Photography, Fine Art, Wet Plate Collodion, Alternative photography

Wet plate collodion process and silver-bath maintenance

with 19 comments

My daughter Lučka is 9 years old and she's riding horse from age of 4. During summer break she didn't ride a horse, so she made up this toy horse with two brums. Brum behind is a tail. Today I've finished with boiling and filtering silver nitrate  and made this ambrotype, format 8x10" that's 20x25cm.

My daughter Lučka is 9 years old and she’s riding horse from age of 4. During summer break she didn’t ride a horse, so she made up this toy horse with two brums. Brum behind is a tail. Today I’ve finished with boiling and filtering silver nitrate and made this ambrotype, format 8×10″ that’s 20x25cm.

My last post was about my commision in Switzerland. I’ve shot many plates and when I’ve came back I was sunning the bath for a day (bright sunny day), filtering, etc, but I was still not getting that super sharp shining silver on my plates. With usage of silver-nitrate bath, alcohol, ether, iodides, organic particles and other stuff they dissolve in the bath and you can not get them entirely out with barely sunning.

Common practice is that silver-bath is regularly sunned and boiled only once or twice a year. That goes for ambrotypes, that’s positives. Whereas wet plate collodion negative technique reveals all dirty secrets of silverbath (not to mention photographer’s secrets) and if you want to get a good negative frequent boiling is necessary. Major enemy of wet plate negative is excess of iodides in silverbath and the syndrome of that are white dots in negative or black dots in positive. Or to quote Mark Osterman: “free iodides” cause pinholes in collodion images.”

So what I’m trying to say is that I very often boil my silverbath for usage in wet plate negative, but I also fall in love in the quality of ambrotypes that are produced after freshly boiled and cleaned silver-bath.

How is it done? You can find this technique in The NEW Scully & Osterman Collodion Manual. I can explain you how I am doing it, but I must warn you that I’m Slavic origin and not Germanic or even Anglo-Saxon origin, so if you can use an advice about cleanness from a Slav, then you must be pretty desperate…


Boiling silvernitrate with Sodium bicarbonate (baking soda)

Boiling silvernitrate with Sodium bicarbonate (baking soda)

Add one small table spoon of baking soda in about one liter of AgNO3 solution. At this stage the pH should be about 6-7pH. I must warn you that boiling silver-nitrate with Sodium bicarbonate (baking soda) will look like the end of your wetplate career, but that’s how it should look. To be clear, the silver-nitrate in the picture above looked perfectly clear before boiling, but since I’ve sensitized about 30 plates format 10×12″ (cca. 2.25 square meters) I knew it’s full of iodides, alcohol, ether and dissolved organic matter. Only when I started boiling it with soda all the feces came out…

A friend asked me the other day how to raise pH in silver-bath after you added few drops of nitric acid. This is the best way. On FB a colleague Michael Koerner wrote a comment: “Plus the sodion bicarbonate (NaHCO3) will (when acidified with nitric acid) turn to carbonic acid (H2CO3), which will over a short time turn to water (H2O) and carbon dioxide (CO2) – bubbles away.”

After boiling you need to add water, filter it, sunn it, filter it, measure gravity of AgNO3, add nitric acid so the pH is back to 4 and you’re finished! Your silver-nitrate bath is reseted. You must know that silverbath like that will be more aggressive then your usual silver-bath, so it’s good to shorten sensibilisation time. I shortened to 2:15 minutes at room temperature. Mark Osterman is highlighting that sensibilization process is judged visually and not measured by time. I think I know what he means, but I need to confirm with him that I truly understand this part of the process, next time when I will see the master. I’m planning to join his workshop of Carbon Printing in Rochester in November. So exciting!

To sum up. I love to reset my silverbath, because then I’m getting best results. Boiling does take toll. I loose about 13.722% of my silverbath solution due to filtering. After boiling I filter the solution about 4 times through double coffee filters. Personally I find it worth the effort, but in wetplate process everyone have their own way of doing things and I’m not saying this method is better than any other. It works for me and that’s the true beauty of this hand-made images. You do it your own way! Ha!

PS: I’ve changed the title of this blog. Before it was Photography Down the Rabbit Hole, but the title Topshit Photography blog is way better. Topshit happens!

PPS: TOmorrow I’m going back to Switzerland to do some more work. Obviously they think the work that I’ve done is worth the money, so more work is waiting for me. Topshit happens!

PPPS: Relevant links: Scully & Osterman Studio (Alex Timmermans)
– My first post about boiling and sorting pH of silver-bath LINK

An ambrotype of my daughter Lučka and her imaginary horse and very real dogs.

An ambrotype of my daughter Lučka and her imaginary horse and very real dogs.

An ambrotype of my daughter Lučka and her imaginary horse and very real dogs.

An ambrotype of my daughter Lučka and her imaginary horse and very real dogs.

19 Responses

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  1. Great how-to! I will link it to


    1 September, 2013 at 05:59

  2. Glad you like it Gerald! Using an advice on cleanness from a Slav is a risky thing, but hey who would say ten years ago that Chinese Communists will be making the world go around!?!

    Borut Peterlin

    1 September, 2013 at 07:14

  3. I was suggested this blog by my cousin. I am not sure whether this post
    is written by him as no one else know such
    detailed about my problem. You’re amazing! Thanks!


    9 September, 2013 at 22:16

  4. Asking questions are really pleasant thing if you are
    not understanding something entirely, however this piece
    of writing offers fastidious understanding even.

    11 September, 2013 at 14:12

  5. Sometimes a man must be a man and so I followed your advice in regard of boiling the silver bath yesterday. After one year of usage without maintenance my silver bath caused now small black holes (like hot holes) on the collodion layer, The surplus ammount of iodides, right? Well, what a mess, The bath turned into yellowish green soup immediatly which turned black during the booling. Now after filtering and adding dem. water its sitting on the shelf for sunning. Borut, how many drops and concentration of nitric acid did you add to one liter? (only for ambrotypes, I have no possibility to measure the ph) And please tell me, that my silver bath is working fine after this crazy slavic torture!

    Andreas Reh

    26 September, 2013 at 10:23

  6. Dear Andreas,
    if you didn’t put inside baking soda, then your pH will not change. It will remain almost the same as it was before. If you did put baking soda inside, then it’s no other way than to do it with pH checker. A drop of concentrated nitric acid could mean one pH step lower and then you have to boil it again with baking soda to raise the pH again. It’s not that you might ruin anything, but you might lose couple of days to get it back between 3-4 pH. So don’t add soda or nitric acid if you don’t have pH checker.
    Good luck, you’ll see it’s definitely worth it. I’m doing almost on weekly basis. For negative you need to boil a lot. Good luck my friend!

    Borut Peterlin

    26 September, 2013 at 11:58

  7. Most of the stairlifts have fold-able chair seat to prevent any encumbering on the stairway.

    It includes quiet ride up and down the stairs with smooth starts and stops.


    2 October, 2013 at 03:05

  8. Hi Borut!
    Got my first pinholes today and I believe (after 8 months use, lots of filtering and only sunning occasionally) it might be time to boil the soup down!
    In your description above, you mention that after boiling, the bath will be more aggressive and you recommend shortening sensitizing time. What exactly do you mean by ‘more aggressive’? I have yet not completely understood the importance of duration of the plate in the silver bath, how important is this ‘time’?
    Thanks for your advice.



    27 February, 2014 at 00:11

  9. Well, bath is more active, since it’s purified. Remember we are talking about chemical reactions. You don’t need to shorten time if you experience no problems, but if you would work at temperature say 25C, then you would get severe fog, because too much silver would “catch-up” on the plate. For ambrotype you do not want density! OK, time is not as important as it is general understanding. Mark Osterman is teaching that you observe plate after a half a minute, minute, two minutes and you can observe the progress of sensibilisation and then you know if your silver is worn out and you might want to sensitize for five minutes or shorten to two minutes. It’s not an easy concept to explain. At least not in English 🙂

    Borut Peterlin

    1 March, 2014 at 22:42

  10. When observing a plate sensitizing in silver – if you see “legs” – as you would on the inside of a wineglass holding sweet wine – it’s not ready. When you inspect the plate and the surface is smooth, it’s ready to be set, blotted, and put in the plate holder for exposure. I took a recent workshop with Mark.


    3 June, 2015 at 11:39

  11. Hi, I am currently trying this method and was wondering about filtering.
    I boiled 550 ml or silver nitrate (ph 2) with ~1/2 a tablespoon of baking soda and it turned black as expected.
    I am now trying to filter it, (double coffee filters) but even after my third filter it remains just as black as it began. I can see a lot of the black sludge is being removed with the filters, but it seems almost hopeless to get it back to a perfectly clear solution.
    Do you have any tips or words of encouragement for this worry?


    23 October, 2015 at 23:01

  12. Sure, I usually sun it unfiltered for a day or two sunny days. Filter it and then sun it again. There will be a thick mud kind of sediment. You can leave that on the filter and chuck it the filter and sediment away. On the end you should have a perfectly clear water like solution. Don’t forget to top up silver and lower pH with nitric acid. Lower pH slowly, very slowly, measure it frequently. Litmus papers aren’t good, aren’t precise. I use hama pH checker. Good luck.

    Borut Peterlin

    23 October, 2015 at 23:31

  13. Thank you very much!
    Your blog has certainly been the most helpful and thorough getting the kinks out of the process.
    I will try sunning for a couple days before filtering. Also thanks for the ph testing suggestion, I have been using the strips with a lot of frustration matching colors to numbers…


    24 October, 2015 at 02:00

  14. You’re welcome. I must make a video how to do that properly. I might do it soon.

    Borut Peterlin

    24 October, 2015 at 07:04

  15. Got to learn how to do this boiling thing right. Thanks for your help Borut.

    Gerry Yaum

    7 July, 2017 at 19:14

  16. i have used about 100 to 120 4×5 plates in my siover bath exacty one year ago and now i have suuned it continuously for last 4 days so can i filter it and use it without boiling and what else i need to take care of

    ashish sahoo

    15 January, 2018 at 19:38

  17. Ashish, filter it and add silvernitrate. For ambrotype or tintype it should be good.

    Borut Peterlin

    17 January, 2018 at 21:13

  18. Hi Borut,
    I followed your advice about resetting silverbath. This because my silverbath Ph was 2,3 ! I used Ph strips in the past but i bought Ph meter because the Ph paper sucks big time. And so i found out that my Ph was in fact 2,3.
    So i added Sodiumbicarbonate to Ph 6.1….and boiled until i had 1/3 left. I filtered and brought density and Ph back to 1.072 and Ph 4,3
    BUT i lost a LOT of silver. I have about 150 grams of black deposit left and that containes silver. In your video on youtube you say you can get the silver back and you would make a video about how to do this. I have not found that video… there a video from you how to get the silver back?
    If not can you explain how to do this? I gave tried to dissolve this black deposit in some HNO3 nitric acid 54%. And that does work. I even see white cristals forming and i think this is silvernitrate. But the Ph of this is 0.2 ! So much to acid.
    So xan you explain how to get the silver back from the black deposit that is left after filtering?
    I hope to hear from you.
    Kind regards
    Gerard de Vrueh

    Gerard de Vrueh

    19 May, 2018 at 14:53

  19. Thank you for your question. It depends how much baking soda have you put in. If it was only 6 pH, then that’s perfect. The sediment is the organic matter that was in the solution and it fell out. I presume you started not with 7% of solution, but much less, so you evaporate water and it appears that you lost silvernitrate, but silvernitrate does not evaporate, so my presumption is that it wasn’t there in the first place. I haven’t made the video how to extract the silvernitrate. I will eventually, but do not expect the financial gain, it’s more ecological motive.

    Borut Peterlin

    19 May, 2018 at 19:05

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