 7.5 g of metol you need a scale that is accurate to 0.05 g. However practicality you really couldn't tell the difference in D-23 containing 7.0 g from one containing 7.5 g, or one containing 7.5 g from one containing 8.0 g.

Steve Roberts · Oct 14, 2014

I use a digital electronic balance that I bought locally from a jewellery store. It weighs to 100g in 0.1g increments and has proved more than adequate for my needs. Cost was £20.
Steve

Europan · Oct 14, 2014

There’s the method of division.

Instead of trying to measure half a gram of something you measure for example ten times the value, that would be five grams here.
Having layed out the substance evenly on a suitable support, you geometrically divide it into as many equal parts as you need, be it cake-style, be it after a regular grid. A knife is all you need. You can use only that tenth portion and pour the rest back or progress making ten mixtures.

Gerald C Koch · Oct 14, 2014

Europan said:
Theres the method of division. Having layed out the substance evenly on a suitable support, you geometrically divide it into as many equal parts as you need

This is the sticking point. After careful weighing you then visually divide the substance. Not that accurate a method.

Anyone interested in mixing their own developers needs to invest in a good scale. If you wish to use one of the phenidones which are used in very small amounts you need a scale accurate (at the very least) to 0.01 g.

Remember the rule for determining the accuracy of a scale, It is one half of the smallest division indicated on the scale. So for a scale weighing in 0.1 g increments any weight is accurate to ±0.05 g. An amount of 0.05 g can be significant for some chemicals.

There are many models and prices for scales and it pays to shop around before deciding on a particular one.

Mustafa Umut Sarac · Oct 14, 2014

Hello friends ,

Thank you very much for your all valuable suggestions. I think Bill Burk and Europan method is that I can. I can find coins , learn their weight through internet and test the grocery scale for its precision. If it is precise and the weight is so small to measure , I can prepare 2 ,3 times of it ,fill a test tube and divide the height in to 2 or 3 and use the powder.

Yes , digital scales are excellent but I dont want to spend money at coming months.

And there can be a precise digital scale at drug store , sometimes they prepare some lotions with doctor's direction. I can get help.

Thank you,

Umut

removed account4 · Oct 14, 2014

john_s said:
Please be aware that spoon measures are different in different countries!

from what i understand a tsp and tbs being off a tiny bit won't matter one bit with this developer
as long as the OP uses the same tsp / tbs every time to mix it.
i'd be more worried about how saturated the metol and sulfite are with water than i would about a
teaspoon / tablespoon being off a microgram.

YMMV

JW PHOTO · Oct 14, 2014

jnanian said:
from what i understand a tsp and tbs being off a tiny bit won't matter one bit with this developer
as long as the OP uses the same tsp / tbs every time to mix it.
i'd be more worried about how saturated the metol and sulfite are with water than i would about a
teaspoon / tablespoon being off a microgram.

YMMV

John,
That's what I was getting at too. Consistency being more important than being of .5 grams of sulfite or even metol for that matter. I would have no problem mixing D23 with the spoon system as long as I did it the same way every time. John W

Dr Croubie · Oct 14, 2014

This cost me all of $6, and certainly works well enough for the amounts that I needed for Caffenol-C-L (5g of Vit C and 0.5g of KBr).

ps, in Aus a Teaspoon is 5ml, Dessertspoon is 10ml, and a Tablespoon in 20ml. But lately we seem to be getting in a lot of American (or from somewhere) Tablespoons that are 15ml. Worrying about a microgram or two is one thing, but a 33% difference can be a bit more drastic than that.
Weighing (solids and powders) and using volumes in ml (liquids) are the only real way to do things IMHO. Volumes of powders are never accurate, most of the time not even repeatable to within 5% depending on humidity and settling.

JW PHOTO · Oct 14, 2014

Dr Croubie said:
This cost me all of $6, and certainly works well enough for the amounts that I needed for Caffenol-C-L (5g of Vit C and 0.5g of KBr).

ps, in Aus a Teaspoon is 5ml, Dessertspoon is 10ml, and a Tablespoon in 20ml. But lately we seem to be getting in a lot of American (or from somewhere) Tablespoons that are 15ml. Worrying about a microgram or two is one thing, but a 33% difference can be a bit more drastic than that.
Weighing (solids and powders) and using volumes in ml (liquids) are the only real way to do things IMHO. Volumes of powders are never accurate, most of the time not even repeatable to within 5% depending on humidity and settling.

True, but I think D23 would still be fine with your spoons or mine since the ratio would be very close to the same. Now the dilution would be a little different, but that should be no problem at all. You can use Perceptol, D76/ID11 and even D23 diluted 1:3 and only have to adjust your development time some. So the spoon measure would be no different. If the OP were going to mix something like Pyrocat-MC it would be a whole different ballgame.

Bill Burk · Oct 15, 2014

That's a cute little pocket scale.

I actually used the trick I recommended... I have a scale with 10g resolution and I weighed a bunch of wooden "Risk" game pieces - Then I balanced as many as I needed on a "line gauge". In my case I wanted to mix up a small batch of "New Coccine"... And that stuff does need to be carefully measured... there's not much of it around.

Soeren · Oct 15, 2014

Dr Croubie said:
This cost me all of $6, and certainly works well enough for the amounts that I needed for Caffenol-C-L (5g of Vit C and 0.5g of KBr).

ps, in Aus a Teaspoon is 5ml, Dessertspoon is 10ml, and a Tablespoon in 20ml. But lately we seem to be getting in a lot of American (or from somewhere) Tablespoons that are 15ml. Worrying about a microgram or two is one thing, but a 33% difference can be a bit more drastic than that.
Weighing (solids and powders) and using volumes in ml (liquids) are the only real way to do things IMHO. Volumes of powders are never accurate, most of the time not even repeatable to within 5% depending on humidity and settling.

Well weight arent either they also differ depending on how much humidity the chems has soaked. Biggest problem converting from weight to tsp is the different density of the chemicals. 1tsp does not always equal e.g 5g
This could be a solution though an expensive one
http://www.instructables.com/id/Lego-pan-balance/

JW PHOTO · Oct 15, 2014

Soeren said:
Well weight arent either they also differ depending on how much humidity the chems has soaked. Biggest problem converting from weight to tsp is the different density of the chemicals. 1tsp does not always equal e.g 5g
This could be a solution though an expensive one
http://www.instructables.com/id/Lego-pan-balance/

Looks pretty corrosion resistant, but I'll pass! I have two of the Chinese digital jobs, one for real light stuff and one for heavier stuff. Cheap and they work. When they stop I'll just buy another. I also have a beam scale. Might be more accurate, but it's less handy that's for sure. I still would have no problem doing volume measurement for simple D23. John W

Doremus Scudder · Oct 15, 2014

I'm surprised no one has mentioned the obvious way to measure out very small quantities: First, make a solution from a well-weighed out larger quantity, say a 10% solution. Then simply measure out a smaller volume of the liquid using a graduate. Simple and very accurate.

I can mix 100g of something to make a 1 liter solution and have a 10% solution. That means I now have 1g of the chemical for every 10ml of solution. If I need half a gram, I just measure out 5ml, and so on. Some chemicals are less soluble, but the principle is the same.

A 1% solution of phenidone means that I have 1g of chemical for every 100ml. If I need 0.5g, then I simply measure out 50ml. Easy-Peasy.

Many developing agents will dissolve in TEA or glycol or alcohol and will keep for a very long time, ready to measure out at a moment's notice.

Best,

Doremus

Gerald C Koch · Oct 16, 2014

The one developing agent which can present difficulty is Phenidone or one of its derivatives which are typically used in very small amounts. As pointed out by Doremus developing agents can be dissolved in a glycol. I would not reccommend using TEA in the case of phenicones due to decomposition. (The post is unclear on this point.) Some recommend a water solution of Phenidone with sodium sulfite as a preservative. Others use a methyl alcohol solution. These solutions do not keep very well and soon become pink indicating decomposition.

Some people use powder scales used to reload bullet cartridges. There is a small problem with them in that they give weights in the English system of grains so weight conversion is necessary.

Preparing little weight chemicals for mixing developer

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