Golf ball dimples exhibiting two distinct hardness regions derived from a single cover layer and methods of making same

A method of forming a golf ball, comprising:

• preparing a castable formulation comprising at least one prepolymer that is a reaction product of an isocyanate-containing component and an isocyanate-reactive component, at least one curative, and at least one free radical initiator;
• providing a core of a golf ball;
• casting the formulation over a core in a golf ball mold;
• curing the formulation to form a provisional golf ball comprising a cover layer having a first crosslinking density and a first hardness, wherein the golf ball cover layer comprises a plurality of dimples;
• placing the provisional golf ball into a second mold, wherein the second mold masks a first portion of the golf ball cover layer and exposes a second portion of the golf ball cover layer;
• and
• subjecting the second mold to ultraviolet light such that the second portion of the golf ball cover layer undergoes additional curing and has a second hardness and a second crosslinking density,
• wherein the second hardness is at least 20 percent greater than first hardness.

A method of forming a golf ball, comprising:

• preparing a castable formulation comprising at least one prepolymer comprising a conjugated diene hydrocarbon, at least one curative, and at least one peroxide;
• providing a golf ball core;
• casting the formulation over the golf ball core in a first mold;
• curing the formulation to form a provisional golf ball comprising a plurality of dimples, wherein the provisional golf ball has an outermost cover layer having a first crosslinking density;
• placing the provisional golf ball into a second mold, wherein the second mold comprises exposure areas and masked areas;
• and
• contacting the areas of the outermost cover layer exposed via the exposure areas with a heated protrusion to form a golf ball comprising the exposed areas, wherein the exposed areas of the underlying outermost cover layer have a second crosslinking density greater than the first crosslinking density and a hardness of about 55 Shore D to about 75 Shore D and the masked areas of the underlying outermost cover layer have a hardness of about 30 Shore D to about 50 Shore D.