New to Black and White developing...........

[Michael Kadillak]

In unique circumstances as appears to be your case with higher than normal salt content I guess I can understand. I went back to the Negative by Adams and he mentioned that only when one finds negative marks in the drying stage to be a problem does one revert to distilled water or other problem solving procedures. My point is that especially with formative questions to darkroom procedures we need to make sure these qualifying attempts at verifying the need for each individual before assuming these are SOP. Adams does say that under unique circumstances that one can go to a "soft sponge" wiper but as delicate as some emulsions are at this stage of the process I would have to be at the end of my rope before going down that road.

[Pere Casals]

Well, Adams sure had no problem with Yosemite crystaline water , this is water !!

I agree that a final rinse with distilled water is not the SOP, but IMHO it is a very good practice. Let me add a little more to this off topic. Water may contain from 30mg/L to even 1500mg/L, of salt, and this is what (as you quoted from the Negative) will impose a method.

A 8x10 sheet may contain from 4gr to 10gr of water in the emulsion before drying (just weight film before and after drying), hight salt content tap water can have until 1500mg/L and this may leave until 15mg (as a maximum, perhaps from 2 to 10), of bicarbonates and other in intimate contact with organic dyes of color slides and negatives, this is for a 8x10 sheet or roll. Is this harmful ??

PhotoFlo (even with Ca sequestring activity) do not remove salts from water, rather it spreads salts uniformly in the surface and inside the emulsion so no marks are seen.

Salts can be corrosive... I cannot say the actual impact, but long time ago a lab technician warned me about that potential risk, and told me that final salt content in the emulsion was a process quality parameter, but I don't know the real importance.

I see it way less problematic for (non chromogenic) BW film, were marks would be the main concern. Sometimes that I had run out of distilled water I used bottled mineral water of about 35mg/L, with no marks.

That lab technician also told me that if using a 2 stages bath with distilled water (like with fixer) then distilled water consumption is very low and end salt content result is very, very low.


Distilled water is also the perfect job for BW, not necessary perhaps, but the perfect job. At the end even car washing facilities use deionized water for the final rinse



I've also tried the "soft sponge", but at the end I managed to remove droplets with an air blower (a salvaged hand dryer) in 5 seconds, not an "air knife" like in the industrial processors, but good enough. Even with a hair dryer it worked ok.

So finally with distilled, the blower and an HEPA filter I find myself confortable: no scratch, no dust, no mark and no bicarbonate in the Velvia emulsion... before that I had clear problems with all that, (anyway I don't know the actual salt effect with organic dyes for preservation)



PD: Calculation:

With a 20microns thick emulsion (0,5ml of dried emulsion for a 8x10) and 8mg of salt remaining in the sheet then it would be 4mg of salt in each side, as most of the salt would be on the surfaces of the sheet, this it would be a salt concentration of some 5grs of salt per liter of dried emulsion... It would be interesting asking Mowrey if it has an impact for long time preservation...

[xkaes]

Why in Gods name would you ever subject a negative to a squeegee? A print yes, a negative hell no. You are inducing a risk variable that is completely unnecessary to the process.

Because some "gods" have worked in industrial/commercial situations where super-fast drying is essential. And that's why special film squeegees -- and drying liquids -- are made and sold. If they are used according to their instructions, they are safe. In fact, the instructions on Yankee's Instant Film Dryer specifically states to use a film squeegee after immersing the film. With the Dryer and a squeegee you can have dry film in about 100 seconds -- pretty impressive. Those days of fast turn around are behind me, and I've only used a film squeegee once or twice on my own film, but they have a completely legitimate use.

[Pere Casals]

film squeegee

A requisite for that should be rinsing before with very clean water, some tap waters can include little mineral and metallic particles that have to be filtered out for that, as minilabs do by routine. Anyway best possible squeegee is high speed air, IMHO.

[neil poulsen]

Hi John,

A couple of points to keep in mind.

1 - Shadow density (thinnest areas of the negative) is controlled ONLY by exposure.

2 - Highlight density is controlled (mostly) by development.

Obviously, mid-tones are a bit of each.

Best place to start - Manufacturers' recommendations.
That includes film speed, exposure, and processing.

- Leigh

Not to disagree w/Leigh necessarily . . .

A common speed to use is half the mfg. recommended film speed.

Development is typically based on lab testing done in one's own darkroom. The development depends on the degree of contrast in the scene being photographed.

[Horseman]

Ok everyone

I have developed my first 6 in a patterson with mod45 and apart from putting them in " emulsion side out " and an unknow light leak on 3 of the 6 ( on the same side of the tank ) was delighted.

But

If i use open trays to dev 2 sheets . do i use 1/3 of a ltre, constantlty rock and agitate ....or do i still need a lire?

My gut feeling is 2 sheets in 330 ml of develeoper etc will be right if the right time is used?

JM

B

[Horseman]

not sure what happened to the "t" in litre....

might be the excess amount of " gin and onic , onight "

lol

[Pere Casals]

A thousand times I've heard and read about acetic acid stop bath being the the big offender in darkroom smells...

"● The fumes which emanate from acetic acid stop baths are perhaps the single greatest health hazard in the darkroom"

page 103: http://www.ssnpstudents.com/wp/wp-co...m-Cookbook.pdf

There if nothing wrong in using acetic or citric. Anyway plain water does the same, single thing is that with plain water you should shorten the developent time by a few seconds, 10s perhaps, because it takes a bit more to stop development develoment.

I use plain water as stop bath and I'm perfectly happy with it.