pinhole light on blackout blinds
I can't find the original post, but I think I remember someone having a problem with light leaking through their blackout blinds from the stitching of the rings.
Anyhow, today I was looking at a site for instructions on diy blinds (it's an excellent site btw) and found that they sell a paint-like pen to dab on the lining where the ring sewing holes are. Maybe a regular white paint pen would work too.
Here is a link that might be useful: paint pen: