I have had several spray foam cans and I've noticed that after they are used once and not emptied, the straw in the spray foam can obviously gets full of spray foam. How do you clean it properly to have no spray foam in it after use ? I tried tilting the can upside down to blow air into the straw but that didn't work. Is there a recommended way to clean that straw ? I checked the can and NOTHING was provided for that. Thanks.