Playing with sulfur sensitization

Hi everyone,

After reading PEs book several times I thought I would take an emulsion recipe and try to sensitize it with sulfur. I was going to make The Light Farm's amonium bromide recipe. Maybe it is not appropriate to try and sensitize this recipe and that could be part of my problem. I mainly want someone to check to see if I calculated the proper amount of sulfur. I see there are previous threds on this but I would like someone to check how I did this and figure out my horrible mistake.

So the recipe calls for 5 grams silver nitrate. I figure silver nitrate is about 169.87g/mol and silver is about 107.87g/ mol or about 64% the total mass of silver nitrate. In 5g Silver nitrate there is about. 3.2g silver. 3.2g Ag/107.87 is approximately 0.03mol Ag.

PEs book suggests sensitizing with 100mg Na2S2O3/1 mol Ag. So 100mg x 0.03mol Ag = 3mg hypo.

To get 3mg hypo I disolved 1g hypo in 100g H20, a 1% solution. I then took 1g of this solution and mixed it with 10g water to make a 0.1% solution. I think this would give me 1mg hypo in 1g H20. I added 3ml of this solution to the recipe after washing and then cooked for 60 min as directed in the recipe.

The result was total and complete fog. Black! I made this recipe without trying to add sulfur and it worked just fine. Very little fog and a very nice emulsion. So I am thinking my math is way off or it is not appropriate to try and sensitize this recipe for some reason. I also expect various recipes need different amounts of sulfur and it is not a one size fits all sort of thing. I also realize trying to measure 1g is a problem as I dont have a great scale but I think I am close. I thought i might have problems but I was very surprised with how absolutely black the plates turned out. I could use these as welding goggles no problem!


Any help is much appreciated as always.

Hi John,

I've never sulfur or sulfur+gold sensitized my ammonium bromide recipe. It's meant to be super basic, simple and essentially foolproof. It's the recipe I whip up to keep my Rolleiflex filled and with me always. But, I can't think of a reason sulfur+gold wouldn't work with it. Also, I've never sulfur-only sensitized. I figure if I'm going to go the trouble and have to watch my time and heat like a hawk, I might as well get the most bang for the buck .

If you get the time and interest, you might try this recipe: http://www.thelightfarm.com/cgi-bin/htmlgen.py?content=29aDec2011
Starts there and goes for three pages. The recipe is on the third page. There you'll find instructions for a sulfur+gold sensitizer (my adaptation of Steigmann's formula) that will probably work for any recipe of similar nature.

Hope it works for you as well as it has for me.
d

Thank you Denise. I just got all the ingredients for your Steigmann's and your recipe is next on my list to try. I was just in the midst of reading PE's book and playing around with your ammonium bromide recipe and thought what the heck I might as well try throwing in some sulfur! Needless to say I had less than encouraging results. I just could not think of a reason why it would not work.

John,

Well, now you've done it. You've set loose a bumblebee in my brain. I'm going to make AmBr with Steigmann's tomorrow. I'll be able to let you know how it works on Monday or Tuesday. Do you have preference for colorblind or ortho?
d

Hmmmm....... Ortho I think. Neat. I am excited to hear how it turns out. I probably wont get to try your recipe until next week. It is finally showing signs of spring in Duluth and garden work and a bit of plumming are on my list for the next few days.

Excellent! It will be great fun to compare results. Dialogues are so much more productive than monologues .
d

p.s. Glad you like the AmBr recipe.

Hi All,
I have been using Steigmanns for my NH4Br/I emulsions for some months now. I see no reason to NOT do it. Before reading the above reports I was thinking of posting what I found yesterday. A Br/I emulsion I made was showing what I thought to be fogging. But when I turned off the little Bright Lab Jr. Safe light (red safe light about 3 feet above coated and dried plate) and left the coated and dried emulsion in a tiny amount of ambient light, the "fogging" went away. I now realize that some emulsions that I had discarded as "fogging" were simply sensitive to safe lights.
Just my two cents. To keep everything in perspective, none of my emulsions contain gelatin. Just to be Stubborn, all of my emulsions are based on silane functional PVA. I have used this as a base for Pt/Pd/ Au printing, as well as dichromate/ pigment printing and Carbon Tissue. I guess I am stuck on it. And stuborn.
Bill

Yes you can sensitize that emulsion with Sulfur or Sulfur + Au. The problem is that each emulsion takes a different quantity of sensitizer solution or time or temp.

The simplest way to test "finish" level is to heat a tiny amount of emulsion to 60C and then place 1 drop on a blotter. Add the appropriate amount of sensitizing solution for the quantity of emulsion. Wait 10mins and take a 1 drop sample and place it on the blotter next to the last one. Continue every 10 mins for 1 hour and then develop this.

The appearance of fog is the indication of the fact that the emulsion is overdone. Back off 5 or 10 mins and you have the correct time.

See the figure, courtesy of Nick Brandreth.

The correct time for this emulsion is about 15 mins for the best speed and fog. It is my latest brainstorm, and Nick is working with it to learn the ins and outs.

PE

Thank you Denise, Bill and PE. I remember reading about the blotter test in a different thread and forgot about trying it when I got the bright idea to toss sulfur into this recipe.

Since I had this batch of totally fogged emulsion I thought I would try the PMT just for the heck of it since i never used the stuff before. You are right PE that it it a VERY powerful anti fogging agent. I actually got crystal clear plates after adding it to the completely fogged emulsion. The film speed went down to nothing but it certainly worked. I am thinking I need to be a bit more controlled in my future endeavors.

Start PMT at about 1 mg / mole of Silver.

Go up from there until fog goes away. You will have some speed left.

PE

Speaking of fogging,
Today I made an emulsion that contained 10.0g of AgNO3 AND 1.1 X the moler equivalent of NH4Br, with a very small amount of NH4I. With 6 drops of steigmanns it had a fairly high level of Au and S. The finished emulsion showed some, but not much fogging. So I added o.1 moler equivalent (to AgNO3) of NH4Br. Then, I put the whole darn thing on the mixer, intending to mix for 1/2 hour at 90C.
Well, I forgot the darn thing for about 90 minutes. I cursed and expected total fog. And BEHOLD! Absolutely NO-zero- fogging. Maybe some Deity dose watch over Fools.
bill

What happened to speed and contrast?

PE

PE.
I will have an answer to those questions on Monday. my emulsions take longer to dry than gelatin emulsions. I will coat my plates tomorrow night. But judging from tests on paper, the speed at least seams to be fair,
Bill

John Sager said:

Hmmmm....... Ortho I think. Neat. I am excited to hear how it turns out. I probably wont get to try your recipe until next week. It is finally showing signs of spring in Duluth and garden work and a bit of plumming are on my list for the next few days.

Click to expand...

Same here. The forecast rains stopped early and I have been out in the garden trying to keep up with the spring jungle!

Congratulations on finally getting out in your garden! I hear about your weather at least twice a week. I grew up about 100 miles west of you and my family still lives there. Spring in Duluth comes even later! (One of the really special places in the US, though.)

Hi to all,
Unfortunately, the emulsion I spoke of above was too low in viscosity to get a good coating on glass. coated onto white cardboard the emulsion is fast with good contrast. considering that my developer is D19. I will do it over with less water. Bill

John,

I just tested the AmBr-ortho with Steigmann's. Good news: Absolutely no fog. Crystal clear base and excellent contrast. Bad news: The 'good news', as far as I can tell, is because the amount of Steigmann's I added had absolutely no effect. I just guessed the amount, of course, but it was the amount that produces full effect in an ammoniacal emulsion. 4 drops in 5 ml Everclear, added right after the 10% KBr in Everclear before the washed noodle ripening (the Light Farm recipe).

It is a dark, dark day here. Not raining but it really wants to. I made my test shots (the standard stuffed animals on a garden bench) at f/8 and 1 sec. The lighter colors are very good on the negatives, but the dark colors and shade pretty much registered as clear film.

I won't be going further with this. It's not the role of AmBr to be speedy, at least as I photo with it. But, I would be absolutely delighted if you pursued S or Au+S for more speed with the recipe. If you do, I hope you let us know how it goes. At least you know where to start for no fog.

I can post the negatives tomorrow after they dry if you want, but you probably know what they look like. Puff, Miss Piggy, and Pancho get a lot of press .

Denise, the SRAD is probably coarser grained and takes less Steigmanns than the one you are studying now (AmBr Ortho). This new one is probably finer grained and will take much more sensitizing solution. Also, more KBr might have been retained, and this retards chemical sensitization.

Sensitizing dye added before Steigmans can retard Steigmans as well. The addition order of the dye is not clear.

PE

That pretty much follows my train of thought. It's why I recommended John try "TLF#2", an ammoniacal emulsion that benefits from Au+S sensitization. Making an emulsion with ammonia only adds a step. On further thought, though, I can see why someone who can't stand the smell of ammonia would want to squeeze as much speed as possible from a plain silver emulsion. It is unlikely to ever get up to handheld speeds, but a quarter of a second is a lot faster than one second in some situations. And, of course, just understanding the ins and outs, ups and downs of emulsions is itself a worthy pursuit . I hope John, or someone else, follows up on it. For myself, I find that I am very happy with my trio of emulsions. Different strokes.

John,

I will toss a thought onto the pile. Do you have any idea what the pH of your AmBr emulsion was when you added the sulfur? pH affects sensitizing speed and the higher the pH, the faster sensitization takes place. This was described by Carroll and Hubbard. I am wondering if an AmBr emulsion would be more alkaline than a BrI? (I have no idea OTOMH) IIRC you want the pH around 6.5 - 7.

My latest AgBrI wonder is sensitized with sodium thiocyanate, which I found to have more of an effect than sodium thiosulfate in this mixture - although you can reportedly actually use both at the same time. Haven't added any Au yet. Anyway in order to get the sensitization to work, I needed to move pH to the correct range of ~6.2 from ~4.7. In doing so, I overdid the addition of NaOH and drove the pH up to about 10. The emulsion was instantly and totally fogged like you describe. The same amount of sensitizer (50mg/mol Ag) at a pH of 6.2 produces no fog at all and about a 3x gain in speed from the base emulsion.

Denise's TLF2 emulsion is quite nice. I have made plenty of it. If you are careful you ought to be able to get the speed at least to 50. Make certain it is well washed for the after-ripening step.

Also, for the sensitizing time breakdown that Ron describes with the blotter paper, if you don't have blotter paper, matte inkjet photo paper makes an acceptable substitute. I have also used glass microscope slides which are cheap and re-usable.

-- Jason

Thank you all very much! No. I do not know what the pH was when I added the sulfur. I just did it as a larf because I was waiting from my gold chloride etc from the formulary to be delivered to try TLF2. I think before I go off willy nilly again I am going to try TLF2 following the recipe EXACTLY and see how that goes. I do want to play with sensitizing the AmBro though but for now I need a little success. I have tossed out a lot of plates lately.

So here is a very silly question. In my day job I have done much water quality sampling and I am very familiar with pH meters etc. How exaclty do I measure the pH of an emulsion? PH paper? I cant see myself dunking a pH probe in an emulsion and I cant see how pH paper would work well either. It is a very silly question but.......

A pH probe works just fine, but it is best to avoid long times in the emulsion and try to avoid a calomel electrode due to the Mercury.

PE

P.E.
I finally finished another batch of emulsion in which I reduced the water content and once again kept it at 90C for 90 minutes. As of now I can only say that it is completely free of fog. I will coat more glass plates tonight or tomorrow and find out about speed and contrast. I do not expect low or medium contrast with D19. So I will look at another developer.
Bill