Alcohol

[Simon Howers]

I note that many emulsion recipes call for the use of alcohol. Those in the US cheerfully buy "Everclear". In the UK such things are restricted. I have been using isopropyl with commercially available emulsions for coating and have had no problems. Can this be used more generally in the manufacture of emulsions or do I need to use Ethanol ?

 

[AgX]

What is restricted?
Alcohol (Ethanol) is highly taxed in some countries, with low taxed "denatured" Ethanol as alternative. (With varying denaturing addives that might be troublesome.)

 

[Gerald C Koch]

In the US the availability of isopropyl alcohol has largely replaced that of denatured ethyl alcohol for external medicinal use. The common denaturant for this purpose is sucrose octa-acetate which has an intense bitterness and causes stomach upset. Quinine is also used for its bitter taste. The federal government lists dozens of denaturing ingredients depending on the ultimate use of the alcohol. Besides the ones mentioned there is also methyl alcohol and nicotine. Both make the alcohol unfit to drink. During Prohibition strychnine was approved for use. It was advocated by rabid Prohibitionists.

Probably the main practical difference between the alcohols are their volatilities. Methyl alcohol would have the highest and isopropyl the least. I am unsure as to what would happen to an emulsion if a substitution was made. Drug stores also sell 90% or higher percentages for needle sterilization.

 

[dwross]

Hi Simon,
This is the easiest "problem" of any to solve. Use plain vodka. It's essentially half ethanol. Double the volume Everclear called for and then subtract the extra water from the water called for in the rest of the recipe (except the water in the precipitation step -- that particular water/gelatin ratio is usually precise). Good luck and fun.
d

 

[Photo Engineer]

Ethanol is not used in any emulsion today AFAIK. It was only used in early emulsions as a surfactant and antifoamant and both of these, as chemicals were unknown back then. Today, you can achieve this by a variety of means. Photo flo is a siimple surfactant and can be used at the rate of about 1 - 2 drops per 100 ml of emulsion. Use of a gold mesh coffee filter will do wonders removing bubbles.

If you insist on using an alcohol, make sure it is NOT denatured, as these can do bad things to emulsions. To demonstrate, most harmful denaturants will turn cloudy on addition to water. This haze is not good.

PE

 

[wy2l]

"Alcohol - The cause of, and solution to, all of life's problems." - H. Simpson

 

[dwross]

I think perhaps it is time to refresh our agreed-upon vocabulary. It's far too easy for us old-timers to forget that new folk come through here all the time and probably aren't familiar with our shorthand. It would be a shame if they came away with wrong impressions. Unless someone specifically asks about factory procedure, perhaps we can agree that the question is about making emulsions in a home darkroom. Only a suggestion, of course, but I do think it would reduce misunderstandings .

When PE says "ethanol is not used in any emulsion today AFAIK" he is referring to modern emulsions, almost by definition factory emulsions. I don't know for sure that ethanol is not used today in some factory or another, but I assume he does. Point being, of course, we are not making factory emulsions. Every handmade emulsion recipe I'm familiar with, including all The Light Farm ones and the dry plate recipe made at the Eastman Museum workshops, contain ethanol. The Osterman recipe on TLF calls for 95% grain alcohol, i.e. ethanol/Everclear.

btw: Be careful with Photo-flo in dry plate recipes. It's great for paper, and a small amount is OK with film, but in my experience it takes very little Photo-flo to lift emulsion straight off glass. I've eliminated it in my plate work.

 

[Photo Engineer]

Ok Denise. Alcohol (ethanol or methanol or propanol) have not been used in any Kodak (or other modern) facility for making or coating emulsions. t-Butyl alcohol was used in making as a foam suppressant until good antifoaming agents became available in the '60s.

Now, as for plates and film, Mark has used both Photo Flo and Everclear, but recent emulsions and coatings by Nick at GEH use either nothing or Photo Flo. He is now asking me for alternatives in addition to the Photo Flo. They have had no lift problems AFAIK.

He uses 0.5 ml Photo Flo in about 200 ml of emulsion. This is the level used in my book.

PE

 

[dwross]

Many good paths through the forest.

 

[Hexavalent]

As ethanol is available only in 'booze' form here (meaning ridiculously expensive), I use 99% isopropyl instead. It works fine.

I also obtained some t-butanol (on PE advice), and dissolved in isopropyl, it makes an extremely effective de-foamer and coating aid.

For glass plates, I got into the habit of first subbing the glass with very dilute gelatin and chrome alum as one would do for microscope slides. Subsequent emulsion coating sticks very firmly.

 

[Photo Engineer]

Chrome Alum is the preferred hardener for glass plates anyhow.

Good to see you here Ian.

PE

 

[Photo Engineer]

As I noted, some denatures can cause problems.

 

[Hexavalent]

Hi Ron!

Indeed subbing with very dilute gelatin + Cr Alum creates a very tenacious coating. It's not so easy to strip and re-use plates without some fairly ferocious cleaning.

 

[alanrockwood]

One comment about alcohols. One big difference between ethanol and isopropanol is that ethanol is a much more polar compound. This might make a difference, or it might not, but the two compounds are not interchangeable in every application, though they are in some applications.

 

[Simon Howers]

Vodka it is then!

Hi Simon,
This is the easiest "problem" of any to solve. Use plain vodka. It's essentially half ethanol. Double the volume Everclear called for and then subtract the extra water from the water called for in the rest of the recipe (except the water in the precipitation step -- that particular water/gelatin ratio is usually precise). Good luck and fun.
d

Thanks Denise.
I'm off to the supermarket for some cheap vodka!

Simon

 

[Photo Engineer]

Ian, (Hexavalent) reminded me of one fact I had forgotten to mention here. And yet, it is one well known to me and one that I had researched early on in my home emulsion work.

Alcohol was abandoned early on for this reason:

https://en.wikipedia.org/wiki/Silver_fulminate

It has the potential to be very very dangerous if this reaction should take place, and the conditions in an emulsion are quite appropriate for the formation of Silver Fulminate.

Thanks Ian. I thought I might post your reminder to me since you appear to be off-line.

Best wishes to all.

PE

 

[dwross]

Thanks, Ron, for the important safety tip: don't mix silver nitrate with nitric acid (or cross the streams).

 

[Photo Engineer]

Denise, an acid emulsion, due to the presence of AgNO3 or after pptn, the NaNO3, contains Nitric Acid!

All emulsions contain some quantity of HNO3 if the pH is lower than 7!

PE

 

[dwross]

Well, dang. You're serious, aren't you? I suppose I should at least try to be, too.
....Nope, can't get there. This isn't an issue in emulsion making. (How did sodium become a character in this tale?)

 

[Photo Engineer]

AgNO3 + NaBr -> AgBr and NaNO3.

Elementary Denise.

And yes, explosions have taken place even at small volumes.

PE

 

[Simon Howers]

From the Micklethwaite Explosives Factory

AgNO3 + NaBr -> AgBr and NaNO3.

Elementary Denise.

And yes, explosions have taken place even at small volumes.

PE

Yikes! I'll do my best not to explode the darkroom.

Thanks for all the input everybody.

Denise, I really enjoyed your book. When do you think the others will be published?

Simon.

 

[dwross]

Thanks, Simon! That is a lovely thing to read early on my Thanksgiving Day! I enjoyed writing it. Volume 2 is already in progress. (The stars willing) it will be done either spring or fall 2017, depending in whether I need one summer or two for outside testing and photography. I might break it down into two separate books, so that people who aren't interested in color processes don't have to pay for those pages.

You are sure to have questions along the way. Please feel very free to contact me. From a selfish point of view, I find questions invaluable. They are the very best way to build a rigorous field of knowledge (the only way, actually). There will be a section in Vol 2 that addresses the problems, questions, and alternate solutions and insights that new emulsion makers have come upon.

Case in point: Exploding emulsions. I got very curious about this one last night. Urban legends have to start somewhere. Unfortunately, there isn't a Snopes.com for chemistry! It turns out that if one is really careless and forgetful, you could get ammoniacal silver to go boom. If a solution of ammonia and silver nitrate isn't used when it's made, but rather sits for several weeks, it can form an explosive complex. (I will spare people the formula.) For emulsion making, this isn't going to happen because we use the stuff as soon as we make it. Here's the thing, though, and why it's so important that we keep open, honest, and non-defensive conversation going: if you didn't wash your emulsion making glassware soon after you made your emulsion, the drop of ammoniacal silver that was left in the prep beaker could dry and become a potential explosive. It would be a teeny, tiny explosion, but who wants even that . My darkroom is too small and my glassware too limited to not clean things immediately, but I can imagine someone else treating darkroom dishes like my college roommate treated our kitchen dishes. This is a useful bit of info for us all.

Well, it's off to the kitchen for me! I'll try not to explode the turkey .
d

 

[Hexavalent]

Case in point: years ago there was an explosion in a nearby high school lab - a student decided to wash some silver nitrate xtals with ethanol. Fortunately, the only damage was a shattered erlenmeyer.

It only takes a moment of inattention, an unlabelled beaker, etc., for mishaps to occur.

 

[dwross]

Perhaps a sticky with common sense safety rules for working with chemistry would be helpful. I'm sure I'm not the only one who is dismayed by how fearful too many people are becoming about anything and everything. Education is the best way I know to combat that. I'd hate to see a generally good idea like "don't run with scissors" become "don't run" just because people couldn't be bothered to understand the concept of sharp and pointy.

Reading the material safety data sheets (MSDS) is always a good idea (or Wiki). Labeling beakers is a great one! I've always stressed cleaning up glassware and the darkroom ASAP after any work session. That's been mainly because dirt dust and chemical dust are not the BFF's of emulsion making, but it's apparently also a good safety tip .

 

[TheMissingLink]

I doing wet lates since some years and as the plates became necessarily larger and larger the expense for alcohol (ethanol) increased.
Our government added a new additional tax on it too.
So I decided to give it a try with denat. ethanol. We only pay 5% of the price of the pure alc. Until today ( 3years) I didn't notice any changes with my plates, the same problems like always ;-)
I use either denat. one or the one called bio-ethanol (also denat.) for the funnel.
Just startet to use it also for carbon and photogravure ... in 200 or 300 years I perhaps can report either success or failure ;-)

ho.