Golf irons went from hand-forged heads with names like mashie and niblick, to numbered matched sets in the 1930s, to perimeter-weighted cavity backs in the late 1960s, and finally to hollow "players distance" irons after 2017. Each step made irons more forgiving, and every one of those designs is still out there on the used market.
What were golf irons called before numbers?
Early irons were forged one at a time and had names instead of numbers. A cleek was a low-lofted iron for long shots. A mashie was roughly a modern 5 iron, with a mashie niblick in the 7 iron range and the niblick close to a 9 iron or wedge. There were others too, like the jigger for low running shots near the green. Lofts weren't standardized, so one maker's mashie could be another's mid-iron.
When did irons get numbers?
In the early 1930s Spalding sold standardized, numbered matched iron sets, and the old names gradually faded out. Steel shafts helped make matched sets possible. The USGA allowed steel shafts in 1924 and the R&A followed in 1929, so for the first time every club in a set could feel and flex the same.
What is a blade iron?
For decades almost every iron was a forged blade, also called a muscle back. The weight sits in a band directly behind the center of the face. Strike it in the middle and it feels incredible. Miss toward the toe or heel and you lose distance and direction, because the club twists. Blades still exist today for strong ball strikers, and Mizuno in particular kept forging when much of the industry moved to casting. Our post on what Grain Flow Forged means covers that story.
Who invented the cavity back iron?
Karsten Solheim, the engineer who founded Ping, is the name most tied to it. Instead of stacking weight behind the center, he moved it to the perimeter of the head, which makes the club resist twisting on off-center hits. Ping's Karsten I irons arrived in 1969 and were investment cast, meaning molten steel was poured into a mold. Casting made complex cavity shapes affordable to produce in large numbers. Traditionalists didn't love the look. Regular golfers loved the results.
Why was the Ping Eye2 such a big deal?
The Ping Eye came out in 1978 and the Eye2 followed in the fall of 1982. It combined perimeter weighting, a wide sole and consistent cast quality, and it became one of the best-selling irons ever. By 1988 Ping held about 28 percent of the iron market, according to MyGolfSpy.
The Eye2 also started golf's biggest equipment fight. Starting in 1984, Ping used U-shaped grooves. The USGA said they measured too close together, a difference often described as the thickness of a dollar bill, and moved to ban them. Ping sued the USGA and the PGA Tour. The USGA settled in 1990 and grandfathered the Eye2 irons in question, and the PGA Tour settled in 1993. If you're trying to figure out which Eye2 you own, our guide on how to identify your golf clubs walks through the color dot system.
What is a players cavity back?
Through the 1990s and 2000s, brands built irons for better players who wanted a blade look with some cavity back help. A thin topline, modest offset and a shallow cavity or partial muscle behind the face. Titleist's AP2 and Callaway's Apex line are good examples. These are some of the best values in used irons today. Read about the history of Callaway Apex and how Titleist splits its lineup in T100 vs T150 vs T350.
How did hollow irons change things?
Hollow irons weren't brand new, but TaylorMade's P790, launched in September 2017, made them mainstream. It paired a thin forged face with a hollow body filled with SpeedFoam, a polyurethane material that supports the face and quiets the sound. From address it looked like a players iron. At impact it launched and forgave more like a game improvement iron. The "players distance" category took off and most major brands released their own version. PXG pushed thin hollow faces even further; see inside the thinnest face in golf.
What changed in irons after 2017?
- Grooves. A USGA groove rule took effect at the elite level in 2010, limiting sharp-edged grooves on irons and wedges. Most everyday golfers can still play older grooves in casual rounds.
- AI-designed faces. Callaway used artificial intelligence to design driver faces starting with the Epic Flash in 2019, then brought the idea to irons with the Mavrik line in 2020. Background in our Callaway Epic post.
- Stronger lofts. Modern game improvement irons often have much stronger lofts than older sets. A new 7 iron can be lofted like an older 5 or 6 iron, so compare lofts, not numbers, when you shop.
What does this mean if you're buying used irons?
Every era is still playable. A forged blade from the 2000s will feel great but won't forgive like a hollow players distance iron. A cast cavity back from ten years ago can be a bargain for a mid handicapper. Check lofts, shaft and grip condition, and groove wear on the short irons. Browse used iron sets, or go by brand: Ping, Mizuno and TaylorMade.
Common questions
What's the difference between forged and cast irons?
Forged irons are shaped from a solid piece of heated steel. Cast irons are made by pouring molten metal into a mold. Forged irons are known for soft feel. Casting allows more complex shapes like deep cavities.
Are old Ping Eye2 irons still legal?
For casual golf, yes. The Eye2 models covered by the 1990 settlement are treated as conforming, and the groove rule that took effect in 2010 only applies in certain elite competitions.
What was the first hollow body iron?
Hollow irons existed before 2017, but the TaylorMade P790 is the one that turned them into their own category.
Are blades harder to hit than cavity backs?
Yes, for most golfers. The smaller sweet spot punishes off-center hits more.
Part of our GolfRoots history series. Also see the Golf Terms Glossary and are used golf clubs worth it.
