Conversion Gel on Hard Light Bridges...
1)Is it possible to do it?
2)If so how do you go about trying this?
I can think of some interesting puzzles to try this feature out but cant work out if its possible because the gel doesn't currently react with the light bridge. 
The portal gun shoots right through lightbridges. Therefore even though conversion gel can be applied to a lightbridge, it doesnt actually do anything.
post39712.html?hilit=white%20gel%20light%20bridge#p39712
I don't know if they actually got this working in the end, but people were making attempts at this before.
Climbing Companion
Was about to say that this is the third topic with this question. Please use the search (advanced) feature before posting.
Or try to put a clip in the bridge (it only works in solo)
So you paint the clip and put a portal on it, but the player loks as if there was some paint on the bridge
http://portal.biringa.com/images/d/d4/Announcer_prehub18.wav
Don't even try finding solutions to this problem. You can't place portals on hard light bridges. The simplest way of explaining this is because the light bridge isn't wide enough to hold a portal.
look at my post in the thread i started then i did not find any thing useful and you may use the solution i used post60947.html#p60947 the only bad with that solution is that you cant shot throe the layer but that is a small price to pay