Name of the colour plastic that goes over lights?

I am having a halloween party and want to change the colour of my spot lights without changing the light bulbs and i remember when i was at college we used a very thin plastic sheet that came in many colours to change the effect of light in a room and can't remember the name of the stuff so i can try buy some.

It was see through of course, thin and you can get many colours.

Help!Name of the colour plastic that goes over lights?Mylar. It's what they use in theatrical lighting.
Name of the colour plastic that goes over lights?
Celophane...just be careful with contact distance from the bulb, the stuff can melt/burn if you're not careful.
Name of the colour plastic that goes over lights?
Mylar

Experiences with best bed sheets and ones to avoid

hair show