Patent Publication Number: US-8979679-B2

Title: Golf ball having hydrophilic and hydrophobic portions

Description:
BACKGROUND 
     The present invention relates generally to a golf ball having hydrophilic and hydrophobic portions. 
     The game of golf is an increasingly popular sport at both amateur and professional levels. A wide range of technologies related to the manufacture and design of golf balls are known in the art. Such technologies have resulted in golf balls with a variety of play characteristics. Modern golf balls generally comprise either a one-piece construction or several layers including an outer cover surrounding a core. The outer cover of golf balls often becomes slick in moist playing conditions. As a result, the golf club face may slip as it contacts the golf ball. This slippage causes the golf ball to experience a lower trajectory flight path, and also decreases spin on the ball. This decreased spin reduces the amount of control the golfer has over the golf ball&#39;s flight path and landing conditions. It would be advantageous to be able to make a golf ball that does not become slick in wet playing conditions. 
     SUMMARY 
     In one aspect the disclosure provides a golf ball that may have a core and a cover layer substantially surrounding the core. The cover layer may include at least one dimple. The at least one land area may be adjacent to the at least one dimple. A portion of the surface of the golf ball may be hydrophobic and a portion of the surface of the golf ball may be hydrophilic. The hydrophilic portion of the surface may be adjacent the hydrophobic portion of the surface such that moisture is drawn away from the hydrophobic portion and drawn toward the hydrophilic portion. The hydrophilic portion of the surface may include multiple portions of the surface. The hydrophilic portions of the surface may be surrounded by the hydrophobic portion of the surface such that moisture is drawn away from the hydrophobic portion and drawn toward the hydrophilic portions. The at least one dimple may include multiple dimples and the hydrophilic portions may coincide with the dimples. The hydrophilic portion may coincide with the at least one dimple. 
     In one aspect the disclosure provides a golf ball that may have a core and a cover layer substantially surrounding the core. The cover layer may include at least one dimple. The at least one land area may be adjacent to the at least one dimple. The surface of the at least one land area may be hydrophobic and the surface of the at least one dimple may be hydrophilic. A hydrophilic coating material may overlie the at least one dimple. The hydrophilic coating material may include a hydrophilic polymer. The hydrophilic coating material may have a uniform thickness. The hydrophilic coating material may have a maximum thickness in the middle of the at least one dimple. The thickness of the hydrophilic coating material may taper toward an edge of the at least one dimple and the edge may be adjacent the at least one land area. The hydrophilic coating material may overlie the entire surface of the at least one dimple. The hydrophilic coating material may overlie only a portion of the surface of the at least one dimple. The at least one dimple may comprise multiple dimples and a hydrophilic coating material may overlie at least one of the multiple dimples. The hydrophilic coating material may overlie all of the multiple dimples. The surface of the cover layer may be superhydrophobic. 
     In one aspect the disclosure provides a golf ball that may have a core and a cover layer substantially surrounding the core. The cover layer may include multiple dimples and at least one land area adjacent to the dimples. The surface of the at least one land area may be hydrophobic and the surface of at least one of the multiple dimples may be hydrophilic. Coating material may overlie the at least one of the multiple dimples that may be hydrophilic. The surface of at least one of the multiple dimples may be hydrophobic. 
     Other systems, methods, features and advantages of the invention will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the invention, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is an exemplary golf ball before and after a coating material has been applied; 
         FIG. 2  is a cross section of the golf ball of  FIG. 1 , before and after a coating material has been applied; 
         FIG. 3  is a zoomed in view of a water droplet landing on a land area adjacent the dimple of  FIGS. 1 and 2  after the dimple a coating material has been applied; 
         FIG. 4  is an illustration of contact angles between surfaces and water that may be used to quantify whether the surface is hydrophilic or hydrophobic. 
         FIG. 5  is a cross section of a golf ball of an exemplary embodiment, before and after a coating material has been applied; 
         FIG. 6  is a zoomed in view of a water droplet landing on a land area adjacent the dimple of  FIG. 5  after the dimple a coating material has been applied; 
         FIG. 7  is a cross section of a golf ball of an exemplary embodiment, before and after a coating material has been applied; 
         FIG. 8  is a zoomed in view of a water droplet landing on a land area adjacent the dimple of  FIG. 7  after the dimple a coating material has been applied; 
         FIG. 9  is an exemplary golf ball before and after a coating material has been applied; 
         FIG. 10  shows two similar flight paths of two golf balls, after being hit by a golf club swung by a golfer in normal weather conditions; and 
         FIG. 11  shows two different flight paths of two golf balls, after being hit by a golf club swung by a golfer in wet weather conditions. 
     
    
    
     DETAILED DESCRIPTION 
     Golf balls typically include a core substantially surrounded by one or more layers. For example, a golf ball may be of a two-piece construction, having only a core and a cover layer, or a golf ball may have one or more intermediate layers located between the core and the cover layer. Golf balls within the scope of this disclosure may be of a two-piece construction, or may have additional intermediate layers between the core and cover layer. Referring to  FIG. 1 , a golf ball  100  may include a cover layer  102 . Cover layer  102  may include dimples  104  and a land area  106 . Dimples  104  may generally be arranged on cover layer  102  in any pattern, as may be known in the art of golf balls. Various known dimple packing patterns are known in the art. Dimples  104  may generally be of any shape, such as circular, triangular, or multi-sided. Dimples  104  may be of uniform shape and size, or the dimple pattern may be made up of two or more different types of dimples having (for example) different sizes or different shapes. Land area  106  may be part of cover layer  102  that separates at least two dimples  104  and that is not indented or otherwise part of the dimple. Generally, land area  106  may be the “ridge” or “fret” between adjoining dimples  104 . 
     In the embodiment shown in  FIG. 1 , a coating material  108  may be selectively applied on dimples  304 . In such an embodiment, coating material  108  may have a higher level of hydrophilicity than the level of hydrophilicity of the material of cover layer  102 . Accordingly, after coating material  108  is applied to dimples  104 , dimples  104  may have a higher level of hydrophilicity than the level of hydrophilicity of land area  106 . Hydrophilic means attracting water and hydrophobic means repelling water. If dimples  104  are hydrophilic and land area  106  between dimples  104  is hydrophobic, then water may be drawn away from land area  106  toward the dimples  104 . As a result, moisture may be less likely to collect on the surface of land area  106  and the surface of the land area  106  may be dryer than the land area on a conventional golf ball would be. The cover layers of conventional golf balls often become slick in moist or wet playing conditions. This moisture is a problem because it makes the club face slip as it contacts the golf ball. Also, the moisture present on the conventional golf ball may affect the aerodynamics of the golf ball and cause the golf ball to not travel as far as the golf ball would travel in dry playing conditions. Thus, preventing moisture from settling on land area  106  may prevent these problems associated with the presence of moisture on land area  106 . 
     The hydrophobicity of a given substrate surface may be measured using a water droplet shape analysis method, for example. The higher the contact angle, the higher the hydrophobicity. A surface that makes a contact angle with water (“θ”) of less than 90° is considered hydrophilic. A surface that makes a contact angle with water (“θ”) of more than 90° is considered hydrophobic. A surface that makes a contact angle with water (“θ”) of more than about 150° is considered superhydrophobic. The term “hydrophobic,” as used herein, is inclusive of surfaces that are considered superhydrophobic. The relative hydrophilicity of two surfaces can be determining by comparing the contact angles between the surfaces and water. For example, a surface that makes a contact angle with water of 60° is less hydrophilic than a surface that makes a contact angle with water of 30°. 
     In some embodiments, cover layer  102  may be made from any known hydrophobic material. In some embodiments, cover layer  102  may be treated to become hydrophobic by any known methods. Suitable hydrophobic materials and methods of achieving hydrophobic surfaces are disclosed in, for example, commonly owned U.S. Patent Publication Number 2010/0261538, entitled Golf Club Having Hydrophobic and Hydrophilic Portions, published on Oct. 14, 2010, and applied for by Lee, the disclosure of which is hereby incorporated by reference in its entirety. Suitable hydrophobic materials and methods of achieving hydrophobic surfaces are also disclosed in, for example, U.S. Patent Publication Number 2007/0213143, entitled Exterior Coatings for Golf Balls, published on Sep. 13, 2007, and applied for by Chinn et al., the disclosure of which is hereby incorporated by reference in its entirety. The cover material used for cover layer  102  and/or methods of achieving a hydrophobic surface may be selected based on a variety of factors. For example, the cover material may be selected based on the desired hydrophobicity of land area  106 , desired aerodynamic properties, hardness of cover layer  102 , and/or the type of coating material  108  used. 
     In some embodiments, coating material  108  may be made from any know hydrophilic material. In some embodiments, coating material  108  may treated to become hydrophilic by any known methods. Suitable hydrophilic materials and methods of achieving hydrophilic surfaces are disclosed in, for example, commonly owned U.S. Patent Publication Number 2010/0261538, entitled Golf Club Having Hydrophobic and Hydrophilic Portions, published on Oct. 14, 2010, and applied for by Lee, the disclosure of which is hereby incorporated by reference in its entirety. Suitable hydrophilic materials and methods of achieving hydrophilic surfaces are also disclosed in, for example, commonly owned U.S. Patent Publication Ser No. 8,393,979, currently U.S. patent application Ser. No. 12/822,470, entitled Golf Ball with Hydrophilic Coating Layer, filed on Jun. 24, 2010, and applied for by Fitchett, the disclosure of which is hereby incorporated in its entirety. Suitable hydrophilic materials and methods of achieving hydrophilic surfaces are also disclosed in, for example, U.S. Patent Publication Number 2007/0213143, entitled Exterior Coatings for Golf Balls, published on Sep. 13, 2007, and applied for by Chinn et al., the disclosure of which is hereby incorporated by reference in its entirety. Coating material  108  and/or a method of achieving a hydrophilic surface may be selected based on a variety of factors. For example, coating material  108  may be selected based on the desired hydrophilicity of coating material  108 , desired aerodynamic properties, hardness of coating material  108 , and/or the type of cover material used. 
     In some embodiments, such as the embodiment shown in  FIGS. 1-3 , all of dimples  104  may be hydrophilic. In some embodiments, dimples  104  may be selectively hydrophilic. For example,  FIG. 12  shows an embodiment of a golf ball  1200  having a cover layer  1202  with dimples  1204  and a land area  1206 . A portion of dimples  1204  may be selected to have a layer of coating material  1208 . The number and location of dimples  104  selected to be hydrophilic may be selected based on a variety of factors. For example, the number and location of dimples  104  selected to be hydrophilic may be selected based on the total number of dimples  104 , the materials used, the weather conditions golf ball  100  is intended to be used in, the shape of dimples  104 , and/or the size of dimples  104 . 
     In some embodiments, coating material  108  may have a variety of profiles and/or patterns.  FIGS. 2 ,  3 , and  5 - 8 , which are discussed in detail below, show exemplary profiles. In some embodiments, dimples  104  may include different profiles of coating material  108 . For example, in the embodiment shown in  FIG. 13 , a golf ball may have a core  1320  and a cover layer  1302  having a first dimple  1360 , a second dimple  1370 , a third dimple  1380 , and a land area  1306 . Each of the dimples may include a coating material with a different profile. First dimple  1360  may include a first profile of coating material  1362 , second dimple  1370  may include a second profile of coating material  1372 , and third dimple  1380  may include a third profile of coating material  1382 . In some embodiments, the dimples may be selectively coated with a variety of profiles. In some embodiments, the coating material may be applied in a pattern on dimples. For example, the coating material may be applied in a pattern of stripes or dots. The profiles and/or patterns of the coating material may be selected based on a variety of factors. For example, the profile of the coating material may be selected based on the total number of dimples, the materials used, the weather conditions golf ball is intended to be used in, the shape of the dimples, and/or the size of the dimples. 
       FIG. 2  is a cross-sectional view of dimples  104  and land areas  106  shown in  FIG. 1 .  FIG. 2  also shows core  202 , which may be covered by cover layer  102 . In  FIG. 2 , coating material  108  may be coated on dimples  104 , forming a thin layer of coating material  108  on a cover layer  102 . As shown in  FIG. 2 , the profile of coating material  108  within dimples  104  may be such that the maximum thickness of coating material  108  is in the center of each dimple  104  and the thickness decreases toward the edge of dimples  104  adjacent land area  106 . In some embodiments, coating material  108  may have a maximum thickness within a range of 0.1 mm and 3 mm. For example, in some embodiments, coating material  108  may have a maximum thickness of 0.5 mm. In some embodiments, coating material may have a maximum thickness of 0.3 mm. In some embodiments, coating material may have a maximum thickness of 0.1 mm. In some embodiments, the maximum thickness of coating material  108  may be selected based on a variety of factors. For example, the thickness of coating material  108  may be selected based on the type of material cover layer material used, the type of coating material used, the number of dimples, shape of the dimples, and/or the depth of the dimples. 
       FIG. 3  illustrates how a water droplet  310  landing on land area  106  may be attracted to coating material  108  in dimples  104 . Because cover layer  102 , and thus land area  106 , includes a hydrophobic material, water droplet  310  may be attracted away from land area  106  toward the more hydrophilic coating material  108  in dimples  104 . 
     With reference to  FIG. 4 , a surface that makes a contact angle with water (“θ”) of less than 90 degrees is considered hydrophilic. A surface that makes a contact angle with water (“θ”) of more than about 90 degrees is considered hydrophobic. A surface that makes a contact angle with water (“θ”) of more than about 150 degrees is considered superhydrophobic. The term “hydrophobic,” as used herein, is inclusive of surfaces that are considered superhydrophobic. The relative hydrophilicity of two surfaces can be determining by comparing the contact angles between the surfaces and water. For example, a surface that makes a contact angle with water of 60 degrees is less hydrophilic than a surface that makes a contact angle with water of 30 degrees. Land area and dimples, as described herein, may be hydrophobic and hydrophilic, respectively. Alternatively, land area and dimples may be weakly hydrophilic and more strongly hydrophilic, respectively. The difference in contact angle with water (“θ”) between that of land area and that of the surrounding portion is usually at least about 5 degrees and often ranges from about 10 degrees to about 150 degrees, more usually from about 25 degrees to about 125 degrees or from about 40 degrees to about 100 degrees. 
     Referring back to  FIG. 3 , a water droplet  310  may land on land area  106 . Because cover layer  102  may include a hydrophobic material, water droplet  310  may contact land area  106  with a contact angle of more than 90 degrees. For example, water droplet  310  may contact land area  106  with a contact angle of 120 degrees. In another example, water droplet  310  may contact land area  106  with a contact angle of 150 degrees. In some embodiments, the contact angle between land area  106  and water droplet  310  may depend on the level of hydrophilicity of the cover material used to make cover layer  102 . Water droplet  310  may be repelled from land area  106  while simultaneously being attracted to cover material  108 . As shown by the arrows, these forces acting on water droplet  310  may cause water droplet  310  to gravitate toward cover material  108 . Because cover material  108  may be hydrophilic, water droplet  310  may flatten onto the surface of cover material  108  such that water droplet  310  makes a contact angle of less than 90 degrees is considered hydrophilic. For example, water droplet  310  may contact cover material  108  at 45 degrees. In another example, water droplet  310  may contact cover material  108  at 0 degrees. The contact angle between coating material  108  and water droplet  310  may depend on the type of coating material used to make cover layer  102 . 
     Because water droplet  310  may flatten out on the surface of cover material  108 , water droplet  310  may form a layer  312  of moisture on the surface of cover material  108 . In some embodiments, multiple water droplets may combine to form layer  312 . In some embodiments, as shown in  FIG. 3 , the profile of layer  312  may be the same as the profile of coating material  108 . For example, the profile of layer  312  may be such that the maximum thickness of layer  312  is in the center of dimple  104  and the thickness decreases toward the edge of dimple  104  adjacent land area  106 . In some embodiments, the profile of layer  312  may be uniform so that the thickness is substantially the same in the middle of dimple  104  as the thickness toward the edge of dimple  104  adjacent land area  106 . In some embodiments, layer  312  may have the opposite profile of coating material  108 . For example, the profile of layer  312  may be such that the maximum thickness of layer  312  is adjacent land area  106  and narrows toward the middle of dimple  104 . The thickness of layer  312  may depend on the amount of moisture present on golf ball  100 . In some embodiments, layer  312  may change the depth and/or shape of dimple  104 , which may affect the aerodynamics of golf ball  100 . To counteract this change in depth and/or shape, in some embodiments, dimple  104  may be formed with a deeper depth or different shape than a golf ball used in dry weather. In some embodiments, the depth of the golf ball may be adjustable. A golf ball with changeable dimples is fully described in commonly owned U.S. Patent Publication Ser. No. 8,602,915, currently U.S. patent application Ser. No. 12/916,955, entitled Golf Ball with Changeable Dimples, filed on Nov. 1, 2010, and applied for by Oldknow, the disclosure of which is hereby incorporated in its entirety. In some embodiments, coating material  108  may include a hydrophilic water-swellable material allowing coating  108  to physically change upon exposure to water. In such embodiments, layer  312  may be present or absent. Suitable hydrophilic water-swellable materials are disclosed in, for example, commonly owned U.S. Patent Publication Ser. No. 8,393,979, currently U.S. patent application Ser. No. 12/822,470, entitled Golf Ball with Hydrophilic Coating Layer, filed on Jun. 24, 2010, and applied for by Fitchett, the disclosure of which is hereby incorporated in its entirety. 
       FIGS. 5 and 6  illustrate an exemplary embodiment similar to the embodiment of  FIGS. 1-3 . The difference between the two embodiments is the profile of the coating material. Like the embodiment of  FIGS. 1-3 , the embodiment of  FIGS. 5 and 6  may include a golf ball having a core  520  and a cover layer  502 . Cover layer  502  may include dimples  504 . Coating material  508  may be coated on dimples  504 , forming a thin layer of coating material  508  on a cover layer  502 . As shown in  FIG. 5 , the profile of coating material  508  within each dimple  504  may be such that the thickness is substantially consistent throughout the surface of dimple  504 . In some embodiments, coating material  508  may have a thickness within a range of 0.1 mm and 3 mm. For example, in some embodiments, coating material  508  may have a thickness of 0.5 mm. In some embodiments, coating material  508  may have a thickness of 0.3 mm. In some embodiments, coating material may have a thickness of 0.1 mm. In some embodiments, the thickness of coating material  508  may be selected based on a variety of factors. For example, the thickness of coating material  508  may be selected based on the type of material cover layer material used, the type of coating material used, the number of dimples, shape of the dimples, and/or the depth of the dimples. 
     As shown in  FIG. 6 , a water droplet  610  may behave in substantially the same way water droplet  310  behaves in  FIG. 3 . As shown in FIG.  6 , water droplet  610  may form a layer  612  as water droplet  610  settles in dimple  504 . In some embodiments, the profile of layer  612  may be uniform so that the thickness is substantially the same in the middle of dimple  504  as the thickness is toward the edge of dimple  504  adjacent land area  506 . As discussed with reference to layer  312 , the profile of layer  612  may also vary based on a variety of factors. Similarly, the depth and shape of dimples  504  may be adjusted in the ways described above with reference to  FIG. 3  to compensate for the change in depth and shape of dimples  504  caused by water layer  612 . 
     In addition to the coating materials having various profiles, in some embodiments, the coating material may partially cover the dimple such that the dimple is partially hydrophilic. In some embodiments, portions the dimples may be selectively hydrophilic.  FIGS. 7 and 8  illustrate an exemplary embodiment similar to the embodiment of  FIGS. 1-3 . The difference between the two embodiments is the profile of the coating material and the amount of the dimple covered by the coating material. Like the embodiment of  FIGS. 1-3 , the embodiment of  FIGS. 7 and 8  may include a golf ball having a core  720  and a cover layer  702 . Cover layer  702  may include dimples  704 . Coating material  708  may be coated on each of dimples  704 , forming a thin layer of coating material  708  on a cover layer  702 . As shown in  FIG. 7 , the profile of coating material  708  within each dimple  704  may be such that the only a portion of dimple  704  is coated. For example, coating material  708  may only coat a bottom portion of dimple  704  and may have a maximum thickness at the center of dimple  704 . The thickness of coating material  708  may decrease toward the edge of dimple adjacent land area  706 . In some embodiments, the portions of the dimple  704  covered by coating material  708  may have a profile different from the profile shown in  FIGS. 7 and 8 . For example, the profile of coating material  708  may have a uniform thickness. In some embodiments, the portions of dimple  704  covered by coating material  708  and the profile of coating material  708  may be selected based on a variety of factors. For example, the portions of dimple  704  covered by coating material  708  and the profile of coating material  708  may be selected based on the type of material cover layer material used, the type of coating material used, the number of dimples, shape of the dimples, and/or the depth of the dimples. In some embodiments, the portions of the dimple  704  covered by coating material  708  may have a profile different from the profile shown in  FIGS. 7 and 8 . For example, the profile of coating material  708  may have a uniform thickness. 
     As shown in  FIG. 8 , a water droplet  810  may behave in substantially the same way water droplet  310  behaves in  FIG. 3 . As shown in  FIG. 8 , water droplet  810  may form a layer  812  as water droplet  810  settles in dimple  704 . In some embodiments, the profile of layer  812  may be such that the maximum thickness of layer  812  is in the center of dimple  704  and the thickness decreases toward the edge of dimple  704  adjacent land area  706 . As discussed with reference to layer  312 , the profile of layer  812  may also vary based on a variety of factors. Similarly, the depth and shape of dimples  704  may be adjusted in the ways described above with reference to  FIG. 3  to compensate for the change in depth and shape of dimples  704  caused by water layer  812 . 
     In some embodiments, the land area of a golf ball may be coated with a material having a lower hydrophilicity than the cover layer. For example,  FIG. 9  illustrates an embodiment including a golf ball  900  having a cover layer  902  including dimples  904  and a land area  906 . A hydrophobic coating material  908  may be applied to land area  906 . In such an embodiment, cover layer  902  may include a hydrophilic material. Thus, dimples  904  may be hydrophilic. In some embodiments, portions of dimples  904  may also be coated with coating material  908 . Suitable hydrophobic materials and methods of achieving hydrophobic surfaces are discussed above with reference to  FIGS. 1-3 . The same suitable hydrophobic materials and methods of achieving hydrophobic surfaces may be used to make land area  906  hydrophobic in embodiments in which the land area of a golf ball may be coated with a material having a lower hydrophilicity than the cover layer. 
       FIGS. 10 and 11  show how golf balls in accordance with the present disclosure may be used to compensate for wet weather conditions. Although not wishing to be bound by any particular usage or effect, the change in dimple depth and surface dryness from the dry state to the wet state may generally allow golf ball  100  to compensate for the effects of wet weather conditions that would otherwise disadvantage conventional golf balls. Specifically, during wet weather, water on a conventional golf ball may decrease the amount of friction between a golf club face and the golf ball during a shot, cause a golf ball to experience a lower trajectory flight path and reduced spin. 
       FIG. 10  shows a golfer  1012  golfing in fair (i.e., normal, or non-wet) weather conditions. Under these conditions, golf ball  100  (from the embodiment shown in  FIG. 1 ) is in the dry state. Golf ball  100  may follow flight path  1006  toward the tee  1004 , achieving a maximum vertical distance of  1010 . For comparison, conventional golf ball  1016  is shown following a substantially similar flight path  1008 . Conventional golf ball  1016  has the same general aerodynamic properties as golf ball  100  in the dry state. 
       FIG. 11  shows golfer  1012  golfing in wet weather conditions. Specifically, rain  1014  lands on golf ball  100  and golf ball  1016 , as well as the green  1002 . As a result of being exposed to water in the form of rain  1114 , the land area of golf ball  1016  becomes slick. As a result of the wet weather conditions, conventional golf ball  1016  experiences reduced friction between its cover layer and the golf club face during the shot. Therefore, conventional golf ball  1016  experiences a flight path trajectory  1118  having a lower maximum height  1112 . Conventional golf ball  1016  also experiences reduced spin, resulting in poor control of the shot upon landing. In contrast, golf ball  100  compensates for wet playing conditions by repelling moisture from land area  106  and drawing moisture toward coating material  108 . The reduced moisture on land area  106  prevents a loss of friction between the club face and land area  106 . The reduced moisture also prevents reduced spin, thus preventing poor control of the shot upon landing. Accordingly, the present disclosure provides golf balls better able to compensate for wet weather conditions. 
       FIG. 14  illustrates a comparison between golf ball  100  when wet and dry. A golfer  1420  may swing a golf club  1422  toward golf ball  100  on a tee. If golf ball  100  is dry, then golf ball  100  may exhibit play characteristics as shown in the upper half of  FIG. 14  upon being struck by golf club  1422 . Specifically, golf ball  100  may exhibit a high rate of rotation  1408  around its center of gravity  1412  because less moisture may be present on coating material  108  in dry playing conditions. With less moisture present on coating material  108 , the moment of inertia of dry ball  100 , as graphically illustrated by the length  1404  of the moment arm  1400 , may be relatively low. On the other hand, when golf ball  100  is wet, golf ball  100  may exhibit a lower rate of rotation  1410  about its center of gravity  1412  because more moisture may be present on coating material  108 . With more moisture present on coating material  108 , more weight may be concentrated on the surface of ball  100 . As a result, the moment of inertia of wet ball  100 , as graphically illustrated by the length  1406  of the moment arm  1402 , may be relatively high. This effect on the moment of inertia of ball  100  may be more noticeable in embodiments with thicker coating materials, since more moisture may be attracted to thicker coating materials. Because golf ball  100  may display different play characteristics depending upon whether golf ball  100  is wet or dry, certain golfers may find it more desirable to use golf ball  100  in dry weather or wet weather based on the golfers&#39; preferences. 
     While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.