Believe it or not I have had a heck of a time trying to polish synthetic scales. I tried, Maas, Flitz, Simichrome, and Eagle one. All put a nice shine on the scales but not good enough, if you know what I mean. Then I remembered, I had a convertible with a rear plastic window and would use Maguires plastic cleaner and Maguires plastic polish. I tried it on some scales and I got what I was looking for.

Sacles that look new. The cleaner will remove minor scratches and actually give the scales a nice shine. The polish does the trick.

They sell a combination Maguires but I never used it. I use the seperate bottles. Maguries Plastic Cleaner, Maguires Plastic Polish. A little hard to find. Pep Boys is a good try but I ordered it directly from Maguires on-line. You would work this stuff just like polishing a car. Put it on and keep rubbing until it's used up.

You don't put it on and ten wipe it off. You clean or polish to a shine. It is a little expensive at $8.99 a bottle for each, but with the size of scales I'll never have to buy anything else.
Vince