forced drying of film

greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread

In over 40 years i have never forced dried negatives nor do i recommend it to my students. Someone is giving the art center a drying cabinet. I realize that i am very old school in some areas, this being one; however, i would certainly be open to supporting information regarding forced drying. I am sure that in the commerical world negatives are forced dried all the time. I just want to be able to give my students an option based on facts now that we have the equipment that will allow a speed up in drying. Any thoughts out there?

-- Ann Clancy (clancya@mediaone.net), February 20, 2002

Answers

Ann, Force dry them in the cabinet with slightly cool air (95-100F) and your negatives will be nice and flat. I've been doing it for years this and you will not damage anything. Another thing I have done is to put a damp towel in the bottom of the dryer to be a dust collector! Cheers, Scott

-- Scott Walton (walton@ll.mit.edu), February 20, 2002.

A 60 second final rinse in isopropyl alcohol speeds drying time to about 5 minutes without heated and forced air flow. FWIT

-- Gene Crumpler (nikonguy@att.net), February 20, 2002.

I have a home made dryer from 3 old coffee cans a foam inlet filter & a used fan from a kitchen stove. I will never go back to air drying. I no longer use a wetting agent before drying,the films are dried on the reel & whilst it is not fast;it is faster than hanging the film but most of all No dryng marks.

-- Melvin (bramley@nanaimo.ark.com), February 21, 2002.

Is there any controversy over heat drying? Commercial labs do it all the time, and have done for many years. If the film is stretched or weighted to prevent curling, and the drying cabinet is dust filtered and limited to about 45 celsius, then it's difficult to see what possible harm the film can come to. Most modern films are coated on a polyester base anyway, which makes them as tough as old boots.

The only thing I'd have against using drying cabinets in a student environment is getting students to follow proper procedures. This means not sucking dust into the cabinet by slamming the doors open when it's already in use, and not scratching other people's film by careless hanging.

-- Pete Andrews (p.l.andrews@bham.ac.uk), February 21, 2002.


There should be no problem with forced drying. As others have stated, don't turn the heat up too high; temperatures around 100-110F should dry the film suitably. Higher, and you run the risk of differential drying, which can result in a density shift in the center of the film.

Just to clear up some confusion, very few films are coated on polyester; most use a form of acetate. But all modern films are robust enough to withstand forced drying. Just make sure the intake is filtered so that you don't blow dust on the film.

David Carper ILFORD Technical Service

-- David Carper (david.carper@ilford.com), February 22, 2002.



Moderation questions? read the FAQ