One-bath blue toner for fiber and PE Papers. Kit for 6-10 liters toner solution.
The image tone depends on which paper is used, but it can range from light to dark blue, and even shades from green-blue to magenta-blue are possible. With different mixtures of the three main chemicals and the addition of the two optional solutions you can create fine differentiations of the blue tone.
The Berliner Blue toner reacts to alkali. Long washing times after toning should be avoided. To quickly remove the yellow color from the fericyanide, an acidic de-yellowing agent is supplied. This should be used at a dilution of 1+9. As soon as white areas of the image are cleared, wash for about three minutes. If the blue tone should be pushed more towards violet or blue-grey, use a alkaline finishing bath. A 10% alkaline solution is included with the kit: add 5 - 10 ml to one liter water to change the image tone. You can also use the left over alkaline solution to clean any toner stains from the darkroom trays.
With most toners there is the problem that the toner, after extended use, produces not only the desired Berliner Blue, but also the unwanted "Turnbull Blue". This color stains not only the darkroom trays, but also the gelatine and the paper edges blue. But this evil can be combated: the MT7 contains a stabiliser that binds to the "Turnbull Blue" in case it occurs after heavy usage or long standing time in an open tray.