About October of 1924 a few sheets of stamps were printed on a distinct type of paper. This paper is usually referred to as "thin". There is no noticable difference in the thickness of the stamps, but in fact the paper appears to be less dense than normal. This may have been the result of a small batch of different paper being supplied, or may have been a deliberate attempt to use less paper by weight and hence to reduce costs.
This paper is known to have been used to print plates 21 and 22 of the 5c Violet, and plates 182, 185, and 186 of the 2c Green. It is quite possible that some of the other 2c plates were also printed on this paper.
The best way to distinguish "thin" paper is to look for the distinctive cross hatching that is obvious on stamps printed using this paper. Normal stamps will show at most, a very faint amount of cross hatching.
Most stamp catalogues will show "thin" paper varieties for other values, particularly the 7c Red Brown. These so called varieties are not printed on the distinctive "thin' paper, but probably result from small variations in the density of the paper stock. It is possible to find examples from any denomination that have some trace of cross hatching, such as the example below.