We're planning to put up a chair rail in our dining room and I think the
walls need some definition. Because the area is so small, I've decided to
do the faux finishing of adding stripes in the same color but in different
sheens.

FIRST QUESTION: I currently have a satin finish on the walls - do you think
I can go ahead and tape off my stripes and paint every second one with
semi-gloss/glossy or should I repaint the section in flat paint first?

SECOND QUESTION: should I use semi-gloss or glossy paint?

Has anyone done this before and if so, can you give me some tips!

Thanks...
CC