Paper taxonomy

I have received many questions about this issue and I think the time has come to have a detailed answer for how I clasify P y R I.

Originally I only thought there were six papers:

First watermark Early, 1E
Unwatermarked grid, NGR
Unwatermarked opaque, NOP
Clay, CL
Second watermark, 2
First watermark late, 1L

In 2006, I saw the Moscatelli exhibit at the Washington 2006 international exhibition. This exhibit showed me that there were something like 16 papers. At first I was unable to absorb so much new information. Moscatelli showed measurements in ranges for the RAs, and I knew from looking at so many of these stamps that these measurement ranges weren't particularly enlightening. Sometime in early 2008 I took a look at my 30c 1Es and noticed clear differences. This was the first time I could see that the 1E2, for instance, is very different from the 1E1. I was able to take the next significant step after Rein taught he how to differentiate the three 1E3s.

This is what I know today:

There are six 1E papers.
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1. 1E1 dates from October 1935 and all of 1936. This paper is thick and cream.
2. 1E2 was used in 1937 and 1938. The watermark is usually perpendicular to the 1E1 watermark. This paper is thin and white.

1E3 is very difficult to type because the key differentiating characteristic is the thread pattern on the back of the stamp.

3. 1E3a of 1939, is identical to 1E1 except that the paper is thinner and white. The grid is rectangular and symmetrical (makes a perfect X on the back of the stamp).
4. 1E3b of 1946/47 has a square symmetrical grid.
5. 1E3c of 1941-44, has an asymmetrical rectangular grid. This X is not drawn from the four corners of the stamp. This stamp is porous, making the grid difficult to see. In addition, it has straight lines over the grid. This is one of the most difficult papers to type.

6. 1E4 of 1940 with large RA perpendicular to the 1E1/3 and the same as the 1E2.

I used to think there was a 1E5, but it turned out to be a later paper (the 1L6).

There are at least four clay papers.
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I still need to study these papers in detail. So far, I find at least four:

7. CL1A, with watermark same as the 1E4 but with a light coating on the printed surface. This paper was used for the 5c and 10c Brown typographed stamps during 1939/40. This 10c Brown is very rare on cover.
8. CL1B, 30c, 1p, 2p (the rare one, with dark colors), 20p of 1943. I classify the 40c with dark colors from 1948 as this paper, but I still need to study this stamp in detail.
9. CL2A, 1949 for the 10c, some with very dark blackish brown color.
10. CL2B, 1952, the thin clays, 40c light colors, 50c, 2p.

Second Watermark
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11. Straight Rays diffuse watermark on cream paper from 1943, the 2D. The rarest of these is the elusive 1/2c.
12. Straight Rays clear watermark on white paper from 1949, the 2C. This watermark is found in two directions, meaning that there are two separate types of the watermark roll used to make the paper.

Unwatermarked
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13. Unwatermarked grid of 1945, NGR.
14. Unwatermarked opaque of 1947/8, NOP. There may be a second NOP for the 20p, which I find used in the mid 1950s.

The late papers.
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These are best studied using the 50c.

15. 1L1, with straight lines on the back, same watermark as the 1E1/3s, and brilliant colors like the 2C stamp.
16. 1L2 of 1952, big RA, similar paper to the 1E3c.
17. 1L3 of 1955/6, thick white paper with small RA, the 50c has a deep yellow shade for the background.
18. 1L4 similar to the 1L2 but with disfigured RAs from a worn out watermark roll. I doubted their existence but I keep finding them.

19. 1L5, all Zarate. There are at least two: white and onion paper.
20. 1L6, similar to the 1L3 but with a clear rectangular symmetrical grid.