Xtol: way to prep less than 5 liters?

[David Goldfarb]

If you've got a scale to divide up Xtol, which is a bad idea, you could use the scale to mix up your own developer from bulk chemicals in whatever quantities you want, which is a great idea. Check out the new edition of Steven Anchell's The Darkroom Cookbook to get started. Paul Lewis's Mytol is the closest homebrew substitute for Xtol.

 

[snip]

Mixing partial packages is one of those things that is theoretically a bad idea, because you can never be sure that the components are evenly mixed in the powder, which in turn means that your five one-litre batches may differ quite widely -- even to the point of unusability.

In practice, quite a lot of people get away with it -- except when they don't. Personally it's not a risk I'd take.

Edit: I just realized that I answered the wrong question and that Justin answered it properly. Sorry!

Cheers,

R.

Ah! that's why it should be avoided, I was just pondering that part, yes of course, that makes a lot of sense. Didn't stop to think that there is more than one component in each powder 🙂 Doh..


//Jan

 

[Freakscene]

Edit: I just realized that I answered the wrong question and that Justin answered it properly. Sorry!

Ur, me too, obviously.

Xtol is a little more stable at if mixed more concentrated than normal stock because of the higher sulfite concentration. You can get aa 5L pack of Xtol to dissolve into 2L of water with a little heat and a lot of stirring. make sure you stir in a way that doesn't encourage aeration; this can promote oxidation and "sudden Xtol death syndrome".

>Paul Lewis's Mytol is the closest homebrew substitute for Xtol.

The closest homebrew substitute is to follow Formula #1 in US patent # 5,853,964 and add boric acid until the pH of the diluted developer behaves the same way Xtol does. There are two very useful things about Xtol - the greatest advantage is in using ascorbate as a developing agent, but the strong metaborate/boric acid buffer that provides the alkali is also extremely advantageous and is not replicated in many formulae for mixing yourself.

Or you can buy 1L packages of Fomadon Excel.

Marty

 

[Freakscene]

I repeated my shake and develop experiment. I thought I should report back. _How_ you shake is very important. The problem with the sonicator method of shaking is that it shakes very regularly and doesn't seem to separate out the particles, it more just mixes them up. Some other kinds of less predictable shaking do seem to make the particles separate by density, including being left in my car for a couple of weeks, storage in a bag attached to an automatic door and attaching Xtol packs to punching bags at a gym (cool huh!?). The variation was all in comparison to controls shaken the same way but where the whole 5L was mixed at once.

Mix small batches of Xtol at your own risk, you might be okay but you might not be. Kodak know what they're doing when they tell you to mix it all up at once.

Marty

 

[dfoo]

As mentioned above I mix my XTOL into 2.5L tap water. Obviously I then compensate when developing.

 

[Freakscene]

As mentioned above I mix my XTOL into 2.5L tap water. Obviously I then compensate when developing.

There is a huge difference between mixing all the powder into less water and dividing the powder up and mixing small batches.

In 2.5L of water the sulfite concentration of a 5L Xtol pack is close to saturated, so you run into a separate set of problems. You need to be careful that everything is dissolved if you do this.

Marty

 

[semilog]

This is not recommended. You will be better off dissolving everything and pouring it into smaller glass bottles to the brim, and then capping tightly, this way it will last for a long time.

As an alternative, consider one of the mylar coffee-in-a-box or wine-in-a-box bags. No headspace means no oxidation. Empty boxes and bags can be gotten from some restaurant supply places.

Currently I'm using bottles (with good performance from XTOL stock stored, unopened and with the cap taped with parafilm, as long as 10 months) but this looks much, much more convenient.

http://en.wikipedia.org/wiki/Bag-In-Box

It's probably a good idea make your XTOL stock in distilled or de-ionized water. It's likely that most or all of the "XTOL failures" reported in the early days of this developer were due to contamination by dissolved metals (principally iron) in tap water. (I make all my stock solutions in distilled water, not just XTOL.)