Ascorbate/VitaminC developers: DTPA is now being sold by Artcraft Chemicals

[albada]

If you self-mix ascorbate developers in water, such as E-72 or E-76 or an XTOL look-alike, and you want to ensure that the solution lasts weeks or months, you should add some DTPA to it to prevent the Fenton reaction from destroying the ascorbate.
It's now being sold by Artcraft here:
Diethylenetriamine Pentaacetic Acid Pentasodium Solution

Note that this is a 40-60 solution (w/w), so you must multiply the desired dry-weight by 2.5 to get the liquid weight.
The XTOL patent specifies 1 g/L, but I've read that that might be too low. Ilford patents I've read specify 2.5 g/L, so 2.5*2.5 is 6.25 g/L of liquid.

Mark

 

[Milpool]

That’s good news! It was more difficult to source before, and this is cheaper than I paid too. I’ve always had good experiences with Artcraft.

I agree with you it is probably best to use more than the 1g in the XTOL patent. My reasoning is simply that the patent formula would probably/likely (?) have assumed higher purity ingredients (particularly sulfite) than the technical grade typically available to us home mixers at reasonable prices from the standard bulk photochem suppliers.

If you self-mix ascorbate developers in water, such as E-72 or E-76 or an XTOL look-alike, and you want to ensure that the solution lasts weeks or months, you should add some DTPA to it to prevent the Fenton reaction from destroying the ascorbate.
It's now being sold by Artcraft here:
Diethylenetriamine Pentaacetic Acid Pentasodium Solution

Note that this is a 40-60 solution (w/w), so you must multiply the desired dry-weight by 2.5 to get the liquid weight.
The XTOL patent specifies 1 g/L, but I've read that that might be too low. Ilford patents I've read specify 2.5 g/L, so 2.5*2.5 is 6.25 g/L of liquid.

Mark

 

[relistan]

That’s good news!

 

[lamerko]

Note that DTPA is a very poorly soluble acid (4.8g/liter) and as an acid it has a low pH of 2.5. On the other hand, its salt DTPA.5Na is sold as a solution and has an alkaline pH of 11-12. Artcraft sell the salt, not the acid.

 

[albada]

Note that DTPA is a very poorly soluble acid (4.8g/liter) and as an acid it has a low pH of 2.5. On the other hand, its salt DTPA.5Na is sold as a solution and has an alkaline pH of 11-12. Artcraft sell the salt, not the acid.

Yes. I should have mentioned that Artcraft is selling what we need -- the pentasodium salt of DTPA, as that's what Kodak's and Ilford's patents specify.

 

[albada]

We've been bemoaning for years that DTPA is hard to source, yet all it took was one phone call to Artcraft. I explained to him why it's needed for ascorbate developers, and he stocked it. That simple.
If there's some chemical you need, I encourage you to call him.