10 lessons in photography!

[Harold_4074]

"I am somewhat familiar with the wet plate processes (from reading) and

this is TOTALLY different"

----No kidding! It sounds like this is a sort of pseudo-tintype, possibly based on a graphic-arts type of developer. There are some chemistries that are (or were) used to create printing plates and which involve a solubilizing developer; maybe Rockland is borrowing from one of those technologies. It seems odd that the image doesn't change with fixing; I understood that the Ag-Plus product was just a high-silver gelatine emulsion, otherwise fairly conventional. If your finished tintype depends on a silver halide image for visibility, I wouldn't recommend offering any guarantee of longevity...

The odd thing is that in order to get continuous tones, you have to create transparency in proportion to exposure. The usual way to do this (as in collotypes) is to expose through the base, hardening the coating so that the part nearest the base is firm enough to hold everything together. Working from the "top" as it were, it seems that one of two situations would have to exist: the exposure and development would be closely and delicately tied to the emulsion thickness (in order to be able to display mid-tones) or there would have to be a proportional bleaching process wherein the actual gelatine stayed in place, but proportionally lost opacity.

I think that in light of your description, most of the available photographic insight (starting with mine!) is going to turn out to be irrelevant.

If someone with a better understanding of the technology doesn't chime in, perhaps you should contact Rockland and offer them the URL of the start of this thread. If it were _my_ product and this many people were interested in it, I would certainly want to get the issue straightened out in a hurry!

You could also try, if you haven't already, the alternative processes forum over on photo.net. Some folks who at least _sound_ authoritative contribute over there on occasion.



Good luck!

[Brian C. Miller]

Since this is all pseudo-tintype, all you need is metal plate. Give the plate a minimal polishing to remove blemishes, base coat it with Maco photo gelatine, top coat it with Maco or Kentmere photo solution, and then contact print the negative.

[Brian C. Miller]

Rockland Gallery: Liquid Light on vinyl records

OK, there has to be a reversal process for this stuff. All of my vinyl records were black, not white. Of course, the reversal developer for the tintype kit may have been used.

[Ole Tjugen]

I think the original "real" tintypes were often developed in the "iron blue" developer, an acidic iron sulfate developer. It has been very unpopular for many years, but might well be the right thing for tintypes.

If you have looked at an underdeveloped negative against a black background you will have seen that the full range of tones is visible since the silver grains reflect light. That is what the tintype is based on - very thin negatives against a black background. It is possible that Rockland's developer (or emulsion) is auto-toning, in that it tones the silver to some lighter colour.

I'm tepted to mix up some iron blue developer to see what it does to liquid emulsion...

[Calamity Jane]

OOPS! My previous response was full of sh!# (Sorry!)

I took one of my good plates and scratched it. The whole images (full range of tones) is contained within the emulsion layer and the plate colour does NOT show thru, even in the darkest areas.

I should have remembered one plate I tried to do on brass where the primer didn't adhere and the whole image came off in one thin sheet and looked the same off the plate as on!

Please excuse my misinformation!

Fire when ready Gizzley ;-)

[RichSBV]

The plate color does NOT show through????

Then their emulsion is in an opaque base and the developer would be a simple reversing one. Smart on their part. And it also means you don't really have to worry about the color of your plates.... And you couuld look around for any of the many reversing developers to replace Rocklands. I don't know of any commercial, but there are quite a few formulas around.

Now I'd like to see a Rockland "tintype" next to a real one... Without the comparison, I think the idea we came up with a few years ago about bleaching the emulsion on a black plate will look more like the real tintype... When I get the time (yeah), I have to go back and check the develpers for real tintypes. I do this every few years when the subject/interest comes up. Somehow I never find the time to put it all together to actually make one though....

[Brian C. Miller]

I emailed the lady who did the Liquid Light on vinyl records. She said she painted the records first.

[Harold_4074]

Well, it finally occurred to me to do what any competent industrial spy would do, and look at Rockland's Material Safety Data Sheet (MSDS) file for the tintype products. The developer contains the usual hydroquinone, metol, carbonate, sulfite and bromide. Down near the bottom, there is a note that the container is marked...........Dektol! There are apparently two other components, probably supplied as solutions or powders in separate containers. One is sodium thiosulfate (i.e.--hypo) at fairly low concentration (in solution, probably) and the other is ammonium thiocyanate.

This is starting to look an awful lot like a unibath formula (developer and fixer combined, so that the developer finishes just before fixation takes over) with a sulfur source (the thiocyanate) that for some reason deposits in the highlight areas. We _really_ need the services of a photographic chemist about now!

There is no guarantee that the MSDS is accurate (Federal law notwithstanding) since to my knowledge there is no mechanism to audit for accuracy or track changes in formulation. However, it is a safe bet that Rockland didn't invent this from scratch, so there may be some obscure formulas out there that can be identified with the odd chemical (thiocyanate).

If this really is a unibath process, then I would probably take issue with one of CJ's original points, namely, that the Rockland tintype is suitable only for amateur use. More likely, it would be suitable for a fixed-site operation with a steady process flow where the variables can be fully controlled, but not for small-batch processing: too many things have to happen simultaneously and to the right extent for the result to be acceptable.

Wet collodion with a traditional (iron based) developer is starting to sound more and more reasonable!

[Calamity Jane]

" take issue with one of CJ's original points"

Yes, you are right. My comment about "professional use" simply related to TOO many factors being beyond the photographer's control. Some of the vagueries happen in Rockland's production and some in the photographer's production. Of course the photographer knows what he/she has done but is never sure what "potency" the Rockland developer will be.

On the subject of Dektol, Rockland say a small quantity of Dektol can be used in the tintype developer to increase contrast.

[Harold_4074]

Okay--a quick search for "reversal" and "thiocyanate" turned up scads of postings and articles on reversal processing.

The two-cent summary is this: an otherwise conventional developer (D-19, for example) is modified with thiocyanate and/or thiosulfate as silver solvents to remove metallic silver and prevent fogging of the highlights. After development, a bleach step removes all metallic silver, and either chemical or light fogging makes the remaining silver halide developable. Any conventional developer, or a toner, is used to reduce the halide to metal (this is done to completion, since the image tonality is controlled in the first developer) and the result is clear highlights and black shadows: a positive.

If this were placed on a black background, the image would be hard to see; it sounds as if Rockland is counting on a thin surface image to be underlain by essentially unaffected (opaque whitish) emulsion. If there is no separate bleach step, then the silver solvent in the developer must be doing this job, but I can't figure out how the shadow areas get reduced to black. It all sounds more like a parlor trick than a viable photographic process.

A conventional (develop, bleach, expose, redevelop) reversal process using _white_ painted tin seems like it would work for "pseudo-tintypes". Everything after the first developer can be done in daylight, which might lend an element of showmanship to the process. Watching the positive image appear after the bleach step is really neat; I remember making black and white slides this way as a kid. And it is faster than doing two complete develop-fix-wash-dry cycles to make a printed positive.