DEFECTS IN NEGATIVES AND PRINTS 543 



whereas if they are on the plain side of the negative or upon the glass plate of the 

 printer, the images will be less sharply defined. (6) Formation of an air bell on the 

 print during development prevents the developing solution from acting on the spot 

 covered by the bubble, so that no development takes place and a white spot results. 



3. Prevention.- — (o) Cleanliness is the only preventive where spots are due to 

 dust, lint, dirt, or other foreign matter, (b) See Air Bells, page 541. 



4. Remedy. — Careful spotting and retouching will be required. 



Mechanical Defects 

 Curling of Prints. 



1. Distinguishing Characteristic. — Prints curled upon drying. 



2. Cause. — The emulsion contracts to a greater extent than the paper backing 

 on prints, so that, upon drying, prints tend to curl with the emulsion on the concave 

 side. 



3. Prevention. — Curling may be prevented by washing the print in a bath con- 

 sisting of from 1 to 2 parts of glycerin in 10 parts of water. The print should be 

 washed in this bath for 5 min. (or until the back paper support is thoroughly saturated 

 with the solution), after which the print may be dried in the usual manner without 

 further washing. The prints may also be dried fiat by laying them (emulsion side 

 down) on the drying stretcher and sponging the back paper slightly with alcohol or 

 water. With this method, the total time required for drying will be increased, but the 

 prints will dry much fiatter than with ordinary drying. 



4. Remedy. — Prints may be straightened by drawing the print, emulsion side out, 

 over a smooth, rounded corner of a drawing board, table, or similar surface in such 

 a way as to impart concavity to the back of the print. While this method is quite 

 satisfactory, care should be exercised. Care is especially necessary with prints having 

 a glossy surface, as the surface of the prints may be cracked. 



Frilling. 



1. Distinguishing Characteristic. — Emulsion separating from the paper backing. 



2. Cause. — (a) Processing solutions too warm. (6) Careless handUng of print. 



3. Prevention. — (a) All solutions should be between 60 and 70°F., and all solutions 

 should, preferably, be at the same temperature. They may be brought to the same 

 temperature by setting them in a water bath for a length of time sufficient to have all 

 solutions reach equilibrium. (6) Care in handling prints is the only prevention in this 

 case. 



4. Remedy. — None. 



Spotty Glazing. 



1. Distinguishing Characteristic. — Surface of print not uniformly glossy. 



2. Cause. — Imperfect or improper ferrotype glazing due to (a) imperfect contact 

 between ferrotype plate and print, (6) improperly prepared surface of ferrotype tin, 

 or (c) failure to squeegee the print on the ferrotype tins. 



3. Prevention. — (See chapter on Washing, Fixing, and Drying for proper method of 

 ferrotyping.) 



4. Remedy. — Sometimes spotty glazing may be remedied by soaking the print in 

 water and again drying on the ferrotype plate. 



White Deposit on Print. 



1. Distinguishing Characteristic. — White deposit covering emulsion side of print. 



2. Cause. — Use of exhausted or incorrectly mixed fixing bath; impurities in fixing 

 bath. White precipitate in bath deposits on print. 



