Thank you Brian,

I am usually afraid of using abrasive compounds and steel wool on antique collectible items. I was surprised how many people recommend their use on porcelain signs. That is why I have been hesitant to deep clean it. I know it is a glass like surface, but I also know glass scraches and abrazes easily. I used soap and water and mr. Clean magic erasers to get it where it is, but that did not accomplish much. Thank you for the word of caution. I will tread lightly.
Jay