Those forms are okay, but I don't like the way the caps are after they've been through the washing machine. Over the holidays I bought a bottle of spray cleaner at LIDS in the mall.
DH accidentally wore his non-work cap to work, realized it when he was about to wheel under a car and set it in the bay next to where he was working, because it was an off-work day. His boss decides to pull in and never saw the hat and drive over it, leaving nice black dirt all over the hat.
I didn't want to take any chances ruining the hat by washing it and asked the clerk at LIDS what he would recommend. They have two products and I decided on the spray. They also had the form and a product for the washing machine. You need a small brush (DH used a nail brush) and water to aid in removing the dirt and it helps clean the inside band and refresh any odors.
DH's cap looks practically new.