Stop bath strong enough for Amidol

[Jarin Blaschke]

Hi:

My usual stop bath for film and prints is 15g of citric acid in a liter of water. I don't have any acetic acid around, and would prefer to keep it that way. I've been printing with amidol and chloride paper this year and I wonder if I need to strengthen it, given how powerful amidol is - the developer itself has 3g of citric acid in it already. The short developing times with chloride (I use 60-90 sec) probably require a total halt of development for accuracy and consistency. I've seen no apparent issues yet with my 15g, but I've only been "proofing" and not really fine printing with matching prints.

Any strong opinions on the matter?

Jarin

 

[Andrew O'Neill]

I prefer citric acid stop baths. I only ever used 3 or 4 teaspoons in a litre of water, even for Amidol developed paper. If it's working, just stick with it.

 

[Peter Schrager]

I use 28% glacial for prints...try it and see

 

[Gerald C Koch]

I use 28% glacial for prints...try it and see

Its either 28% or glacial (98%) but it cannot be both.

 

[Photo Engineer]

Remember that Amidol develops in acidic solution, so a stop is not guaranteed to stop unless the developer is diluted enough and acidified well.

PE

 

[Craig]

If Amidol develops in acid shouldn't the stop be a base?

 

[Photo Engineer]

No, because Amidol develops in Alkali as well.

PE

 

[Alan9940]

I use 100ml of 28% acetic acid to 2L water for Amidol developed prints and I've never noticed any issues with this combo.

 

[Jarin Blaschke]

Remember that Amidol develops in acidic solution, so a stop is not guaranteed to stop unless the developer is diluted enough and acidified well.

PE

The developer I'm using is this:

Water: 1L
Sodium Sulfite: 30g
Citric Acid: 3g
Amidol: 10g
1% Benzotriazole: 40ml


Today, the stop I used is this:

Water: 1L
Citric Acid: 20g

With what I'm using, do you think I'm achieving a full stop?

Jarin

 

[dE fENDER]

With what I'm using, do you think I'm achieving a full stop?

Jarin

Amidol begins to develop at pH 4, so check the ph of your stop.

 

[Photo Engineer]

There are ways to check out continued development, but the above post pretty much says it all.

PE

 

[mshchem]

When in doubt use pH

 

[Jarin Blaschke]

Amidol begins to develop at pH 4, so check the ph of your stop.

Thanks - looks like I need to get a ph meter! Do we have consensus that I just need ph below 4?

 

[Photo Engineer]

I vote YES!

 

[Gerald C Koch]

The developer I'm using is this:

Water: 1L
Sodium Sulfite: 30g
Citric Acid: 3g
Amidol: 10g
1% Benzotriazole: 40ml


Today, the stop I used is this:

Water: 1L
Citric Acid: 20g

With what I'm using, do you think I'm achieving a full stop?

Jarin

Citric or lactic acid is sometimes ADDED to Amidol developers to increase the tray life of the developer. It's addition is otherwise not necessary. Usually the acid is not even listed as part of the formula leaving it up to the user to add it if needed.

 

[juan]

Look at Michael A. Smith’s website. Unfortunately this iPad will not allow me to type in the url. It’s Michael and Paula .com all run together. Michael has used amidol and citric acid stops for decades.