Distinguishing ATN papers

In my previous post about ATN Machins, I noted that collectors divide the papers into three categories - dull, intermediate and bright. This refers to the brightness under long-wave ultraviolet light.

(The first-class gold Machin is in a group by itself. It has always been issued on a very dull paper that became known as RMS, as I noted in the previous post.)

When I started working with the ATN Machins, I developed a pretty good way to determine the brightness of any stamp. Here I am going to tell you how I did it.

There are three different scenarios that you may find yourself in with regards to this identification:
1. You have a single stamp with no margin (or selvage/selvedge) attached.
2. You have a single stamp with some margin attached.
3. You have a multiple of stamps with a margin on which the printing date has been inscribed.

I'll take these in the reverse order.

Some years ago, printers started putting the printing date in the margin of each sheet of stamps, as shown on the block above. This is the actual printing date, not the first day of issue. These are generally collected as blocks of eight.

With one or two exceptions, De La Rue only used one type of paper each day, so the printing date identifies the paper. That is, it does so if you have a listing of all the printing dates and the paper used on that date.

Such a list can be found in the Machin Collectors Club's QEII Specialized Definitves Stamp Catalogue. There is also a list on the Modern British Philatelic Circle's web site, but you must be a member of the circle to access it. (If you collect Machins, you should be a member anyway!) And many dealers publish their own list disguised as a price list.

(Douglas Myall's Complete Deegam Machin Handbook identifies all the different papers that were used for each denomination, but it does not include all the printing dates.)

Date blocks are an easy way to identify the paper (no UV lamp needed!), but it is also an expensive way. You are more likely to be in one of the other two situations.

Considering that Machins have a very small area that is not covered by colored ink, and much of that white area is covered by phosphor bands on the vast majority of Machins, life is much easier - if you define your life by the ease with which you can identify Machin paper varieties - when you have a stamp with a piece of margin attached.

At least until you get the hang of it, shining your UV light on a single stamp may not be too helpful. What you really have to do is compare the paper with some known examples.



I gathered three marginal copies of the 4p Machin, one on dull paper, one intermediate and one bright. There was nothing special about the 4p - any denomination, or a mix of denominations, would do.

When I want to identify a stamp that has a margin attached, I put it and the three known copies in an arrangement so that all the margins are near one another, as I've shown here. The unknown is the 5p stamp.

I then shine the UV lamp on this group of four, and I can then tell which 4p paper matches the 5p.

Under UV light, the bright paper appears very light gray, almost white. The intermediate and dull papers are pale purple, with the dull paper being darker, and more purple, and the intermediate paper.

In my opinion, it's always easy to tell a bright paper, but it is sometimes hard to differentiate between intermediate and dull. The brightness is determined by the amount of optical brightening agent (OBA) added to the paper, and since this amount varies, the paper brightness varies over a range. It's hard to know exactly when dull becomes intermediate. (This is nothing new - identifying Machin papers has always been an inexact science.)



If you have a stamp without a margin, the comparison has to be done using the white border on the top or bottom of the stamp that is between the phosphor bands. Here I've shown how I arrange three stamps. The unknown stamp is in the middle, and stamps with known brightness are above and below. I cover the sides of the stamps so that the phosphor bands are completely hidden, because otherwise the fluorescence of the bands is so bright that I can't see the brightness of the paper.

Shining the UV light on the middle stamp allows me to compare it to the two known ones. I use bright and dull for my first examination. If the unknown stamp matches the bright one, I'm done. If it is closer to the dull one, then I replace the bright stamp with the intermediate stamp and then compare the unknown against intermediate and dull to see which is closer.

One important note. The comparison I've done above is with the papers that were used until spring of 2005. At that time, as I noted in the previous post, a new paper known as RMS was introduced. It is even duller than the pre-2005 dull papers. You'll probably need a reference copy of this paper as well, and you may have to modify the methods I've shown above accordingly.

I should note that my identifications were done with mint stamps. I don't know if the soaking process to remove a used stamp from paper will affect the brightness.

--Larry