Tinted paper, offsets and aniline papers.
Tinted
The Government Note Printing Branch used tinted paper in its first printing of the 1948 re-issue of the 1938 5/- Coronation “Robesâ€. The tinting was caused by the use of an ink that was strongly absorbent with the result that the paper became “tinted†in appearance.
The stamp has a dull off-white appearance around the edge.
Aniline
Mint unhinged aniline stamps are very scarce and used aniline stamps are ruined by the ink “bleeding†when immersed into water. Aniline ink was an ink with a coal-tar base; it was an early attempt to prevent the stamp from being re-used. It worked as a preventive thwarting re-use but a nightmare for collectors of used stamps.
This early preventative was first used with 19th century stamps and was last used in Australia in 1952 on the very scarce 7½d.
Offset
1) A printing process that transfers an inked image from a plate to a roller. The roller then applies the ink to paper. 2) The transfer of part of a stamp design or an overprint from one sheet to the back of another, before the ink has dried (also called set off). Such impressions are in reverse (see Mirror image). They are different from stamps printed on both sides.
There are various offset varieties; a scarcer type is shown below.
Various stages of onset on the reverse of the 1949 wallaroo (small kangaroo).