series of <#commem=commemorative>  <#poststamp=postage stamps> (late 1950s to early 1960s) honoring foreign nationals who sought freedom in their homelands.  Example: <#scott=Scott> 1125.

a <#stamp> on which the color has been changed as the result of a chemical reaction.

see <#semi=Semi-postal>.

a paper with a 15 to 20% mineral content, used to print a small quantity of stamps in 1909.  Example: <#scott=Scott> 331b.   Some authorities dispute the existence of China Clay paper.

the seaplane depicted on the three "China-Clipper" <#amstamp=air mail stamps> of 1935 and 1937 (<#scott=Scott> C20-22), and the 1985 <#ampc=Air Mail Postal Card>, <#scott=Scott> UXC22, which carried mail across the Pacific to and from San Francisco, with inaugural service to Manila on November 22, 1935, on <#fam=FAM> 14.