Since 1917 all Silca pumps have used steam pressure-formed leather cup washers to achieve high pressures. The 731 (formally 73.1) is the classic 28mm diameter washer used on pumps produced between 1917 and 2008. In 2008, Pista and SuperPista pumps moved from steel barrels with 28mm inner diameter, to aluminium barrels with 30mm diameter. The 741 (formally 74.1) Leather Washer fits all 2008 and later pumps with 30mm inner diameter. Since the 1960's all SILCA leather washers have come from the same leather converting house in the fashion district of Milan, Italy. For more than 5 decades the same supplier has cut these washers from the excess material left over from the production of exotic handbags, Italian luxury cars interiors, and high-fashion luggage. A small press is used to hand cut and then pressure form these washers from pieces of leather otherwise sent to the trash. Silca receives these parts by the hundred and it is always fun to sift through them looking at the various finishes and textures while thinking about the exotic sports car interior, $2000 briefcase, or handcrafted luggage sets from which they share history. From a purely functional standpoint, inexpensive o-rings are most commonly used in this application, but no o-ring can match the smooth feel and zero-stiction action of a leather gasket. It is common today to find Silca leather gasket pumps throughout the professional peloton (especially during the spring classics) as o-ring seal pumps struggle with heat and often are unable to seal once the pump barrel is hot from inflating more than a few wheels.
