Reading a Hardness Certificate
Every session here ends with a printed certificate most clients have never seen the like of before. Here's what's actually on it and why each line matters.
A hardness certificate from this bench lists one row per head tested, and each row carries the same handful of fields: the club, the reading itself, the accepted band we're checking it against, and a pass or flag notation. It looks simple because it is — the value is in what the number represents, not in the format.
The Reading
A single number on the HRC scale, taken from at least two indentation points per head and averaged if they agree within a tight tolerance. If two readings on the same head disagree by more than that tolerance, we test a third point and note it — that kind of local disagreement usually points to an uneven heat-affected zone rather than tester error.
The Accepted Band
Most forged iron and wedge heads we see target somewhere between 20 and 24 HRC, though the exact band varies slightly by manufacturer and alloy. We check each reading against the manufacturer's published target where one exists, and against our own general accepted range when it doesn't.
The Pass/Flag Column
A head inside the accepted band gets a plain pass notation. A head outside it gets flagged, along with a plain-language note on what that likely means — too soft, too hard, or inconsistent between test points — and a recommendation on whether it's worth a rebuild, a return to the manufacturer, or just something to be aware of.
The certificate isn't a sales document. It's the same kind of paperwork a machine shop keeps on a batch of parts, applied to a golf club.
Why to Ask for One Even If You Didn't Build Here
If you're getting a set built or repaired anywhere, asking whether the shop tests hardness and can provide a certificate is a fair question, not an unusual one. A shop that already does this routinely will have an answer ready. A shop that's never been asked before is worth a follow-up question about how they verify a build actually matches its spec.