This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Clearing. When intensification is found to be complete, rinse the plate, for a few seconds, in running water, and immerse them from 30 seconds to 1 minute in permanganate solution H, (clearing solution) which does not contain any sulphuric acid. When out of the solution the plate shows light yellow stains. These will disappear in the fixing solution, owing to the clearing action of sodium bisulphite, which chemical should not be omitted.
Fixing. Although unnecessary to fix the auto-chrome plate when the simplified method of development is employed, yet it is necessary to fix it after intensification. This is an absolute necessity. After a brief washing, fix in the acid hypo solution I, for about 2 minutes. If the intensity of the image shows any reduction it means that the second development has not been sufficient.
Washing. Four to five mnutes washing in running water is sufficient to eliminate all traces of hypo from the sensitive film, which is extremely thin. When the whites of the image show a light yellow discoloration, this can be removed by a fresh immersion in solution H, followed by another in solution I.
Drying. The plate is finally drained and dried, as quickly as possible, in a well ventilated room, at a temperature not exceeding 70° Fahr.
Varnishing. When drying is complete it is ad- visable to varnish the plate in order to increase the brilliancy of the image and insure its preservation. This must be done with varnish J, no other, which is applied in the usual way.
Rubbing Film. Never rub the sensitive film when wet, as it is extremely delicate.
Don'T Use Alcohol. Never use alcohol in any manipulation of Autochrome plates, as the color will disappear entirely.
Trays. It is advisable to use glass trays in preference to porcelain ones, as the latter are liable to crack and thus become difficult to keep clean.
Time Limit For Use. Autochrome plates keep their qualities for a few months, provided they are protected from dampness and excessive heat. On each box is stamped the practical limit for use.
Delaying Final Development. If for any reason it is thought advisable not to complete the development of an autochrome plate at once, it can be discontinued after the first development and reversing of the image in Solution No. 2, or C. Then, after washing, the plate may be left in the dark, and the development completed several days later. The operations such as intensifying may also be discontinued after the second development. This will be found advantageous in warm weather, as the film becomes harder after the first drying.