Would you measure Vitamin C with teaspoons to get long-lasting dev?

albada

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I'm thinking of designing a developer that requires you to add Vitamin C (ascorbic acid) separately using a measuring spoon.
Would this be too much extra hassle?

You would do the following:
1. Pour developer into your beaker as usual.
2. Measure out 1/2 or 1 teaspoon of Vitamin C.
3. Stir until dissolved (a couple of minutes).

I discovered that ascorbic acid can be measured consistently (within 5%) using a measuring spoon by first scooping out a heaped spoonful, then compacting it by pressing firmly upward against a flat surface, and then scraping it level. That gives you an accurate packed-and-leveled spoonful.

Adding ascorbic acid separately means you can mix your own ascorbate-based developer and have it last many months instead of just a few weeks. For example, you could mix your own XTOL-clone, and then you would not need to mix 5 litres of XTOL and waste much of it when you can't use it all. But you'd need to do the teaspoon-routine each time you develop. Is it worth the extra effort?

Mark Overton
 

jcoldslabs

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That would be totally worth it to me. Presently, I mix HC-110 from concentrate for each developing session, so I'm used to the mixing aspect. If I could get Xtol-like results with a long shelf life simply by adding some vitamin C each time, no problem!

Jonathan
 

Bruce Osgood

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If you are talking about adding the Vitamin C to a previously mixed and stored, ready-to-go stock solution when preparing to develop film, then yes, as a single, last minute addition with a teaspoon would not be a hassle.

But if you are talking about making a stock solution that uses a teaspoon amount of Vitamin C in the formulation stage, I think I would find it easier to use weight rather than volume since I've set up to weigh all other ingredients.
 

Gerald C Koch

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Measuring by volume rather than weight is inaccurate as it depends on crystal size. It doesn't take that much more time to weight out the correct amount. For small amounts a square of paper works well to protect the pan on the scale. For larger amounts paper baking cups work well. Remember the tare weight of whatever you use.
 
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albada

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Interestingly, it's possible to formulate a developer so that sloppy measurement of ascorbic acid makes little difference. An example is (there was a url link here which no longer exists). For example, if AA is low, then having less secondary dev drops activity, but the rise in pH boosts activity, cancelling each other out, yielding about the same activity.

Regarding weighing, here's my sermon:
As Jerry said, measuring by weight is more accurate. Electronic scales with .1 or .01 g resolution cost only US$12-15 on amazon. That's the cost of just 3 rolls of film. So there's no excuse to not have one (or two). Search for "scale .1g" or "scale .01g".

Bruce Osgood said:
If you are talking about adding the Vitamin C to a previously mixed and stored, ready-to-go stock solution when preparing to develop film, then yes, as a single, last minute addition with a teaspoon would not be a hassle.
Click to expand...

Yes, a last-minute addition for single-shot use is what I had in mind. Sorry that I didn't make that clear.

Mark Overton
 

Keith Tapscott.

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I don't know if it's worth the extra effort. You could try a simple fine-grain formula like DK-76b and add some vit-c to the working strength solution to see if it works well, otherwise stick with Xtol.

http://www.digitaltruth.com/data/dk76b.php
 

Worker 11811

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Just a shot in the dark.

What about making a saturated solution of ascorbic acid in distilled water then measuring a certain amount of the liquid? (tablespoons full, etc.)
It's a lot easier to measure liquids accurately and, assuming room temperature ≈20ºC, you should always get the same amount of solute.
 

P C Headland

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If you want something like that, you might want to make up some PC-TEA. Simple to make, lasts at least 5 years, and (for me at least) seems to have a combination of the best bits of Rodinal and Xtol. Like Rodinal, it can turn from a pale straw colour to dark tea, and still works the same. Like Xtol, it gets good film speed and shadow detail, with little grain.

Oh, the Vitamin C goes in when the concentrate, so no need to add any later
 

jp498

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I'd be happy with shoveling in ascorbic acid, liquid concentrate (I have cheap pipettes for that), or how about "sugar packs" or tablets of the stuff.
 

Gerald C Koch

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The use of ascorbic acid in the food industry is wide spread. Why, because it readily scavenges oxtgen and therefore protects other chemicals. Because of this it is unstable in solution so making up a concentrate solution is really of no help. As has been stated over and over again on APUG the main problem is Fenton oxidation which is catalysed by iron and copper in the chemicals themselves and in the water used to make up solutions. Use only de-ionized water for making up solutions. Do not use distilled water as this is often made using copper equipment. The stabilitry of ascorbates is improved with the use of certain chelating agents such as salicylic acid and TEA.

My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use

OR

use the two chelating agents mentioned and use only de-ionized water.
 
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albada

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Gerald C Koch said:
My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use
OR
use the two chelating agents mentioned and use only de-ionized water.
Click to expand...

Alan Johnson said:
What evidence is there that the phenidone and sulfite part of the developer would be long lasting?The question is based on an unproven assumption.
Click to expand...

Alan and Jerry quickly perceived my evil plans.

In ascorbate developers, the ascorbate typically is destroyed first (by Mr. Fenton), so my idea is to add it separately. But as Alan points out, the sulfite and Phenidone might not last long either. PE has said that Dimezone S is more resistant to hydrolysis than Phenidone, and we know it lasts for over 6 months in capped bottles of XTOL. Sulfite is oxidized by air, changing it to useless sulfate, but my calculation of air-moles versus liquid-moles says this won't be a problem in typical usage. So maybe, just maybe sulfite+Dimezone will last long. Only testing will prove that, and I wanted to know if this add-C-separately idea appealed to people before doing that testing. Hence my posting.

jp498 suggested tablets. That's a good idea: Vitamin C pills are widely available in 250, 500 and 1000 mg sizes. That would solve the measurement problem. Hmmm...

Mark Overton
 
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albada

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Michael R 1974 said:
I'm confused about the Phenidone/Sulfite part. Would this be mixed in a solvent like TEA that does not readily transfer Oxygen? Otherwise wouldn't a Phenidone-Sulfite-Water solution be pretty short-lived/unstable? I'm thinking of POTA for example.
Click to expand...

Yes, this would be water-based ready-to-use developer like D-76 or XTOL, except that some Vitamin C would be added just before use. And Phenidone is subject to hydrolysis, so I'm hoping that Dimezone S will last longer.

Mark
 

Alan Johnson

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Here I can buy a 120w 6-speed hand held mixer for GBP 8.
The ascorbic acid and phenidone could be mixed together then measured out with a spoon?
On second thoughts that's a bit industrial and not safe for amateur work.
 
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Zathras

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Since I prefer Metol to Phenidone, I've been playing with the idea of using D23 as a sort of stock solution since the required amount of Metol is only .2 grams per liter of Gainer's formula. I plan to make the working solution by starting with 900ml of water, adding 2.0 grams of ascorbic acid, 26.6ml of D23 and 6.0 grams of sodium metaborate, in the form of PMK "B" solution and topping it up to 1.0 liter. I figure that the 100 grams of sodium sulfite in the D23 should preserve the Metol for at least 2 months if stored properly.

I'm basing my idea on Pat Gainer's Vitamin C developers, but trying to eliminate errors in weighing out small quantities of Metol every time. Since I do use D23, I thought that it might make a good stock solution for the Metol, and if I don't like the results from Gainer's developer, I still have D23.

When diluted, there will be less than 3.0 grams of sulfite in the developer compared with none according to Pat's formula. I don't know if that would make a big difference or not, so I'll need to test carefully. When I have the chance, I'll run some BTZS tests with a couple of films and see what happens.

Since I'm not trying to make a developer that works like Xtol this may not be what the OP has in mind. I was just considering an alternative.
 

Gerald C Koch

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There are 3 ways to eliminate impurities in water

1, Distillation, the oldest method. Water is vaporized, leaving the impurities behind, then allowed to cool using a condenser to form liquid water again. Traditionally a copper condensor was used for its large heat transfer capabilrty. If a metal condensor or catch container is made of metal then the water may become contaminated with metal ions. A particular problem is with copper. Even ordinary glas is a problem in preparing water for conductivity experimnts. The sodium in ordinary glass leachs out. Only fused silica equipment can be used.

2 De-ionization, the water is passed throught a mixed resin ion exchange column. Metal ions are replaced with hydrogen ions and anions with hydroxide ions. The hydrogen and hydroxide ions combin to form water.

3 Reverse osmosis, water under great pressure is forced through a semipermeable barrier. Large ions cannot pass through leaving, in theory, pure water.

Iron and copper are common contaminants of the chemicals used for making developers. The wrorst offenders are probably sodium sulfite and sodium carbonate. So just using purified water may not help. A chelating agent is the best way to insure the storage life of ascorbate developers. Salicylic acid chelates iron and TEA does the same for copper.

With the right amount of iron III all the ascorbate in a solution can be destroyed in an hour or so. It can be that fast.
 
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albada

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Gerald C Koch said:
With the right amount of iron III all the ascorbate in a solution can be destroyed in an hour or so. It can be that fast.
Click to expand...

And that's why I started this thread: My idea was to add the ascorbate at the last minute.

Here's a related idea: Add the Vitamin C as pills!
You can buy 1000 mg Vitamin C pills that are actually powder in gelatin capsules. Here are examples:

It's easy to pull gelatin capsules apart, and pour out the powder into your beaker. So the procedure for developing would be:

1. Pour developer into beaker.
2. Add contents of a couple 1000 mg Vitamin C pills, and stir until dissolved.
3. Develop as usual.

This avoids the inaccuracy of using teaspoons, and eliminates the need for a scale. Is this appealing?

Mark Overton
 

Doremus Scudder

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Hello Mark,

I have used both vitamin C tablets and capsules as developer additives (I add ascorbic acid to PMK for expansions). Unfortunately, it's not so simple as "add contents ... stir until dissolved." All the vitamin C products I've tried also have binders and anti-caking ingredients (usually corn starch, etc.) which needs to be filtered out. I usually dissolve the powder from the capsule/tablet in a separate small amount of water and then filter that before adding it to the developer. Unless you can source some ascorbic acid in capsules that is in pure form, it may be more trouble than just weighing out the right amount of powder.

Best,

Doremus


www.DoremusScudder.com
 
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albada

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Your posting made me take a closer look at the links I provided yesterday. Of the two makers of capsules, one includes 20 mg of ascorbyl palmitate, which Wikipedia says is only slightly water-soluble. The other is "Pure Ascorbic Acid" by Thorne Research, and its ingredients-list says it's indeed pure. But having only one brand of suitable capsules available is risky. A google search for "pure ascorbic acid" turns up several vendors of powders, so it's prudent to stay with powder as you suggested.

Mark Overton
 

Clay2

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In pharmacy that used to be called stricken or struck measure. A heaping measure was struck level with a card.

Remarkably repeatable.

Best regards,

/Clay
 

Zathras

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Trader Joe's sells pure ascorbic acid powder in one pound jars for $11.99 in the vitamin section. I've used it for making vitamin C based paper developers. It works quite well.
 
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albada

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Zathras said:
Trader Joe's sells pure ascorbic acid powder in one pound jars for $11.99 in the vitamin section. I've used it for making vitamin C based paper developers. It works quite well.
Click to expand...

You guys will like this. I made 6 stricken 1/2-teaspoon measurements of four brands of vitamin C powder, 24 weighings in all.
The maximum deviation from the average weight was only 4%! The typical variation was under 2%.
The average weight was 2.33 g.
As Clay said, "remarkably repeatable". Clay, thanks for describing struck/stricken volume measurements. I'd never heard of that.

The four brands were: Solaray, Jimbo's store brand, Photographers' Formulary and The Chemistry Store. And I drove by a Trader Joe's this afternoon on my way to Jimbo's to buy some AA, but hadn't read Zathras' posting yet so I didn't know. Sigh.

My 1/2 teaspoon is marked "2.5 ml", and my teaspoon is marked "5 ml". Not all teaspoons follow the 5 ml standard, so check the size.
Here was my exact procedure:
1. Scoop out a heaping 1/2-teaspoon of ascorbic acid powder.
2. Firmly press the spoon up against the bottom of a glass beaker.
3. Scrape the spoon level
4. Pour into a cup and weigh.

I'm surprised at how well this works. "Remarkably repeatable" indeed.

Mark Overton
 

Clay2

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They didn't normally compress the heaping measure first. Poured a small bowl full, then just dipped
and struck it off clean.
Best regards,
/Clay
 
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