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Grade 5 emulsion for enlarging paper

di de

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Marseille, F
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Hello everybody here
I'm back to emulsion making !

I would like to obtain a high contrast emulsion for enlarging paper (so bromide I presume), an equivalent of grade 4 or 5.

Is it simply possible ? Which way(s) should I explore ?

Thanks
 
TLF ClBr All-purpose Kodabromide-type, condenser enlarger, and a high contrast developer.
 
Thank you Denise
I've tried some things with the bromide paper emulsion for enlarging that is in your book without any success, will try with ClBr
But I've not a condenser enlarger
I use ID-14 1+1 as developer, what would you advise ?
 
Bromide paper is by its chemical nature a soft paper with a long density range. It's most suitable for very dense and/or very high contrast negatives. It was the enlarging paper of choice when photographers were moving from the various POP papers to silver gelatin enlarging, but still wanted to use the negatives they had made for the old papers. ClBr papers were developed later, when more photographers made negatives with enlarging in mind from the start. Also, for the smaller negatives that were coming into use. (35mm was once called "miniature"). Chloride paper is by nature very contrasty, but slow. A ClBr emulsion is the best of both worlds -- good for both contact printing and enlarging, and quite responsive to different developers. A diffusion enlarger will give you a bit softer result, but it will work. I've never used ID-14, so I can't speak to it. I like Agfa 108. It's in Steve Anchell's Darkroom Cookbook, page 247 of the 3rd edition. I'm sure there are others, but that's the one I can recommend. Good luck. I'd love to hear how things turn out.
 
You could try adding washing soda to your print developer.

I add it to HC110 for developing prints and no problem with weak blacks. (30ml HC110, 15g washing soda, 1 litre water.)

I did read of someone reporting weak blacks using straight HC110 for prints so I assume that the washing soda adds some ferocity.
 
I tried ClBr but my set up wasn't well prepared and the temperature of my second waterbath was only about 50°C.
My emulsion is a bit more contrasty but very far from a grade 5 print from a multigrade paper, I also have very much pepper (I used ID-14 full strength), but I coated on two different papers and got pepper only on one...
 
If I can't get exactly what I want for this paper print emulsion, I will try to gain contrast on my negative emulsion (which is TLF#2), not sure it would be less difficult...
 
di de said:
Is it simply possible ? Which way(s) should I explore ?
Click to expand...

What addition time are you using ? Digestion? Rippening ?

To increase contrast you may try to make addition time well shorter, with also shortened digestion and rippening times, not allowing much grain growth and size dispersion or, better said, to allow a lower crystal size dispersion until you have the contrast you want without decreasing emulsion speed too much.

A pictorial emulsion consists in crystals of different sizes (and different ISO), as you have a variety of crystal sizes you increase emulsion latitude and decrease intrinsic contrast (beyond development degree adjusting contrast).

A microfilm type emulsion (ADOX CMS 20) is "monodisperse", meaning that all crystals have similar size, the more "monodisperse" the emulsion is the more contrasty, ideally a pure monodisperse emulsion tends to have "infinite" contrast, you have black or white, but not gray scale, for this reason CMS 20 (and ancient Techpan) required extra low contrast processing.

With that you'll also get an speed decrease, so you should balance what you do.

If not doing it yet, I'd recommend you to make a technical approach for those experiments, use an Stouffer T2115 to make contact copies, and calibrate your emulsion tests, use a cheap luxmeter with 0.01 Lux scale to have a good reference.

I was trying to develop the high contrast component of a DIY VC emulsion, and I made several experiments in that direction, but I made a temporary break in that project that I'll resume in comming months, playing with those factors it was the next step, so if you try that way please report your findings, it would be nice to know what resulted.
 
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Thank you for your comment

I dump my silver nitrate all at once and ripening time is 45mn at 65°C
 
di de said:
Thank you for your comment

I dump my silver nitrate all at once and ripening time is 45mn at 65°C
Click to expand...

Realistically, it's probably going to have to be a dual run emulsion with good process controls to get anywhere close to grade 5 at enlarging speed - and that's severely understating the complexity/ enormity of the task (from my understanding). The other problem will be substituting any of the nastier heavy metal salts traditionally used as curve modifiers before the move to the more sophisticated high chloride/ converted chloride emulsions with very high monodispersity used from the 1970's onwards & the use of extensive ballasting etc to get full range Multigrade materials. Don't be discouraged, but it's going to be a lot of work.
 
Well, I don't know much about emulsion making, that's why I was wondering if that was simply possible... I guess now it's out of (my) reach, but I will play a little bit longer with some variables to see where i can get...
 
di de said:
I dump my silver nitrate all at once and ripening time is 45mn at 65°C
Click to expand...

(Edited: next is wrong)

I'd try 55ºC, then I'd extract samples at 5 min, 10 min, 20min and 40min.
 
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this is an unwashed emulsion

I will try this sampling method, thanks,
 
Lachlan: Do you have a source for your opinion about dual run? I'd love to read it. Not my experience, fwiw.
Contrast control masking is a classic way to achieve a high level of contrast control. Not just "grades," but additionally an early form of variable contrast.
 

Lowering the ripening temperature and reducing the time both reduce the contrast.
 
Denise, I will also try masking but it will not be so easy on 120 format...
 

Ron's book, pg.140, mainly because making a G5 emulsion seems to me to be something that will need a specific and controlled Cl:Br ratio, and ideally with a quite monodisperse character (ie a higher chloride content?).

Are you able to achieve an ISO (R) of 50-55 with your technique? Or to put it another way, what grade does the SPSE/ Woodlief Thomas emulsion max out at if the cadmium salt is omitted?
 
di de said:
Denise, I will also try masking but it will not be so easy on 120 format...
Click to expand...

If you use a piece of fixed & washed 4x5 film, cut out a suitable aperture & tape in your neg with dimensionally stable (ie polyester) tape, you can then use 4x5 film as masks etc & the 4x5 sheet is much easier to punch for registration/ more dimensionally stable etc. Age old technique (the dye transfer folk used it all the time) and you can incorporate a grey scale along the edge of the neg if you want. Main issue is that you will need a 4x5 enlarger...
 
Not sure there is an enlarging paper with that high an ISO. A pure bromide paper is only in the 6 to 12 range, at best. Not sure where ISO relates to contrast grade, at least in any functionally meaningful way. The question about maximum grade isn't meaningful without specifying the components of the test. Light source (condenser or diffusion) and developer choice are both important variables.
 

ISO (R) is the density range, ISO (P) the speed of the paper. ISO (R) of 50, should equal a 0.5 density range.
 
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