XTOL is a "fine grain" film developer providing excellent film speed (shadow detail) that comes in two-part powder form. You dissolve the powders sequentially in warm water to make a stock solution that can be stored for a few months in full PETE or glass bottles.
It can be used at stock concentration (one-shot or replenished), or more commonly at 1+1 (one-shot only). Higher dilutions are generally not recommended as they often lead to unexpectedly low developer activity, though you can still find old published starting times for 1+2 and 1+3 dilution.
The fine grain effect is achieved using a silver solvent, sodium sulfite, which dissolves the edges of the film grains. This provides additional smoothness of the final image at the cost of reduced resolution and fine detail. The solvent action is reduced by dilution or by ageing of a replenished solution.
XTOL is an ascorbate-based developer and is therefore relatively environmentally friendly. It provides smoother grain, better resolution and better shadow detail than D76 (both at 1+1 dilution).
This is the easiest way to use XTOL, gives very good film speed, some solvent action (smooth grain) yet more resolution because the solvent is more diluted.
The drawback is that if you are using an inversion tank, the economy is poorer than necessary, e.g. 250mL for a single roll of 120, whereas the quoted capacity is 75-100mL per roll. This is still an economical option for rotary development systems like Jobo because much less liquid is required to cover the film.
This is an expensive way to run XTOL (300-500mL per roll with inversion tanks) but will give the greatest solvent action and therefore the smoothest results with very coarse films such as SFX200 and IR820.
This approach has great economy for inversion tanks because you consume only 75-100mL per roll, no matter the quantity required to cover the film. The initial performance with fresh developer will be the same as one-shot undiluted because no XTOL Starter is available but once the developer seasons a little and accumulates a little bromide from previous rolls, the performance becomes very similar to that of XTOL diluted 1+1.
See how to operate replenished developer.
Development times must be adjusted as the developer seasons, beginning with the one-shot undiluted time and tending towards a longer time as the developer seasons. Failure to extend the time will result in severe underdevelopment and the loss of approx one stop of film speed (less shadow detail).
This technique is most suitable when large quantities of film are being developed, which makes it easier to keep the process in control; it is not recommended for beginners.
Small white floaty bits that look like shredded tissue can form in XTOL stock when stored. Developer in such a state should not be used in stock form because the floaties are highly active and will cause unsightly dense spots on the film, however dilution to 1+1 will cause them to go back into solution and it will work properly.
XTOL is infamous for "XTOL Death", wherein stored developer suddenly becomes completely inactive with no warning signs such as discolouration or a gradual reduction in activity. Causes typically blamed for XTOL death are:
Therefore when making up XTOL, follow these precautions:
XTOL made up in this way can last for 6 months with no issues. If you have a batch that hasn't been tested for a couple of weeks, it's probably prudent to run a test roll (at least a few frames) to make sure it hasn't died before developing anything important.
A 5L pack of XTOL can be dissolved into a smaller quantity of water, e.g. 4L. The reduction in the quantity of water present means a reduction in the quantity of dissolved oxygen and therefore (theoretically) better keeping properties. The higher concentration must be accounted for when using the developer though, e.g. use 2+3 dilution to obtain the normal 1+1 concentration.
See general tips on how to store developer.
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