Australia #394-417 (SG#382-405a, 414) 1c to $4 Queen Elizabeth II, Birds and Navigators, 1966-1973 Decimal Definitive Issue, A Specialized Lot of 101 Fine and VF Used Stamps
A super specialized group of 101 fine and very fine used stamps, covering nearly all the stamps of the 1966-1973 decimal definitive issue, from the 1c to the $4, with many different unlisted shade, ink, paper varieties, and differences in the strength of the Helecon coating on the paper. The only missing stamps are the 3c coil (#404) and the 24c Azure Kingfisher (#395). The 4c, 4c and 5c on 4c include several booklet singles and a booklet pair.
The Australian equivalent of tagging is called Helecon, which is a chemical in the zinc sulphide group that fluoresces orange-red under long-wave UV light. The very first stamp to be issued with Helecon coating applied to the paper was the 11d Rabbit Bandicoot from the 1958-1964 definitive issue. Later, the 5d orange-red Queen Elizabeth II stamp from the 1963-1966 issue was issued with the Helecon incorporated into the ink. By the end of 1965 all stamps issued had Helecon applied to the paper. On this issue, some stamps are found with a uniform coating on the paper that glows orange-red, while others have the paper impregnated with Helecon, so that it appears greyish white from a distance under UV, but under magnification, tiny orange-red dots can be seen on the surface of the paper. Most of the chalk-surfaced paper stamps from this issue are like this, while the engraved stamps tend to show a Helecon coating on the paper.
The comparison pictures shows some of the differences that can be found on the stamps of this issue. As you can see the fluorescence of the paper varies from dead to bright fluorescent (probably low and medium fluorescent on the scale).
Gibbons lists the basic stamps at 44.65 pounds (approx. $89.30) for fine used. The stamps here grade between 70 and 84.