Use of X-ray film: technical discussion with example images

[andrewch59]

A strong stop bath may cause pinholes in the emulsion. I've had this happen with x-ray film as well (at least that's my working hypothesis). X-ray film emulsion is very soft and it damages easily. It makes sense to me that hitting the alkaline-soaked emulsion with a strong acid can cause carbon dioxide bubbles within the emulsion, blowing tiny holes in it. If you insist on using a stop bath, try diluting it to 50% or even 25% of its recommended strength - or be like Randy and don't bother with it at all.

No wasn't the stop bath, oxidized fixer? contamination from the around the lid thread?

[koraks]

So to get it straight, are these dark specks in the negative or clear ones? If they're dark on the negative (white on the positive), it could be debris. But that usually leaves quite uneven patterns; what does it look like? Can you post a scan or photo?

[andrewch59]

They are both light and dark depending on background, so I don't think it is the film, as they are not uniform, yes I think they are contamination. I have used RO9 and Rodinol and get the same result, so my guess is it is the fixer oxidizing. Will check today with a different fixer.
When I saw the oxidizing on the bottle neck I did filter the fixer through a coffee filter.
Have tried to post a pic for the last week but internet speed is poor at the present.

[koraks]

They are both light and dark depending on background

This suggests you have (at least) two different problems.

I'm not sure what you mean by the fixer oxidizing, but generally, when fixer decomposes, the thiosulfate is broken down into elemental sulfur, rendering it ineffective, but it doesn't cause specks in my experience. Crud, dust and to a lesser extent iron contamination of the developer can cause issues though.

[andrewch59]

finally managed to get an upload in, this is a cropped part of the pic, about a tenth of the 4x5. You can see the snow on the ceiling of the gallery, but it covers the whole pic.

[koraks]

That looks like an interesting exhibition, I wish I could see it in person!

The picture isn't very conclusive; what I see looks mostly like grain. Are you sure it's not just the grain of the film that you're running into? I find x-ray film isn't particularly fine-grained for its speed. Another possibility is reticulation, which could occur if there are quite large temperature differences between the processing chemicals. A notorious example is developing at 20C and then using a stop/rinse at a much lower temperature. However, I can't be sure as I haven't had any films reticulate yet in my darkroom despite my habit of washing film with unheated tap water (around 10-12C during colder spells in winters).

[andrewch59]

Hi Koraks, no I don't think it is grain, although it covers the whole pic it is not uniform. I will have to try rotation again, it was giving me great contrasty results, the only prob was the constant threat of scratches. I have a close gallery next week for an important visitor and don't want to ruin my one chance at a good pic. May have to do some practice shots through the week. Yes I have 17 pics on display, all done with xray negs. 30 or so large format cameras, magic lanterns and the three in the pic are two hunter penrose and one deardorff studio.

[andrewch59]

Heres a rotary negative I did today, same dev, same fixer. Contamination must be coming from my second hand print washer.

[Thodoris Tzalavras]

Agfa HDR film, cut down to 13x18cm.
Super Angulon 90mm at f64 and 1"
Rodinal 1+100 at 22C for 8min in glass plated 10x12" tray.
Scan from negative, finished in PS.

[andrewch59]

Thodoris not much in the way of feedback coming your way, so I'll say it a pretty damn good shot for xray. I love my new to me super angulon 90mm too. Its a pretty adaptable lens, from landscapes to architecture to studio stills.