Bromide drag?

ChrisR

ChrisR

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I don't understand the term "bromide drag", but I'm wondering if this is an example...

Bromide drag.jpg

There are white streaks appearing to emanate from the top of the church tower (that's St Mary Magdalen's I think, Taunton). This is Tri-X, devved (with Ilfosol 3) in a Rondinax, so the film is moving longitudinally (vertically in this image) semi-continuously. (I don't wind all the time, but do two partial winds, wait two seconds, repeat... no idea why but it usually seems to work.)

I used to think that the streaks were the result of depleted chemicals, but it's a negative, so the tower (under-exposed) has received less light, and so the chemicals should be less depleted there, rather than more. Can anyone explain for the simple-minded, please? (Oh, I can usually understand a technical explanation, perhaps with a few questions...)

Thanks!
 
I thought bromide drag created dark streaks (i.e. patches on the negative which are too thin)? This looks like the opposite where the developer has worked harder to add density to the negative. Hmmm...maybe because the developer is not being agitated randomly, but instead is moving vertically across the image. It's passing over large areas where it's not working very hard (the dark areas) then hitting the sky and working too quickly. Either that or it's the Wrath or God passing through the church tower and smiting the negative.
 
Are you sure you haven't captured some sort of supernatural event there? :eek: Joking aside, your theory about winding in one direction might have some grounds, especially if this frame was parked at the top of the arc and the chemicals drained down the reel from the spires. :confused:
 
Bromide inhibits development, and is a by product of development; hence the importance of agitation to ensure that local effects aren't possible. The "by product of development" bit means that areas which have highlights will produce more bromide; and if it trickles over into less developed areas, it will inhibit development there; hence lighter lines. And dark lines in the print. of course.

Alternatively (and still considering effects of agitation) the sky area is high density and hence will exhaust the developer more quickly than the church tower; if the less exhausted developer trails over the sky, it will increase the activity of the developer and give lighter lines.

For this explanation to apply to your negative, the direction of turning would have to be such as to result in the developer flowing from the bottom to the top of the negative ("bottom" and "top" being relative to the print).

I can't think of any explanation that doesn't involve insufficent agitation...
 
I've checked the negatives... the base of the church is nearer the beginning of the film, which is wound into the centre of the spiral. During development, the winding continues in the same direction, so that's consistent with @StephenM 's 3rd para.

So: less exhausted developer flowing from the tower into the sky area, causing a bit more development in the streaked zones!

I took these as I usually do for portrait mode, with the camera rotated so the winder (and shutter button) is at the top (counter-clockwise, viewed from my position). I did notice this when scanning this film, as the very first shots (of a completely different subject) was oriented the other way... it was on the monopod with the Manfrotto portrait head, and I'd just flopped it the wrong way. Presumably if I normally took portrait shots in this clockwise orientation, there would be less of this effect, as it would be exhausted chems flowing into the shadow areas. Though that might produce the effect that @FujiLove talks about...

How else to avoid this (which, TBF hasn't happened to me very often)?

a) I do wonder if my Ilfosol 3 is a bit past it. I've been adding marbles as it's been consumed, but it's now got to the point where I can't add any more, so there's more air in there. And it must be about a year since it was opened. Maybe time to chuck it?

b) I think on this occasion I did wind continuously for the first 30 seconds or so, before reverting to my wind, pause approach. It's possible that's when this happened.

c) I could try a little wobble in the pause, so as to move the chems around a bit rather than always in the same direction.
 
No John, one of the great joys of F&C is how you continually surprise me! ;):D
 
Looks more like spirit strikes from the heavens to me. Usually they are invisible. But the conditions must have been just right.
Perhaps there was a sevice going on at the time.
 
I was just reading (as one does) "The Science of Photography" by H. Baines and in the chapter on development I came across the following. I think I've proof read it accurately, and the one word in italics was italicised in the original. The penultimate sentence seemed possibly very relevant. It's found on pages 133-134.


Bromide Effects. - One of the products of development is alkali bromide, itself a restrainer of development (p. 126). An area which has received a heavy exposure will on development form a local high concentration of alkali bromide which will tend to restrict later stages of development not only in the area of high density but, by diffusion, in adjacent areas. If the film is vertical (as in developing tanks), the high bromide concentration formed at high densities sinks in the solution because of its high specific gravity, and causes a streak where development has been restrained. Such effects are known as 'streamers' or 'top hats', and can be mitigated or avoided during development by appropriate agiation. Uniform agitation, as for example the uniform rotation of film in a spiral holder, may cause bromide streaks in the wake of high densities. Some such technique as a vigorous periodic shake is found to be most effective.
 
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Great find, @StephenM . Might be more relevant in the future as I think several people are expecting Lab Boxes when they become available (modern version of the Rondinax). Looks like "wind and wiggle" will be the order of they day!
 
Are you from Taunton? I walk down that street every morning to work.
 
Craigus said:
Are you from Taunton? I walk down that street every morning to work.
Click to expand...

I was brought up (mostly) in Halse, about 7 miles away, and my sisters still live not far from there, so I was visiting. I've always liked that church; something really graceful about the tower and its framing! Lucky guy to live there (although IIRC the traffic in Taunton is horrendous!).
 
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