Picture 1: Polychrome print (Lith+Siena) on Fomatone without toner
Picture 2: Gold Toner MT9 for 1:30 minutes
Picture 3: Iron-blue Toner MT7 for 30 seconds after gold toning
Picture 4: Bleached after gold toning and redeveloped in SE6 Blue.
Polychrome prints on warmtone paper cannot always be toned in iron-blue toner right away, without loosing highlight density. This is because, in these zones, the picture is predominantly made up of oxidation products attached to the finest chloride-silver grains. Bleaching would result in a total loss of pigment density. Only when the highlights are as dense as to show no pure paper white (like in picture 1) - meaning the print appears soft and obscure -, toning in iron-blue is an option, which results in brighter highlights. The prussian-blue pigment of iron-blue toner is unstable in alkali, so that excessive rinsing in tap water, which is also slightly alkaline, can result in fading colours and loss of the brightest highlights. If gold toner is used to protect the silver of the highlights, the original densities are preserved (picture 2).
By means of toning in MT9 Gold Toner, the highlights are fully toned and mid tones receive a colour shift, without being fully protected. The transition is smooth from highlights to shadows, so that the deep blacks with high silver density remain virtually unprotected. Except for the highlights, there is enough silver present to be converted to prussian-blue pigment by iron-blue toner. The blue-green hue, which emerges after toning, can be shifted towards magenta-blue by a weak ammonia solution (picture 3). This also removes most of the yellow cast that bleaching left in the gelatine. If only this cast is to be removed, common salt solution is sufficient. Final rinse should be no longer than 5 minutes!
If a less intensive hue is desired, you can bleach (potassium ferricyanide/ potassium bromide) after toning in gold and redevelop in coldtone developer. SE6 with Finisher Blue was used in picture 4.