Painting varnished wood?

[eemaan]

Hi guys I'm new here, I hope you can help.
I just wondered, my mum in law wants to paint her old mahogany dining set a lighter colour, will she have to sand it first so that the paint will stick? I told her if she paints on top of the varnish the paint is likely to chip off really easily, is that right?
Or is there a way she can stain it a lighter colour of wood?
I'd be very grateful for any advice, TIA
Eemaan

 

[NickStone]

If she's been using polish on the wood, she'll need to strip that off first with white spirit. Then she can rub down with sandpaper to give the paint a 'key'. Primer first, maybe two coats, before the top coats.