The coated papers for the PyR I series are not quite explained so far. The earliest in 1939 for the typography 5c and then a big gap till 1943...
In the commemoratives in the 1935-1944 period there are only the 4th of June 1943 revolution stamps issued in July already! The 3 stamps [5c, 15c, 20c] have a coated paper that shows at the front a pattern of horizontal bars. The watermark is supposed to have a multiple sun + AЯ - it does! - but I do not expect anybody to have checked it really as you can barely see it. Just trust your favourite catalogue be it Samowerskyj or Petrovich or Tello Meggia....
As we can see the watermark is orthogonal (line of AЯ horizontal ; direction of paper vertical hence perpendicular or orthogonal) and the paper wire is asymmetrical [see the horizontal lines!].
The 1941-1944 commemoratives had 2 types of paper:
- parallel, symmetrical wire with a loose web: 24/20 lines hor./vert. described by Dario A. Bardi as "tela"
- orthogonal, symmetrical wire with a tight web: 30/20 lines hor./vert. WRONGLY described as "rayos rectos"!
I have seen NO other type of paper so far for the commemoratives. The 1945-1947 period has only unwatermarked paper!
Reprints from 1948 and later can show the so-called "straight-rays" or "Rayos Rectos" that have not so much straighter rays than the other watermarks but rather a slighty longer diagonal rays.... Much more important to recognize this is the whitish appearance from the back of stamp [no gum to annoy us, please!] and the almost shaven character of the paper surface - you get the impression to see inside the paper itself! If the surface of the back is completely smooth, equal, then you have a different type of paper at hand... And the R.R. have a asymmetrical wire as well...
Reprints [?] of the 5c red of the June Revolution set - in the same year already - have uncoated paper - referred to a "mate" in Argentinean catalogues - with 2 options:
Symmetrical wire and orthogonal watermark:
Symmetrical wire and parallel watermark, coarse lines 24/20 also know as "tela":
Both completelty in line with the types of paper of the 1941-1944 period