Painting - Polyeurathane over paint?

I know this sounds weird...
I want to paint my bathroom walls a light (cornflower) blue and I want it to look kind of waxy ( not flat but not shiny). I know I can't get it to look that way with paint alone. My thought is that I could get it to look the way I want by painting over the blue paint with a few coats of satin finish polyeurathane.
Would I have any problems with this? Is it a problem in a bathroom. I don't shower in that room very often. Are there any special things I should do if I decide to try it?
Thanks, Becca

In my experience, true polyurethanes (alkyd-based synthetic varnishes), can cause a reaction called 'blooming' whereby the basecoat tone is altered, sometimes significantly, by the synthetic. For example, I have sprayed several coats of urethane over blue and observed blotchy 'greenish blooms' as the urethane reacts with the paint. To achieve your effect, I would strongly recommend an acrylic urethane (such as Moore's 'Stays Clear') or simply recoat with a sheen of your choice (such as a pearl from Moores). You can also lightly buff the surface with 400 grit paper to give the surface a very subtle burnished effect and take the edge off the sheen, whatever you decide. Best of luck.

Keith

I havent personally put a clear over a painted finish,except for when I restored a rifle stock some years ago,but I figure it is still the basics and I would stick to acrylic clear gloss if the wall paint underneath is acrylic.
If the wall paint underneath is an oil base,I would go for a satin polyeurathane.Oil paint is shinier than acrylic and also for a bathroom I would go for the oil rather than the acrylic as the acrylic clear tend to be pourous and trap mould.
Hope that helps