New Bare Wood - Paint Systems

[poisson rouge]

I always understood that when painting new woodwork you always applied a 3 coat system, ie. primer, undercoat and topcoat.

Here in France I find it near impossible to get wood primer. When I ask, they say its not necessary, just thin down some undercoat and apply before a second (undiluted) coat (and, do I really want to apply an undercoat. What for, they ask?).

I've seen the DIY store full of various manufactures paint (topcoat) that say these can be applied directly to new bare wood.

I admit I've not done any DIY paint jobs for over 10 years, so accept I'm way out of touch with current paint technology.

Is this correct, what's the current norm for painting new woods?

Thanks for any 'elp!

 

[Zampa]

I must be honest, thats what I do.....cant remember the last time I used traditional wood primer....its also common practice in the trade too...I find it dries quicker and doesnt raise the grain of the wood too much.

As an alternative you surely must be able to buy acrylic (water based) primer undercoat out there....

But dont forget to know it first.....thats crucial.

And whatever happens dont use emulsion....that really is bad practice.

There are also a few paints out there that do the lot in one can....straight onto bare wood....but you still need 2/3 coats

Sadolin Superdec is one.....

 

[poisson rouge]

Zampa,
Thanks, I'll do a test piece and see how it turns out. But the main thing is that I want it to last and not see the paint blistering after only a couple of years because maybe the woods resin has started to work its way out.

Anyway, what is the chemical difference between primer and undercoat, any idea's?

Your right about those top coat paints you apply directly to bare wood, after 4 coats I'm still having to have to apply another, may two to get a good color finish!

Cheers

 

[Zampa]

Chemical difference.....hmm...not to sure about that but tradition softwood primer probably does have a higher oil to pigment content than undercoat.

It takes longer to dry, thus the grain in the wood has more time to swell and fur up.

I have had no come backs on jobs over the years that ive used thinned out undercoat on.

The most important thing is that whatever you use soaks into the surface and doesnt just sit on top.

Believe it or not I once used some thinned out masonry paint on bare wood.....some tweenty years ago and its still solid now...masonry paint is full of acrylic.

Paint companies wouldnt aadvocate te use of thinned undercoat but I feel that they accept it has now become the norm and is adequate.

The resin in the wood working its way out wont be a problem....useing oil based primer would not have made any difference....just make sure you knot the knots and resinous areas first.

Ask a paint company and they will not guarentee the success of a paint system if you use thinned undercoat as a primer.....ask a painter....and you may get a different answer.

 

[poisson rouge]

Zampa,

Many thanks for your experienced advise. I'll use oil based undercoats as primer as you've suggested.

You mentioned masonry paint, which brings me nicely to another question I have.

Here in France I've not seen many (if any) buildings finished in gloss masonry paint. They all seem to be coated with a matt finish. Whereas, in the UK I can remember all those years ago, seeing gleaming gloss finished buildings, especially in and around London.

Gloss, to me seems an obvious finish choice for outside masonry as a total water repellant. Buildings here (mine included) with matt or satin finish, seem to absorb the water and remain wet/damp longer after a down pour.


What's your views / experience on this?

Cheers

 

[Zampa]

I think you may have been talking about the buildings around central London....Regents Park areas etc?....many of them are 'crown properties' own by the old lady who lives in that big house not far from Traflager Square..

They were all painted with a colour called 'crown cream' and it was lead based....still in use today up there I beleive.

But things have moved on.....gloss is ok on an outside but doesnt take to well to movement in the substrate..plus there are now environmental considerations too.

The original Sandtex (the slightly textured one) does take a while to dry because of the water hanging arounf on the rougher surface....thats why you see it going green sometimes too....whereas the smoth variety tend to repel the water thus less mould problems.

Many paint companies though now make a water based masonry gloss alternative to the tradional one.....Sandtex being one of them.