Di-Xactol developer

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Has someone tried the Di-Xactol (British) two bath film developer ? It is a staining formula (like pyro) and has all the advantages of a two bath developer. I started doing tests with it, but haven't yet drawn any final conclusions... It seems to me that it resembles the PMK formula, only made in a two bath form (you can also use it as a one-bath chemical, too)...

-- George Papantoniou (papanton@hol.gr), June 08, 2001


George, I've used it extensively over the past year as a single bath developer with lovely results on 4x5 and 120 Delta 100, 120 SFX200, 35mm Kodak IR and Delta 400. You get a good stain on Delta 100 and the gradation and sharpness are excellent. However I do find its not as fine grain as PMK Pyro. Regards,

-- Trevor Crone (trevor.crone@uk.dreamcast.com), June 09, 2001.

George, I agree with Trevor's response. DiXactol is nice, but PMK does exhibit finer grain. The tonality and such are more subjective, but they are more similar than different. The biggest difference is price: PMK is much cheaper, and better yet, you can buy the chemicals and make your own. The DiXactol manufacturer has chosen to sell his product in equal sized bottles, of which you need several times more of "B" than "A." "B" is sold separately, and at an exorbitant price, considering that it is nothing more than a solution of sodium hydroxide, which is very, very inexpensive. So even if DiXactol was the equal of PMK, I'd use PMK because I resent the screwing DiXactol's maker tries to pull on his customers.

Incidentally, the formulation of PMK and DiXactol are completely different. The only similarity is that both developers tan and stain the emulsion. PMK uses pyrogallo as it's primary agent and DiXactol uses pyrocatechin (catechol); Accordingly, PMK produces a greenish/yellow stain and DiXactol a brownish stain. Ted Kaufman

-- Ted Kaufman (writercrmp@aol.com), June 10, 2001.

Thank you both for your help. Ted, isn't then PMK more toxic than DiXactol ? I think (but am not sure) that Pyrocatechol is not as toxic as Pyrogallol. If it is so, then I would find it a good reason not to choose PMK (although I don't want you to think I am trying to advertise Thornton's product). DiXactol may be more economic in its two bath version, if you have many films to develop every time you prepare a quantity of working solution of course. Can't someone prepare his own solution B to avoid paying the price to the manufacturer ? Since it's a simple strong alkali solution, it must not be so hard.

-- George Papantoniou (papanton@hol.gr), June 10, 2001.

George, Pyrocatechin is just as toxic as pyrogallo. Neither will cause your arm to shrivel should you get a few drops on your hands, but if you are developing film in trays, use gloves. That is a good idea no matter what developer you use. Even metol (D76) will cause skin disorders over time. Anyway, don't choose DiXactol over PMK because of lower toxicity. For some reason there is the misconception over the web that pyrocatechin is not very toxic. It is highly toxic. But then so too are selenium, amidol, p-phenolinediamine, among many other popular photo chemicals. The keynote is to use common sense.

As for the "B" alkaline solution used in DiXactol, yes, you can make your own. The chemical is sodium hydroxide. I would estimate its concentration at about 3% (3g/100ml). That should put you in the ballpark. Ted

-- Ted Kaufman (writercrmp@aol.com), June 10, 2001.

There is also Sandy King's PyroCat formula, which can be mixed yourself. It uses pyrocatechin and glycin. No I havent used it because being accident prone I like to avoid the more toxic photo chems, but if I ever decide to try a staining developer thats probably what I'd try.

I dont know that pyrocatechin is as toxic as pyrogallol-at least not from what I've read-but it is certainly more toxic than most developers.


-- Wayne (wsteffen@skypoint.com), June 11, 2001.

I just looked up in the Merck catalogue of chemical supplies and the LD 50 oral for Brenzcatechin is 360 mg/kg body weight, Pyrogallol is 760 mg/kg. In the Swiss rating for poisons Brenzcathine is rated as more toxic (class 2) than Pyro (class 3), in the German rating both are classified as Harmful, which is one class below toxic. For comparison hydrochinon, harmful, LD50 oral 320mg/kg, Swiss class 3. LD 50: lethal dosis 50% of test species dies

Referring DiXactol bath B, I ran some experiments with two bath dev. based on catechine, so bath B needs strong alkali plus some anti-fog to reduce base-fog otherwise your filmbase will be toned as well, try 0.5-1 g KBr/ 100 ml stock solution



-- Wolfram Kollig (kollig@ipfdd.de), June 11, 2001.

I've used a fair amount of DiXactol, and it is worth trying as an alternative to PMK, but only as a single bath developer - as a two bath, there appears to be recurring risk of uneven development, which apparently is due to water quality and contamination rather than to the agitation method. There's probably little to choose between PMK and DiXactol, despite all the talk about the different colour of stain having a different effect when printing on VC paper. Both are very sharp, and come into their own for N and N- development. For N+, I still think that it is difficult to beat Rodinal.

-- fw (finneganswake@altavista.net), June 11, 2001.

Hey, Wolfram, your info is really great !! Where did you get all that from ? I really find it interesting, although I din't like the part where the test species dies (especially if I am the species in question)... Well, I will use my gloves and mask more frequently now, I will be a good boy. About the advantages of the one bath development, I have to admit that I also experienced some development unevenness when using the two bath option. On the other hand, the two bath development offers superb control on the highlight density, being the "ultimate" compenstation development. Combining a staining developer (that offers fine grain) and two bath development seems to me like being a perfect combination (that is the reason why this specefic chemical interests me a lot). If I wanted to use a single bath developer, I would probably use something else (like PMK, for instance). About the unevenness now, I have tried the DiXactol (two bath) diluted with water from the tap, but I have a complicated deionizer filter systed installed, that cleans out most of the crap in the water. What I might try to do next, is use simle distilled water and a new developing tank (because it seems that chemicals left on the inside of the takn might affect the DiXactol). If you have any other ideas, please share them with me.

-- George Papantoniou (papanton@hol.gr), June 13, 2001.

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