How do you distinguish the 12 1/2 comb and line
​Perforation Variations in the Chalon Series?

  
How do you sort the "Chalons" perforation varieties.
 
1. - Check the stamp is not a perf 13 with a known 12 1/2 perforation stamp (any cleanly cut 4d stamp or one of the later changed colour issues that does not have the obvious perf 10 will do)
 
2. - Compare the top or bottom perforations to determine whether it is 12 1/2 or 13 (starting the perfs together at one end the other end will result in a perf aligned with a tooth and a hole if 13).

3. - Next thing to look for is the top left and right corners. On the comb perf, the horizontal and vertical perfs should share a single hole in most (but not all) cases.

4. -  If the two holes overlap, it’s likely to be line perf. 

5. - Next, look at the width of the stamp; if it’s narrow or wide, it will be line perf. 

6. - After that, look at the side perfs and the height of the stamp. A comb will have only 16 holes.

7. - If it has more, it is line perf.

8. -  In the case of vertical multiples, look at the stamp below, and whether the comb has shifted to left or right slightly; if the vertical line of perfs is not continuous, it’s comb. You can try matching the stamp with the two sets of pins as shown in Bob Odenwellers book "The Postage Stamps of New Zealand, 1855 - 1873, The Chalon Head Issues", and possibly will be able to find which position in the row it may be. Remember that the wrong head might have been used on the denomination involved.

9. - Dated copies or printings that have specific dates, the comb perf was introduced in 1864 and retired about early 1867. 

10. - Later printings of the perf 12 1/2 will be line perfs, as will all the changed color printings.
  

K. J. McNaught - Double, Mixed and
Irregular Compound Perforations (part 1.)

K. J. McNaught - Double, Mixed and
Irregular Compound Perforations (part 2.)