Scott 408 Flat Plate
Washington Head
Denomination in Numerals 1¢
Imperforate
Scott 531 Offset
Watermark Check: You must first determine if the imperforate stamp was printed using the flat plate or offset method the 1¢ rotary press imperforate stamp was not issued. If the stamp is offset, it does not have a watermark. If it is flat plate, you must check for the presence of a watermark.
| Printing Method | Watermark | Number | Privately Perforated by the Following Companies/Types |
| Flat Plate | Single-line | 408 | Brinkerhoff I, II, IIa, IIb; Farwell 4A, 4B, 4A5, 5A4; International Vending Machine; Mailometer I, IV; Schermack III; USAV I, II, III |
| Flat Plate | none | 481 | Schermack III only |
| Offset | none | 531 | Schermack III only |
see also Private Perforations - Vending and Affixing Machine Perforations
