The original un-overprinted Hindenburg stamps with swastika watermark were printed over a long period, and all values were first printed as rotary press stamps. The upper selvage of the 1 pfennig stamp on the cover below shows the rotary press printing's characteristic stripes. Later, the 5, 12, 20, 40, and 60 pfennig un-overprinted values were also done as flat plate printings.
Interestingly, this black bordered "mourning" set of 6 values (3, 5, 6, 12, and 25 pfennigs) was a special printing. They were all from one print run as flat plate printings, except the 8 pfennig value. The "mourning" stamp blocks on the cover have the blank (not striped) flat plate upper selvage. To quote the Michel Spezial, ""Printed in one run except the rotary press printing of Michel Nr. 551 (8 pfennig stamp)." The 8 pf. flat plate printing of the "mourning" stamp (see cover) is tougher to find than the rotary press printing, and carries a nice premium.
