After intensification the Autochrome must be rinsed for at least half a minute, more rather than less, and is then placed in plain permanganate solution " H " for a minute. It is again rinsed for a full half-minute, and slipped into the hypo " I," in which it will be completely fixed in a minute. Five minutes' washing under the tap will complete the operations, and give us the finished Autochrome, needing only to be varnished and bound up with a protective cover-glass. It is dried in a rack ; the coating being thin, the operation only takes a few minutes. No heat must be used, and the plate must not be placed where it may stand with its lower edge in a pool of water that has drained from it. Should the colours weaken in the hypo, the blackening in the second development was not done in a bright enough light or was not carried far enough, or else the washing before and particularly after the application of the " H " solution was not sufficient.
To varnish an Autochrome, the dammar varnish is merely flowed over the surface, and poured off in the ordinary way. Again no heat must be used, and the benzine being highly inflammable, the operation must not be conducted near a naked flame. Although the plate appears to dry almost instantly, the varnish actually remains tacky for an hour or two, and the autochrome should be put on one side until this time has elapsed.
One dish may be used throughout the operations, and although it may get stained at first, the after operations should remove the stains from the dish as well as from the plate. In the same way, stains on the fingers can be removed by the " H " solution followed by the acid hypo, or in bad cases by the " C " solution. It is better not to get stained fingers, and if a glass dish is used, there is no need to pick the plate up at all, or a celluloid clip may be employed, and this is particularly useful when intensifying the plate.
The actual operations will be seen to be very simple, consisting merely of development, reversal and redevelopment followed by washing and drying. The film is so thin, that none of these take more than five minutes, and even the final washing is complete in this time. As the plates dry very quickly, it is therefore easy to get a complete finished dry Autochrome in about half an hour. The intensification and other processes should only be employed, when an error in exposure has made them necessary ; correct exposure and the standard development will yield as brilliant and vigorous a picture as anyone can want without them.