Trying To Identify Stamp Scott 441 Versus 448

I have these sets of Washingtons. I dont believe their both 448, but I inherited it labeled as both 448. I think the coil of 4 is 441, but I am still unsure of myself.

The strip looks like it should be Scott. 441 and the pair looks like it should be Scott 448 or 486 depending on whether or not it has a watermark. If that is true the designs should be slightly different in size. Place the pair on top of the strip and see if there is a difference in sizes. Don't measure, align top of design to top of design. Measuring can be inaccurate.

Okay , thanks for the information. I took some extra photos and the pair appear quite larger. Also , I provided a pic of the back and wonder if you can tell if a watermark has already been detected.

The pair was printed by Rotary press and therefore Scott 448 or 486. The strip of four was printed via the flat plate method and as you thought it was Scott 441. I think that I see an inverted "P" on the top stamp of the strip, but nowhere else. I do not see a watermark on the pair, but that does not mean it is without watermark. If you do not have watermark fluid, try back lighting it with a strong light, but not close enough to harm the stamps.

Thank you very much. I'm not familiar still with the watermark fluid. I'd like to get with someone more experienced first. So afraid to ruin what I have. I did play with the lighting while trying not to bother the stamps too much. I see some figures, but I need more practice. I'll show you, but you wont hurt my feelings if the image is not recognizable. I believe I see a P and on left some other marking.

Rotary press coil perforations are aligned between rows while flat plate perforations are randomly aligned. At high magnification, flat plate perforations are elongated in the direction of the row while rotary press perforations are elongated at right angles to the row. Rotary press perforations measure 10-80 on a Kiusalas gauge while flat plate perforations measure 10-79. If a rotary press coil and a perf 10 flat plate stamp are matched perforation to perforation on one end of the row, the other end will not match.