Canada #531 6c Dark Green, Yellow & Black Donald Alexander King, 1970 Sir Donald Alexander Smith Issue, 8 VFNH Singles With Various HF & HB Horizontal Ribbed Papers With Smooth & Streaky Gums

8 VFNH singles of the 6c dark green, yellow & black Donald Alexander Smith from the 1970 Sir Donald Alexander Smith Issue with various HF & HB horizontal ribbed papers with smooth & streaky gums. The lot contains:
• HB12 – horizontal ribbed, smooth dex
• HB11 – horizontal ribbed, streaky dex
• HB11, horizontal ribbed, paler green background, smooth dex
• HB10, horizontal ribbed, streaky dex
• HB10 – horizontal ribbed, smooth dex
• HF9 – horizontal ribbed, smooth dex
• HF8 – horizontal ribbed, smooth dex
• HB10 – horizontal ribbed, paler green background, streaky dex

Unitrade values these at $2.4. The stamps offered here grade between 80 and 84 as follows:

Centering/Margins: 50/70, 54/70

Paper Freshness: 5/5

Colour: 5/5

Impression: 5/5

Absence of Visible Paper Flaws: 5/5

Perforations: 10/10

In describing fluorescence on these issues and all the stamps issued after 1970, it is critical to understand the Irwin-Freeman scale of fluorescence, which ranges from 0 to 12 and that a particular designation like say HB or HF will correspond to more than one fluorescence level. One pitfall that many collectors fall into is to compare the papers, rank the fluorescent reactions from low to high and then try to force them into the DF/LF/MF/HF and HB nomenclature, rather than recognizing that three different levels of reaction may actually correspond to the same designation. This is why Unitrade's listings for this period are so confusing. Generally HB corresponds to levels 10 through 12; HF, levels 8 and 9; MF, levels 7 and 6; F, level 5; LF, levels 3 and 4; DF, levels 1 and 2 and finally NF corresponds to 0.