Photo Rambles
By P.G. Ramblings
Durst RT20 Colour Processing in Black & White

Having previously experienced the not uncommon everyday traumas associated with sourcing a reliable commercial photo lab capable of producing quality colour enlargements on a consistent basis, it can now be further reported that it really is mission impossible when searching for a lab to print your black and white enlargements. Seems you can have any colour that turns you on but not black and white. Very probably we'll soon be confronted by trendy little stickers similar to those that have for some time famously declared... batteries not included... except the photo lab version will probably proclaim... black and white not included.

After conducting some investigations by Internet and phone, the earlier encountered colour problems were solved by the acquisition of a Durst RT 20 RA4 Processor along with a DeVere 504 Enlarger and despite having no experience whatsoever of colour printing, a few short weeks later, we were in full production mode. Now some years later, having decided to embark on a new adventure in black and white, the ever increasing shortcomings existing within the photographic laboratory industry presented yet another seemingly insurmountable challenge. However, still not being the type to be easily dissuaded from a chosen path, we decided to utilise the now redundant Durst RT20 and attempt a B&W conversion. Hence, after a few modifications and a glamour makeover, the same equipment has once more galloped to the rescue.

For those unfamiliar with such user friendly beasts, I'll not over tax the brain and deal only with the Paper Processor this week and the enlarger along with another recent addition to the lab, an Arkay 35mm Film Processor, at a later date or to put it another way... when moved to do so by the spirits.

The Durst RT (Roller Transport) family of fully automated paper processors (RT 20, RT 30, RT 42, RT 62) were designed for busy professional labs but because of their low solution capacities they are equally suitable for low output situations and take photographic paper in roll or sheet form in widths ranging from 20.5 inches to a maximum of 61 inches. The RT20 that we are discussing is primarily used for processing sheet paper up to 30x20 inches and it does so very efficiently with the minimum of maintenance and perhaps more importantly for some... us included, it occupies very little in the way of floor space. Although originally designed for either EP-2 or RA-4 chemistry, as mentioned, it can and has been relatively easy and cheap to convert for black and white chemistry use.

Due to the design of the machine which allows easy access to all parts of it, the conversion was relatively simple to perform and mainly involved converting one of the five tanks which are when supplied: Developer, Bleach, Stabiliser/Wash, Stabiliser/Wash, Stabiliser/Wash. Being thrifty cheapskates, we had in the beginning, naturally opted to dispense with the expense of purchasing stabiliser chemicals and had instead plumbed in a Pro-CO water control unit to circulate controlled amounts of temperature correct water throughout the three wash tanks. Now that we were going to have to run a Developer, Stop Bath, Fixer, Wash, Wash configuration, the first wash tank obviously would have to be utilised for Fixer use which meant it would require heating, circulation and replenishment. The only other necessary change we made was to swap the second 9 Roller Rack Assembly (originally the Bleach Tank) with the 5 Roller Wash Rack Assembly. This was to allow the prints less time in the stop bath and more in the wash. Cleanliness obviously being next to what'isname in the processing world and speaking of which...

The most time consuming task of the conversion turned out to be the cleaning process. To avoid contamination of the new chemicals, ensuring that the Developer and Bleach tanks, racks, pipes and pumps were thoroughly washed and free of all traces of RA4 chemicals was of paramount importance.

Very few parts are actually needed for this type of conversion and are: 1 circulating pump, 1 replenishment pump, 1 heater, some additional plastic piping and sundries, all of which are readily available from Northern Photo Electronic Services and various other sources.

We however, took an alternative route which has proved to be highly advantageous as well as cost effective and that was to replace all of the original heaters, circulation pumps, replenishment pumps and piping with more modern units scavenged from a decommissioned Gretag 740 MasterLab which are equipped with highly efficient and reliable Iwaki pumps.

Removing the print collection bin allowed easy access to the Power Distribution Interface Board (Left Hand Side) into which the additional heater and pump was connected and apart from that we simply made up new alloy support brackets for the new cirulation and replenishment pump assemblies.

When completed, the processor was fired up and left to run over a 6 hour period with a constant supply of warm water being circulated through all of the tanks and pumps and then a further 2 hours with several sheets of paper being passed through the rollers to make doubly sure that everything was spotlessly clean and operating as it should. This also allowed us to check and make any necessary adjustments to temperatures, speed, flow rates etc.

Was it worth the effort? Very much so. Six weeks on, with a stock of Ilford chemicals and RC papers in place, we're a fully functional lab again but more importantly, we're spared the daily ordeal of listening to 'lab technicians' depressingly explain that in their opinion, the appalling prints they've just produced are of an 'acceptable' quality... which quite simply... is not acceptable.

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