Freezing Emulsions

[wildbillbugman]

Just Curious,
I have read somewhere in this forum that freezing an emulsion will ruin it.
Why?
Do the silver-halide crystals come out of suspension? Do they aglomerate?
Or do the crystals change in some more basic way?
Or is it the gelatin that deteriorates,changing the suspension characteristics of the crystals?
I remember years ago purchasing a pint of Liquid Light. I THINK that I remember the data sheet stating that it COULD be frozen. But that was long ago.
Bill

 

[bsdunek]

My current bottle of Liquid Light says it may be refrigerated or frozen - it's in the freezer now. I have never mixed my own emulsions, so I can't comment on that.

 

[Ian Grant]

Freezing can damage the emulsion. But it should be stored well chilled.

Ian

 

[Photo Engineer]

What Ian said.

PE

 

[wildbillbugman]

Ian and PE,
Thanks for the answere. However, my question realy was "What happens to an emulsion when it is frozen and thawed?" I am intrested in the Hows and Whys here.
Call me a life-long three year old.
Bill

 

[Photo Engineer]

Lets see now, how can I put this in terms that a 3 year old will understand. JK Bill.

The gelatin loses its ability to peptize silver properly and it also loses water to some extent and ends up being less elastic and the silver halide crystals can then aggregate. This causes coating defects and pepper grain.

PE

 

[Ray Rogers]

Lets see now, how can I put this in terms that a 3 year old will understand. JK Bill.

The gelatin loses its ability to peptize silver properly and it also loses water to some extent and ends up being less elastic and the silver halide crystals can then aggregate. This causes coating defects and pepper grain.

PE

I understood that.
I must be younger than I thought!

Actually, however, freezing is and has been practiced in some circles.
That the emulsion will "fail" is by no means a given.
It depends on the emulsion and the technique.

Ray

 

[Photo Engineer]

Ray;

All well and good, but we found that no emulsion could be made and kept reliably if it were frozen. It was better to refrigerate at 2 - 4 deg C and use a very good bacteriostat/fungicide.

PE

 

[Ian Grant]

It may well also depend on what else is in the emulsion. Back in the 70's I was Rockland Colliods first ever UK customer, I only ever bought the one bottle but it had a very aromatic alcohol smell, it may be that it doesn't freeze unless the temperature falls well below 0°C.

But from my experience a frozen emulsion doesn't gel properly when coated, and has other defects, I learnt the hard way. As Ron says close to freezing but not frozen.

Ian

Ian

 

[Ray Rogers]

Different Goals

Ray;

we found that no emulsion could be made and kept reliably if it were frozen. It was better to refrigerate at 2 - 4 deg C and use a very good bacteriostat/fungicide.

PE

It looks like what you are descrbing was directed at emulsion storage,
and for that I agree. I never store uncoated emulsion frozen.

Ray

 

[Photo Engineer]

Ian;

Some use of i-Propyl Alcohol and t-Butyl Alcohol is made as an antifoamant and that would lend an aromatic odor. Also, some bacteriostats and fungicides have a decidedly aromatic odor, not medicinal as one might think.

PE

 

[wildbillbugman]

Thank you Ron,
That answere as what of the type I was looking for.

Bill

 

[Ian Grant]

Ian;

Some use of i-Propyl Alcohol and t-Butyl Alcohol is made as an antifoamant and that would lend an aromatic odor. Also, some bacteria stats and fungicides have a decidedly aromatic odor, not medicinal as one might think.

PE

They may also tend to prevent an emulsion freezing at moderate sub zero temperatures, of course depending on how much is present.

My impression of Rockland Colloid's Liquid Light was it had a high level to prevent deterioration while not refrigerated, particularly during transit etc which could be a few days, and often at summer temperatures. Not the kind od conditions ideal for emulsion storage.

Ian

 

[Photo Engineer]

Ian;

That could be, but then t-Butyl Alcohol is slush at room temperature and a solid in a common refrigerator. The freezing point is depressed by water, but I was rethinking what it might do in an emulsion. The iPA is probably more common for that reason. IDK. Common shipping should not hurt. I have shipped my emulsion in mid July with no problem, and someone has sent me samples of theirs in August. The tests of both seemed normal.

Of course, long periods of heat will destroy emulsions and something is needed to terminate the sulfur and sulfur + gold reactions that they undergo. This will eventually fog them along with the damage that "bugs" do.

PE

 

[Ray Rogers]

Salts also depress water's freezing point.
Yea! for home hand cranked Ice Cream!

 

[Ray Rogers]

My impression of Rockland Colloid's Liquid Light was it had a high level to prevent deterioration while not refrigerated, particularly during transit etc which could be a few days, and often at summer temperatures. Not the kind of conditions ideal for emulsion storage.
Ian

You might be right.
I did not know it from that period, but that was quite a while back and they did go throuh a formula change/adjustment if I recall correctly.

(Did the stuff you got contain a seperate bottle of AF?)

Ray

 

[Ian Grant]

(Did the stuff you got contain a seperate bottle of AF?)

Ray

It's 32/33 years but no, I think I'd have remembered that..

Actually I tried it and it wasn't that good, compared to what I was already making on a very small trial scale. it was slower, had a higher fog level. The rest sat in a fridge for years before it went for silver recovery.

The problem is we don't know now what they used around 76/77 and what's more important is what we (or rather you) would use now. For the present my emulsion making days are on hold as they have been since 1986

I still have the instruction sheet, I think back in the UK.

Ian

 

[Photo Engineer]

Ian;

The way things are going, you may be back to making your own emulsions in the near future!

PE

 

[Ian Grant]

Working on that

Ian

 

[Ray Rogers]

Actually I tried it and it wasn't that good, compared to what I was already making on a very small trial scale. it was slower, had a higher fog level. I still have the instruction sheet, I think back in the UK. Ian

Ian,

I would like a copy of that instruction sheet next time you go back...
They had some trouble for a while with fog which is why I asked... I seem to recall that they did sell it at one point with an AF solution....

However, I should point out that they aimed their product at people who would be working in less than good darkroom conditions, frequently artists who did for themselves what you did commercially. The material I tested 10 or 15 years later was essentally a contact speed emulsion, with a very high D-max, good contrast and covering power and passable fog.

Afterwards they offered other, faster emulsions as well.

 

[Emulsion]

Whilst not directly related to a jar of homemade emulsion....the following Kodak publication has some brief information on freezing unprocessed film. They suggest -18 Celcius for long term storage of unprocessed Motion Picture film.
(My domestic freezer reaches around -25 Celcius.)

http://www.kodak.com/global/en/consumer/products/techInfo/e30/e30.pdf

As the publication pints out this won't stop gamma/cosmic ray fogging.

Emulsion.