Elastic, especially in clothing such as sweatpants, can be uncomfortable if it is too small; to avoid purchasing a larger product, wearing out elastic products to fit your size is a good alternative. To alter the size of elastic materials, understanding the material can help you achieve your goals. Elastic is a type of plastic, so heating elastic while stretching it can better assist in enlarging the banding material without causing any damage to the actual clothing.
Things You'll Need
Humidify your workspace. Run a humidifier in a small room, ideally a bathroom, for two hours or more to prevent the elastic from drying out if it is old.
Heat your material, holding the gun about a foot away from the elastic. Heat the elastic material evenly with the heat gun. If you do not own a heat gun, a hair dryer on high heat will suffice. Hold the elastic band in one hand, while allowing the other end to hang, and evenly heat the entire band with the heat gun in your other hand.
Stretch the elastic. Stretch the elastic and continue to apply heat to it. Use anything non flammable as leverage to stretch the elastic. Use your foot or a door handle to hold onto the elastic band, as you apply heat, and pull on the other end of the elastic.
Check frequently. Stop the stretching process frequently and allow elastic to settle so you can keep a close observation on the elastic's current size to avoid stretching the elastic too much, as it is a lot harder to make elastic smaller.