Ask the Expert Question-and-Answer Archive

by Ron Joseph

January, 2009

#4 Ford Cup

Q. Is it a requirement to use a #4 Ford cup per MIL-STD-22750 and MIL-STD-23377 in our company?

A. There is no need for you to use a Ford #4 cup to measure viscosity unless you want to compare the viscosity values with those written in the specifications. Since you are an end user of MIL spec paints, you can also use a Zahn cup; either a #2 or #3 depending on the viscosity of the paints. Plese bear in mind that the Ford #4 viscosity readings will be very different from those measured with a Zahn cup.

Regards,

Ron Joseph