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.
Developing. While any developer intended for gaslight papers may be employed, yet, owing to the fact that the emulsion of each brand of paper is different, they require a developer properly balanced to suit the emulsion, and where one formula is used for all papers, the proportions of the different ingredients will need to be altered to suit the paper employed; for example, some papers require more alkali than others; some work soft and, therefore, require less metol than papers that work hard and contrasty. As the emulsion used in sensitizing post cards is somewhat the same as used for coating the regular stock, a developer suitable for the regular stock of any brand will also answer for developing post cards. Very fine results are obtained by using the prepared metol-hydroquinon or ortol-hydro-quinon solutions supplied by the different paper manufacturers. Both of these solutions work well and are always ready for use. With different degrees of dilution splendid results can be obtained on any of the different products.
Substitution Of Ortol For Metol In The Developer. The metol-hydroquinon developer usually gives the best results; however, ortol may be substituted for metol. Metol possesses somewhat of a poisonous nature to some, often causing an itching and a soreness of the skin. With ortol there is no danger of poisoning, and the same results can be produced. When ortol is used, use the same quantity as metol.
Note. - See Vol. IX for Making Post Cards for Quick Delivery. Detailed instruction is given there for both exposing and developing the plates, as well as printing, developing, fixing and drying the post cards.
Drying. The greatest difficulty to overcome in drying photographic post cards is to prevent their curling. One of the best methods is to stretch cheesecloth tightly over a light wooden frame. Place your cards, face down, on this frame and allow to remain there until dry. Previous to laying them on this cheesecloth, carefully blot them and place the cards between two blotters to remove all surplus water from the prints.
1076. Another most practical method is to nail strips of wood about 1/4 of an inch thick, on a board, placing the strips about four inches apart. Lay the cards, face up, between these strips with the ends resting against the strips. This will bend the card to almost a half circle. If allowed to remain in this position until dry they will readily flatten when stacked together.