Getting a scale for Metolian consistency

[Alan Klein]

You can always sell it to the cartel when you no longer need it.

[Ulophot]

youre measuring chemicals as if you are baking a cake?... hahahaha
get a scale!

https://www.amazon.com/triple-beam-s...ple+beam+scale

also see tc scale?... $7!

I got the SmartWeigh Gem 20. Smaller than expected; included "cup" is too small for my Metol. Folded wax paper does the trick, but it's good that my amount is small.

[Doremus Scudder]

Philip,

Now that you have a reliable scale, and assuming your Metol is of uniform consistency, weigh out a level teaspoon a few times and take the average. Use that for your spoon recipes. Do that with your sodium sulfite and you should be able to figure an accurate spoon recipe for D-23. Then it's just like baking a cake!

Doremus

[Ulophot]

Doremus, good in theory, but as noted, the Metol consistency is a question mark for me, since the stuff is so very compressible and, in this batch, sticks together so well that it slips around in the spoon when levelling. I'm happier with weighing. My sulfite, borax, and carbonate crystals are no problem for spoons, and I can use the scale on the rare occasions I need small amounts, e.g., for SLIMT stocks.

Any wisdom to offer on my timing issue (yesterday's posts in this thread)?

[Michael R]

I’m confused so hopefully Doremus answers

Based on post #7 I was thinking you were used to using two compacted spoonfuls before checking the scale so I thought the scale was telling us you had effectively been using approx 5.5g/l metol to make your stock D-23. But now you’re saying you were using 3.6-3.7g (non-compacted spoonfuls).

[Drew Wiley]

I'm confused about the difference between Metolians and Martians, or perhaps Metropolitans, as well as the substitution of metol for baking soda when making a cake. But otherwise, I've always been a little leery of interchanging spoonfuls of anything in the lab for actual prescribed gram weights. Decent gram scales are cheap enough. And a hundred little poly weighing dishes don't cost much, and will last a long time, since you can simply rinse them out afterwards. Metol is fairly aggressive, and relatively small errors in quantity can have an outsized impact on the overall formula consistency.

[Paul Ron]

Plus chemistry is all abouit weights not teaspoons. Sometimes that extra variable gram is the problem with your results.

[Ulophot]

I’m confused so hopefully Doremus answers

Based on post #7 I was thinking you were used to using two compacted spoonfuls before checking the scale so I thought the scale was telling us you had effectively been using approx 5.5g/l metol to make your stock D-23. But now you’re saying you were using 3.6-3.7g (non-compacted spoonfuls).

I am more confused than you, Michael, but my wife could have told you that decades ago. On the matter at hand:

I had been used to using fairly uncompressed spoonfuls, levelled, but, with the scale having arrived, I found that each was only something like 1.8 g, at least with this new batch, with its noted characteristics. I mixed up a fresh liter using the scale to measure 7.5 g and used my usual 4 Tbs of sulfite, which measures easily.

I developed one for 7 minutes and found it to be way too thin, much to my surprise and chagrin. I am just waiting for another neg, developed for 9 1/2 minutes, to dry. If it's close, I'll be more confused than ever, since my old time was 9 minutes -- except that that was for using my coldlight head, which was adding more contrast than I realized. From the initial appearance of this latest neg, I expect 9 or 9 1/2 minutes to be on target, and then will simply apply the percentage change to my other times and only adjust further if a particular time is off. I'm close to being done with this painfully extended exercise. Hallelujah!

[Michael R]

There have certainly been some twists and turns so hopefully not too much testing left.

Ending up with a longer development time with roughly twice the metol concentration would be a little strange, though I wouldn’t be all that surprised if the times were closer than one might expect. I say this because we need to keep pH in mind. The normal pH of fresh D-23 is 8. This is the net result of the alkaline sodium sulfite and acidic metol salt. Since we think you might have been using significantly less than 7.5g metol, it is possible the pH of your version of D-23 (let’s call it D-23U ) was a little higher. I’d have to measure it to know for sure. A higher pH would boost the activity of the weaker solution, lessening the expected difference in development times due to the difference in metol concentration alone. I wouldn’t expect this small pH increase to completely offset the lower metol concentration though, so perhaps there is also something being contributed by the change in enlarger light source. That would be expected since the two types of lighting put out different wavelengths.

I am more confused than you, Michael, but my wife could have told you that decades ago. On the matter at hand:

I had been used to using fairly uncompressed spoonfuls, levelled, but, with the scale having arrived, I found that each was only something like 1.8 g, at least with this new batch, with its noted characteristics. I mixed up a fresh liter using the scale to measure 7.5 g and used my usual 4 Tbs of sulfite, which measures easily.

I developed one for 7 minutes and found it to be way too thin, much to my surprise and chagrin. I am just waiting for another neg, developed for 9 1/2 minutes, to dry. If it's close, I'll be more confused than ever, since my old time was 9 minutes -- except that that was for using my coldlight head, which was adding more contrast than I realized. From the initial appearance of this latest neg, I expect 9 or 9 1/2 minutes to be on target, and then will simply apply the percentage change to my other times and only adjust further if a particular time is off. I'm close to being done with this painfully extended exercise. Hallelujah!

[LabRat]

To hold chems while measuring, I use standard Dixie paper drink cups... They are remarkably even in tare weight (within less than 1/10gm one to another), easy to shake chems in/out, large enough to hold enough chem for more than a liter to mix, and cheap enough to use a fresh one for each chem...

Easy way to measure, then shaken into the solution with the magnetic mixer...

Steve K