SLIMT, short for Selective Latent Image Manipulation Techniques, is a technique for pre-bleaching of exposed, but undeveloped, prints and negatives in order to control shadow and highlight contrast in a largely beneficial direction without adversely affecting overall micro-contrast. For prints, one generally manipulates shadow contrast and for negatives one generally manipulates highly contrast.
Originally inspired by Sterry, David Kachel originated and refined this technique to something much more consistent and beneficial to both film and paper. The original articles should absolutely be read as David really knows his stuff and most importantly thinks outside the box:
http://www.davidkachel.com/historical/nw_strry.htm
http://www.davidkachel.com/historical/cont_pt3.htm
http://www.davidkachel.com/history.html
The basic approach for prints:
1. Mix a 10% solution of Potassium Ferricyanide by dissolving 100g of it in 900ml of water (1ml of water == 1g of water) to create a stock solution which will last a very long time (over 100 printing sessions).
2. This stock solution is then diluted further into a working stock solution by diluting 10ml of stock with 990ml of water. This 1L of working stock will be used throughout an entire printing session and then dumped at the end.
3. To create the actual bleaching solution used for a single print, one mixes between 10-100ml of working stock with 900-990ml of water to arrive at 1L. In my case I simply added 5ml of working stock to 500ml of water in an 8x10 tray by using a teaspoon.
4. After exposing the print, one completely immerses the print in the bleaching tray, and bleaches for 1-3 minutes just as they were normally bleaching an entire print. Remove the print from the tray and transfer directly to developer (pot-ferri bleach [especially at this incredibly low dilution] cannot survive in alkaline environments and will *not* harm your developer). This single-use bleach bath is dumped and remixed after normal processing of the print. There is no need to do anything special with the developer.
If one feels they have a print which could benefit from SLIMT, the recommended approach is to expose and bleach with a simple 5ml/500ml mix for around 1 minute and see how it looks compared to the unbleached print. You can then up the concentration on the next tray mix or just bleach for longer. In my case I found 5ml and 1-2 minutes to be ideal for the particular print I was testing with. A test strip wouldn't hurt to see if one could benefit from altering the exposure as well.
The negative I used for testing was a naturally contrasty sun-lit frame shot on Fujifilm Neopan 400PR (generally a contrasty film) developed in Rodinal 1+25, and then printed on Emaks K-888 #4 paper developed in Selectol 1+1 for 3 minutes. I wanted to align as many things in the "wrong" direction of too much contrast to see how SLIMT would benefit this pathological combination of materials. Normally I would never print this negative on #4 and reach right for #2 just by looking at the negative as it was dense, contrasty, and full of hot highlights from direct sun. However, it's still a typical negative that doesn't print straight out of the box.
These are straight scans of 3 different 8x10 prints using an Epson V700. The straight normally processed print is on the left in both cases. No selenium or other stunts were used - just SLIMT for comparison and traditional bleaching for another comparison. Obviously there are many different ways to handle this print, but the point of this is to focus on SLIMT and not exploring every way to skin this cat. I wouldn't normally print this frame on #4, but as mentioned previously there's a reason I chose it.
Straight vs Post-bleaching (5ml of 10% stock/500ml, until shadows opened slightly/brightness punch):
Straight vs SLIMT (5ml/500ml, 2 min):
It's painfully obvious that this technique works effectively and doesn't carry the drawbacks of lost micro-contrast from pre-flashing or manipulating development dilution/water-baths, etc. (I still recommend considering those techniques as additional tools to have). The straight print is far too contrasty and highlights are difficult to balance without printing more open and burning in or sacrificing the shadows and printing down (which is unacceptable for this type of photograph). Actual hassle is fairly low as mixing the tray mix for each print that needs it takes around 15 seconds (Use a 5ml tsp and mix into 500ml of water in a tray).
The amount of options afforded to the printer through use of grade choice combined with SLIMT is great. There is no reason one cannot use #2, #3, or even VC grades to arrive where they want to through educated trial and error (which is how most people print in the first place). One can print the shadows down and then use the SLIMT bleach bath to open the shadows back up while leaving the upper-mids/highlights unaffected and properly exposed but retaining high contrast. This is also somewhat possible with post-bleaching but I feel SLIMT offers much more latitude and affects things differently - but there is also no reason the two techniques cannot be combined.
There are previous references to SLIMT on APUG, including one major (there was a url link here which no longer exists) related to it started by David himself. Sadly he was railroaded out of that thread by our own members and not given the respect he so rightfully deserved.
Should you be using this technique? Absolutely. You'd be out of your mind not to try it.
Originally inspired by Sterry, David Kachel originated and refined this technique to something much more consistent and beneficial to both film and paper. The original articles should absolutely be read as David really knows his stuff and most importantly thinks outside the box:
http://www.davidkachel.com/historical/nw_strry.htm
http://www.davidkachel.com/historical/cont_pt3.htm
http://www.davidkachel.com/history.html
The basic approach for prints:
1. Mix a 10% solution of Potassium Ferricyanide by dissolving 100g of it in 900ml of water (1ml of water == 1g of water) to create a stock solution which will last a very long time (over 100 printing sessions).
2. This stock solution is then diluted further into a working stock solution by diluting 10ml of stock with 990ml of water. This 1L of working stock will be used throughout an entire printing session and then dumped at the end.
3. To create the actual bleaching solution used for a single print, one mixes between 10-100ml of working stock with 900-990ml of water to arrive at 1L. In my case I simply added 5ml of working stock to 500ml of water in an 8x10 tray by using a teaspoon.
4. After exposing the print, one completely immerses the print in the bleaching tray, and bleaches for 1-3 minutes just as they were normally bleaching an entire print. Remove the print from the tray and transfer directly to developer (pot-ferri bleach [especially at this incredibly low dilution] cannot survive in alkaline environments and will *not* harm your developer). This single-use bleach bath is dumped and remixed after normal processing of the print. There is no need to do anything special with the developer.
If one feels they have a print which could benefit from SLIMT, the recommended approach is to expose and bleach with a simple 5ml/500ml mix for around 1 minute and see how it looks compared to the unbleached print. You can then up the concentration on the next tray mix or just bleach for longer. In my case I found 5ml and 1-2 minutes to be ideal for the particular print I was testing with. A test strip wouldn't hurt to see if one could benefit from altering the exposure as well.
The negative I used for testing was a naturally contrasty sun-lit frame shot on Fujifilm Neopan 400PR (generally a contrasty film) developed in Rodinal 1+25, and then printed on Emaks K-888 #4 paper developed in Selectol 1+1 for 3 minutes. I wanted to align as many things in the "wrong" direction of too much contrast to see how SLIMT would benefit this pathological combination of materials. Normally I would never print this negative on #4 and reach right for #2 just by looking at the negative as it was dense, contrasty, and full of hot highlights from direct sun. However, it's still a typical negative that doesn't print straight out of the box.
These are straight scans of 3 different 8x10 prints using an Epson V700. The straight normally processed print is on the left in both cases. No selenium or other stunts were used - just SLIMT for comparison and traditional bleaching for another comparison. Obviously there are many different ways to handle this print, but the point of this is to focus on SLIMT and not exploring every way to skin this cat. I wouldn't normally print this frame on #4, but as mentioned previously there's a reason I chose it.
Straight vs Post-bleaching (5ml of 10% stock/500ml, until shadows opened slightly/brightness punch):
Straight vs SLIMT (5ml/500ml, 2 min):
It's painfully obvious that this technique works effectively and doesn't carry the drawbacks of lost micro-contrast from pre-flashing or manipulating development dilution/water-baths, etc. (I still recommend considering those techniques as additional tools to have). The straight print is far too contrasty and highlights are difficult to balance without printing more open and burning in or sacrificing the shadows and printing down (which is unacceptable for this type of photograph). Actual hassle is fairly low as mixing the tray mix for each print that needs it takes around 15 seconds (Use a 5ml tsp and mix into 500ml of water in a tray).
The amount of options afforded to the printer through use of grade choice combined with SLIMT is great. There is no reason one cannot use #2, #3, or even VC grades to arrive where they want to through educated trial and error (which is how most people print in the first place). One can print the shadows down and then use the SLIMT bleach bath to open the shadows back up while leaving the upper-mids/highlights unaffected and properly exposed but retaining high contrast. This is also somewhat possible with post-bleaching but I feel SLIMT offers much more latitude and affects things differently - but there is also no reason the two techniques cannot be combined.
There are previous references to SLIMT on APUG, including one major (there was a url link here which no longer exists) related to it started by David himself. Sadly he was railroaded out of that thread by our own members and not given the respect he so rightfully deserved.
Should you be using this technique? Absolutely. You'd be out of your mind not to try it.
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