subject: Printing For Profit in Platinum From Digital Negatives - The Concise Guide - Part 3/7 [print this page] Printing For Profit in Platinum From Digital Negatives - The Concise Guide - Part 3/7
Museum cotton mount board.....................................framing equip. supplier
Now things start to become interesting because we are going to prepare our own chemicals. Of course you could buy all the chemicals premixed but it would be a big waste of money, and if you are going to print in platinum for a profit that is not the way to go. For example the developer I use and recommend is potassium oxalate, in powder it costs $35 for 1Kg from B&S, which makes approximately four liters of solution. Since the developer is never discarded you may think that four liters may go a long way, which is not true. Every printing session I have to replenish 100 to 200 ml of developer. My advice is making potassium oxalate yourselves mixing oxalic acid and potassium carbonate which you can buy in bulk. If you call a chemical company (we have plenty even here in a small country such as Ireland) you will find out that a 20Kg bag of oxalic acid costs very little, same for potassium carbonate. Unfortunately I forgot the cost because I bought my last supply of chemicals (20Kg bags) six years ago and still have plenty for years to come. As said it was cheap, like $100/$150 for the entire supply which by the way included two bags of the clearing agent that I recommend, citric acid. Of this you will need plenty, and since from B&S it costs $12 for 1Kg, once again I recommend a chemical company which will supply you with a 20Kg bag for probably about the same price. Since all these chemicals come in powder form, if properly stored they will never go bad. I believe, however, that even photo suppliers like B&S can provide you with chemicals in bulk, but I would check with some chemical companies anyway. Please note that suppliers like B&S and Photographers Formulary have helped many to get started in alternative processes, they also sponsor forums etc. so, if you can, buy from them rather than from non-photographic businesses. I personally can not afford to import from the US and pay a premium for what is, in fact, a terrific service and support, of which B&S and others are well known. Alternatively you could also join a user group such as Apug where you can maybe participate in a group purchase to save some money, especially when purchasing the metals. Luckily, ferric oxalate and Na2 are not expensive (Na2 is actually expensive, but one 20% solution bottle will last you ages). One thing I would not do, though, is buying those kits with a little of everything, including the paper, just to get yourself started - I believe that is a waste of money.
Before starting with the procedure a word of warning: the chemicals used in platinum are very toxic (more toxic than silver printing) so be careful and if you go the way I recommend i.e. stock purchase of oxalic acid etc. please keep them in a dry, sheltered place and away from kids and pets.
Procedure to make potassium oxalate:
Use a large (10 liters) plastic bucket. Sign with a marker the 5 liters level. Pour in 3 liters of tap water. Dissolve 900gr of potassium carbonate completely. Dissolve (slowly!) 800gr of oxalic acid. This is potentially dangerous, it will make lots of bubbles and it will become hot. Wear a mask, gloves and goggles and stay in a well ventilated area. When finished, top up to 5 liters. Finally add another 150gr of oxalic acid. First times you use the solution do not expect great results, what I mean is that it is a brand new developer, and in time it will become old, darker and better like a good wine. You can squirt in it a syringe of palladium if you want, to make it richer. I always prepare a 10 liters bottle of solution which I use to replenish my normal two liters working bottle, which is now several years old. Note: if you leave the solution in the tray for a long time i.e. 24+ hours it will start to oxidize and become greenish, so please avoid that. Also, after some time you will probably find at the bottom of the working solution bottle some green crystals, these are easy to remove just pouring in the empty bottle one tray of used citric acid solution and shaking.
The clearing agent is mixed when needed, just three teaspoons in 1.5 liters of water. I use three trays with 1.5 liters each in sequence and every 3-4 prints I discard the first and make a new one. The last batch should always be clear.
To make the solutions for coating proceed as follows:
Palladium: Use a 100ml bottle. Prepare 110ml of hot water (preferably distilled, although I use tap water). Fill about 3/4 of the bottle with hot water, dissolve in it first 7gr of kitchen salt, then 10gr of palladium chloride. Pour the rest of the water in. B&S 100ml bottles will accept 110ml. Shake until dissolved.
Platinum: I would prepare 50ml only. Just dissolve 10gr of potassium chloroplatinite in 50ml water. Platinum and palladium never go bad and obviously are not light sensitive so there is no worry if you prepare a lot of them.
Ferric Oxalate: I would prepare 50 or max 100ml of this, since it does not last long (store it in the dark). For 50ml, first dissolve 0.7gr of oxalic acid, then 15gr of ferric oxalate. Oxalic acid would not be needed, but it keeps the solution for longer and avoids fogging. Be careful with these small quantities, because if you overdo this, the resulting prints will show more contrast, and you will not have a clue why. One of the things I like printing in platinum is that if you make a print now, and then after three years you have to make the same print again, it will come out just the same, provided that you are consistent with chemicals preparation and procedures. I have never managed to obtain this level of consistency with silver. Back to our sensitizer. Unfortunately this solution needs a really good shake (that is why I recommend preparing 50ml in a 100ml bottle). I shake for a while then I prepare a kettle of boiling water, bring the bottle's temperature up immersing it in hot water for a while, than shake again etc. Leave overnight and if the morning after you see stuff at the bottom of the bottle, you will have to shake it again all over. Ferric oxalate in powder is a very nasty 'powdery' stuff sort of baby talc, and very toxic (and light sensitive) so be careful. Use a mask even when mixing small quantities and clean thoroughly the area afterwards. Also, in my experience, FO is very often the culprit when it comes to printing problems: low contrast, or blotchy, or fogged prints, first thing to do is to mix a new bottle of FO from a fresh batch.
Na2 (Sodium Chloroplatinate). This is the contrast agent. It comes from B&S as 20% solution. Buy the 10ml bottle, it will last a long time since we will almost not be using it. I am against contrast agents in general because they ruin the print. Our negatives will be spot on so we will be using only 1 or 2 drops of Na2 at 2.5% to avoid fogging. You will need three more 25ml bottles, labeled as follows: 10%, 5%, and 2.5%. To make the 10% solution mix one full dropper of 20% and (obviously) one of water. To make the 5% solution mix one full dropper of 20% and three droppers of water. To make the 2.5% solution mix one full dropper of 20% and seven droppers of water. With the exception of special situations, badly developed or non-digital negatives etc. you will be using mostly the 2.5% so mix accordingly.
