Re: [APML] Cheap Dessicant to store film with

[Jerry Lodriguss <jerryapml@astropix.com>]

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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