The use of epoxy resins for historic preservation work, not merely as adhesives but as fillers (with suitable additives) for decayed wood, is described. For fillers, either silica beads or phenolic resin are mixed with the fumed silica thixotropic agent to blend into the resin mixture for improved flexibility of the plastic wood. The analysis of historic mortars and paints is also described. This includes the use of the polarizing microscope for determining refractive indices and optical properties, and of spectrum microscopy together with a spectrophotometer to calculate hue and chroma readings.