Pinholes in sheet film

[Howard Barron]

I have for years processed sheet film and have been bothered with occasional pinholes in the emulsion. I've tried presoaking the film, using water instead of stop bath, and I still have them. Today I processed some HP-5 in D-23 developer and found several pinholes in the emulsion. I would like to eliminate this plague. Any ideas?

[Mark Woods]

Use some pencils to fill the holes. There is no guarantee that the emulsion is spread equally. Sad but true.

[Glenn Thoreson]

If you find a foolproof solution to this, let me know. I get them now and again in APX 100. It seems they know which are the best negatives, too. I only have a little of this film eft, then we'll see if those holes can find the FP-4. Grrrrrr.....

[Frank Bagbey]

I pre-soak in water with quite a bit of wetting agent in it, at least two minutes, when developing sheet film. The developer also has wetting agent in it. I have never had a pinhole in 8x10 or 4x5 sheet film. For 35mm, I add wetting agent to the developer (no pre-soak), and also never have pinholes.

[Gene McCluney]

A lot of time "pinholes" are actually just places where dust settled on the film when it was in the film holder prior to exposure, thus creating an absolutely clear "dot" when film is developed, since that spot didn't get any exposure. I always dust out my holders with an air compressor and air gun, and I blow thru the light trap. It is amazing how much dust comes out. Sometimes with old holders it can take a while for all the dust to work its way out, but I can see progress with less and less dust "pinholes" on the film as time goes by and they get cleaned over and over. I shoot lots and lots of film, primarily 5x7, often 60 sheets on a single day.

[PBrooks]

Howard, could it be undesolved pieces of fixer?

[Martin K]

Can also be a too rapid change from alkaline to acid as in not using a stop bath at all and going straight to fixer. I have seen it on 10 inch wide 500 ft rolls of aerial film. We tried for various reasons to reduce the wet time of the film and added lots of accelerator (kodalk) to the developer making it very alkaline. The stop was a very brief water bath and then into strong fixer. It was sorted out by using a moderate acid stop bath.

I agree though that what often looks like pinholes are in fact either dust on the film during exposure or even deposits on the film during processing.

[Ash]

It can be caused by the stop bath because, as you said, the rapid change of pH causes a reaction. If you use stop bath, dilute it more than usual, but don't necessarily get rid of it entirely.

[Ted Stoddard]

I pre-soak in water with quite a bit of wetting agent in it, at least two minutes, when developing sheet film. The developer also has wetting agent in it. I have never had a pinhole in 8x10 or 4x5 sheet film. For 35mm, I add wetting agent to the developer (no pre-soak), and also never have pinholes.

I like Frank's way seems to work the best... I occasionally get pin holes to so I am going to try this method...Frank what wetting agent do you use? or does it make any difference?

[Kirk Keyes]

I'd suggest looking at dust being the issue here for a couple reasons.

First, modern films are designed to resist pinhole formation. The emulsions are hardened and my understanding is that they simply do not form pinholes like films of years gone by or even films from second or third tier manufacturers. (With first tier manufactuers including Kodak, Ilford, Fuji, and formerly Agfa.)

Second, pinholes are actual holes in the emulsion that are caused by the formation of minute gas bubbles inside the emulsion. Carbon dioxide is the gas that forms with certain developers when the film is placed into a stop bath - the acidic conditions of the stop neutralize the carbonate which is used in some developers to make the developer basic for development to occur.

Overly acidic stop baths could be a cause of pinholes if you are using a developer with a lot of carbonate or use deep tanks, but you should not have problems if you are mixing the stop as per the manufacturers instructions.

The reason I think you are not having actual pinholes formed is that there is no carbonate present in D-23. That developer consists of only of metol, sodium sulfite, and water. No carbonate.

Since you don't have any carbonate there to form the pinholes, I think it's pretty unlikely that you are having problems with actual pinholes.

Can you scan some of your negs so we can see what they look like. Also, are the spots white or black on prints? Perhaps you are having what ware called "air bells"?