Scientific examination can be very useful as a preliminary to planned restorations. As an example, the examination of two shutters attributed to Hieronymus Bosch in the Rotterdam Museum Boymans-van-Beuningen is briefly discussed. Stereo x-radiographs and cross sections of paint samples were essential in estimating the extent of original paint covered by overpainting, thus contributing to various restoration decisions. The altarpiece with the <i>Adoration of the Shepherds</i> by Dirck Barentsz in the Gouda Municipal Museum was extensively examined prior to its restoration in 1985-1987. X-radiography, raking-light photography, and ultraviolet fluorescence were used to assess the condition and the measures to be taken. Paint cross sections showed many areas to contain discolored smalt and oxidized copper resinate glazes, thus predicting only little improvement there after cleaning. Scientific examination sometimes leads to recommendations which run counter to other interests. The polychromy of a 16th-century Antwerp Passion altar in the cathedral of 's-Hertogenbosch, Bois-le-Duc, was blistering, very dirty, and repeatedly overpainted. Cross sections showed that it would be very difficult to remove the later overpainting, in particular, the blue paint. Cleaning of surface grime and consolidation was suggested. However, the church authorities preferred showing as much brilliancy as possible. The result is a mixture of 16th-, 18th-, and 19th-century surface layers.