®


Up
Our Galleries
Bygone Forest of Dean
Latest Additions
Bygone Britain
Greeting Cards
Picture Framing
Stockists
Order Form
Book Collection
Vintage humour
Links Page
Pictures Wanted
Trading Terms
Important Advice
Contact Us
Post & Packing
How to Pay



Pay us securely with any major credit card.
(A PayPal account is not
necessary for this service.)

Add Forest Prints to your favourites list by right clicking here.

What is a Photochrome?

First of all, is it spelled “Photochrome” or “Photochrom?”
The process was initially developed in Switzerland and was spelled without an “e”, so the correct original spelling was actually “Photochrom.” When the process was introduced in America, the “e” was added to aid pronunciation.

A Photochrom is a colour photographic lithograph, produced from a black-and-white negative. The final prints were created using different colour impressions from multiple lithographic stones. The stones used by the Detroit Photographic Company were imported from Bavaria and coated with a special Syrian “asphaltum” substance that would be chemically sensitised to light, put in contact with a photographic negative, exposed to the sun for up to several hours, then “developed” in oils of turpentine.

The areas of the very thin asphalt gel most exposed to light would harden, becoming insoluble; the less exposed residue would be washed away. Tonal values of the remaining positive image could be manipulated by varying the chemistry and development times. Technicians could do the equivalent of photographic burning and dodging by retouching the brush and polishing with fine pumice powder. The final steps in preparing the stone were an acid etch to bond the remaining image with its very fine grain, and a glycerine bath.

A separate stone would be made for each colour to be used. A minimum of four stones and as many as fourteen stones might be used for a given image. A transparent ink would be applied to the stone, then transferred to high-quality paper whose texture resembled the smooth photographic printing paper of the day.

The final steps was a varnish which gave each print added depth and richness. Because the process involved a number of crafts people and because the stones had to be re-ground occasionally, substantial variations may be noted between different editions of the same image over the years.

Please note: When viewing the pictures on your computer, please bear in mind that the low resolution that the internet demands for fast downloading cannot do justice to the quality of these superb prints.

Click here to return to the main Photochrome Gallery, or use the "Up" button in the links bar.


 

 

Pay us securely with any major credit card.
(A PayPal account is not
necessary for this service.)
 
We welcome payment via
     © Forest Prints. Old photographs of the Forest of Dean,
Gloucestershire& most British & Irish counties.
© WazUK Design 2005 - 2013
        All rights reserved.