The question was asked by Andrew Rice on social media and I put it up as a pole. What plays the bigger role in generating spin between the grooves and flat spot between the grooves?
When looking at spin the biggest factor is friction. That means how clean of contact there is between the wedge face and golf ball. Although spinloft matters we are just talking about what effects the spin more: face or grooves.
Chatting with PING engineers they created a wedge with no grooves on it. Their conclusion is that a flat wedge spins just as much as a new wedge with grooves in a dry controlled environment. Andrew Rice had access to the wedge and hit a few shots and put the findings HERE.
Let’s take a look in a different area: Racing. When the track is dry they use race slicks in order to get the most grip on the road. When it starts to rain they switch tires to the tread in order to channel the moisture and get better tire to track grip. That is where the grooves come into play on the wedge. They help channel the debris (moisture, grass, etc) away from the surface so there can be better ball to club face interaction.
When reading through USGA Equipment Rules there are parameters on area roughness and grooves for a wedge. My Golf Spy Article summed it up nicely with this quote “In simple terms, square grooves would have to be further apart than ‘v’ grooves because they can channel away more grass and moisture.” The roughness also helps channel some moisture so there is a limit on the face milling. The last area of grooves that are regulated is the sharpness of the edges. There needs to be a minimum of a 0.010″ radius. This rule is due to the sharpness of the top edge in the role of generating spin.
Conclusion is that in a lab where you can guarantee there will be no debris/moisture getting between the face and the ball then the flat surface between creates the most friction. As golfers we all play on a golf course where the situations are always changing from morning dew to grass heights. Even on a tight lie there still is a little grass that gets trapped between the face and the ball. The grooves are there in order to help move the debris away form the contact spot. The sharpness of the upper groove edge will help reduce the slippage as the ball works up the face resulting in a little more spin.
SO if you are looking to create maximum spin make sure your lie is dry, tight, and you are using a new wedge and premium golf ball. Take a look at a warn wedge compared to a new wedge below. You can see how smooth the surface is which would result in more friction and also how sharp the grooves are in order for the upper edge to add a little additional grip.
One last note is that companies are starting to come out with new finishes and coatings. This helps the moisture move off the face faster like a fresh wax on your cars paint. PING released their Glide 3.0 wedge with Hydropearl and tests are coming out with significant results. See image below from TXG’s Moisture Test Video
Do yourself a favor and go test your current wedge. See your local PGA pro and do a spin test. Check your wedges compared to a new wedge. First hit 3-4 balls off a small tee with your current wedge and the new wedge to guarantee a clean strike between face and ball. Next repeat the same process and add a little moisture to the ball and the club face. Finally hit a few off the turf. The numbers should speak for themselves. I like to replace my most used wedge once a year due to practice and play with the other wedges being replaced every 2-3 years. Depending on your playing and practice habits that might change for you.