I wash mine about every few months. I get way too much starch on them and by the time I wash them you could use them for constuction projects they are so stiff and can stand up on their own. Do note I found that if I use an old terry cloth towel on top of my regular ironing board cover , it really keeps the blocks from distorting while pressing , it holds the block or strip right where I put it... minimal stretching or distortion. Granted not all ironing/pressing needs this added resistance to stretching and there are times when I do want more fabric movement, but I just take the towel off !