Today, records are broken around the world on a regular basis. After a successful attempt there is celebration. And while there may be a gear check in various organizations, no one questions the accuracy of the weights on the bar.
The answer lies in the evolution of the sport. As late as the 1980s, non-calibrated plates were the norm and were used from local meets all the way up to World Championships. After a record lift, it was not unusual to witness the spotter-loaders break down the bar so that officials could weigh the bar, collars, and plates for certification. Or plates would be weighed before-hand and marked with their actual weight so that officials could manually total the bar, collars, and plates to arrive at an official weight.
One example was the record setting performance of Don Reinhoudt in 1975. For the uninformed, Don was one of the greatest Super Heavyweights of all time. Don was a 4-time IPF World Champion, holder of 40+ World Records, a World Record holder in every lift including the total and was the 1979 World’s Strongest Man. In one of his most memorable record setting performances, Don set the World Record total at a stated weight of 1098 kg (2420 lbs). Upon weighing of the bar, collars, and plates the total was certified at 1084.5 kg (2391 lbs.) as some of the plates were determined to be light.
On the other end of the spectrum was the story of Joe Bradley. In 1981, Dr. Fred Hatfield brought Joe to the Regional Championships in Austin, Texas, to assault world records held by Mike Bridges in the 67.5kg /148 lb. class. After breaking the squat record, the plates, bar, and collars were weighed. Joe received an additional credit of approximately 7 kg (15 lbs.) due to heavy plates.
How could this happen?
Consider that powerlifting was still a growing sport and specialized equipment was still in its infancy. At this time, the majority of plates were simply cast in molds that were calculated to produce an approximate weight based on average iron density and mass. Iron is an alloy that can have varied contents depending on the type of iron and specific batch. As a result, each batch could vary and often did.
As the sport grew, specialized manufacturing addressed these inconsistencies. The first improvement involved using denser, higher grades of iron. The iron was cast into molds that featured cavities to insert weighted plugs. The plates were then machine turned to produce flat, smoothed, back surfaces. This produced the distinctive swirl patterns characteristic of this type plate. Each plate was then weighed on calibrated scales to determine the expected and planned weight deficiency. A technician would then choose the appropriate weighted plug(s) that would make the plate true to international standards. These were then screwed in and followed by a coat or coats of paint. Some manufacturers cover their plugs while others prominently display them.
Often taken for granted, calibrated plates offer several distinct advantages. The plates offer great presentation, are slimmer, produce less rattle, and keep the plates closer to the center of gravity which reduces bar whip. And of course, lifters and officials can perform and break records without ever having to question the accuracy of the weights.