Varnishing over painted MDF?

[KemoSabe]

I did a search but couldn't find any similar posts so here goes!

Hi all

I need to gloss finish some mdf which has been prepared with mdf sealer and painted. I tried some samples and the water based ronseal quick dry varnish (tin says quick drying and touch dry within 1hr) which I used dry's to the touch but even after days I can still make finger nail impressions in the varnish and its been like that for more than a week.

Is it, that varnish can't be used on sealed painted surfaced wood?

I would like to use a quick drying varnish so should I try another brand of water base varnish or will I be wasting my time?

Thanks.

 

[Johnboy54]

I painted some wardrobes I built with MDF, and then varnished them to give a harder finish.
No problems.
I put blown-vinyl on my staircase and painted it with vinyl-silk.
Major problems!
It never dried after several months.
Sounds like you've got a similar problem - but different.
I rang Dulux, and it turns out you should only use matt paint on blown-vinyl.
I'd suggest ringing Ronseal customer services for further advice.