Using emulsion as an undercoat on wood trim?

[Kaymo]

To explain...

I am in the process of putting lining paper up and have already rubbed down all of the woodwork. Its a big room and a lot of wood (shutters and panels in bay area and I am going to use a Wagner HVLP sprayer that I have recently bought.

I am thinking of spraying the ceiling and walls with contract matt as a finish for the ceiling, and an undercoat for the ceilings, and was thinking that instead of masking the wood I could just paint over it with the emulsion, partly as an undercoat and partly to see where I am at with the woodwork and if it needs any more filling sanding (it was a bit of a mess when I started off).

Any issues with this, it wont affect the adhesion of the wood paint or anything will it? (The emulsion would be water based Leyland contract matt, and the wood paint is leyland water based satin, both white, but the original pain that I have sanded down might be oil based)

Thanks.

 

[Mottie]

I’ve always used emulsion as an undercoat on wood indoors.

 

[johnny2007]

I've heard many decorators say it's ok, but then when it comes to do it they buy the proper undercoat.
I suppose that if you already have the emulsion, go for it, but if you have to buy, go for the undercoat.
If wood is bare, use a combined primer-undercoat.

 

[DiyNutJob]

Bare stuff should be primed. There maybe some failures when painting water paint directly over sanded oil paint. You could spot repair them or use primer in the first place.

 

[Kaymo]

Thanks for the replies all.

Generally, in the other rooms so far, I haven't used an undercoat, I have just sanded down the existing paint to get a key, and sprayed on the new water based satin. As there is no colour change I hadn't seen the need for an undercoat. Its been ok so far.

In those rooms I sprayed the trim/panels etc first, then masked/covered them before spraying the ceiling/walls. I actually abandoned the sprayer for the emulsion in the last room and switched to roller, but I think the issue was the paint being too thick to begin with and I am going to give this another go using the contract matt and watered down by 10% from the start. The paint was also borderline a little old so may have had a few lumps.

This time I am just thinking of changing the order, I know that some people spray ceiling first and don't worry about a little overspray falling on to the trim, but I just thought that for the minimal extra effort I could give the trim a coat of emulsion before using the wood paint. The trim is very old, so I saw the emulsion coat as an easy opportunity to get an even base to show up areas that need more filling/sanding, before putting the final coats on.

P.S. I am using primer on any small areas that have gone back to bare wood

 

[johnny2007]

I've never been a fan of spraying emulsion.
One little lump in the paint and things go titts up.
Also, when using a roller, if anything goes on the wall you can just wipe it off with your finger and pass the roller to a perfect finish.

 

[Kaymo]

I've never been a fan of spraying emulsion.
One little lump in the paint and things go titts up.
Also, when using a roller, if anything goes on the wall you can just wipe it off with your finger and pass the roller to a perfect finish.

The Jury is still out on this for me too.

The first time I did it, about a year ago it was really worth doing. It was a big room with an all white but elaborate cornice and ceiling rose. Spraying emulsion on these saved me a huge amount of time as I would have been at it for hours with a small brush getting into all of the details. Better finish too.

The second time was a disaster and as you say, I think it was small lumps. I also followed the manufacturer advice to try first without watering down, which was a bad idea as the pipe and nozzle just got clogged with undiluted paint and the diluted paint couldn't fully dislodge it. I should probably have completely cleaned it all out and started again, but I just abandoned it and went with the roller.

I've decided to give it another try in this room, but I might try diluting by 10%, then straining the paint first. I would like to get it working as I have a very large hall stairs and landing to do next, and I think spraying would be worth the set up time here. I think for a small room its probably not.

The other main problem I have found with HVLP spraying is that it can tend to blow off the masking. The last time I used yellow painters tape to edge, and stuck the drop cloth to this, but the air pressure was getting close to dislodging the painters tape. It was a bit of a catch-22 as the yellow tape wasn't strong enough, but other tape might have been too tacky for the newly painted surface.

I would swear by it now when using water based satin on wood, especially in an old house like this when there is a lot of wood panelling around windows and you can't just go at it with a roller. Much better finish than I am able to get with a brush, and if you are painting everything else anyway you don't need to mask if you do the wood first.

I like the idea of spraying for emulsion, and I need to mask edges anyway because my cutting in is so bad. I also like that the new Wagner sprayer I got has a direct feed pipe for emulsion, so you can draw it straight out of the tub and so don't need to keep filling up a roller or topping up a tray with paint. The theory is nice, but we'll see how it works out in practice!