Metallic wall paint can present a few problems when its time to paint over it. Planning and a bit of preparation can solve these issues. It is best to put a coat of good, oil based primer over metallic wall paint. This will cover the shiny areas and give the new paint a coating to adhere to. Metallic wall paint can make it difficult for new paint to adhere, and may show through the new paint if it isn't primed. Primer will prevent the new paint from peeling away from the metallic surface of the old paint.