Panama hat manufacturers block the hats as the final step in shaping them. When a hat becomes pulled out of shape from wear damage, blocking it again restores its original shape. To block hats efficiently on a large scale, you need to invest in special equipment. Modern manufacturers use hydraulic presses rather than traditional wooden blocks and hand-shaping, but you can follow the traditional hand process to block a hat with homemade equipment to make a one-time repair.
Dampen the hat with a wet sponge. Locate the exact front or back of the hat. Look for the seam in the sweat band to find the back or you may be able to find a mark inside indicating the front or back.
Pull the crown of the hat down onto a hat block of the size and shape you want. Align the exact front or back with the front or back of the block. If you don't have a wooden hat block, you can make a temporary one by starting with a shape that's close to right, such as an upside-down pot, and filling it out to the size and shape you need with layers of padding covered with duct tape.
Turn the block upside down and prop it over a source of steam such as an open pan of hot water. Check the hat every few minutes as it softens and smooth it against the block, pressing it down so it takes the shape of the block without any wrinkles. When it is shaped against the block, remove it from the steam and set it upright.
Dampen a cloth, wring it out and lay it over the hat. Iron the hat with an iron set at a low temperature so you avoid scorching the fibres. Remove the damp cloth and rub the hat to polish it with a piece of cheesecloth or paper.
Remove the hat from the block, turn it upside down and slip it down into a flange (a ringlike form) which is shaped the way you want the brim, so the top of the brim rests against the flange and the crown of the hat extends down through the opening in the middle. Stretch a piece of cloth tightly over the underside of the brim (which is now facing upward), smoothing the brim down against the flange, and tie the cloth in place with a cord around it below the flange. Dampen the cloth with a sponge.
Heat a sand bag and lay the hot bag on top of the flange, pressing the brim against the flange for fifteen minutes. Remove the sand bag and cloth and let the hat dry, then remove the finished hat from the flange. To make a sand bag, sew together two pieces of cloth to make a flat bag a few inches larger than the brim of the hat, leaving a small unsewn section to use to fill it. Fill it with sand so it will be about 5 cm (2 inches) thick and sew it closed. Warm the bag in an oven set at 65 degrees. The bag's heat and weight shape the brim against the flange.