filters for black and white film

I have two filters that I found with my dads old camera. One of them is red, and the other one is yellow. Does anyone have a clue what each filter does?

thanks

The red filter will make the sky almost black as well as give more definition to clouds. Yellow is also used to increase contrast in general. Usually b&w filters will lighten the color in the subject that's the same color as the filter (green filters lighten leaves, etc).

If you look thru a b&w filter (as in just hold it up to your eye and look thru it) everything will be monochromatic; different shades of red or yellow. Filters for color film (like a blue 80A for correcting incandescent light) will still let you see other colors.