It turns out Galaxy convinced Slavich to repackage their photo-booth paper into larger formats and perhaps reformulated the reversal chemistry. As annoying as the website is I think it is all to the good that they are generating interest and support in traditional photography.
The biggest complaint I have is there is very little technical information about the product and as such one is reliant on their chemistry which is fine but never seems to be in stock at least in the UK. (This seems due to some restrictions on shipping some of the chemicals in Europe.)
Having a 8x10 large format camera now I want to use the paper so I suppose I need to create my own reversal chemistry.
Reversal is a clever process used in slide film and black and white and colour movie stock. It consists of a normal exposure and development. Next a bleach (non-halation) is performed to strip away the developed silver. What is left is undeveloped silver with a density that varies inversely with the amount that was stripped away. Previously dense areas leave thin silver and vice versus. Next the film is re-exposed and then redeveloped. Done right one gets a positive image with good contrast and tonal range.
Of course one can see getting the correct amount of silver to remain behind and the re-exposure done properly introduces a lot of sensitivity to the process.
I researched what I could based on Potassium Permanganate bleach. Dichromate seems much more popular but I have none the consequence of having already sided with the less toxic Potassium Permanganate. (A debate has raged on forums about the relatives dangers.) I had to researched formulas and settled on one from Liam Lawless and Ed Buffaloe who are referenced a lot for reversal processing.
- Permanganate Stock
- 25g Potassium Permanganate
- Water to make 500mL
- Sulphuric Acid Stock
- 25mL Concentrated Sulfuric Acid
- 475mL water
Some Warnings on above Potassium permanganate is an oxidizer and therefore a fire hazard. Dispose of carefully. Dry crystals and concentrated solutions are caustic. Do not breathe dust or fumes. Handle with gloves.I then make a working solution at 1+9 by adding 50mL of Permanganate Stock with 50mL Sulphuric Acid stock and 900 mL of water.
Concentrated sulphuric acid must always be added to water slowly, never water to acid. This chemical is highly corrosive and may cause severe burns if it comes in contact with skin or mucous membranes. Wear eye protection at all times and handle with extreme caution. Do not breathe fumes.
A clearing bath is needed after the bleach to remove the bleach by products. There a few of these. I opted for Sodium Sulfite (Sodium Metabisulphite is popular) as I had some of this as well. I hunted around and found a simple formula
- Clearing Solution
- 10mg Sodium Sulphite
- Water to make 1L
What I learned however is it doesn't work. I found this thread that indicates it needs to be acidic. I then would use 200ml clearing solution (100ml is supposed to be sufficient) per print and added some stop bath (acid) at 50ml of 1+9 stop bath. This is single use for me.
A day's experimentation gave me results but I needed to make sure the paper was initially exposed at ASA 16. I tried bracketing around the box rated 120 ASA but everything turned mostly black with a faint image (after reversal). I reasoned I need more exposed silver to bleach out hence more exposure. I also needed to be careful even then with flashing the paper after bleaching. Initially I would turn the room lights on during the clearing phase and afterwards. This overexposed the remaining silver making the image very dark. I ended up gradually flashing the paper as it developed in the developer. Once this is dialed in I think consistent prints could be made.
Another thing to note is a dim red safe light was invaluable and I found sparing use of it did not fog the paper despite the paper's speed.
Finally I guess there are some substantially different aspects of the Galaxy chemistry that make the results easier to get consistent and resolve the difference in speed I experienced. I know they chemically fog the paper (sepia toner?) to eliminate the difficult light flashing. This may be setup to yield the higher paper speed as perhaps it exhausts the fogging agent and has developer and fixer included in the same bath. (There are only four baths apparently.)
So my steps I ended up with were.
- Expose paper at ASA 16
- Develop Ilford Universal PQ 1+9 2 minutes (1 minute is probably sufficient but I want all exposed silver developed)
- Water stop bath 1 minute (could be acid but I lacked room for the tray and you would want to wash after acid stop anyway.)
- Bleach (as above) 1 minute. A faint image is still visible, not to worry the clearing bath will remove what is left.
- Wash 30 sec
- Clearing 2 minutes (or until clear by inspection under dim red light)
- Wash 30 sec
- Flash (tricky part as my light and timings are not calibrated.)
- Redevelop 2 minutes Ilford Universal PQ
- Fix! 1 minute rapid fixer
- Rinse 5 minutes.
The results of tests below...
|ASA 16 flashed with lights on during clearing and developing|
|ASA 16 flashed with room lights for 7 seconds during developing|
|ASA 16 flashed with enlarger for 8 seconds during developing|
The final image is pretty good. It lack some contrast however. Besides I ran out of time by the time I finished it.