vsotillos52 it seems that the overexposed red channel was due to the papers that I put to attenuate the flatbox
Do you have an IR cut filter in your optical train?
The reason I ask is that IR easily passes through paper (even brown cardboard boxes), and that can affect the red component of the flat frames if your camera is sensitive to IR. Your paper could be cutting the shorter wavelengths but letting the longer wavelengths through.
It is essential to cut the IR part of the spectrum since all CMOS camera are sensitive to it; some more than others. You always need some filter to cut the IR, unless your intention is to actually do IR imaging.
Try using white T-shirts instead of paper; see if they are better.
Chen
