As your bowling habits and your hands change, you will sometimes find that you need to alter your bowling ball. For whatever reason, whether a thumb or finger hole have gotten too small, or the holes are no longer comfortable, you may want to plug them up and begin again. After all, it will be far less expensive to plug a hole than to purchase a new ball. You can keep your old reliable ball and enjoy new, better fitting finger holes by simply plugging up the old holes and then creating a new set.
Check the temperature. In order for most urethane plug compounds to work, the temperature of the ball, the compound and the general environment must be between 68 and 72 degress Fahrenheit.
Mix your colors so that the plug matches the ball. If you want the urethane plug to match the color of the ball, then you will need to add coloring to it. Mix this before adding hardener.
Add the hardener to the mix. This is entirely product specific, so find your measurements using the product directions. At this point in time, you will need to move quickly before the urethane plug compound starts to set.
Level off the urethane compound in the hole. This may not be entirely smooth because the ball is round. Just do the best you can and then let the entire thing dry for at least 24 hours unless your compound states that it will set more quickly than this.
Round the hole back into shape. Use the sanding gloves and discs to remove only the amount of excess need to keep the entire surface of the ball rounded.
Check to be sure your ball is smooth. Roll it gently on the floor to be absolutely sure the plug is flush, and if needed, re-sand and re-polish if necessary.