Problem with Gel
I just downloaded the Portal 2 Authoring Tools, and ran into a problem getting an info_paint_sprayer to work. The gel appears to work correctly, except that it won't stick to any surface. The gel simply disappears upon hitting a surface and does not coat it in paint. I have no idea what I'm doing wrong: I even tried copying an info_paint_sprayer from an example map on the wiki (which did compile and work correctly), but in my map it doesn't work. What's going on here? What am I missing?
Did you make sure that "paint in map" is set to "yes" in the map properties?
That was the problem. I didn't even realize such a property existed. Thanks!
Don't forget to turn that off when you have a map without paint! Otherwise you're going to unnecessarily load the paint shader.
I have the same problem but changing the map settings didn't help. any suggestions?
Does the gel work, just not show up? If so, just add lights to your map.
I have the same problem. It works like it should, but I cant see it... so I am trying to add some light into the map. I have heard that I need to set mat_fullbright 0 to see it work... but I cant set mat_fullbright 0 ... it doesn?t change. Its like the config file is read only or some... 
Any idea why mat_fullbright is stuck in 1?
Did you turn on sv_cheats 1?
sv_cheats is now 1. It still does not work.
Do you have lights in your map?