Can you put high gloss paint over simi gloss?

Answer 1

I'm assuming your talking about house type paint and not something high end like car paint. If so, the answer is yes, but you must de-gloss it first to open pores in the old paint and give the new paint something to grip on too.

To de-gloss, you can use sandpaper (150 grit and above is better) to "scuff" sand (just scratching the surface a bit, not really sanding anything off of the wall), or use a commercial de-glosser (such as krud kutter's "gloss off" etc...) which in most cases, you have to rinse off before repainting, but does do a more through job. If the old paint is really hard and shiny, you might have to de-gloss AND use an adhesive primer (also called "bonding" primer) first to insure your new paint sticks and doesn't peel.