Anon, on a different note, would you mind sharing your XTol modified formula?
Well, I'm back home, so I can post my modified formula, along with some general information. It is based on the formula found in
patent US5853964A, example 1, page 5 of 7 and here are the modifications made:
- DTPA-5Na (Diethylenetriaminepentaacetic acid, pentasodium salt) isn't easily obtainable and it was replaced by 2 g of Sodium Hexametaphosphate per litre. Since DTPA-5Na is quite alkaline and Sodium Hexametaphosphate is neutral, this will probably lower the pH of the solution, so pH adjustment will be required. This will also affect the keeping properties of the developer and the Fenton reaction that kills this developer is more likely to happen. I don't have any ambitions about making it a long shelf life developer and use it right after I make it. Keep in mind that this is optional and can be omitted if using distilled, or deionised water.
- Sodium Metaborate isn't available to me, so I make it in solution using the right amounts of borax (Sodium Tetraborate decahydrate) and Sodium Hydroxide.
- Dimezone-S (4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone) is a derivative of Phenidone. I don't have Dimezone-S, so I replaced it with Phenidone. Molecular weights, as well as activity levels differ, so there's no easy way to tell how much will be needed. I just used the same amount per litre, 0,2g. I make a 1% w/v solution of Phenidone in Propylene Glycol, which has excellent keeping properties and use 20ml of it.
- Sodium Isoascorbate isn't something I have. It can be replaced by the same amount of Sodium Ascorbate, which is an isomer. If you only have Ascorbic Acid, as I do, you can use an equimolar amount of it and neutralise it with sodium carbonate, or bicarbonate, or hydroxide. I opted for hydroxide, since I use it to make Sodium Metaborate, but also to adjust pH.
So, the resulting formula is this:
Sodium Hexametaphosphate | 2g |
Sodium Sulfite | 85g |
Borax | 2,77g |
Phenidone | 0,2g |
Sodium Metabisulfite | 3,5g |
Ascorbic Acid | 10,67g |
Sodium Hydroxide | 3g |
Water to make | 1l |
Target pH | 8,2 |
In practice, I noticed that I need slightly more Sodium Hydroxide to reach the target pH of 8,2, 3,2 instead of 3g, but this also depends on the purity of the chemicals used.
You can simplify things quite a bit by making a long shelf life solution consisting of some of the ingredients listed above
at double the concentration. So, you can mix Sodium Hexametaphosphate, Sodium Sulfite, Sodium Metabisulfite and Borax to a total volume of 500ml. When I want to make some developer, I measure half the volume I will need, then add the Phenidone, Ascorbic Acid and Sodium Hydroxide. I then top up to the volume of stock developer required. At this point, I adjust pH, after which I can further dilute the developer to 1+1.
Theoretically, I could make a solution consisting of everything except Ascorbic Acid, since this is what oxidises and kills makes the developer fail. If you do so, the solution will likely be copper coloured, because of the hydrolysis of Phenidone. The addition of Ascorbic Acid will make the solution water clear, something that you might experience when mixing part B of Xtol. In the end, I decided that it's better to add Phenidone (and hydroxide) just before use, because I don't know how well it would keep.