From the early 1880s, the NSW Government Printer used an ordinary ungummed white stamp paper which was watermarked with a Crown over NSW. This paper was the same as had been used for the 1d Centennial stamp issued in 1888. Gum was applied after the printing had been completed.

An image of the paper is shown below:


Watermark sheet
Copied from the excellent article by N. J. Sheppard (Fig. 2, p. 22).

The sheet has:


Those measurements were the size of the 2½d (2/6) stamp but the 1d (1/-) stamp reversed these as it had a horizontal design.

Printing the 1d (1/-) design.

In the printing process for the 1d (1/-) design, the page of watrmarks was rotated clockwise by 90°.
The sheet arrangement for this stamp then became 6 rows of 5 stamps.
The watermark on each stamp had 4 designs with the top of the Crowns on the right when viewed from the front of the stamp.
The NEW SOUTH WALES POSTAGE watermark appears at the left and the right of a marginal block as shown.
An inverted watermark would reverse the above description and the top of the Crowns would be at the left of a stamp viewed from the front.

watermark pattern for the 1d (1/-) stamp, rotated anticlockwise 90 degrees to show orientation

 

Printing the 2½d (2/6) design.

In the printing process for the 2½d (2/6) design, the arrangement was flipped (or rotated) clockwise by 180°.
Again the watermark on each stamp had 4 designs but with the top of the Crowns at the base when viewed from the front of the stamp.
The NEW SOUTH WALES POSTAGE watermark appears at the top or the bottom of a marginal block as shown.
An inverted watermark would reverse the above description and the top of the Crowns would be at the top of the design.

watermark pattern for the 2 halfd (2/6) stamp, rotated 180 degrees to show orientation