3 of us were riding in pelting rain in Montana a few years ago. I was leading but couldn't see much, the Visor was completely fogged.
I finally pulled over as it was getting very dangerous.
One of my riding friends got a cloth out of his pannier. He had sprayed some Lemon Pledge cleaner on it before leaving home 5 days earlier. He had been using the cloth for his Visor and general cleaning so he wasn't sure if there was enough Lemon Pledge remaining to defog my Visor.
We tried it and it worked beautifully, I had a crystal clear Visor for the rest of the trip.
Even two days later, when rain hit again, the protection was still there.
Glen