View Full Version : B&W developer for DoMac processor

al olson
17-May-2011, 17:50
Years ago when I bought my DoMac processor there was a company that supplied chemicals that were specially designed for it, both for black and white and for color.

For those who are not acquainted with the DoMac I will explain briefly how it operates. The processor has two troughs to pass the paper through the developer and the fixer or the blix. There are three sets of powered rollers, one pair to push the paper into the developer, another pair to pull the paper from the developer and push it into the blix, and the last pair to pull the paper from the blix.

In each trough there are acrylic tubes (idlers if you may) to hold the paper down in the solution. The troughs are temperature controlled at 98 degrees and the speed is designed so that the paper is exposed to the solutions for the prescribed time, approximately 45 seconds. All of this was working very well while I was using their chemicals. Even the b&w developer was used at 98 degrees.

Now I can no longer get the special chemicals. It turns out that most RA-4 chemicals work with no problem. The problem is using b&w chemicals. For convenience I would like to use this processor for b&w again.

I have been using Dektol and am finding that after processing a few sheets there begins to develop a brown stain, more or less in a line across the width of the paper. The stain appears to be transfered from the idler rollers in the developer. It seems to form where the surface of the solution makes contact at the roller while it is still.

From readings of photo chemistry in the '50s I recall that when hydroquinone oxidized it formed a brown aniline dye which accounted for the stain that we would get on our fingers. I assume that is happening here, amplified by the higher temperature.

So the questions are:
1. Are there any additives that I can use to inhibit the oxidation of Dektol. I have tried as much as 3 teaspoons of sodium sulfite with no results.

2. Can you recommend an alternative print developer that doesn't stain. I have checked Steve Anchell's Darkroom Cookbook, but not found anything that looks feasible.

An alternative is to use the processor at room temperature (I have not tried that yet), but I am concerned that 45 seconds in the developer may be a little short. I currently use 90 seconds when I tray develop and that gives me the results that I prefer. I also make final 16x20 prints with the Jobo using the same development times. I would not like to be using longer exposure times to accommodate a shorter development time, but keep the processes consistent.

Your help is appreciated.

Brian Ellis
17-May-2011, 21:22
Have you tried just cleaning that first rubber roller every few prints? I had a DoMac though I never used it for b&w. However, most problems involving lines or marks on the print could be fixed by cleaning that first rubber roller. I used to just wipe it off with a damp warm cloth every few prints and that would usually fix any such problems.

Hadn't thought of the DoMac in years. It was a great little processor for about $900, much less than any other roller transport processor then on the market.

17-May-2011, 22:03
Try Ethol LPD or Ansco 130. You might also try adding Glycin and/or Vitamin C to Dektol.

al olson
18-May-2011, 07:39
Actually, Brian, the stain appears to be forming on the acrylic roller where it intersects the surface of the developer. I have been cleaning these rollers, but it gets to be a hassle and I lose the convenience. (I paid somewhere around $1900 for mine. :( )

Nicholas, do Glycin or vitimin C retard the oxidation? Or what is their purpose? I will check out the Ethol LPD and Ansco 130. I believe I have seen them available commercially.

I had been thinking of trying something like XTOL, although that is a film developer. But I have processed 8x10 film in Dektol that was handy in the tray and that seemed to be okay.

Thank you for your suggestions.

Mark Sampson
18-May-2011, 08:16
Kodak used to make a liquid-concentrate developer for their roller-transport processors; first called 'Dektomatic', then, like everything else they made, 'Polymax'. There was also a 'Kodamatic' developer that we used for paper, in a Kodamatic 42A roller-transport machine that was meant for graphic-arts use. I don't know if they still offer anything like this (unlikely), but the recipes were designed to deal with the issues you mention. I think Ilford has, or had, something similar. Fuji-Hunt also made chemistry for these purposes.
Film developers are generally not strong enough for paper, even at 98F.