Undercoat - what is it exactly?

[mattylad]

Hello, I'm wondering about undercoat.

I have some new wood architrave & skirting to fit shortly & have a silk top coat already.
BUt before I go out & buy some undercoat specially for this & with me always being one to recycle etc is there something else I can use instead?

For instance, can I do the same with emulsion or some old paint etc?

(I have already used knotting solution on it).

If not what does the undercoat consist of & do?

Cheers.

 

[Zampa]

You have given it a coat of vinyl silk emulsion already?..over the knotting?....not good to use vinyl silk as a primer

Undercoat is a base for gloss..it serves 3 purposes..

1..to help flatten any surface irregularities

2..to blot out the existing colour

3..to provide a base for the gloss or top coat..i.e undercoat by means of its resin and type of pigment content binds itself to the surface..as opposed to gloss which has a higher oil to pigment ratio..and provides the sheen.

If you dont want to buy a seperate tin of primer you can use thinned undercoat as a primer.

 

[mattylad]

(I have already used knotting solution on it)

But cheers for the rest.

 

[mattylad]

Just re read that, so for new wood I dont really need undercoat, I need primer?

OK the tin of undercoat er indoors got today can go back

 

[mattylad]

I take it that I thin the undercoat with white spirit?

The tin does not say what to thin with, but it has white spirit in it.

cheers.

 

[Zampa]

Yep..if its oil based undercoat thin it with about 20% white spirit for the primer coat..then use it for for undercoat.

 

[mattylad]

OK cheers.

Changing topic slightly, has anyone actually invented a paint roller where the roller does not slide off yet?

the cheap ones do it so I got some more expensive Dulux ones, and they were even worse! grrr, time for dragons den methinks... lol