I would like to make an outdoor sign using green patina on a copper sheet. I have the copper sheet but I want to use your green patina solution. Can the copper be used outdoors with your treatment or will it need to be top coated with a lacquer?

The Jax Green Patina can be used on copper intended for exterior applications with no problems at all. If you are using virgin copper we would either: install the sign outdoors and let it sit for a while or darken the copper a bit with Jax Brown-Black and then apply the Jax Green Patina over the Brown-Black for a more authentic look. Regardless, do not apply the Jax Green Patina on hot copper (it will evaporate and do nothing) or on a day when it will rain on the sign (too much patina will just wash off on that first day).