Now what I'm wondering for a month from now, when it comes to black re-edging of the doublet, is if acrylic base black should be used, to avoid possible bleeding from an oil base paint re-dissoving the sap at that time and leaching into the sandwich. I might note that there is quite a bit of edge surface area, as the edge of the back element is ground at quite an inward angle. I certainly don't like the idea of a black sharpie pen. Not exactly a hard substance in thicker coats.