5x4 processing marks. Wetting agent?

[Paul Greeves]

Hi,

I have an issue with processing marks on my Ilford FP4 5x4 sheet film. I appears to be like a greasy deposit on the emulsion side of the film. It does clean off, once the negative has dried, leaving marks to the emulsion. I suspect it has something to do with the wetting agent. I am using Kodak Photo Flo - just a few drops in a litre of water. Am I using too much or too little, or is something else happing to my film? Your expert knowledge would be greatly appreciated. I don't want to waste anymore time/film.

Thanks

Paul

[otto.f]

Is it just one sheet or more and if so, is it on the same place every sheet?

[Paul Greeves]

It has happened on several sheets and always in the same place. I appears on the upper most corner when drying.

[Tin Can]

are you certain your fingers are NOT a culprit

I wash my hands with Dawn and thoroughly dry them with fresh cotton towel just before touching any film

[John Layton]

You'd mentioned that these artifacts occur in the "upper-most corner" - which implies the same corner from which they are hung to dry. This makes me want to ask what you are using for hanging clips? Wood clothes pins? Metal or plastic clips? Are they clean, dry, and free of residual wetting agent (or any other residues for that matter) prior to each use?

[Paul Greeves]

Thanks John. I use Paterson film clips. There is only the point of the pin touching the film.

[Ken Lee]

Tray development ? Tank development ?

You might find it helpful to clean your hands and fingers with Isopropyl Alcohol whenever handling your sheet film. That means before taking it out of the box, before loading the film holders, before removing it from the film holders, before development, etc. Be sure to clean your trays or tank with a solvent to remove any grease as well.

When unloading sheets before development, do you place them in a box or set them somewhere briefly, or do you place them right into the first tray - like a water bath ? If you set them down somewhere temporarily, be sure to determine if that place is free of a grease spot too.

Have you inspected an unexposed and undeveloped sheet, right out of the box ? This will remove almost all the variables. If every sheet is contaminated this way, you may have a "defective" box of film. Perhaps the person who initially packed it, forgot to wear gloves or clean their hands properly.

Have you tried developing an unexposed sheet ? Without Photo-Flo ? This will remove several other variables, including any grease or dirt inside the film holders and additional handling. If it's easier to see the greasy deposit on a more densely exposed area, then leave the lights on while you process the film. You'll find out how often you touch the corners.

[Paul Greeves]

Thanks Ken. I use a Combi Plan tank. I loaded the sheets from a combination of sheets stored in an old film box and from the dark slides. There were marks on both. I think there were more marks on film that had a few drops less wetting agents. I will take your advise and degrease my hands before touching the film. I use other formats like roll film and 35mm, where I haven't had the same issues. I might try heating the drying area before hanging up the film to speed up the drying. Also, I could try to remove most of the water before hanging up the film.

[Tobias Key]

Thanks Ken. I use a Combi Plan tank. I loaded the sheets from a combination of sheets stored in an old film box and from the dark slides. There were marks on both. I think there were more marks on film that had a few drops less wetting agents. I will take your advise and degrease my hands before touching the film. I use other formats like roll film and 35mm, where I haven't had the same issues. I might try heating the drying area before hanging up the film to speed up the drying. Also, I could try to remove most of the water before hanging up the film.

I use a combi plan tank and have found I get the occasional mark on the film if I don't make sure the emulsion side of the film is facing away from the middle of the tank. Also make sure you thoroughly clean the tank after use by unscrewing the valves and rinsing them out, they can hold wetting agent from the previous dev session which can land on your film before development starts leaving a patch or mark. Other thing to check for is that possibly two sheets touched during development. I always give the sheets a little pull with my finger tip to check they are secure.

[Paul Greeves]

Thanks. They were in different holders.