Flash gels - what are they, exactly?

[FidelCastrovich]

Not their function, but what ARE they? What are they made of? Is it really gel?
More importantly, can i make one out of a piece of translucent colored plastic sheet?Or do the real gels have some unique properties that a plastic sheet doesn't have?
Normally i Google things like this (read - easily DIYable at first glance), but all i can find is where to buy them and how to get samples, which are not available where i live.

Thanks.

 

[Digital Matt]

They are plastic and you can make your own sure, but since they are designed to adjust and balance color temperature, the ones you buy are really a specific color to match tungsten and florescent light. If you are just using them to add different colors to a scene, try using the colored plastic wrap.

 

[chris]

They are basically a transparent coloured plastic and you can make your own, but do be careful if using them with tungsten or halogen lighting - they can easily melt and may be a fire hazard. Manufacturers, such as Lee Filters (www.leefilters.com) produce versions for high temperature use. They also ensure good colour matching, even dyeing of the material etc, especially important if the gels are tio be used to match or adjust colour temperatures.

 

[RyanLilly]

Aside from gels specifically made for photography,
gels are predominately used in Theatrical and entertainment lighting; People who shoot video typically use the color temperature adjusting filters and diffusion. Check out Lee, and Rosco, I know Rosco has some good PDF's with information, mostly concentrated on theater though, You can but gel locally at a supplier of theater lighting equipment, gel is sold in 18"x24" sheets for about $6, or in much larger rolls.
Gel is cut to the correct size and inserted into a sheet metal frame to hold the gel rigid, then you slide the frame onto the front of a lighting instrument(fixture). I don't see any reason not to try these with a flash, keeping in mind that most colors were created considering a halogen light source.

And yes Historically it was actually Gel.