Photography, Fine Art, Wet Plate Collodion, Alternative photography

Contrast control in Wet Plate Colodion process

with 9 comments

Plate on the left was normaly exposed (5 seconds) and normaly developed (18 seconds), plate on the right was exyposed for 10 seconds and developed for only 8 seconds.

Plate on the left was normaly exposed (5 seconds) and normaly developed (18 seconds), plate on the right was exposed for 10 seconds and developed for only 8 seconds.

Few days ago I’ve finished a bacis collodion workshop and part of my workshop is a demonstration of contrast control in wet plate collodion process. I thought this might be intersting topic, so here’s a short post. Plate on the left is normaly developed and exposed and plate on the right is overexposed and underdeveloped. As you can see the middle tones are about the same, but the plate on the left has no details in highlights. This is usual push / pull process that is very well known in film photography and the same goes for wet plate collodion process.

Have you ever heard that a collodion mixture becomes more contrasty with aging? Well, that’s merly a false myth. Collodion becomes less sensitive and if a photographer is using the same exposure times with old colloodion, the plates are in fact undrexposed and on top of that overdeveloped, so of course the end result is much more contrasty then it was with fresh collodion, but if you want to have low contrast with old collodion, you only need to overexpose and underdevelop! So the cause of contrasty plates is not the age of collodion, but underexposure and overdevelopment.

This is what I’ve learned from Mark Osterman.

Here are two more plates that I’ve manages to make a reproduction of.




9 Responses

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  1. Knowledge rules!

    John Fink Jr.

    23 August, 2016 at 23:53

  2. How old was the collodion of your tests above? Thank you

    Jan Kratochvíl

    24 August, 2016 at 11:01

  3. My collodion is always quite young, like one month or so. I’m using a lot of it, so although I’m mixing a litre of collodion every month, it never happens that a bottle would get too old. Even if I have a bottle with few decilitres of old collodion, I chuck that into a mixture of young collodion, so nothing is thrown away, everything is recycled.
    I’m always starting with Mark Osterman’s formula: 3gr CdBr, 4gr KI, 140 ether, 140 alcohol, 220 USP collodion, then I adjust it for summer, winter, negative, positive…

    Borut Peterlin

    24 August, 2016 at 11:20

  4. Hi Borut! 🙂
    Based on short exposure and development I understand you’re talking here about positives. Am I right?
    How about negatives? Same? About double exposure time and half of development time?

    Adam Gust

    24 August, 2016 at 18:01

  5. Yes Adam, you are correct. On the end of the day we are talking of layers of silver on glass. Ambrotype is based on reflective principle of silver, whereas negative is based on light blocking properties of silver. Do you remember our course, when I made a demonstration with sheets of paper, as it would be layers of silver? I should do a video on that too. Plus why ID11 or D76 is more contrasty developer if diluted 1+3 (for your professors 🙂

    Borut Peterlin

    24 August, 2016 at 23:48

  6. Thank you Borut!

    Jan Kratochvíl

    27 August, 2016 at 14:51

  7. Sure I remember!
    Yesterday I had problem with my flashlights and my exposure was longer than I’ve expected. Only think that came to my mind was this post about controlling contrast so I cut developing time to about 20s and result was ok. I’m not sure if it’s because of short developing, but it looks like grain is bigger.
    PS: It was 1+7 dilution, but don’t mention my professors – they are gonna kill me, and I’m not 100% they are source of this fail knowledge 😉

    Adam Gust

    9 September, 2016 at 13:55

  8. Hi , thanks for your post. I have a question concerning the contrast. I was making acceptable tintypes till one day that I started to have high contrast and a blue in some areas. I tried already to make so many different things, finally I got new chemicals and started from 0 and is happening again super high contrast and the blue. Any Suggestions? thanks!


    30 March, 2017 at 19:16

  9. Sure, with ageing collodion is loosing its sensitivity, so under same light old collodion appears to be more contrasty, since the image is in fact underexposed. Just increase the exposure for one f-stop and you will will have the same contrast back.
    About the bluish phenomenon. I haven’t seen your plate, but it occurs when developer is not washed well off the plate, so developer + fixer will create bluish effect. Usually appears at the edges of plates.

    Borut Peterlin

    31 March, 2017 at 12:54

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