Suggestions - Gelatin Hardening Additives for Home Brew Emulsions?

**Ed K.** · 4-Jul-2006, 00:17

Hi -

I'm experimenting with some alternative emulsions. I'm looking for some suggestions for hardening additives that will help gelatin adhere to paper well, and hopefully not demolish the image too much over time. A vast body of research has been done on this ( see US Patent 4612280 at the gov patent search site for a good list and discussion of it), however I'm not looking to produce a new commercial product or buy complicated machines and a team of scientists to do it like Fuji did ). Actually, reading the patent was interesting for its discussion of issues - those guys really know their stuff!

Surely, there are some tried and true gelatin hardeners that work pretty well for manual coating, no? Please post suggestions if you have some. Chrome Allum? Others? I do expose with UV, so possibly UV activated solutions could be interesting too. Also, I have some LPE512 that I will try tomorrow as a direct addition to the emulsion instead of in the first clearning bath ( tried that tonight, it helped a lot, but didn't quite work in the end ).

I make an abosolutely rich and lovely brown print with a perfect color tonight on heavily gelatin sized paper, however it washed off the paper ( don't laugh at me to hard ) - I think I'll have something terrific if I get a nice hardener that still allows iron to be removed in a wash. The look of the print was really special, so I'd like to get this nailed.

Also, if anyone has sized paper with Agar Agar or other gelatin substances with good results, I'm curious to hear about that.

Thanks in advance for suggestions!

**Donald Qualls** · 4-Jul-2006, 08:41

Do you mean the sizing gelatin washed off, or did you coat a second layer of sensitized gelatin over the sizing? One thing that can help is to use a harder gelatin to begin with -- a higher bloom number. Knox gelatin is said to be on the soft side for this application, though it has the advantage of being easy to get. Beyond that, there are some tricks I've seen mentioned in connection with salted paper printing (which is the underlying chemistry for albumen as well, and is often used with gelatin sizing and even applied in gelatin solution prior to sensitizing with silver nitrate); it might be worth looking up the information on salt printing with a gelatin salt solution applied to gelatin sized paper.

You might also ask over at APUG; PhotoEngineer there is Rowland Mowry, a former emulsion development engineer for Kodak, and he's recently started giving workshops on making hand coated emulsions suitable for paper, film, or even glass plates (including reinventing coating blades that are affordable for ordinary photographers, capable of putting a commercial quality coating on an 8x10 area of a 10x12 sheet). I'm certain he has the information you need, though I'd be pretty surprised if it didn't come to "use a photo grade gelatin of X bloom and it's not a problem."

**Ed K.** · 4-Jul-2006, 15:03

Hello Donald!

Thanks for suggestions - here's a tad more info -

While waiting for a different batch of photo gelatin to arrive, I tried using a very pure gelatin from Maco - LPE410. The bloom number is not listed, however it is specified as an extremely pure photo gelatin. Previous experiments with Knox proved undesireable, mostly due to contaminants or some additives in it perhaps. I was unable to find a bloom specification for the Maco product.

While soon I shall try emulsions that incorporate gelatin, I used a mixture to precoat the paper, however I did use 20% more gelatin than recommended. After an initial drying period, sesitizer was absorbed into the gelatin at about 3x the normal amount needed to single-coat paper, however the paper itself got very little gelatin. In other words, the image barely sunk into the paper, and a generous amount of sensitizer remained in the gelatin layer. On exposure, flattening pressure between the neg and the dry gelatin resulted in a smooth, slightly glossy surface with very rich tones and great range. When I cleared in water mixed with a hardener from Maco, followed by water, the image was utterly fantastic looking. Fixed it, and it looked even better. I couldn't believe my eyes. Alas, after soaking in the wash tank for about 12 minutes, the emulsion disolved and only the small part that got way down inside the paper remained, the image washed off.

Previous experiements with starches were inconsistent and generally grainy looking, plus there were issues with contamination. The gelatin experiements are producing the best colors and finest grain / most vigorous looking image. Having a gelatin layer on the paper makes the coating rod work like smooth magic; a nice feel and good coat.

I have heard of adding hardener to fixer instead or in addition, which might work, however I need more adheasion and hardening at the first step. Today, I'll try the Maco hardener in the coating steps or in the pre-coat steps, and in a week or so, I'll just try some early formulae for emulsions that contain gelatin; they sound promising.

It is also possible that a very small amount of starch, such as rice starch, might be a good addition to hardeners because starches do adhere to things. If the hardener I have works, I'll be looking for a less toxic formula that still gets the job done.

Thanks DQ!

**BrianShaw** · 4-Jul-2006, 15:32

Formaldehyde?? A long, long time ago I used to use this to cure (harden) gelatin sizing on paper.

**Ed K.** · 4-Jul-2006, 16:05

Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

**Don Bryant** · 4-Jul-2006, 18:34

Originally Posted by Ed K.

Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

Ryuji Suszuki <sp?> has recommended gluteralhyde <sp?> as a hardner. Also some have recommended glyoxal. I have used glut for hardening gelatin for gum printing. Formalyn, glut, and glyoxal are have potential helath risks involved so beware of those issues before using any of them.

I beleive the Maco hardner contains glut.

Don Bryant

**BrianShaw** · 4-Jul-2006, 20:57

Originally Posted by Ed K.

Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

It worked pretty good. The sizing actually stuck to the paper -- no wash-off. I, too, desired something less dangerous. Formaldehyde is pretty nasty stuff. Buying it was an interesting experience. The chemical supply company insisted on asking lots of questions to assure that I was knew what I was doing and then giving me a long safety briefing.

**sanking** · 5-Jul-2006, 10:22

Originally Posted by Donald Qualls

You might also ask over at APUG; PhotoEngineer there is Rowland Mowry, a former emulsion development engineer for Kodak, and he's recently started giving workshops on making hand coated emulsions suitable for paper, film, or even glass plates (including reinventing coating blades that are affordable for ordinary photographers, capable of putting a commercial quality coating on an 8x10 area of a 10x12 sheet). I'm certain he has the information you need, though I'd be pretty surprised if it didn't come to "use a photo grade gelatin of X bloom and it's not a problem."

I second the suggestion about getting in touch with Ron Mowery on APUG. I sent a few days with Ron at the Formulary this month and we talked about emulsion hardeners all morning. He worked with this stuff for a living for several decades and really knows his stuff, not just the theory but the real down and dirty of practical use.

Sandy

**Ed K.** · 5-Jul-2006, 15:57

Thanks Brian & Sandy - since you know him, would you mind inviting him to post here? Otherwise, no problem, I'll get in touch with him. And thanks again Donald.

Update on the experiments -

Finding that argyrotype and "van dyke" brown print are similar, with the argyrotype being more picky about contaminants, I did last lights experiments with argyrotype juice, the Dr. Ware formula. It lets one easily see how much iron is being removed at first, so it's a partial indicator.

The Maco hardener addittive did produce substantial hardening after curing for 24 hours, however the gelatin was still soft enough to swell during processing. No wash off, rich deep brown color, even better more rich dark brown color when gold toned prior to fix, and only a bit of "dry down" effect - mostly in the shadows. I ferrotyped one for fun, and it dried to a hard gloss, the air dry one had just barely a bit of gloss, really 80% matte, with paper texture showing up fine. Deep, satisfying tones, great shadow detail and nice clean highlights. The gelatin road seems worth looking into a lot more at this point. The color and richness of the image was wonderful. Speed of Argyrotype juice in gelatin is about the same as POP, however the Argyrotype in gelatin has more contrast in the shadows by far and a deeper tone before and after a short toning. The matte with just a hint of gloss on the texture is very pleasing to me, as is the ability to tone or leave as-is for an interesting image color.

In addition to the gelatin issues and perfection of that aspect, the spector of proper removal of unused metals seems challenging. Gelatin does seem to slow the release of residual iron, although visually it comes out. I'll try salt and/or citric acid for iron removal. If anyone has suggestions as to how to test for good removal, speak up.

**Donald Qualls** · 5-Jul-2006, 19:52

Aldehyde hardeners are potentially bad news -- glutaraldehyde in emulsions have been implicated as being at the root of a number of folks who got extremely ill from being in the room with X-ray film processing, and formalin is at least as bad (and more volatile). Chrome alum (in acid fixer) is the old school method, and is probably what's in the Maco hardener.

Potassium dichromate will harden gelatin when exposed to UV light, but that's an entirely different alt process...

The big key for removing residual iron salt is to acidify the water a little; if the water is alkaline (as tap water is in many regions in the summer and some year-round) the iron will form the insoluble hydroxide and you'll never get rid of it. Recommendations I've seen in connection with VDB are to do the first wash with either acetic or citric acid about 1/4 the strength of stop bath. If you add a little salt to this bath, you'll also convert any unreacted silver nitrate to the chloride, so it fixes away cleanly and doesn't hang around in a sensitive form to darken your print in the wash.

Say -- acetic acid, and salt -- that sounds like pickle juice!