DIY Effervescent Developer Tablets?

[athbr]

I just saw Tetenal's announcement that they are trying to bring back effervescent tablets. Got me wondering if it could be replicated at home for BW chemicals

I scratch mix d76 and ID-68 as needed and discard immediately after developing a batch. This would be perfect for me.

So here are is my idea:
1. Weigh out chemicals for dev and fixer as normal
2. add baking soda and citric acid
3. press into tablets

I have three questions here on formulation:
1. For a roughly 100g tablet to mix in 1L how much baking soda and citric acid do I need?
2. The effervescence will likely knock down pH of developer. Can I tackle this by adding extra borax? How much?
3. Should I not worry about pH control for the fixer as it is already an acidic solution?

Cheers.

 

[Photo Engineer]

The answer is yes, you can do it.

For these ideas:

1. It is a molecular calculations which needs chemistry skills. I don't feel like doing it for you. Sorry.
2. The effervescence is not significant, again a simple calculation will tell you the minor correction that you need.
3. Don't worry about fixer if you use a stop or rinse after development.

PE

 

[Kodachromeguy]

What are effervescent tablets? I do not recall hearing about them in photography.

 

[athbr]

The answer is yes, you can do it.
1. It is a molecular calculations which needs chemistry skills. I don't feel like doing it for you. Sorry.
PE

Touché PE. Thanks for the help!

 

[athbr]

What are effervescent tablets? I do not recall hearing about them in photography.

You know those tablets people use for stomach aches? You put them in water and they start to fizz which helps dissolve the chemistry.

Baking Soda + acid + water = Fizzing (effervescence)

A company called tetenal used to package photochemicals this way. Makes things smaller, lighter and faster to mix.

 

[koraks]

I was thinking the same thing last night while brushing my teeth. If the baking soda and citric acid are stoichiometrically balanced, there should be little effect on pH, although the buffering capacity would increase. I'd use a buffer calculator to get as close as I can in terms of added borax or carbonate. I'd also try to keep the baking soda and citric acid as low as possible so that their influence is minimized. In the end, the only thing the soda/citric needs to do is break up the tablet; not all that much may be needed.
But this is just a thought; I haven't run any numbers on this. Some calculation and testing would be necessary.
I don't have a tablet press, that would be another thing to work out.
One potential concern would be if the water in the borax (decahydrate!) would influence the keeping properties of the tablets.

 

[JPD]

I tried a developer containing Sodium carbonate and used an acid stop bath. The negatives got millions of micro-bubbles in the emulsion and were unusable. I'm not sure if the bubbles were created during development or in the stop bath. If it was in the stop bath, and I used a neutral water one instead, the bubbles could then have formed in the slightly acidic fix.

Effervescent tablet developers raises a red flag in my eyes, but they would be tested a good deal before being put on the market.

 

[koraks]

I tried a developer containing Sodium carbonate and used an acid stop bath.

Virtually all developers I use are based on carbonate, sometimes buffered with additional borax. I always use an acid stop bath. This combination is so insanely common that it cannot be singled out as an unequivocal source of a problem. In fact, this problem is only likely to occur with the combination of (1) a developer with a very high pH (2) an acid stop and (3) a film with a very fragile emulsion. The vast majority of today's emulsions are sufficiently hardened to prevent this problem entirely. It may be possible to replicate the problem with a modern film when using a developer with a pH of, let's say, 10-11 and a stop bath that is made up much too strong (ph < 2). But I haven't managed it, that's for sure.
In an effervescent tablet setup, the effervescence only appears when mixing; it'll disappear within a minute. Neither would it trigger the mechanism that causes the pinholes in your problem description, as there is no chance that the emulsion will soak up a solution of a high pH and then be hit by a very low pH causing CO2 to form within the emulsion itself within the developer bath. This mechanism really needs two separate baths with sufficient time in the first bath for the emulsion to soak up the first solution.
Hence, no need for red flags.

 

[JPD]

In fact, this problem is only likely to occur with the combination of (1) a developer with a very high pH (2) an acid stop and (3) a film with a very fragile emulsion.

I think you hit the head on the nail with the italics. The film was Efke R 50. I don't remember which developer I used (I'm sure it's in the notebook I have in the darkroom), but it was an old formula.

 

[AgX]

What are effervescent tablets? I do not recall hearing about them in photography.

It is a stupid term due to a wrong translation (I guess by one of our german fellows.) By this erroneously hinting at a fizzing tablet.

Meant are developer chemicals all pressed by means of a binder into a tablet that will dissolve in a given amount of water to form the working solution.

Introduced by Tetenal about 20 years ago. Still within their offer when they closed.

 

[AgX]

Adox just released a kind of bound, non-dusty blend in a pouch.
Just pour the content into a given amount of water. Quite similar in handling to a tablet.

 

[koraks]

The film was Efke R 50.

Yes, that explains a lot. As I understand, the EFKE films were notorious for their very soft emulsions!

 

[Ian Grant]

It was a drug company Burroughs Wellcome who first introduced developers and other photo chemistry in tablet form, using the name Tabloid. The company were based in Dartford, Kent in the UK and had their own photographic club, H. Wellcome was the President.

Ian

 

[AgX]

You are a source of information!
see also:http://himetop.wikidot.com/burroughs-wellcome-co-s-tabloid

However Tetenal got a patent on their tablet even without any hint at Burroughs Wellcom.

 

[Ian Grant]

You are a source of information!
see also:http://himetop.wikidot.com/burroughs-wellcome-co-s-tabloid

However Tetenal got a patent on their tablet even without any hint at Burroughs Wellcom.

I have a boxed bottle of Burroughs Wellcome Tabloid Amidol developer. I've no idea how old, it is definitely pre-WWII though, packaging looks 1920's.

Ian

 

[Photo Engineer]

And here again is the bubbles in the emulsion using a 3rd tier film!

No stop bath needed, just a water wash and an acidic fix with carbonate somewhere in the process or an effervescent developer.

PE

 

[pentaxuser]

It is a stupid term due to a wrong translation (I guess by one of our german fellows.) By this erroneously hinting at a fizzing tablet.

Meant are developer chemicals all pressed by means of a binder into a tablet that will dissolve in a given amount of water to form the working solution.

Introduced by Tetenal about 20 years ago. Still within their offer when they closed.

Wasn't this part of the thread of another thread about C41? I think the tablets were called "pearls" and were available until a few years ago as you say AgX. If I recall correctly, Nova Darkroom before it became Permajet sold them. Tablets for C41 which could develop say 1 film per set of tablets would be beneficial to those who might only want to do the odd C41 and only occasionally. It wouldn't even need to be in tablet form as the right amount of powder in a sealed packet would be fine.

Nova used to sell what it called a "Press Kit" for C41 and it worked very well when I tried it. The name came from the fact that a photojournalist might want to develop a colour film in a hotel with the minimum of equipment and with a powder kit he could do so. The problem was that you had to mix all the powder at once and use it pretty quickly but it was designed to do several films so doing one film or even two only meant wastage. However is Tetenal really considering tablets and for C41 or B&W? If it is, I must have missed the announcement. Can anyone say where I might find it?

Thanks

pentaxuser

 

[athbr]

It is a stupid term due to a wrong translation (I guess by one of our german fellows.) By this erroneously hinting at a fizzing tablet.

Meant are developer chemicals all pressed by means of a binder into a tablet that will dissolve in a given amount of water to form the working solution.

Introduced by Tetenal about 20 years ago. Still within their offer when they closed.

Hi AgX,

Am I correct in understanding these tablets are not actually effervescent?

What action dissolves them then?

My key interest is in thorough dissolving without having to heat up the water.

 

[koraks]

Even of they are effervescent, stuff like borax needs a little heat to go into solution easily. The c41 components don't, so then a tablet only makes sense in terms of ease of use and keeping qualities.

 

[Anon Ymous]

Instead of trying to correct any pH change due to the use of carbonate and citric acid, you may as well use the combination of carbonate and metabisulfite. This will create effervescence and also create sulfite, which is a key component of most developers.

Having said that, the dissolved carbon dioxide in the resultant solution will probably throw pH slightly off to a lower value. Anyway, to each his own, but IMHO this is more of a solution to a problem that doesn't really exist.

 

[athbr]

Instead of trying to correct any pH change due to the use of carbonate and citric acid, you may as well use the combination of carbonate and metabisulfite. This will create effervescence and also create sulfite, which is a key component of most developers.

Having said that, the dissolved carbon dioxide in the resultant solution will probably throw pH slightly off to a lower value. Anyway, to each his own, but IMHO this is more of a solution to a problem that doesn't really exist.

1. Is this potassium or sodium metabisulfite or is it either/or?
2. This would replace say the sodium sulfite in the formula?

 

[athbr]

Even of they are effervescent, stuff like borax needs a little heat to go into solution easily. The c41 components don't, so then a tablet only makes sense in terms of ease of use and keeping qualities.

My hope is that for 2g of borax the effervescence would get the job done.

Granted as you can tell my knowledge of chemistry is small.

 

[koraks]

I don't think the effervescence is going to help much with that.
And yes, the sulfite resulting from @Anon Ymous approach replaces (part of) the sulfite of the original formula. This is also why this approach is not a good idea for C41 developer as you'll likely end up with way too much sulfite.

 

[Anon Ymous]

1. Is this potassium or sodium metabisulfite or is it either/or?
2. This would replace say the sodium sulfite in the formula?

1. I meant the Sodium salts, although I doubt that exchanging one metal for the other would make much of a difference, if any, as long as you use an equimolar amount.
2. Yes, exactly, replace Sodium sulfite with a carbonate - metabisulfite mixture that will give you the same quantity of sulfite.

 

[athbr]

Thanks guys for all the help.

My gut reaction from all the comments is that this isn't a terribly practical idea. But I have the materials anyways so I'll give it a shot sometime.

That said I think tablets are pretty nice anyways (effervescent or not) as they sure make storage easier.