A question for the chemists

[Barry Kirsten]

I know there are chemical residues in the man-made environment that can fog undeveloped film - things like vapours of solvents, plasticisers etc., although with most substances the effect may be very small even after considerable exposure time.

I have just built an insert for an ordinary backpack which allows me to carry a 6x9 Linhof with lenses and accessories in padded compartments. I started off with a frame of mat board (yep, just cardboard), and strengthened it with pieces of old cotton singlet and polyester resin - light in weight, but very strong. Each compartment is lined with 3 mm foam, held in place by dabs of contact cement.

The whole thing will do the job very well, however there is a strong chemical smell, mainly from the polyester resin, which I suspect will be present for quite a time. I'm wondering if anyone has any information about effects of commonly used substances of this sort on undeveloped film.

Thanks, Barry.

[Drew Wiley]

I always make sure the plastic containers are poyethylene rather than vinyl, including
any lids. Vinyl will outgas plasticizers and maybe a little odor. I don't know if it will
cause a film problem or not. Many backpack and camera bag fabrics have a urethane coating which will start to stink as it breaks down. And I notice that some of the bags recently coming in from China smell so bad even brand new that they make me literally sick. I've been given several big cordura bags that I had to throw away. Don't know what they're treated with, but I assumed is a poorly-done urethane system. In any event, I always wraps my filmholders or film boxes in polyethylene garbage bags,
so moisture, dust, or random chemicals will not be a potential problem.

[Drew Wiley]

Sorry - got interrupted, but per polyester resin per se, outgassing would probably be
due to some inbalanced mixture between the catalyst and resin itself. Not healthy in
a confined environment, and if anything like MEK is gassing off, bad indeed for film.
Just wrap well as I described above. For such applications I use carbon fiber board,
but it's quite expensive. When you get some hot dry weather, set your noxious materials in a shaded outdoor spot for a week or so. I will slowly outgass unless the
catalyst went bad, in which case it never will cure completely.

[Barry Kirsten]

Thanks Drew. You've confirmed my suspicions about the resin and its catalyst. I'm keeping the item outside under cover at present while the smell is present. When I start using the bag I'll put the film and film holder in at the last moment, wrapped in plastic, and take them out for storage elsewhere when finished.

Thanks, Barry.

[Henry Ambrose]

The contact cement may cause you problems. I know it will rust steel nearby.
But unless you store your camera and film in this bag I don't think it will be a problem.
Leave it all open to ventilate for a month and see if it still smells.

[Doremus Scudder]

Storing your film in Ziploc-style bags should do the trick. I assume you are shooting roll film, so one each for exposed and unexposed plus one for each roll-film back and you're good to go. Keeps everything together and easy to see.

If, by any chance you are cutting film and using holders, you could probably get two holders into a quart-size bag (they hold one 4x5 holder perfectly).

Best

Doremus Scudder