One  big  disadvantage  of  tilting  the  easel  is  that an  extremely  small  diaphragm  opening  must  be used for depth of sharp focus. The use of a small diaphragm   opening   makes   focusing   and composition  difficult.  This  makes  it  necessary  to use long exposure times. PROCESSING DEFECTS The  prints  you  produce  will  not  be  perfect every  time.  Table  11-3  shows  some  of  the  most common defects found in black-and-white prints. Use this table to identify and correct print defects. Table  11-1-Print  Defects Defect Appearance Cause Prevention Abrasion marks or streaks. Surface of paper abraded Friction or rubbing on Store paper boxes on or  scratched;  results  in the surface of the paper. their  edges;  handle fine dark lines on the carefully;  make  sure  that surface of the processing  solutions  are print, especially with free from grit or glossy  paper. undissolved  particles. Inspect  and  clean  rollers of  processing  machine. Bad definition in parts of Parts of print poorly Buckling of paper in the Check  contact  pad  in print. defined, blurred, as if out contact printer, thereby printer.  Pressure  springs of focus, though negative blurring  these  parts. should  be  firm  and is sharp. strong. Bad  definition  over entire print. Completely  blurred  print In contact prints, because In  contact  printing,the from  sharp  negative. of  printing  from  the paper  emulsion  must wrong side of the always  be  in  contact negative.  In with the emulsion of the enlargements,  careless negative.  Enlargers focusing or, more should  be  braced  firmly often,  vibration  of  the and protected from enlarger, especially at vibration high  magnification. Round  white  (light) Air bells prevent spots on print. Round  white  or  light spots in picture area. Proper agitation of print developer  from  working in developer. on parts of paper. Round dark spots on Round  or  circular- prints. shaped  dark  spots. Air bells on surface of print  in  fixing  bath allows  developer  to continue to work Use a stop bath between developer  and  fixer. Agitate  thoroughly  in fixing bath. Round  discolored  spots appearing  some  time after  drying. Round  discolored  spots in picture area of print. Air  bells  in  washing Thorough  washing  with prevent removal of hypo constant  agitation. in these areas Small,  well-defined brown spots. Brown spots on front or Particles of rust in wash back of print. water from rusty wash Where  quantities  of  rust are present, use a water tanks  or  water  pipes filter in the line. and/or  particles  of chemical dust. 11-21