Diffusion Transfer Reversal

Diffusion Transfer Reversal, or DTR, is possibly the most important photographic process developed in the 20th Century, and almost certainly an important technology that few have ever heard of, but nearly everyone knows something about.

DTR is the basic process that enables instant photography as practiced by Polaroid, Kodak, Fuji, 20X24, and was a key step in the development of integral films such as now made by The Impossible Project.

Here is a link to more posts about DTR, which was invented before WWII.  And here is a link to the Rott patent. Rott invented DTR.

Type 55 was just one of many products that depended upon the use of DTR to produce a negative that is processed in such a way as to rapidly produce a transfer of metallic salts onto a receiver, bridged by a developer. The action of DTR is battery-like and DTR kinetics are complex and still being studied today.

I wanted to show some results of DTR that we have produced here. They are early and crude, but show definite ability to use existing films - in this case EFKE 25 - as an emulsion capable of generating a sharp, high tonal gradient DTR image onto suitable receiver paper.

Below is a DTR image produced using EFKE 25, in our own sleeve, and employing 17 year old T55 reagents and paper that was ruined by humidity, which in itself is very instructive. I shot this today in a Speed Graphic with a 545 holder to point out where we need to buy tooling and obtain materials for a new product.

 We know how to make new, fresh reagent, and we now have a very tonally rich emulsion.  We do not now have a supply of receiver paper.  We do have a source of pod-making equipment, and the ability to mass-produce sleeves, inserts, stops, clips and other parts if we can obtain the tooling at a reasonable price.

Here's the scanned EFKE 25 negative, showing less DTR failure, but with very uneven (slightly exaggerated in the scan) development. Note however, that the cleared portions have a tonality that is not too different than the print, which is good. Perhaps this defect is similar to what we saw with Reagent III and the sponge, but with a spread out appearance.

Here's a shot of the sleeve used for the above, and some of the EFKE (here shown in lower case_ PL 25 M.