A few days ago, I received the Pro Par shipment; I order a week ago. The following are my initial conclusions 1. It will work on copper and bronze without effecting the metal. 2. It is very oily and takes longer to dry than xylene and it does leave a film. (The film can be rinsed off with isopropyl alcohol.) 3. In general it seems safer to work with because of less fumes and less toxicity 4. It will darken any old luster left on silver coins 5. It is much more expensive than xylenol In conclusion my assessment is Pro Par is not worth the expense for people not effected by xylene. In my preparations to use Pro Par, I found a set of 24 4 ounce glass jars with a acetone/ xylene resistant lined lid for about $26 on Amazon. The size is great for soaking coins in acetone or xylene.
