Monday, June 18, 2018

Two Collodion Tests - Acetone and 3 Different Fixers

  This post is about two quick collodion-related tests I did recently.  The picture above  is confusing, I know – it might lead one to believe the two halves of image are, when in fact they aren’t. It’s ok though, hopefully it got you intrigued and reading the post will clarify everything.

  Test #1 – Adding Acetone to Collodion to Bring Back Speed. 
This is something I’ve seen discussed online as a remedy for really old collodion that has gone red and slow.  In my case though, I think one of the salts I mixed was somehow bad, and so iodides got released immediately – making my collodion dark wine red within a couple of hours of mixing.  I rested it and it was 4 stops slower than another batch I was working with, when exposed a lot more though it performed well.  It was time to try the acetone trick…
  The solution people suggest to bring the speed back is to add ONE DROP of pure white acetone per 100ml of collodion.  Let it sit for some days while the reaction is going, and you’ll actually see it going from red to more orange and then to yellow.  I had 200ml of this super-slow red stuff, so I split it into two equal halves.  My memory failed me though, and instead of adding just one drop of acetone to my 100ml, I added 1ml (actually a little more), so over 10x the recommended amount!!!   It still took at least 5 days to reach yellow and gain speed.  

  A few notes.  People say that adding acetone will make your emulsion more fragile and some also say that it will make alcohol-based varnishes dissolve the image.   What I found (and this is after adding WAY more acetone than recommended) is that my emulsion did in fact become A TINY BIT more fragile (less pressure was needed to scratch wet emulsion with cotton ball while wiping off oysters, for example), but the difference seemed really insignificant. No images were dissolved with varnish (I use traditional sandarac formula).  I think the dissolving issue is probably unrelated to acetone.  Dissolving is most likely stemming from the fact that by the time most people try the acetone trick, their collodion has been sitting for many months or even over a year, and by then nitrocellulose actually started to deteriorate.  My actual collodion was new, so nitrocellulose was fresh and acetone didn’t make it be re-dissolvable again by varnish.
  After I did the test and the collodion with acetone performed at ISO 1 like new, I actually combined those refreshed 100ml with the other 100ml of deep red.  Seeing how I had 10x more acetone in there already, I didn’t add any more.  It’s been about a week now and the whole mix is light orange.  I shot Mission Dam plates with it the other day, and basically was shooting at ISO 0.75, so I’ve recovered over 2 stops from its deep red state.  All the plates varnished wonderfully.  I think in a few more days it’ll get to bright yellow, and back up to ISO 1.

TEST #2 – Three Fixers and Their Effect on Plate Brightness.
  A number of years back, when I was just starting my collodion journey, I saw Alex Timmermans’ Three Fixer Test as related to the eternal quest of wet plate photographers to get the brightest possible silver deposit in final image.  The debate is always – is there a way to get around using KCN (KCN is potassium cyanide and is very poisonous) and still have bright warm-tone images.  Alex’s test seemed to show barely any difference in the final look of the image. KCN seemd a tad brighter, followed closely by Amoloco and Sodium Thiosulfate (Hypo).  It seemed so close though, that for years I’ve been telling people that it makes barely any difference.  Personally, I started using KCN from the start – if you are careful with it, there’s really no danger when working with it.  I like how it works, I don’t need to wash my plates too long (as it washes out 4x quicker than conventional hypo), and it’s also very quick-acting, which always is a visual bonus when making plates in front of people.  However, a short while ago, someone with vast amount of experience did make an online remark that made me want to do my own test and see live what the difference really would be.

  The way I went about it is very simple, I pretty much followed Alex’s test procedure.  I had the same Lea #2 collodion that was used as comparison in Test #1. A 1/6th plate size piece of black glass was scored in two places, so that later it would be easier to break it into three pieces.  Using strobe lights, I made one test plate to dial in proper exposure and then made the final exposure on the pre-scored glass.  After development, the plate was rinsed copiously and then split into thirds.   Left part was fixed in Sodium Thiosulfate (Hypo), middle in KCN and right side in Ilford Rapid Fix.  To my surprise, I saw much greater difference than I expected, with KCN showing its usual bright creamy tone, but both Hypo and Ilford tones were duller and almost into the purple range when compared to middle section.  Varnishing with sandarac (last pic below) did seem to bring the tones a bit closer together, but brightness is still visibly different.


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