RE: [APML] Cheap Dessicant to store film with

[Jerry Lodriguss <jerryapml@astropix.com>]

Hi Jason,

No need to apologize!  This is all just for fun, right!

I'm not sure experience is the best teacher though.  I know I never learn 
from my mistakes. I wish I had had someone to tell me that you can't 
piggyback guide a 12" f/8 Newtonian with a C8 in plywood rings held in 
place with twine.  Sigh. Perhaps we can learn from the experience of 
others.  On the other hand, there are some people who just have to beat 
their heads on the wall for themselves. <G>

If the film you are planning on using for your experiment is the film you 
describe as having frost on the leader, I think you have already screwed 
the pooch. It's compromised before you start.  If you store film in the 
cold, it should be in the refrigerator (not freezer) and it should be 
placed into double, or even triple ziploc bags with silica gel dessicant 
before you put it into the refrigerator.  When you take it out of the 
refrigerator, do not take it out of the bags until the film has reached 
room temperature, or moisture will condense on it, and screw the pooch.

As far as your methodology, here is the dilemma you have... you plan to 
shoot two frames on the same night, one stored with your desiccant and one 
not (the control). The problem is that, unless you buy the control film 
that same day as the test, you have the variability of the storage of the 
control, because as you describe your location, it's humid inside for 
storage and too hot outside.  I guess you could keep both in the 
refrigerator with each individually triple-bagged, but with one with 
desiccant and one without.  But then, you wouldn't know if you got better 
results with the desiccant one if it was because the desiccant one was 
"semi-hypered" (highly unlikely) or because the non-desiccant one was 
degraded.

The other problem you have is that film changes as it ages, so even your 
controls won't match over time... unless you are using a professional 
emulsion that has been stored correctly, and even then.

In any event, my best guess is that the variables will vastly overwhelm any 
chance you have of figuring out exactly what was going on, even if you did 
see some difference. But that is just my two cents, and as far as I am 
concerned, I think they should stop making pennies because they are almost 
worthless. <G>

Using desiccant to store the film in the refrigerator is a very good idea 
(in ziploc bags), but please use silica gel.

Jerry




At 03:13 PM 8/4/2004, Lane, Jason R wrote:
>Hi guys,
>
>I apologize for the naivety of my experiments, but someone did once say 
>"Experience is the best teacher."  :)  Besides, do-it-yourself is much 
>more fun.  Who can say they enjoyed sitting in college listening to 
>lectures more than tinkering in labs or shop class?
>
>For clarification, it's the unexposed rolls of film that I'm trying to 
>store moisture-free.  I don't use it up very fast, and my fridge and 
>freezer generate a lot of moisture/frost.  For example, the cardboard box 
>was damp on the last package I pulled out, and the cartridge and leader 
>film had frost on it.  Even though I live in the desert, we use a swamp 
>cooler to cool the house during the summer...while it's very efficient, it 
>generates a lot of humidity indoors.  And I can't really store the film in 
>the dry conditions outside...the film would likely melt in the afternoon 
>heat (no joke!).
>
>The reason I'm using calcium chloride is that I passed by it on the shelf 
>in Wolly World after thinking about desiccants and the film in my freezer 
>the day before.  Yes, it was an impulse buy.  :(  I figure for less than 
>$10 and practically no effort, there's no harm in checking it out.
>
>As for being able to draw valid conclusions from the tests, this is 
>simple.  The easiest way is to use a control.  Jerry, your comment about 
>film being shot on different nights...maybe I wasn't too clear in what I 
>meant.  One test sample shot on same night as a control sample would give 
>one data point.  A test sample and control shot a fiew weeks later gives a 
>second data point.  Several of these over a period of several months and 
>you have an idea of the effect over time.  Of course, as with any 
>experiment, you should always describe the assumptions made and variables 
>that could affect the results.  I thought this was common knowledge?
>
>Thanks to all for the great insight and comments.  That is what I was 
>looking for.  I shall limit my ambitions to just keeping the moisture that 
>develops in my fridge and freezer off the film---which is the main thrust 
>of this exercise---rather than speculating about how well this would 
>"semi-hyper" the film.  :)
>
>Cheers!
>Jason
>
>
>-----Original Message-----
>From: astro-photo-bounces@seds.org
>[mailto:astro-photo-bounces@seds.org]On Behalf Of Jerry Lodriguss
>Sent: Wednesday, August 04, 2004 11:14 AM
>To: Discussion of Film Astrophotography
>Subject: Re: [APML] Cheap Dessicant to store film with
>
>
>
>Hi Kent,
>
>I tend to mostly agree with you. If the purpose is to get the best
>astrophotos, then with the films that are good for astrophotography today,
>such as E200, you pretty much don't need to hyper them at all. So trying to
>hyper by Jason's method would seem pretty much to be a waste of time.
>
>On the other hand, if he is more interested in experimenting with different
>hypering methods for the sake of experimenting, I would say, go ahead and
>knock himself out. If he want's to experiment with real hypering to see if
>there are any new undiscovered films that would be good for long-exposure
>deep-sky astrophotography, I can sell him a complete hypering system real
>cheap.
>
>The problem is, that from a scientific standpoint, it's going to be almost
>impossible for him to isolate the variables and draw any kind of valid
>conclusions from his experiments because the film will be shot on different
>nights.
>
>I don't know why Jason wants to use calcium chloride, when he can get
>silica gel just as cheaply: http://www.safetycentral.com/moisabdespac.html.
>
>I think Chuck Vaughn puts a couple of grains of silica gel in the film can
>and tapes it closed with electrical tape when he stores hypered techpan.
>
>Jason also seemed to imply that he might be storing exposed film with his
>experimental method. If so, I would advise against that. Not only would it
>add another variable, but the latent image on extremely low light level
>exposures does not store well. Long exposure deep-sky images should be
>processed as soon as possible after exposure. I know some people like to
>keep exposed film in the camera over the course of a couple of nights, and
>I have certainly done that while camped out on an astrophotography
>expedition for a week on a mountain, or in the desert, but keeping exposed
>film for months is just crazy to try to save a couple of bucks (literally,
>just a couple of dollars), considering the work and effort that went into
>the exposures.
>
>Now, storing unexposed film in a dry artificial environment with silica gel
>makes a lot of sense if you are in a climate that is wet or high humidity,
>like where I came from in the swamps of Louisiana, or like where I am now
>in the bogs of New Jersey. But in a humid environment, I would certainly
>not take the film out of its original canisters just to put it in a ziploc
>bag with silica gel. I would put the unopened film cans in the ziploc bag
>with the silica get, and only open it just before loading it into the
>camera to shoot it. I wrap a big ziploc bag with silica gel around the
>camera during the exposure (or better, flow nitrogen or dry air into the
>camera during the exposure), and then store the exposed film in the
>original ziploc bag with the silica gel in it for transport back home and
>to the processing lab.
>
>Jerry
>
>
>
>
> >Someone once said that "those that don't learn from history are condemned
> >to repeat it".
> >Or another way of putting it, don't reinvent the wheel.
> >
> >Sure, Damp-Rid or any other dessicant can be useful, but only for storage
> >and transportation of hypered film. The dessication part of the hypering
> >process is to remove water and oxygen from the film being hypered. This
> >requires a vacuum, the stronger the better and this can't be accomplished
> >with just a dessicant like Damp-Dri.
> >
> >You seem to be trying to find a way to 'hyper' film without hypering it.
> >That's an interesting goal, but so is alchemy.
>
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