double-coating pt/pd

[Keith Taylor]

I am hesitant to say this as I am very new to this,so, at the risk of looking stupid. I did read once that Colburn coated both sides of the paper and that Stieglitz was very impressed with the dmax that resulted. As a historical reference this might be worth looking at (or not)

Bill, you're correct - although it was Karl Struss who coated and printed on both sides of the paper. The image on the back side of the paper was reversed. He repeated this up to 12 or 13 times to get a good black. Stieglitz was impressed enough to choose 6 prints for Camera Work and Struss was invited to become a member of the Photo-Secession.

 

[cowanw]

Thank you for the correction. I suppose the registration has to be really good unless you were going for a pictorialist look.

 

[Keith Taylor]

Thank you for the correction. I suppose the registration has to be really good unless you were going for a pictorialist look.

I agree. But Struss was a perfectionist and apparently they were in perfect registration!

 

[Ben Altman]

I am hesitant to say this as I am very new to this,so, at the risk of looking stupid. I did read once that Colburn coated both sides of the paper and that Stieglitz was very impressed with the dmax that resulted. As a historical reference this might be worth looking at (or not)

I've tried this on translucent papers. Seems pretty wasteful as the dark areas expose quickly and then mask the sensitizer on the back of the paper. So most of the stuff on the back goes down the drain. Didn't see much effect.

 

[Keith Taylor]

I've tried this on translucent papers. Seems pretty wasteful as the dark areas expose quickly and then mask the sensitizer on the back of the paper. So most of the stuff on the back goes down the drain. Didn't see much effect.

I think he exposed and processed each side separately, one after the other. Sounds a PITA though.

 

[Ben Altman]

I think he exposed and processed each side separately, one after the other. Sounds a PITA though.

OK I get it. A new way to screw up...

 

[jeffreyg]

Michaelbsc asked what x-ray duplicating film I am using. It is Kodak dental x-ray duplicating film processed with Kodak GBX dev and fixer. Available through my dental supply. If they only sell to dentists you could probably have your dentist order for you. Agfa also has (or had) a similar product which can be processed in the same chemistry.

http://jeffreyglasser.com/

 

[michaelbsc]

Michaelbsc asked what x-ray duplicating film I am using. It is Kodak dental x-ray duplicating film processed with Kodak GBX dev and fixer. Available through my dental supply. If they only sell to dentists you could probably have your dentist order for you. Agfa also has (or had) a similar product which can be processed in the same chemistry.

http://jeffreyglasser.com/

Is this the X-omat 2 film? I've read the data sheet, but I haven't ever had a chance to actually touch it. (For that matter, you might even be the person who gave me a reference to it some months ago that got me to the data sheet for it. It was someone on APUG.)

Is the GBX chemistry a magic reversing bath, or is there something magic in the emulsion that would allow use of any old developer like Rodinal or D-76?

(And if the GBX chemistry is a magic reversing bath, have you tried it on regular film?)

 

[jeffreyg]

Michael,
Yes it is the X-omat 2 film. I don't think the GBX chemistry is the magic elixir. I haven't tried it with any other developers nor have I tried the GBX with other films so I can't help you there. Maybe the folks at Kodak can answer that for you. I have used the GBX in my dental office for x-ray film for ages. It is good for 30 days so you could pour it into a container and reuse it several times for a month.

The film runs $111. for 50 8x10 sheets and the GBX is $15.50 for a twin pack (1qt dev & 1qt fix) they are mixed 1:3 so you don't have to make the full gallon of working sol. if you don't need that much.

Agfa has a 5"x12" film and possibly other sizes. They used to have an 11x14 film but I'm not sure if they still produce that.

Jeff

http://jeffreyglasser.com/

 

[Peter Schrager]

xray

after Jeffrey was kind enough to post here about xray film I went out and got a hold of some fuji and agfa; work fine in hc-110 diluted 1:3 between 2 and 4 minutes @75 degrees...builds density quickly so you will have to do your own tests
Best, Peter

 

[nick mulder]

resurrecting an old thread ...

Anyone got any reports on double printing ? (as opposed to the simpler double coating).

What to use to bond the paper to a sheet of aluminuim ? Could be anything inert to the developer though huh ? White perspex ?

Printing on the reserse, only for thin papers ?

I'm going to get back into Pt/Pd one day soon

 

[keithwms]

I think you may well see what you want simply by coating your print with something like varnish or gum or such. I haven no desire to double down on Pt solution when the price is $1600/oz. But that's just me.

 

[CraigK]

I've tried double-coating cotton papers (platine, cot320, masa etc.) but found no real benefits. However, for coating fixed-out baryta paper, double coating is a must. With a single coat, the image lacks depth in the shadows and just looks sort of "thin". But with two coats, you get awesome d-max and a great richness in the print.

 

[nick mulder]

Although its true that you double coat in the process I refer to - I refer to instead coating once, exposure, development - recoating, register neg again, expose again, develop again.

Hence the requirement for the paper to be stabilized in terms of expansion/shrinkage between exposures - it could refer to many similar processes I guess, tri-color gum and gum-overs being examples.

Anyone done double coat/ double exposure / double development ?

My reply to the cost of Pt is half-hearted (I'm poor!) - but I could try this on for size: after all the work you've done in the imaging process, why wouldn't you want to optimise the output ? If you truly beleive in Pt/Pd enough to do it in the first place, then why not push for that extra dmax and therefore extra range (if done correctly). It's not the only cost in the process - maybe your paper, film, lovely oldlenses, subject and patience deserve it ?

 

[CraigK]

Anyone done double coat/ double exposure / double development ?

Yes. But the nicest ones were cynotype over pt/pd and gum bichromate over pt/pd. Double coating pt/pd on any cotton paper never really made much of a difference for me. As mentioned, double coating on fixed-out baryta makes a huge difference (and is in fact, the only way to go).

For my cyanotype and gum over pt/pd prints I used cotton papers (Platine, Cranes cover and others) with the old "pin through the edges of the neg and paper" trick to register everything. But before I applied the first coat, I soaked the paper for about 15-30 mins and then let it dry. That, in my experience, took care of any issues of dimensional stability between coats and the registration was fine.

FWIW, both the cyanotype and gum second coatings really added a nice extra bit of "umph" to the prints. But the gum bichromate prints have a very nice extra bit of sheen that gave the shadows some more depth.

Here is a lo res photo of one of the cyanotype over pt/pd images. Forget about seeing any of the subtle tones or depth in such a poor reproduction, but you can see that the registration is decent.