When our vented F4 +4 was installed they were very specific about cleaning.  Paper towels, not cotton towels.  The install took place at Wing Ding 2012.  Those of you who were there may remember a bad storm that came though one day during the event.  (How bad was it?  This trailer was blown across the parking lot ramming the tongue into the engine of this beautiful Wing!Our Wing was wet even though it had a full cover on it.  Out to the parking lot I went to dry things off.  Pulling a bath towel I had brought from home out of the Bushtec I went to work.  Okay, I wasn’t cleaning the windshield I was just drying it off…with a cotton towel.  That was when I spotted a hair from our daughter Lindsay on the windshield.  Several months earlier Lindsay had moved into her own place.  Since that time we bought a new front load heavy duty clothes washer and drier.  Several washings later that towel had just deposited one of her hairs on the windshield.  The same towel had from time to time dried on a clothesline where wind may have blown sand into it.  This is the very reason why the folks from F4 Customs tell you not to use a cotton towel to clean the windshield.  I got the message!