When your cowboy hat is too large and slips down too far on your forehead, reduce the hat size by tightening up the sweatband that wraps around the inside of the cowboy hat. Hat makers do this by adding padding along the sweatband, using foam-reducing tape, which has an adhesive side. Distributors selling hats or hat-making supplies typically sell this type of tape.
Wipe along the underside of the sweatband using a damp cloth to remove any sweat or dirt residue. If it is a new hat, skip this step. You need a clean surface to affix the tape.
Measure the length of the sweatband.
Cut a piece of tape the length of the sweatband.
Affix the tape under the sweatband with the sticky side against the hat, along the entire sweatband, so that it wraps around the inside of the hat, making for a tighter fit.