what type of paint will you be applying over the top of the varnish?
i would have thought that a good rub down with some fine sandpaper to roughen the surface of the varnish to give the fresh paint something to "grip" would be sufficient or you could paint on a sealer first to ensure the varnish does not attack the new paint.
i would pop into your nearest b and q warehouse and ask the paint section staff for their advice or try a dulux decorators centre
There are product out there. I use one called e.s.p.. Its a wash base type thingy. You wipe it on with a cloth and then let it dry, 5/10mins and then wipe it off. You can paint over most surfaces then. However if it`s a synthetic varnish I would be careful of sanding too much as it has a tendency to start flaking!! Always use a primer u/coat and gloss in that order, especially over varnish. Otherwise it will be prone to chipping etc.
Regards. PS... 36 years in the business.
Thank you chassyp, if I use e.s.p will it be of to put it on the surface after I have emulsioned the walls? You see it is a dark varnished Dado Rail, and I don't know if I will need to paint it a light colour, until the walls are finished and can then judge if it will be better painted or left varnished.
Will there be any need to sand if I use that e.s.p, or can I just use that and then as you suggest, prime,undercoar & gloss? Thanks.
Yea no probs about painting the walls first. Its ok to use esp on most non porus surfaces, ie oil paints etc. Its main purpose is to give a key to the surface, ie a bond. No!! don`t sand esp when its applied as this will scratch it off. just do what it says on the tin so to speak!!! Any probs get back to me. I dont sand until the undercoat is hard dry on the primer and then only with very fine oo paper.
Just be careful not to splash the emulsion too much onto the woodwork, and visa versa with the esp onto the emulsioned walls. Anyway if you do get a bit on, just wipe it off then touch up with emul.