Originally Posted by
Cliff Opticoat 2.0.
Ask @xCONWRATHx and he can square you away. I assume after you sand, you're polishing right?
I have used Opticoat multiple times in the past for this, as it is one of the products suggested uses, but I've found that it doesn't last more than 6 months or so. I don't believe the product has enough UV inhibitors in it to do the job. Also Optimum is releasing a new product at SEMA specifically for this task, so they obviously know that Opticoat is less than ideal.
Go with shooting a layer of clearcoat over them. Others have even used a layer or two of urethane wood varnish with good results, applied with a brush.
You're headlights come from the factory with a UV resistant top coat already on them. Over time, this wears away and the lights begin to oxidize. You have to use abrasion to remove the oxidized layer, and with it comes some more of the remaining top coat. If you continue to sand/polish each time the headlight begins to yellow, eventually all the top coat will be removed, which will cause the headlights to yellow faster and faster. So, depending on how many times you've done the process you may be able to get away with using a sealant on them once a month (like Meguiars #21), or you will need to go to more permanent means such as clear coating or urethane resin.