Due to a previous life where I had a plane captain give me a spotless canopy before every flight, I am particular about a clean canopy.
Our club Blanik is now 11 years old and the canopy is in immaculate condition. Any smudge is magnified when in the back seat and especially when landing to the west late on a summer day. It is always outside, the canopy is covered with a Bruce's canopy cover and it is cleaned at the start of each day of flying. We are on our second cover with the first cover lasting 7 years. I use a clean cotton T shirt and Pledge. I always clean in the direction of airflow. On my own PIK-20 using Sontara wipes and Plexus, I see no difference between the canopy conditions. There has been no yellowing of the Blanik canopy which some voice as an opinion for not using pledge.
In no case transport a glider with the canopy cover installed, I have personally seen the damage incurred.

- Barry Muhlenberg, CFI-G Cloudniners, O03