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If you've already played a few games with the lacrosse head, it's likely covered in grass or dirt stains. You should clean these off before dyeing the head, or the dye job will turn out poorly. Fill your sink up with warm water and 1-2 squirts of dish soap. Scrub the head with a sponge until all of the grass marks and dirt stains have come off. If you're using a clean, new lacrosse head, you won't need to wash it before dyeing. Pick up a couple colors that complement one another or that match your team's colors. For example, you could dye the head red and blue, black and yellow, or red and green. You'll be able to find lacrosse head dye at most large athletic-supply stores. If they're sold out, you may be able to find the dye at a lacrosse specialty store if there's one in your area. If this is your first time dyeing a lacrosse head, stick with 1 color until you've gotten some dyeing experience. Untie the small knots that hold the string netting to the lacrosse head and set the string net aside. This will keep the string itself from being dyed when you color the head. Set the string aside for now. Some people may want to dye the pocket of their lacrosse head, in which case you can leave the string in! But, this approach is pretty uncommon. Tear off a few strips of duct tape and wrap them around any spots on the plastic lacrosse head that you'd like to remain uncolored. Remember that the spots you're about to tape are going to remain white when the stick is complete. You can get as creative with this as you like! For example, try cutting star or triangle shapes out of the duct tape and spacing them out along the lacrosse head to give it a creative pattern. If you want the numbers or your team name on the lacrosse head to remain undyed, cover them with tape. Or, if you want to dye the head in a striped pattern, alternate taped and non-taped sections along the length of the head. On the other hand, if you'd like to dye the entire lacrosse head 1 colorwhether or not you're using the marbling techniqueyou can skip using tape.

Summary:
Scrub a used lacrosse head with a sponge and dish soap. Select 1-2 colors of dye to color the lacrosse head. Remove the string from the lacrosse head. Place duct tape over parts of the head you want to remain uncolored.