Sewing machine perf

Sewing machine perfs are exactly that, where sewing machines were used to perforate sheets of stamps when a purpose-built perforating machine was broken or otherwise unavailable. The gauge is variable and is not really measurable. Perf holes usually vary considerably in size and may or may not wander side to side along the line of perfs. When stamps are separated, the edges are typically rough since the depth of "perforation" can also vary.

You who expect 21st Century perfection in old or even provisional stamps will probably faint when they see sewing machine perfs, or think they have a fabulous rarity. You shouldn't have ditched that class trip to the museum.  File:Tolima 4c 1903.jpg 

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