Step 1: Take a proper amount of warm water, add neutral detergent, put the hat in and soak it for about 10 minute.
Step 2: Gently brush the outside and inside of the hat with a soft brush, especially where there are stains.
Step 3: Hold the hat with one hand, and put the other hand into the hat to gently squeeze out the water.
Step 4: Spread the hat out, fill it with an old towel (other soft fillers are also acceptable) and put it in a ventilated place to dry.
Tip: Knitted hats can be lightly brushed with a soft brush, but woolen hats are not suitable. Strictly speaking, wool caps are not suitable for cleaning. If there is a stain, scrub it with a mixture of ammonia and the same amount of alcohol. The hat should not be too wet to prevent deformation.