difference between undercoat & primer

[IA76]

Hi

a bit of a newbie question here

what is the difference between undercoat and primer??

i have got a bare pine door to paint so want to know if the first coat should be undercoat or primer....or do they both do the same job?

Thanks

 

[PowerTool]

Primer is to be applied to bare wood to seal it before any other paint types.

So for your pine door :-

Treat any knots with Knotting (stops the sap leaking out)
Prime
Undercoat (may need more than one,depending on colour)
Topcoat

And sand down between coats (when paint is dry) for a smooth finish - just rub lightly with fine paper,as it is almost impossible to paint without having dust land on the wet paint!

 

[Zampa]

Then main difference is primer contains more oil and is generally thinner...its designed in most cases to soak into the surface

Undercoat carries more pigment and its main roles are obliterating the previous surface colour and to 'key' onto the existing surface, providing a suitable base for the topcoat.

 

[IA76]

Thanks all

one final question then.

if i use white primer and i am going to use white paint for the topcoat do i still need to use undercoat or will 2 layers of topcoat be ok?

cheers

 

[Zampa]

Deepends on what topcoat you intend to use...if its gloss id say yes...you need to undercoat, this will help remove surface texture it will also obliterate the surface....using two coats of gloss may not totally cover.

If your going to use satin or eggshell finish then two top coats should be ok as it has more 'body' than gloss.

 

[IA76]

i'm using white gloss as a topcoat so primer-->undercoat--> gloss it is then

thanks for the help