Campbell Center Maintenance Workshop, Follow Up. In June Bob Yapp and John Leeke taught a course on maintenance methods and materials for historic buildings. Many National Parks Service workers attended as well as others involved in caring for historic buildings. This video is a review of window sill weather check filling and sealants, with an additional method of filling checks with traditional linseed oil putty. More about the Methods and Materials for Maintenance of Historic Buildings course: http://www.campbellcenter.org/pages/historic.html#maintenance More about the Campbell Center for Historic Preservation Studies: http://www.campbellcenter.org/index.htmlMore about John Leeke and Historic HomeWorks: http://www.historichomeworks.com/hhw/index.htmMore about Bob Yapp and Preservation Resources, Inc.: http://www.bobyapp.com/ Less