white blotches as cyanotype prints dry - any idea why??

[hellomynameis]

Hello,

I have been having an intermittent problem of what blotches appear as my prints have dried. Images attached.

I cannot workout why. Happens with different papers, different chemistry, different light sources. My best guess is something to do with the original making of the paper, how it dries, where the sizing settles as it dries maybe... but some paper from the same pack and some from the same sheet is absolutely fine.

anybody else had the same problem? any ideas?

I dry all my prints flat. coat in low light, allow chemistry to dry naturally overnight. I use Mike Ware's simple formula

the internet doesn't seem to know, and experienced printers online seem to say nobody is quite sure. I can't really continue to make work not knowing if it will be ruined by this or not!

Really really appreciate any suggestions, pulling my hair out!

Thanks

 

[BJ68]

Try about 1 to 2% Gelatin in your cyanotype solution*....had sometimes problems with very pale cyanotypes @workshops, so I developed a modified two component old mixture, with internal hardening of the layer see https://illumina-chemie.de/viewtopic.php?p=72786#p72786 and later reduced the gelatin content to 4%, because 6% was to sticky for coating.
Made a re-test with the solutions which where made October 2018 and they worked fine: https://illumina-chemie.de/viewtopic.php?p=78036#p78036

*= it should work in the new cyanotype solution, too.

bj68

 

[Donald Qualls]

Looks like alkali coming out of the paper to my (only slightly experienced) eye. Try soaking the paper in citric acid solution and drying before coating?

 

[hellomynameis]

Try about 1 to 2% Gelatin in your cyanotype solution*....had sometimes problems with very pale cyanotypes @workshops, so I developed a modified two component old mixture, with internal hardening of the layer see https://illumina-chemie.de/viewtopic.php?p=72786#p72786 and later reduced the gelatin content to 4%, because 6% was to sticky for coating.
Made a re-test with the solutions which where made October 2018 and they worked fine: https://illumina-chemie.de/viewtopic.php?p=78036#p78036

*= it should work in the new cyanotype solution, too.

bj68

Thanks - will look into it. Keen to know why happening in the first place. Always little resistant to adding more steps to process!

Appreciate info though!

 

[hellomynameis]

Looks like alkali coming out of the paper to my (only slightly experienced) eye. Try soaking the paper in citric acid solution and drying before coating?

Yeh - was my thought too - alkaline in the size of the paper when it's made. This paper is Heritage Rag, an unbuffered printmaking paper so no alkaline buffer on surface, so must be in 'recipe' of paper and maybe it settles unevenly. Perhaps why is intermittent.

(I got into a whole thing with pre-soaking paper in acid solution and were some positives/negatives in doing - highlights stain for one - but did find sulfamic/sulphamic acid a more economical option than citric - similar strength, i.e weak acid.

Thank you, appreciate input - validates where I was headed!!

 

[nmp]

Some questions:

1) When you say the blotches shows up after drying, are you sure they aren't there prior to it - drying brings the contrast out so you are able to perhaps see it easily but the artifacts are there before....no?

2) What physical dimensions are these prints - to get an idea of the magnitude of the white spots.

3) What papers are you using, how many different ones that have the same problems? Any make of paper that never has this problem?

4) Are you using any surfactant like Tween 20?

5) How controlled is the humidity in your work environment? Has it been fluctuating over the different prints - good or bad, over this period of time?

6) What is your develop process - all tap water or part acidified water?

I can't imagine sizing in the paper moving around or dissolve in water since it is generally hardened or chemically attached to the cellulose depending on the type of size.

If you have Christina Anderson's book on cyanotypes, there is a section on what she calls "splotches" that look very similar to your blotches. If you have access to it, you might want to look it up.

:Niranjan

 

[Glenn bech]

Hey,

I have seen this with Cyanotype ii. Do you use that sensitizer or classic? With Cyanotype II have seen this with overcoating and crystallisation of sensitizer in the paper.

I have inspected the white freckles under a microscope and it's just lack of pigment in the paper fibres.

My problems went away when I started rod coating, added 1 drop of Tween per 2ml solution and let the paper dry without forcing it.

 

[glbeas]

Ive seen these spot when I was using to much pressure on the rod when coating.

 

[Glenn bech]

I will add this to my experiments for sure.