Is there something I can coat glass with to hold cyanotype sensitizer?

Michael Meacham

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I want to make cyanotypes on glass to hang in windows or in front of back lights. What can I coat the glass with that will bind the cyanotype chemicals and hopefully be archival when fixed. Since cyanotypes are fixed with water, will that affect the base coat? Has anyone tried this?
 

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Mix the chemicals with gelatin and coat on glass. You may need some hardener to stiffen the gelatin.

Works just fine. Also does fine on other surfaces.

PE
 

koraks

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A local friend of mine has done some testing with this; sizing the glass with gelatin prior to coating and mixing the emulsion directly with gelatin. As I recall, he had some issues with incomplete washing out of unreacted chemistry and unevenness of coating. I think the gelatin concentration and emulsion thickness need to be controlled fairly well for good results.
 

J 3

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One idea is to try the Silane 1100 mix in this article (harder than gelatin subbing) - http://www.alternativephotography.c...ng-platinumpaladiumgold-and-pigment-on-glass/

Another idea I've been meaning to try is using workable fixative (like Krylon Fixatif).

There is this YouTube video on doing this exact thing (forgot how it was done and don't have time to research right now) -
I seem to recall many people who coat glass with gelatin use albumin first to get it to stick better (store bought pre separated egg whites are easier than doing it yourself). Albumin by itself might make a sufficient substrate by itself.

The danger with any method is messing up a big batch of alternative process chemistry so be careful. It's better to brush media on til you know what your doing won't come off in a try of chemistry.

Hope this helps.
 

Nodda Duma

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I would think that subbing and then dipping might work well. How thick/thin compared to an emulsion coating does the cyanotype layer need to be?
 

removed account4

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Hi Nodda Duma
that is what the guy in the video did originally ( he had a different video about the process where he poured liquid gelatin on first and then soon after or right after he poured cyanotype chemistry ontop of the wet gelatin plate ) he says in the new video ( the one in the link ) it is super thin, half the thickness of a human hair, or the emulsion will flake off. I've wanted to make glass cyanotypes for a while but just haven't gotten around to doing it so I am watching this thread with interest
 

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I mix the cyanotype chemistry with gelatin and coat. The proportions and thickness govern the maximum density.

PE
 
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Michael Meacham

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Thanks for the response. Cyanotype mixture has the consistency of water, and if poured onto glass would run right off. Even on paper, you have to brush quickly to keep in from going off the edges. I will try the gelatin. What do you use for the hardner?
 

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I use Chrome Alum.

Use no less than 5% gelatin in the FINAL mix. It should ideally be 8% or so in the final mix.

PE
 

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The Formulary has Chrome Alum. I'm not sure what you mean by fumed Silica. Chrome Alum has been used for over 100 years as the preferred hardener for gelatin on glass.

PE
 
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Michael Meacham

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The Formulary doesn't list Chrome Alum, but I called B&S and they do have it, It is called Chromium Potassium Sulfate. It is not on their website, but is available for order. The video calls for oxalic acid. What is that for? If the chrome alum is added to the final mix, do you mean it is the last item added, and does the 8% mean 8% of the weight of the gelatin?
Thanks for the help.
 

NedL

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For a couple of reasons, I'm a little reluctant to suggest this, but now that you are talking about using chromium and oxalic acid, and having to wait for delivery, I'll mention it.

When I was playing around with VDB mixed with gelatin on glass ( not cyanotype ), I tried using a 2% solution of albumen to sub the glass. I made the albumen by whipping an egg white until it was very stiff, then letting it sit for a few hours and then decanting the thin liquid. After cleaning the glass very well, I put a puddle of this solution on one side, tipped it until the whole surface was covered and then letting it run off one corner. It left an extremely thin, seemingly perfectly clear coating. After it had dried I dipped it in IPA for a few seconds and let it dry again ( this is supposed to harden the albumen ). I was quite surprised how easily and thinly it coated and how perfectly clear the glass looked after it dried. The full-strength VDB solution mixed with gelatin stuck to this surface very well. So well that after some "dud" prints, I had to scrub it off, instead of just wiping it off under warm water.

The caveats are: 1) I was using VDB not cyanotype. and 2) I never kept any results so I have no idea if it might yellow over time or have other bad things happen.

But anyway, it's very simple and easy and uses readily available ingredients.
Have fun!
 

nmp

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Oxalic acid is, as I understand, added in the classic formula as a restrainer to retard dark reaction, which is probably why it is used here - not related to the glass application as such. Look for Dick Sullivan's modified formula.

Actually I am really surprised from the video that the guy mixes everything up (under heat, even) and can store it more than a year and still work (actually he said it works better, the longer it is kept.) In my experience, after mixing A and B, they barely last hours let alone weeks and months without getting all Prussian blueish. What gives? (Or may be that extra oxalic does the trick?)

About chrome alum....again, it is not used in the video. How come he does not need to? Is it that he devlops using ice water?

:Niranjan.
 
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nmp

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nmp

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Michael Meacham said:
B&S doesn't offer Chrome Alum. Would fumed silica work?
Click to expand...

I am not sure where you got the idea about fumed silica but it can thicken up the emulsion all by itself to make it less fluid, presumably helping to keep the sensitizer on the plate in a larger quantity than what you are experiencing. Think ketchup (which incidentally contains fumed silica or at least it did at one point.) The key is to add a small quantity of fumed silica to water and mix it rigorously well, preferably in a high shear mixer, which will "develop" the silica molecules in a sort of network, increasing the viscosity (thixotropy) of the liquid dramatically. This can be used to make the sensitizer then. In theory, it should result in a thicker coating.

:Niranjan.
 
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Michael Meacham

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EPIPHANY?? If I can make cyanotypes on glass, can I take an unexposed plate and put it in my 6.5x8.5 whole plate camera and take a cyanotype photo "in camera"? It should produce a cyanotype negative which could be printed on paper as a normal cyanotype. Why bother? Because, although exposures would be long, (minutes I expect), you could develop on site in 20 seconds, without a darkroom. Didn't Edwin Curtis do something like this? Exposure could be tracked with a spot meter on an18% gray card, and once you know how much was required for a good negative, you could take them any time of day regardless of the amount of sunlight available, just match the exposure time to the meter reading. Is this pie in the sky or for real?
 

nmp

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Have you looked at the late Terry King's cyanotype Rex - which is basically exposing the iron(iii) by itself in camera (presumably it increased the sensitivity) and then developing with ferricyanide. I think he primarily recommended oxalate rather than amm. citrate for this process. There was an article in View Camera magazine at the time:

http://www.viewcamera.com/pdf/2005/king.pdf

Also there is another example of in-camera cyanotypes that might provide some useful insights as well:

http://www.alternativephotography.com/photography-with-iron-iii-salt/

Here the sensitizer is a ferric salt such as a sulfate or chloride in conjuction with oxalic acid.

If you want to make a positive coming out of the camera, you can use ferrocyanide instead to develop like the Pellet process.


:Niranjan.
 

J 3

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Fumed silica does not cause gelatin to plastisize. It could be used as a thickening agent but primarily It's used for some platinum printing in order to act as a light trap to increase the appearent (actual?) Dmax for a print. Being mildly acidic it can also make some papers work that otherwise would need to be soaked in a mild acid solution. It's kind of like a barita layer but for mat media. Sullivan has some videos on It. Fumed silica will not prevent gelatin from becoming liquid at mildly warm water temperatures.

Sandy King has a procedure for making a gelatin coated paper without using chrome alum. It's used for carbon prints but may work here. You mix gelatin with some egg whites and some Dichromated I believe and then leave it out in the sun where the uv will activate the dichromate. I'll try to look it up when I get the chance.

Formaldyhide is another plastisizing agent that can get gelatin to harden on glass.

At a certain level gelatin plastisize so far as to reject water. This is how bromoil works. I don't know that it will come up here but you can certainly harden things too much.
 
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