Dear Angus PT,
Don't clean your face shield with Windex or other chemicals. The high dollar Lucite specific stuff is best, but if you can take it off, any MILD soap and warm water won't hurt the polymers. And cloth is better than a paper towel.

2005 Model . Two Fast Eddy stickers , a bell and a clock . She's Lola . She tinkles and keeps time . http://s649.photobucket.com/albums/uu211/britbike05/