PHOTOGRAPHIC INTENSIFICATION (RT): Chemical treatment of a processed emulsion, usually with an oxidizing
agent, to lessen the density. There may be a change of contrast, depending on the process used.
PHOTOGRAPHIC TRANSMISSION DENSITY (RT): See DENSITY.
PHOTON (RT): An electromagnetic packet of radiation. It has a dual character, acting sometimes like a particle and at
other times like a wave. Photons all have equal velocity (the speed of light), have no electric charge, and have no mass.
PHOTO-SENSITIVITY (RT): A property of a photographic emulsion by virtue of which electromagnetic or particulate
radiation may produce chemical or physical changes in the emulsion.
PHOTOTHERMOGRAPHIC FILM (RT): A blue/green sensitive dry silver film used in conjunction with special
fluorescent screens in vacuum cassettes which can serve as an alternative to X-ray film for noncritical applications.
The principle advantage of this film is that it is processed thermally, eliminating the need for wet chemicals.
PHYSICAL PROPERTIES: The properties, other than mechanical properties, that pertain to the physics of a material;
for example, density, electrical conductivity, heat conductivity, thermal expansion.
PHYSICAL TESTING: Determination of Physical Properties.
PICKLE: Using acid or other chemicals with suitable inhibitors to remove scale or smeared metal without affecting the
PICKLE PATCH: A tightly adhering oxide or scale coating not properly removed during the pickling process.
PICKLE STAIN: Discoloration of metal due to chemical cleaning without adequate washing and drying.
PICKLING CRACKS: Cracks caused by internal stresses being released as the pickling acid eats away the surface of
PIEZOELECTRIC (UT): That ability of a material to convert electrical energy into mechanical energy and vice versa.
PIG: A cast slab of primary metal that must be remelted before use.
PINHOLES: Very small holes; sometimes found as a type of porosity in a casting because of microshrinkage or of gas
evolution during solidification.
PINHOLE (RT): A through hole of small diameter in a sheet of material opaque to radiation.
PINHOLE POROSITY: Porosity, in either castings or metal formed by electrodeposition, resulting from numerous
small holes distributed throughout the metal.
The central cavity formed by contraction in metal, especially ingots, during solidification.
The defect in wrought or cast products resulting from such a cavity.
An Extrusion Defect due to the oxidized surface of the billet flowing toward the center of the rod at the
A tubular metal product, cast or wrought.
PITCHBLENDE: An ore that contains uranium.