Re: Fiberglass itch relief
First, strip naked. Then cover yourself in talc.
Then put a good 1/8" layer of vasoline on your skin, and without putting on any other clothes, put on a tyvek coverall.
If you work hard enough wearing this, you'll come out of the suit looking like you're covered with white frosting!
Just kidding. I'd avoid getting the stuff on you as much as possible... a long sleeved shirt with the cuffs taped shut is good, and talc on exposed skin, or for convenience the coveralls are nice if you can get the right size.
Whatever you do, wear a breath mask or respirator.. your lungs won't itch like your skin will, but the stuff definitely goes in and doesn't come out.
To help with both breathing and itching, try to work in a ventilated area, or work with a dust collector nearby to collect the stuff.
I've made myself a redneck bimini tent out of an old bimini bow and some plastic sheeting. Air comes in via the transom hole, goes out via a shop vac with a hepa filter. Dust gets on me a little but doesn't spread around the shop to be kicked up later.
Erik