Diffusion Transfer Printing ("Polaroid" peel-apart) recipes

Try also https://onyxmet.com/index.php?route=product/product&product_id=1252

Here's an Etsy item:

You can try sodium hypophosphite too (hard to get where I live.)

Alternatively, take a leaf from our palladium/platinum printing colleagues - maybe try a pinch of ferric oxalate with the palladium chloride solution and expose to UV (or leave in the sun). I would still use some PVP as a capping agent. Oxalic acid might work too.

I purchased Sodium Borohydride from "MacPool" in Ireland on Etsy three weeks ago. It arrived last week.

alecrmyers said:

sodium hypophosphite

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Another option would be sodium dithionite. In the US, it's sold in the laundry aisle of the supermarket as Iron Out (not super high purity, but it works as a self-fogging second developer for B&W reversal and might work for a receptor sheet if it keeps long enough).

I did a lot of work with sodium dithionite last year without a lot of success, but I've changed developers somewhat since then so I gave it another go just now. Image is neutral tone (which is good) but Dmax is low - paler than it appears in the photo below. That could be worked on, most likely:

By the way - IronOut is only 15-40% dithionite (aka 'hydrosulphite'). I haven't tried it in place of the laboratory standard reagent.

I don't think the keeping quality is very important: once the palladium chloride is reduced (which process occurs in the vial before the paper is coated), you'd quite like any residual reducing agent to get lost. If it hangs around in the receiver paper then it might diffuse to the emulsion and cause fog.

These two images are made with receiver paper prepared using sodium dithionite, today. I'm trying to reduce the slight yellow colour that appears in the highlights a couple of hours after the print is made (compare the two). But the dithionite does seem to work as well as the borohydride.

That looks like residual thiosulfate or similar. Are those getting a good wash after development? This may be why Polaroid still needed print coaters into the 1980s; the coater applied a layer of some sort of lacquer that blocked oxygen from the receptor sheet (as I recall).

I'm getting good results with the dithionite now. Experimentally I determine that it's necessary to wait some time (nominally 60 minutes) after adding the dithionite before coating the paper - if you do, Dmax is much improved. This could be for two reasons - it drives the reduction reaction to completion, and/or it allows the residual dithionite time to decay. By contrast, the borohydride reductions give good Dmax within seconds of the borohydride being added.

Refering to the colour: this developer doesn't include thiosulphate - in fact it's entirely sulphur free - so it's definitely not thiosulphate staining, but I do have some hypotheses for what it might be. My goal is to formulate a system that doesn't need washing - so most of the sample images are not washed. However staining can (sometimes) be reduced by post-development treatments, of which washing is one possibility.

According to what Land wrote in Neblette, the image coating was necessary to prevent aerial oxidation and sulphurization of the silver, but was only needed for some paper types. Not (obviously) for what Polaroid marketed as 'coaterless' systems. I understand the major deterioration with failing to coat a coated system print was image fade, which took place in days to weeks. My images are (thankfully) fade free. I have tried some Polaroid coating swabs (a Photrio contributor was kind enough to send me some) on various of my print formulations but they don't prevent stain. Land's method to prevent stain was a timing layer and a shutdown layer which automatically lowered the pH a predetermined time after the developer was spread. I don't have access to the sophisticated synthetic polymers that he used for those, nor the patience to experiment with three or more successive coatings on each receiver sheet

Dithionite, however does contain sulfur...

It does, but the staining is present with paper produced with borohydride, which is where I've spent most of my efforts looking at it - it's not a dithionite specific thing.

alecrmyers said:

the staining is present with paper produced with borohydride

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Ah, didn't catch that bit.

Thanks for the links regarding sodium borohydride. One I had anyway but the seller is inactive, one is out of stock and the other say he has had customs problems with prevoius shipments. PVP is also impossible here but I have discovered that some contact lens comfort solutions use it.

I do have ferric oxalate so might have to try that and also have stannous chloride which might possiblty work though it is several years old now.

Regarding image changes over time I do see some change in tone from the cooler tones straight out to more warmer yellowy on prints a few weeks old (paper 212). I did coat half of one print with a Polaroid coater bar and there is a distinct difference now but I don't know how much of that is due to the change in surface ie very shiny gloss that the coating imparts. I did notice when making prints that some came out warmer, slightly yellow as opposed to cooler blue but don't know what processing or exposure differences might account for that.

This is my first sort-of success producing an image on a layer of partially hydrolyzed cellulose acetate containing palladium sulphide. The challenge has been getting the CA to stick to the paper and not slough off. This system is much closer to Polaroid's coaterless chemistry than anything else I've done.

Donald Qualls said:

Another option would be sodium dithionite. In the US, it's sold in the laundry aisle of the supermarket as Iron Out (not super high purity, but it works as a self-fogging second developer for B&W reversal and might work for a receptor sheet if it keeps long enough).

Click to expand...

I went to the hardware store (shop?) and bought some IronOut. It works about as well as lab dithionite, as per the attached picture, which was prepared as follows (let's call it paper type 247)

10g silica sol
0.5g 0.1% palladium chloride solution
IronOut enough to cover one match head
stir for 5 minutes
spread with 1μ wire-type coating bar
Optionally a coating aid such as 2drops PS20 10%, or substitute washing up liquid, or photoflow or similar

I skipped the poly(vinylpyrrolidone), which might affect the keeping quality of the prepared mix, but, who cares?

Alec are you just spreading this on the receiving paper??
thanx!
Peter

alecrmyers said:

Sodium borohydride is a standard laboratory reducing agent. In this case it immediately reduces palladium chloride to elemental palladium. It's not persistent as it decays on contact with water releasing hydrogen (it has been explored as a hydrogen storage medium for vehicle fuel).

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Is there a reason why a more benign reducing agent like Ascorbic Acid or Sodium Ascorbate wouldn't work for this purpose? Apologies in advance if this question doesn't make sense as I have not absorbed all the details in this long thread yet.

Peter Schrager said:

Alec are you just spreading this on the receiving paper??
thanx!
Peter

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With a 1μ spreader bar, yes.

Raghu Kuvempunagar said:

Is there a reason why a more benign reducing agent like Ascorbic Acid or Sodium Ascorbate wouldn't work for this purpose? Apologies in advance if this question doesn't make sense as I have not absorbed all the details in this long thread yet.

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You need something stronger than ascorbate to reduce the PdCl2. I have spent some time trying ascorbate, dextrose, citrate and others, augmented by UV and/or microwave radiation (as described by a lot of papers available online) and I have got some reduction occurring - as I wrote, here earlier in this thread, but not a sufficiently dense production to give a strong image. And having a kg of dithionite and 100g of borohydride on the shelf has been a disincentive to pursue those methods to a sufficient degree. By all means experiment, and if you can get good results I'd love to hear about it.