Blisters on Developing Papers

Blisters on Dry Plates

II. 77.

Avoided by immersing the dry plate, immediately upon their first appearance, in a solution of powdered alum or chrome alum, or a weak solution of formalin. (See reference.)

Blocking-Out - IV

Suppressing, or painting out with opaque paint, any part of the negative which it is not desired to have printed. The blocking-out should be done by painting, preferably on the back of the negative. Ready prepared " opaques" are obtainable from photographic dealers, yet the following will be found very satisfactory:

Blotting Paper

(See Paper, Blotting.)

Blue Glass

Useful in viewing a landscape to secure an idea of the effect when reduced to monochrome.

Ferro-Prussiate, or Heliographic, or Cyanotype Process

An iron printing process. Development effected by water only. Blue-Print Process - Sensitizing Solution - I, 367. Blue Tones on Bromide and Developing Papers - V, 713-715.

Blue Vitriol

(See Copper Sulphate.)

Blurring

When an image has a double or an indefinite outline it is said to be blurred. May be caused by movement of object or by jarring the camera during exposure; also caused by halation, aberration, or poor focusing of image on ground-glass.

Boiling Point of Water

Borax

(See Sodium Borate.)

Bottles

Care should be exercised in selecting bottles for various chemicals. Acids and ammonia should be kept in glass-stopper bottles and the stoppers rubbed with a little vaseline, which not only renders the bottles air-tight but prevents the stoppers from sticking. Solids should be kept in wide mouth bottles. Chemicals sensitive to light should be kept in amber or non-actinic bottles.

Dropping Bottles

A small bottle which will hold liquids, and from which small quantities of the liquid can be obtained in drops.

To Clean Bottles

To remove PHOTOGRAPHIC SOLUTIONS use hydrochloric acid mixed with an equal quantity of water. GREASE; rinse with benzene, then apply a strong solution of sodium carbonate. VARNISH; rinse with alcohol, I ounce, and ammonia, 1 dram; then ammonia, 1/2 ounce, water, 5 ounces, and follow this with a good wash in water.