(44) 
lens camera are individually hand squeegeed and rack dried. Gammas used 
range from 0-6 to 2-6. The U.S. Coast and Geodetic Survey use gammas 
ranging from 1-0 for scene brightness ranges of 10:1 to 1-5 for ranges less than 
3:1. The Air Force use gammas from 1-2 to 1-7 on panchromatic materials 
and from 1-3 to 2 • 6 on infrared. Solution temperatures are 68°F with tolerances 
of ±1° or +2°. No routine sensitometric control is used. Film is supplied 
by the manufacturer in sealed tins. One organization stores it before exposure 
at 70°F and 55% relative humidity. The Coast and Geodetic Survey store and 
print their 23" x 23" negatives at a humidity controlled to the equilibrium 
relative humidity of the film. 
VII. PRINT MATERIAL AND PROCESSING 
Introduction 
The use of diapositives rather than paper prints is increasing for mapping. 
Paper prints are generally not ferrotyped (glazed). This represents a choice of 
best dimensional stability and convenience in writing on the prints at the expense 
of some loss in resolution. 
Australia 
Positives are made on bromide paper using a contact printer and hand 
processing. Exposure is determined by the operator’s experience. Prints are 
not ferrotyped. 
Austria 
A bromide material is used and exposure is determined empirically. Prints 
are not ferrotyped. 
Canada 
Most contact prints are made on double weight chloride paper. A little 
use has been made of Resisto waterproof paper. Many types of printers are in 
use. Practically all have rubber or inflated rubber platens. Several organiza 
tions have made checks of printer contact using as a test negative a print of an 
engraver’s half-tone screen. Such tests have indicated that the printers with the 
inflated rubber platen such as the Pako printer shown in Fig. 14 or the type 
A-14 give best contact. Exposure is generally based on the operator’s judgment. 
Tray processing is used and prints are not ferrotyped. Flowever, ferrotyping 
is recommended where detail is important on the basis of an investigation of 
paper resolving power by Plowlett and Matthews 25 , which showed that the use 
of glossy paper is necessary to reproduce even approximately the full resolution 
of Kodak Aero Super XX film. Another method of improving paper resolution 
was described by Miss Johnson 26 . 
One organization reports on printing conditions as follows: Temperature 
rise of negative in printer, 2°F; ambient temperature, 70°F; ambient humidity, 
40 to 70%. Increasing use is being made of glass diapositives both as contact 
prints from the negatives and as reduced projection prints in the Multiplex