Glossing over previously painted timber

[cameron]

I've used non-drip gloss before on previously painted but sanded back wood work with fairly good results. However. I have been given a large tin of proffesional trade high gloss dulux paint which is fairly runny. Can this be applied straight onto sanded down woodwork ok, or should you apply an undercoat first? The existing paint work is fairly solid and not flaky.

I'm recorating the whole of my hall, stair and landing areas, so there is a lot of woodwork to paint. If I can avoid doing an undercoat as well it would speed things up a lot.

[chris_on_tour2002]

you cannot go straight onto bare wood with gloss. the wood will need a decent coat of primer (or two) followed by a spirit undercoat.

some of the better gloss paints are self-undercoating, however a primer is still necessary. and as it is bare wood i would undercoat as well, even if it is a self-undercoating gloss as it will help build up the opacity.

[cameron]

[quote="chris_on_tour2002"]you cannot go straight onto bare wood with gloss. the wood will need a decent coat of primer (or two) followed by a spirit undercoat.

some of the better gloss paints are self-undercoating, however a primer is still necessary. and as it is bare wood i would undercoat as well, even if it is a self-undercoating gloss as it will help build up the opacity.[/quote]

Thanks Chris. What I really meant was. Can I use the pro. paint straight onto prepared sanded paint work which should act as a key? I've NOT gone right down to the wood!
Thanks

[chris_on_tour2002]

i beg your pardon, i misread your original post.

if using a decent quality, self-undercoating paint then yes, you could go straight on with the top coat. obviously assuming existing paint is sound and the surface dust-free.

if making a strong colour change then an undercoat will be required.

personally i would always undercoat first even on a previously painted surface, especially if a white finish is desired as it will stay whiter for longer.

[chris_on_tour2002]

reading your post again, i can tell you that the gloss you are using is good stuff, very running and tricky to use (runs like crazy if not used to the stuff) but it does give a fantastically smooth, high gloss.

however it is not very opaque and is designed to be used ONLY as a finish, the surface should be perfect before you apply the finish. you CAN go straight onto your existing paint if well prepped but if slightly yellow or there are still old brush marks then i'd give another rub down and recommend undercoating with dulux trade undercoat (solvent based) as it's designed as a system, ie best suited as the best key for your finish.

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[rigga]

cameron, Hi read your post regarding using the trade based paint on well prepared paintwork. No you should always use an under coat with this type of gloss even if the surface is prepared well there will always be small cracks in the wood work which you will see when it dries liquid oil based gloss is very searching which means that it will sink into any gaps and cracks and the opacity will be to low to cover the underlying colour even if it is white already. You could do one of two things buy some acrylic primer under coat and apply with a long bristled brush and a soft foam roller for large areas, which means you will have to paint all the woodwork twice, or buy some thicksotropic gloss (1 coat gloss) which you can apply over the already prepared wood work