Re: isenglass
I find washing with water and a little simple green with a chamois cloth gets isenglass clean. I then follow up with a plastic polish from a company called One Grand. Their stuff is essentially like Armour All which is a plasticizer. Isenglass is not polycarbonate like the clear glass web site implies. It is PVC (vinyl). To make PVC soft and pliable, plasticizer is added to it. Sprinkler pipe is PVC without plasticizer. UV and heat gradually strip the plasticizer out of the isenglass so it becomes stiffer and opaque over time. Rain X doesn't harm isenglass and does improve it's clarity for a short period of time. What ever you use do not use any abrasive cleaners or polishes.