Citrazinic acid in E6 color developer - purpose? subs?

[cinejerk]

This reagent is in all the E6 color developer formulae that I have. What is it's purpose? Is there any substitute?
Very difficult to locate.
thanks

 

[stefan4u]

Citracinic acid reacts as competitive colourless coupler in the higher Densities of the slide in order to reduce the D max. or control the Contrast. This means if you take more Citracinic acid the contrast will decrease, this can be a benefit for reproductions.

If you want to start homebrewing this ingredient can be skipped eventually, if otherwise the option is to toss the whole project…In my Chromebrews I reduced it’s amount about 50% to 0.6g / Litre. for increasing the contrast a bit. That worked fine for me, but to be honest I’ve never thought about substitutes (it will be tricky because of the nonlinear effect)

Maybe sulphite, but this will effect more or less all densities, not only the higher ones, or more silver soluble agent but this will pronounce a loss more in the lower densities...

Regards,
Stefan

 

[Mike Wilde]

I think it gobbles up loose coupler components, but I cannot recall where I heard this.

It seems to be related to contrast control, in my dim memory.

The analog in b&w might be what bromide does, a sort of restrainer, but for color couplers.

I think the opposite effect is had with one that Rowland called H-acid.

Some day I will spring for a copy of Haist, and then I perhaps will have a reference to look to for this type of question.

 

[Mike Wilde]

I bought a small supply from Claire at JD Photochem before she packed up shop. Some day I dream of tracking down what she did with her remaining stock.

 

[Photo Engineer]

Stefan has it correct. Substitutes are "H Acid" and "J Acid". I have no idea of the substitution ratios, nor if they are exactly identical. Citrazinic acid also controls grain as well as contrast. It can have some effects on sharpness as well.

PE

 

[cinejerk]

Ok then it sound pretty important.

Then I guess I need a source.

Or is this just more unobtainium?

I have talked to a lot of chemical vendors and they have never
heard of it ????

 

[Rudeofus]

Then I guess I need a source.

Or is this just more unobtainium?

I have talked to a lot of chemical vendors and they have never
heard of it ????

Sigma Aldrich claims to have some left.

 

[cinejerk]

Thanks Rudeofus
Ouch $75 for 100g
Yea I know, now I complain about price.

 

[Rudeofus]

Thanks Rudeofus
Ouch $75 for 100g
Yea I know, now I complain about price.

It may give you some comfort that I was shown the price 110€ for 100g :confused:

Given the trace amounts of citrazinic acid needed in published recipes the price seems bearable, though, even the European rip off price.

 

[A_Caver]

Purchasing CZA

I have purchased CZA from www.artcraftchemicals.com in Altamont, NY. The CAS number is 99-11-6.

 

[cinejerk]

Oh really !!! A_Caver how much did they charge you for what quantity? thanks

 

[A_Caver]

I purchased 100g for $58.00 last year. It came as 2 x 50g bottles.