We are often reminded by our peers that washing old textiles is dangerous.  As someone who has more than once washed curtains that ended up with less than started in the washing machine (have you ever retrieved just the hems of a curtain from the dryer?), I have respected that warning.  I saw this video of the cleaning of a 17th century tapestry which obviously is an exception to the rule.  The process is interesting.  See: https://www.youtube.com/watch?v=o3xN3rqmfkk&feature=youtu.be