To clean your sign we suggest using soapy warm water, we also suggest the occasional use of a good metal polish, this is to remove any salt that may be left on the sign. Avoid using thinners & acetone etc (solvents) as this can damage acrylics. We also recommend doing this by hand with a sponge, jet washers may cause harm. We suggest doing this once a week to keep your letters looking fresh and ensure the longevity of your sign.