Replacements for dichromates and gelatin hardeners in Europe

ole-squint

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Hello.
What are gum/gum over printers using in Europe using since dichromates have been banned. How are you hardening gelatin sizing?

thanks in advance-------------
 

koraks

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ole-squint said:
What are gum/gum over printers using in Europe using since dichromates have been banned.
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IDK, I'm not a gum printer, but the first thing that comes to mind is switch over to printmaker's friend or zerochrome SbQ

PrintMaker's Friend Studios - Home Page | Thewetprint.com

The Wet Print Studios, your carbon and alternative process printing resource. We deal in all sorts of carbon color printing and stuff!
printmakersfriend.com

zerochrome

[non-toxic photographic printing techniques with pigments and colloïds]
zerochrome.org
I don't believe there's a replacement for dichromate for gum printing. That's at least the conclusion Calvin Grier reached and consequently he got out of gum printing after having mastered the process.

Other, more experimental routes rely on the use of ferric ammonium citrate to harden a number of colloids, but it won't work with gum AFAIK. People have been doing it with soy and a number of other protein-donors. Check the alt photo list on groups.io: https://groups.io/g/altphotolist

ole-squint said:
How are you hardening gelatin sizing?
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It can be done with DAS, chrome alumn (which isn't nearly has harmful as dichromate), glyoxal, formalin, glutaraldehyde and probably a couple of other ways. When it's on paper I generally use chrome alum as it's fast, easy to control, doesnt offgass, doesn't stain badly (unless you use way too much) and is overall just very reliable.
 
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ole-squint

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Yeah, I'm familiar with Calvin Grier's products, but they're quite opaque. I'm looking to lay a thin gum coat over platinums or palladiums (or VDBs or kallitypes, for that matter), to enrich the shadows. I've looked at the catalog for Disactis, but they don't list glyoxal, chrome alum, or formalin.
Any other chemical supply houses on the continent you would recommend?
 

fgorga

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As @koraks says above there is no direct replacement for dichromate in gum printing. You will need to switch to something other than gum if you can't or won't use dichromate.

Gum is a polysaccharide (sugar polymer) none of the replacements for gum are polysaccharides. Rather they are proteins or synthetic polymers. Most of the photosenstizers folks have experimented with to replace dichromate don't work with polymers other than gum. The exception to this is DAS which is hard to source and apparently has issues with staining the paper.

Thus, I think that you are stuck with developing (adapting) one of the newer methods to replace "gum over" other alt processes.

I can't comment on which approach might be best as I gave up gum/dichromate about 20 years ago and have not tried any of the new processes myself.

As for non-photosensitive hardening of gelatin used as a sizing I would recommend glyoxal which is available from Bostick & Sullivan). I have no experience with chrome alum so I can't comment on the pluses and minuses of these two compounds.

I would say far away from formaldehyde it is very toxic and carcinogenic and must be used in a fume hood.
 

koraks

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ole-squint said:
I'm looking to lay a thin gum coat over platinums or palladiums (or VDBs or kallitypes, for that matter), to enrich the shadows.
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Will this be a non-image layer, so basically just a semi-glossy overcoat? In this case, you could use e.g. gelatin or albumen just as well. Either could be dissolved and brushed onto the print; with albumen it'll be easier since it won't gel, but with gelatin it'll be easier to deposit a heavier layer. You may have to soak the print and pour the gelatin on top of it, like you would when e.g. sizing paper with gelatin, or pouring carbon tissue. Albumen could be brushed on, dried and then hardened by spritzing it with ethanol.

Or maybe just coat with gum and not harden it at all? It's not like the gum will drip off in hot weather or anything. Once dry, it's going to stay on the paper.

If it needs to be an image layer (i.e. with UV exposure and all), and you want to steer away from dichromates, then you'll have to forget about gum.

ole-squint said:
Any other chemical supply houses on the continent you would recommend?
Click to expand...

I'm not familiar with the US landscape of chemistry suppliers other than well-known names like Artcraft et al. - but that's where I'd start anyway.

Chrome Alum

aka Chromium Potassium Sulfate
artcraftchemicals.com

Glyoxal, 40% in water (Part#: 1690)

500 grams Sold by weight
artcraftchemicals.com
IDK if they also carry formalin; if you really need it, you can get it in various places including Amazon, but as @fgorga mentions, it's kind of nasty (although in the quantities you need it for e.g. gelatin hardening, I wouldn't be too panicky about it - extremely little goes a very long way indeed in this application.) Anyway, I'd start with either chrome alum or glyoxal.

I usually just Google "buy [chemical name]" and see what turns up.
 
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ole-squint

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Yeah, I used formaldehyde years ago when I was making gum prints. Had to use it outside, ands even then the fumes were pretty nasty.

I use Artcraft almost exclusively for my chemicals, but I'm specifically looking for suppliers in Europe.
 

koraks

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Oh, sorry, I thought you were based in the US. Any country in particular?
Also, eBay works quite well for small volumes of specific chemicals. There's a couple of people in esp. Italy, Germany and the UK selling relevant materials.
 

BJ68

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ole-squint

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koraks said:
Oh, sorry, I thought you were based in the US. Any country in particular?
Also, eBay works quite well for small volumes of specific chemicals. There's a couple of people in esp. Italy, Germany and the UK selling relevant materials.
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I'll be in Strasbourg.
 

Dan Dozer

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Over on our facebook Bromoil and Oil site, Richard Hildred from England has further developed the use of Ferric Ammonium Citrate as the sensitizer rather than Potassium Dichromate for making Rawlins Oil prints and he says it works quite well. However, that is a sensitizer on gelatin rather than a sensitizer on gum, so I don't know if it would work for gum printing.
 

koraks

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Dan Dozer said:
However, that is a sensitizer on gelatin rather than a sensitizer on gum, so I don't know if it would work for gum printing.
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I don't think so. Gum and gelatin are very different indeed, which is reflected in particular in the mechanisms underlying hardening. This is also why DAS, which is a good replacement of dichromate for carbon transfer printing, does not work for gum printing.

It's confusing because superficially, they seem to behave somewhat similarly if you're approaching it from a printing angle. After all, you can make direct gum or gelatin ('carbon') prints in very much the same way (as long as you use dichromate).

The solution that others have been coming up with is to use a different protein (or protein derivatives), in particular from pulses - lupin, soy etc.
 

imgprojts

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I bought "metricide 14 day" from Amazon. It comes with an activator which makes the otherwise stable glutaraldehyde solution into something that lasts 14 days? Why would anyone do that? Anyway I figured I should try it without starting the ticking clock and it works! I bought a gallon because they sell a gallon on Amazon. I used a few drops in a 100ml beaker full of gelatin. It does a great job at making the paper almost look like plastic. And then you can melt regular gelatin processes over it without melting the sizing. I don't know if glutaraldehyde is in any way safer than formaldehyde. It sounds worse. But it's used to sterilize fish tanks and hospital surfaces. So I figure it may be ok if we're just using a few drops. I was incredulous that just a few drops of something would make a big difference but yeah it works.
 

fgorga

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Glutaraldehyde is quite a bit safer than formaldhyde, but not completely safe. Formaldhyde is quite volatile and so one can get significant exposure via the air. This is not the case for glutaraldhyde. You would not want to get either compound on your skin or ingest them.

No clue about the 'activator'. The devil is in the details and 'activator' doesn't say a thing about the specific chemistry. 'Plain old' glutaraldhyde should work just fine for cross-linking (hardening) gelatin as you have shown!
 
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