Second (and third) type of paper
Just as with the 1st type of paper the symmetrical sieve structure is well visible when holding the stamps against a strong light source.
But the 2nd type has irregular grooves at the front with the rhombs at the back while the 3rd type has it the other way around - rhombs at the front and grooves at the back.
At the top the grooves at the front [type 2]e, at the bottom the grooves at the back [type 3].
At the top the rhombs at the back [type 2]e, at the bottom the rhombs at the front [type 3].
The 2nd type of paper exist for all 3 values: 20gr, 40gr, 60gr and so does the 3rd type of paper: 20gr, 40gr, 60gr