One Stock Solution Cyanotype

[Andrew O'Neill]

I always used to keep solutions A and B separate. After about a week, the ferric ammonium citrate solution would go moldy. I don't make many cyanotypes, so mixing smaller batches didn't help,
A few weeks ago, I started mixing the two stock solutions together. After three weeks, no mold. And solutions are still quite active. Having a single stock solution is better for my students. The simpler it is, the better!
Anyone else using a single stock solution?

 

[Donald Qualls]

I didn't even know you could. I understood that the reason to mix immediately before sensitizing is that the mixed solution wouldn't keep. So much for that idea...

 

[nmp]

I don't have a mold problem - I might have had some as long as 6 months without it (touch wood...) However, once the 2 are mixed, it becomes blueish in just a day or two. On the other hand, for student work it might still be fine - the blue stains can be removed by washing longer in plain water I suppose. In my case, I "develop" with acidified water so the next day there is a lot more fogging in the print.

 

[Andrew O'Neill]

I don't have a mold problem - I might have had some as long as 6 months without it (touch wood...) However, once the 2 are mixed, it becomes blueish in just a day or two. On the other hand, for student work it might still be fine - the blue stains can be removed by washing longer in plain water I suppose. In my case, I "develop" with acidified water so the next day there is a lot more fogging in the print.

Prints are coming out very clean, with a nice, vibrant cyan... clearing in plane tap water, and intensifying in hydroxide. We're using very cheap Stonehenge paper, acidified in sulfamic acid.

 

[nmp]

It works if it works...just don't tell the authorities...

 

[nmp]

I wonder if the keeping time can be extended by adding a bit of dichromate in the mixture.

 

[Donald Qualls]

There might be a difference depending on which of the (several) cyanotype formulae you're using, too. Traditional or one of Mike Ware's several versions.

 

[Andrew O'Neill]

There might be a difference depending on which of the (several) cyanotype formulae you're using, too. Traditional or one of Mike Ware's several versions.

So far I've only used the traditional formula.

 

[nmp]

The New Cy is single mixture by design and the Simple one was also introduced as a single bottle sensitizer with longer shelf life than the Classic but later he also suggested a 2 bottle version.

 

[gmikol]

I have some Ware ("New") cyanotype solution I got from B&S 8-10 years ago that has sat idle...I wasn't using it, so I wasn't opening the bottle all the time. Solution was still a bright yellow so I smeared a drop onto a scrap of IJ paper and put it in the sun for a couple of minutes & it turned a nice blue. Haven't had a chance to make any prints with it, but I don't see why it wouldn't work.

Don't know if B&S publishes exactly what their recipes are, but they might be a good option.

 

[pentaxuser]

. We're using very cheap Stonehenge paper,.

I was tempted to buy this paper until I saw the primitive dangerous-looking people who made it. All animal skins and clubs
Just didn't fancy my chances if I needed to return a faulty batch

pentaxuser

 

[Andrew O'Neill]

I was tempted to buy this paper until I saw the primitive dangerous-looking people who made it. All animal skins and clubs
Just didn't fancy my chances if I needed to return a faulty batch

pentaxuser

 

[fgorga]

I always used to keep solutions A and B separate. After about a week, the ferric ammonium citrate solution would go moldy. I don't make many cyanotypes, so mixing smaller batches didn't help,
A few weeks ago, I started mixing the two stock solutions together. After three weeks, no mold. And solutions are still quite active. Having a single stock solution is better for my students. The simpler it is, the better!
Anyone else using a single stock solution?

I have never tried keeping a single (mixed) stock solution.

However, I am not surprised that it does not grow mold. The cyanide in the ferricyanide solution is quite toxic. On the other hand, as we all often see, ferric ammonium citrate (FAC) is a very good culture medium for mold! Two essential elements for living organisms, nitrogen (from the ammonium) and carbon (from citrate), are abundantly present.

Personally, the growth of mold in the FAC solution is not really a problem. I simply filter the FAC solution directly from my stock and into a measuring cylinder. This extra step adds very little time or complexity to the process. Even months old FAC solution with significant growth of mold seems to work just fine... I guess that they don't "eat much"!!!

 

[Andrew O'Neill]

I have never tried keeping a single (mixed) stock solution.

However, I am not surprised that it does not grow mold. The cyanide in the ferricyanide solution is quite toxic. On the other hand, as we all often see, ferric ammonium citrate (FAC) is a very good culture medium for mold! Two essential elements for living organisms, nitrogen (from the ammonium) and carbon (from citrate), are abundantly present.

Personally, the growth of mold in the FAC solution is not really a problem. I simply filter the FAC solution directly from my stock and into a measuring cylinder. This extra step adds very little time or complexity to the process. Even months old FAC solution with significant growth of mold seems to work just fine... I guess that they don't "eat much"!!!

I think a single solution for my students will be best. The easier it is for them, the better!

 

[fgorga]

I think a single solution for my students will be best. The easier it is for them, the better!

As a retired chemistry professor, I fully understand that position!!!

 

[Andrew O'Neill]

As a retired chemistry professor, I fully understand that position!!!