polarizer – Photographing paintings what light mods to use and what how to set up linear polarizing filters?

You should attach the Linear polarizer filter gels to the flash, ideally with barndoors. This will achieve the maximum effect. You may have to change their angle, as you do to the camera’s circular polarizer.

You can not put the light source with a polarizer into a softbox nor bounce it off of a surface as doing so will alter the polarization once again, returning glare properties.