Is there a specialist shop in Paris which sells Autochrome Plates especially nonexposed ones or a shop with a specialist who can understand which autochrome plate have nonvarnished , nonprotected panchromatic emulsion. My sister have no idea and someone must help there.
Try the Albert Kahn Museum in Boulogne-Billancourt. But they're not going to have any to sell. The only way you'll find them is on the 2nd hand market; which isn't to say that some specialist camera shop won't have them, but the chances of finding that shop seem slim.
Since Autochrome plates are sandwiched between two glass sheet the original plate + a protective plate it's very hard to see wether a plate is varnished or not. Maybe your sister can find a box with undeveloped plates at a marchee au puce, there is a big one specialised in antiquities. http://marcheauxpuces-saintouen.com/1.aspx
Thank you . Let me wait another replies , may be there is a autochrome shop like an tin tin shop.
Dominik , I will ask you more about that glass top plate at other thread.