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My Techpan!

I was using 120 Tech Pan and TD-3 two weeks ago: at ISO 25 the negatives look quite thin. They scan fine though. Next time I might try ISO 12. I use Paterson tank and TD-3 recommend agitation method.
 
TD-3 is a waste of time. You’re better off with POTA or one of its variants.
 
Milpool said:
TD-3 is a waste of time. You’re better off with POTA or one of its variants.
Click to expand...

TD-3 works well for me, but it's kind of costly and does not keep for more than a few months, in my experience (tightly capped bottles, but not refrigerated). C41 developer at 20C and semi-stand with dilute Rodinal are convenient and do an acceptable job, but they don't really provide that crazy-sharp almost 3D look that you can get with Technidol or TD-3.

I've never tried POTA, but I've been told it works well. The main drawback is that you have to mix it from constituents shortly before processing. The working solution is only useable for an hour or two after mixing.

Since I'm running out of Technidol and getting tired of spending money on TD-3 I'll likely switch to POTA in the near future.
 
I used TD-3 from Photographer's Formulary, and it's still available from them. Way better than Technidol for me, for pictorial applications at least. It was easy to use and predictable. Tech Pan is not an ideal general photography film by any means, anyway. A lot of loss to highlight and shadow gradation, the proverbial "soot and chalk" syndrome, no matter how you develop it. I used it primarily for actual technical purposes, and sold off my big stash of 8x10 sheets a few years ago to an 8x10 photographer who did want to try it pictorially. Being so thin, it's not ideal in conventional sheet film holders, being prone to sagging.

I had a friend who shot Tech Pan for a number of years in his 6X6 SLR with expensive Zeiss lenses. He got incredible detail, but at the expense of routinely blanked out deep shadows and upper highlights. Plus micro-films like this have quite a few tiny zits or whatever in open skies if seriously enlarged, like from 35mm. Once I turned him on to Efke R25, that was the end of his Tech Pan addiction. But when that film went away, he simply reverted back to FP4 where he had started.
 
Technidol was a POTA-type developer with hydroquinone. The general idea is to use a relatively small amount of HQ with the Phenidone (Dimezone in the case of Technidol) which improves things in a few ways while retaining the low contrast and edge effects of a Phenidone-only developer like POTA.
 
Chuck1 said:
Old technidol wouldn't be worth trying ?
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Depends if it is powder or liquid. Apparently , liquid Technidol was designed for a 3 year shelf life. I heard it was POTA with a preservative
 
I am using old Technidol that came in the foil packets. It works as well as ever. I am also running out of the stuff and I will probably have to try TD-3.

I am not sure about Technidol using Phenidone - my experience with Phenidone is that it goes bad in front of my eyes, as opposed to Technidol's 20+ year life. Maybe Technidol uses some Glycol or other, or as Graig states there is some magic preservative in it. I have never had good results with POTA, but I never bothered finding out why.

My understanding is that POTA was formulated at Kodak for developing photographs of Atom Bomb explosions. I believe a panchromatic-cousin-of-microfilm was also developed for Los Alamos; this A-Bomb film was then sold as Solar Flare Patrol film, which in turn became Technical Pan. Thus explaining Tech Pan's sensitivity to the red hydrogen line and it's popularity with astronomers.

If I had my druthers the last films left standing would be Kodachrome 25, Ektar 25 and Technical Pan. It seems I am not in any sort of majority when it comes to druthers.
 

Looking at the MSDS, it is indeed a glycol solution and has the same Diethanolamine-sulfur dioxide complex that HC110 had.

Not sure about atom bomb explosion film, as Phenidone was an Ilford invention. The early Tech Pan literature gives a POTA formula, noting that Phenidone was available from Ilford dealers and that it was a Trademark of Ilford.

Concentrate:
85-90 Diethylene glycol (000111-46-6)
5-10 Diethanolamine-sulfur dioxide complex (063149-47-3)
1-5 Water (007732-18-5)
1-5 Tris(1-methylethyl)naphthalene sulfonic acid sodium salt
(001323-19-9)
1-5 1-phenyl-4,4-dimethyl-3-pyrazolidinone (002654-58-2)
1 Hydroquinone (000123-31-9)
 
It helps that the Technidol “concentrate” contained very little water. Also, who’s going to know the difference of old Technidol has lost potency vs new.

POTA wasn’t a Kodak invention. It was concocted by Marilyn Levy while working for the military.

The low contrast developers made by Spur for microfilms like Adox CMS20 might be of some use in developing Tech Pan (which isn’t as difficult as document / copy films).


 
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