The subzero temperatures will keep the chemistry from reacting, but lets say you freeze film for a very long time. 10-20-40 years. What are the adverse effects. Can film frozen for long enough get freezer burn (ie dry and brittle).
Does the type of film chemistry matter, B&W, c41, e-6?
I'm interested in building a stock of certain films that may disappear
Good idea 1kgcoffee but you are coming a bit late - would you not say so?
Most of films you should have to work with for the next decades have eben discontinued since years.
Have a look to Kodak E6 films : 14 different emulsions in 2002!
And today?
Another aspect - price increases

.
Ok - never to late to freeze films?
You are right - but what are the problems
with frozen films?
There might be problems of cause.
First - think for the original packaging.
The film boxes (paper/carton) they could
be damaged from moisture (a litte).
To avoid this - the mentioned idea to use
a vacuum sealer with plastic backs is
great.
Just to protect carton of the packaging.
Comming to the films - as Agx stated there is an optimum humidity of the
emulsion.
This should be manufactured and conserved with original NEW films
within the original plastic cans to 135 films.And I see the same procedure with
120/220 films in original aluminium/plastic packaging.
You should not open it or left it before
freezing.
If you will follow this advice you can get
sure that there is an (I name it) "micro clima"/"microclimate" in your original boxed fims witch is stabile to many years.
From this you can be sure that you have also protect the optimum humidity of your emulsion.
So the discussion about dehydration or
"freezer burn" should be no matter to
you.
It you have total unboxed films - there should be a little danger to some theroraticaly effects when you freeze
your films in this way (unprotected).
But this would be in concerns of freezing/defreezing your films often.
Dehydration of the emulsion from first
freezing is within normal tolerances.
But after decades of freezing ? I won't
be very afraid to have big damaging in this example.
The classic dehydration to material works different as from your freezer.
Shock frosting as method of dehydration
does need first very low temperatures.
And secondary absolute vacuum.
More of you can get from a kitchen vapourer.
So you have not to be afraid of these effects at all because it is very unrealistic.
Otherwise you will freeze you films on the
moon with it's vacuum and don't forget
it's temperature (in shadow areas).
Of cause THIS would indeed dehydrate
your films totaly.
Coming at least to radiation effects to
frozen films (after decades) - sorry but I
don't believe to these effects too.
Frozen films on the moon surface - of
cause you would have troubble with cosmic radiation.
But your freezer is protected fromm
1,5mm steel?
If you could handle your films by avoiding
any riscs - take your freezer in your
shelter/basementroom.
The cosmic radiation should be tamed
there in concern to have no effects to films.
At least differences of films to long freezer storage?
I can't see a difference between C-41and
E6. Exeptional the fact that collor crossings to E6 films are more bad as on C-41 films.
But to avoid this you would have the intention to long time freezing - that fine.
Notice : bw films outside a freezer will have in general a longer time to live.
Therefore I would make a difference to
bw films (no need to freeze with extrem
low temperatures in comparison to E6,C-41).
Or freezing together means additional
livetime to bw films.
My advice in concern of temperature in your freezer is -18 degree celsius.
To freeze films for very long times
-24 degree celsius.
And notice : "No frost" freezers
(without ice) are recomended in general
to film storage by freezing.
with regards