is knowing when your done. My son Jarrod could probably do this conservation work but I need to have him spend allot more time with me learning the intricacies of this work. I have 4 painting to clean be fore I leave next week and each one takes about 8 hours. I did this one today. One picture shows the edge of the painting that was concealed from the elements and thus remained almost the original color. This is what shellac will do to painting , furniture and anything else over time. I do allot of cleaning projects but painting conservation is my favorite.