New emulsion maker questions: chemical keeping properties and availability

Hi,

I've been doing a lot of reading on APUG, and a came across a thread that Bill started regarding the small number of home-darkroom emulsion researchers. It made me a little sad and has prompted me to get started in emulsion making and research. Just by the way of introduction, I am an undergraduate student studying chemistry, so hopefully knowing some chemistry will help me in getting going.

Is there a concerted effort by folks in this sub-forum to advance particular research goals, or is everyone kinda of doing their own thing? I eventually hope to get into measuring vAg and automating the precipitation, but I was wondering if there is a particular area of "old-style", SR emulsions that is not well studied. Is there a gap in knowledge that hasn't been investigated very much? I will be starting out with the basic tools (hotplate/stirrer, manually operated syringe, etc), so any research would have to be tailored to techniques possible with that level of equipment.

I've been earnestly reading and rereading PE's book, this forum and TLF and have ordered the basic labware and some reagents. I have been trying to source all the required chemicals, and am having a rather difficult time. I've done my best to look for the answers to the questions below, but haven't found anything conclusive. I thought I'd just put out a few questions to the forum before a spend a chunk of change on chemicals from several different sources and get dinged for shipping multiple times.

Hardener:
It seems as though glyoxal is only available in fairly large quantities (considering only 0.5mL of 40% is required for 100 mL of emulsion). I read that it goes bad in about 6 months even when unopened. I know that chrome alum is best suited to glass plates, but how unsuitable is chrome alum for paper (or film)? Is the slow hardening action of chrome alum quite inconvenient in practice?

What's the shelf life of PMT and TAI solutions? All I can find is that the Sigma MSDS say " Stable under recommended storage conditions", but I'd like to know about a solution, such as is supplied by the formulary.

I contacted the formulary and was disappointed to hear that they no longer stock phthalated gelatin. Of course the best is UF, but I can't afford that now. Am I stuck with noodle washing, or is there another source that carries phthalated gelatin in reasonable quantities (i.e. reasonable price)?

Preservative:
I can't seem to find thymol for sale in Canada anywhere. Is it really only for preserving uncoated emulsions in the refrigerator, or does the final coated material expire more quickly without thymol as well? I imagine the low moisture content and silver salts in dried coated emulsions would be pretty unfavorable to bugs. I guess I can probably do without.

Any source for Erythrosine? I've searched for acid red 51, FD&C 3, etc, but no one seems to sell to individuals. Is it typically sold as a solid or a solution? What are its keeping properties as a solid or stock solution (PE mentions in his book that the 0.1% working solution keeps 1 week to 1 month depending if refrigerated)?

Sorry for the mundane questions, hopefully I'll get going soon enough and have something valuable to contribute. Thanks for your consideration.
Ian

Glyoxal keeps well as a 40% solution for a year or more if refrigerated. Diluted for use, it keeps for a few weeks. Chrome Alum solution keeps well as does the solid. If it turns green it is bad.

PMT and TAI as solids keep just about forever, but in solution I would not use them over a month old unless refrigerated.

PA gelatin is not available and I suggest you use the noodle wash from the book (see the step wise photos). A common potato ricer does well if washed well after use.

Try Kyantec or Antec in Kentucky. They have erytrhosine at very reasonable prices and as a solid it is stable for just about forever. In solution and refrigerated, it can keep for a year or so.

PE

Photo Engineer said:

PMT and TAI as solids keep just about forever, but in solution I would not use them over a month old unless refrigerated.

....
PE

Click to expand...

Ohoh! Methinks I'm due to restock the larder. My TAI and PMT sol'ns are 3+ yrs old, but kept refrigerated at 3° C.

Note to Iandvaag: You can try Nymoc in Toronto for Erythrosin and thymol. A pharmacy that does compounding might also be able to provide thymol.

Hi Ian,

Welcome to emulsion making. Yes, it has been quiet lately. Glad you have stirred things up.

I don't know about specific research directions. Find something that interests you, be it film or paper. Best thing to do is dive in and make something. Guaranteed after that you will want to tweak something and pick a direction. The formulas from Ron's (PE) book are great. Another is the TLF X2Ag. I've made some of the ones in Ron's book and the X2Ag. Not hard to make and work well, but not high speed. Speed is harder but you don't really want to start there.

One thing to bear in mind, if you dump an AgNO3 solution into a KBr solution, you WILL get AgBr, it's just that simple, everything else is tweaking. So pick a formula that grabs your attention and have at it.

As far as chemical storage, as PE says, they have definite shelf lives as liquids. Solids are pretty much stable. I'll differ with Ron on lengths of shelf life as my stock Glyoxal is several years old and seems to work fine. Same for most of the chemicals I have, but mine are all stored in a cool, dry, dark basement.

To start, don't worry too much about dyes. You do not have to have erythrosine. However, you can use the McCormick Pink food coloring you can get in any grocery store. Besides FD&C 3 (erythrosine) it has FD&C 40, which will not affect things one way or the other. I have bought "official" erythrosine through eBay and have also purchased powdered red food coloring on eBay that works just as well. Verify with the seller that it is FD&C 3 and not 40. 40 will do nothing. Sellers don't seem to want to say "FD&C 3" for some reason, but most of it is. The same is also a good source for yellow tartrazine. Pinacyanol is for the advanced.

You do not "need" thymol. It is a preservative. As long as you do not plan to store your emulsion for extended periods (several months) you can regard it as optional.

Most of my "less critical" chemicals come from eBay. Do a little research and buy from reputable sellers that have lasted for a while. Critical stuff I get from Artcraft Chemical or the Formulary. I have better luck with Artcraft. Love the guys at the Formulary but shipping costs from them to me are astronomical, so I only buy there when I have to.

Noodle washing is fine, nothing wrong with it. I use distilled water with 1 tablespoon of Magnesium Sulfate added per US gallon. The MgSO3 keeps the noodles from swelling. Also, if you do not have a potato ricer (I could never find one at a reasonable price, but I am cheap) you can just cut up the emulsion into small pieces with a sharp knife such as a kitchen paring knife. Works fine.

Now, if you are making film, you will need a plastic base to coat it on. Have you given thought to what you will use? To start, I would like to suggest Grafix Dura-Lar Wet Media film. This is a PET film that has a subbing layer applied. The only real downside is that it is a 4 mil base instead of 5, which would be nicer. Lately the price has gone up quite a bit, but worth the money as it will save many headaches. I suspect it is DuPont Melinex 535 which is as expensive as hell if you can even find it as a normal person. Once you get more advanced you can look into subbing your own material.

Lastly, if you enjoyed Ron's book, you may also want to get a copy of Bob Shanebrook's "Making Kodak Film", second edition. He advertises the book here on APUG. AAMOF the ad is at the bottom of my screen as I write. Once you have a little experience you will find parts of this book that are practically an instruction manual in how some of the great EK films of the past were produced. You do, however, need to gain some background knowledge to fill in the blanks.

Anyway, dive in and have some fun. We will all be here to answer questions.

-- Jason

PS: I have a patent in my literature collection with a procedure to make PA gelatin. Haven't tried it yet but it seems simple and straight-forward. I am sure there is a catch.

I got my TAI and PMT from the Formulary about a year ago. I hope it is still good! Haven't even gotten to open the bottles yet!

I have nothing to offer here except to say that beekeepers still use thymol, so see if there is a local society or look online for beekeepers suppliers.

Will Antec sell to "normal" people as opposed to industrial customers? I convinced one of the BIG guys to sell me a few things, but I had to have it shipped to my work address, which my work was not crazy about. They made me run down MSDS's and such and I had to convince them that the stuff would not explode, that I wasn't using it at work and was taking it directly to my car before they would give it to me from the receiving dock.

Antec sold to "normal" people when I bought from them. That is my experience. All of the above is my experience. I refrigerate everything in solution but keep every solid on the shelf. It might indeed keep longer. I am just giving my longest observed usable bottle. I usually use it up before that time.

Sorry, but I am usually conservative. My PMT is nearly 20 years old and my TAI is over 10 years old. These are solids and they still work.

If it works, or if it is in the original condition (not yellowed, etc) I would use it. The dye is a food dye and was used in Merthiolate years ago, so I expect long shelf life from it.

PE

Thymol in Canada is strictly regulated, most likely as an offshoot of the fact that it is used in beekeeping, and there is a reasonably strong government perception of the importance of bees to our environment.
The inadvertent consequence of that strict regulation, is that it is difficult to obtain Thymol if you aren't a beekeeper. Importation of the easily obtained but untested stuff is illegal (to protect the bees) and the bee industry suppliers only supply to registered beekeepers.

It is contained in Listerine and is the major active ingredient. Try substituting Listerine.

I am working on a new bacteriostat that is 40x more potent than Thymol.

PE

hmm. I might become a legitimate businessman as a bootlegger in Canadia.
they will call me the Thymol Tsar.

Ironically, one of the major suppliers of approved, "bee grade" Thymol is Canadian. The rules prevent them from selling to people who aren't registered bee keepers.

Thanks for all the responses. Very much appreciated.

kb3lms said:

I would like to suggest Grafix Dura-Lar Wet Media film

Click to expand...

Thanks for mentioning this. It's nice to know that there's a pre-subbed material out there. I'll definitely keep this in mind down the road after becoming comfortable with paper coating.

kb3lms said:

you may also want to get a copy of Bob Shanebrook's "Making Kodak Film", second edition

Click to expand...

Yeah, I got my copy a couple weeks ago. It's really great!

Photo Engineer said:

Antec sold to "normal" people when I bought from them.

Click to expand...

Kyantec does indeed sell to individuals, and they stock erythrosine. When PE said "very reasonable prices", I thought this was in reference to other sensitizing dyes, but I didn't understand how cheap it really is. Very reasonable indeed.

Photo Engineer said:

All of the above is my experience.

Click to expand...

Photo Engineer said:

Sorry, but I am usually conservative. My PMT is nearly 20 years old and my TAI is over 10 years old.

Click to expand...

Thanks for sharing your experience, that's exactly why I am asking. I want to do repeatable science, and don't want decomposing chemicals to get in the way. Can you recommend any source for solid PMT and TAI? I asked and The Formulary says they do not stock the crystals, only solutions. I know these aren't probably something I need right away, and I don't want to get too ahead of myself. My thinking is this: for the time being there's not a lot I can do with varying precipitation just using manual syringes, but maybe I could look into sensitization, in which case PMT and TAI are pretty useful.

MattKing said:

Importation of the easily obtained but untested stuff is illegal

Click to expand...

Thanks for sharing this information. I assume that something like these thymol crystals would not be legal to import to Canada in that case. Do you have any online reference that outlines the regulation?

Photo Engineer said:

Try substituting Listerine.

Click to expand...

I will look into this. I can't wait to hear about your new bacteriostat.

My hotplate comes in a couple weeks! I'm sure I'll be back with more questions then.
Ian

PMT and TAI are sold in solid and solution form by the Photographers Formulary.

PE

The person I contacted at the formulary (it wasn't Bud) said they sell neither PMT nor TAI as solids. Should I ask again?

They may prefer to sell the solution, but they have both. They must have the solid to make the solutions. But, as a beginner, you do not need either.

PE

I agree, I'm just trying to save on shipping, import costs and additional charges by buying chemicals I anticipate needing in the future since each order has a significant base cost to it regardless of how much is ordered. My Canadian loonies don't go very far! I guess I'll leave it for now. Thanks.

iandvaag said:

Thanks for sharing this information. I assume that something like these thymol crystals would not be legal to import to Canada in that case. Do you have any online reference that outlines the regulation?

Click to expand...

I've been trying to work through this, but it isn't easy.
The problem is that because Thymol has an important role in agriculture (bees in particular), the federal regulations relating to agriculture are used to test and approve and regulate the importation and use of products that contain Thymol.
If you try searches, you will end up with results that deal with the approved products, and penalties for mis-use of approved products or importation or use of un-approved products.
The problem with trying to point you to a clear and concise rule is that the system assumes you want it for your bees, and doesn't really deal with uses that aren't agricultural in nature. When you try to import Thymol though, the shippers, customs brokers and border officials treat it as being intended for agricultural purposes.
The people I know who have brought it into Canada had it shipped to a destination outside Canada and then imported it personally (most likely without formally identifying exactly what they had).

Checked out Antec yesterday. Their prices certainly seem to be reasonable. Saw nothing on their website that said they would not sell to individuals, in fact they specifically mention photographers and hobbyists. I will try them next time I need some materials.

Can you not pour all of the emulsion in one session, therefore omitting Thymol? Yes, I realise film/paper emulsion is way more valuable than say, glop (gelatin laced with pigment for us carbon printers), but still... mix it up and coat it all.

Thymol is absolutely unnecessary. Emulsion keeps in the refrigerator for up to a month. The use of a preservative gained traction years ago when a few of us were trying to learn to make emulsions. There was very little information available, and most of it came from factory-scale recipes. At the time, making an emulsion was considered so difficult and complex a thing to do that people wanted to make a year's supply once a year. Wrong on so many levels it hurts. Fortunately, most of us know better now. Making one of the simpler emulsions is no more difficult than making carbon glop, or making supper for that matter. Make what you need, when you need it.

If you use your emulsion immediately, thymol is not needed, but if you intend to use it gradually in several sessions spread over several weeks or even months, thymol is needed. Even so, there are 2 levels of stronger antibacterials which can extend the life for up to a year or more.

PE

I find it funny that I can buy phenol quite easily, but not thymol. Regulations seem rather arbitrary sometimes. It's good that I can make and coat small batches without the need for preservative since I wouldn't use phenol without a fume hood.

Here in NY Phenol is banned. It is the starting material for things terrorists would love to get their hands on. Phenol is quite dangerous if you get it on your hands. Almost instant blistering unless you soak your hand in 95% alcohol. Even so, your spot where it was spilled can go numb and turn white. Don't ask me how I know.

Sodium Azide is another preservative, but it is nasty stuff as well.

PE

I just wanted to post back to let y'all know I've not given up! I'm still waiting on some items that I've ordered to arrive (magnetic stir bar, filter, monoject syringes), but I was getting antsy and I couldn't wait. So I made PE's basic AgCl emulsion and coated it on some strathmore smooth and some cheap cardstock from Michaels. I really enjoyed the process, and appreciate the support of all you here, particularly PE for his wonderful book and dvd.

I had quite a lot of large black specks (pepper grain?) that I imagine formed because of my woefully inadequate manual stirring as well as uneven/rapid addition with a large tipped medicine syringe. I suspect I'll be able to do better once the stir bar and syringes arrive.

Thanks.