Liquid abrasive ?

This will help:

http://www.amazon.com/NOVUS-7100-Plastic-Polish-Kit/dp/B002UCYRZU/ref=sr_1_1/186-5702136-8747760?ie=UTF8&qid=1450196292&sr=8-1&keywords=novus+2+plastic+polish

Haven't used any specialty stuff on canopies I've muffed,but have had good results with tooth paste,non fancy-schmancy, plain as can be. Moist Q-tip and light touch. Good Luck

Aaron Skinner did a video on removing scratches from clear plastic.  I looked for it on this site, but could not find it.  Perhaps you might have better luck.     P.S.  Found it.  Click on "videos" in the black bar.  And in the search box, enter "clear parts".

well , Hello There !

    I have had phenominal luck with two different approaches . First is the Novus No 1 and 2 system . I have used that for years in reploishing Parts box Buys .

The second is good old toothpaste .First the most old fashioned kind you can find .Then with the polish that is real watery .Do not use Gels .They won't work . Another is a recent find ( I know I said two ) . The materials for polishing headlight covers are awesome so far ! I use the Kit Brand .    T.B.