Wood primer on paint.

[limakilo]

Got some bare wood that needs priming, so got some wood primer. Already got undercoat and gloss to put on. I wanted to put primer on all the skirting and stair parts that are already painted.

It sounds like extra work, but I want to achieve the same finish on all surfaces, new and old. The old painted wood has been sanded/prepped to receive paint already.

Will my wood undercoat react badly with old paint? All the paint that is remaining is sound.

Any help is greatly appreciated!

 

[sparkwright]

You should be able to achieve a uniform finish with undercoat, rather than primer, though some areas may need more coats.

Probably not the end of the world to put primer on prepared painted surfaces, but not really the way to do it IMO.

 

[opps]

Are you using water based or oil based primer? Is the gloss/undercoat waterbased.

If oil based primer, I would recommend that you just spot prime.

If waterbased, then yeah, you can cover the whole lot but I don't see why you would bother. The WB UC will leave deeper tramlines that might need to be sanded flat (depending on the quality of finish that you want).

Primers seal the wood, preventing the paints from continually soaking in. Historically, undercoats provided a surface that the allowed the gloss to sick sufficiently.

Paints such as eggshell or satinwood (theoretically) do not require an undercoat. If you apply gloss directly over primer, you may see it soaking in at a greater rate. The result being a more matt - see through- finish.

Again a lot depends on the primer. WB primer is often referred to as primer/undercoat. It dries fast but

 

[limakilo]

You should be able to achieve a uniform finish with undercoat, rather than primer, though some areas may need more coats.

Probably not the end of the world to put primer on prepared painted surfaces, but not really the way to do it IMO.

Everything is oil based. I'm thinking of using the primer because some of the paint has been sanded down to bare wood in many places, and I think it would be quicker to just put a coat over all of it. My main concern was of an adverse reaction between new primer and old paint. I'm assuming the old gloss is the oil based stuff, it's very old. The primer and undercoat are oil based too.

 

[opps]

Oil base primer over existing paint can be very slow to dry.