Water based paints over oil based

[iewalsh]

Hi,

Just moved house and thought I'd do all the skirts and frames. I'd like to do a really good job once if possible.

All the woodwork looks like its oil based gloss, so if I was to go over it with a water based gloss or satin wood what is the best process?

So, grade of sandpaper to start with, do I need to prime, does water based need any other prep to get a good finish?

Cheers

 

[dcdec]

//www.diynot.com/diy/threads/repainting-skirting-boards-water-based-over-oil.416724/#3233416


Best to use the search function before posting as this is a common subject.

 

[iewalsh]

Fair do's. The post you've pointed me to suggests using a primer after removing the sheen. Other posts have mentioned primer isn't required, so which is it?

Also 300 grit paper. Elsewhere its been said 180.

 

[dcdec]

Acrylic primer undercoat would be best over well prepared surface. You can use higher grades of wet n dry as they remove the sheen fairly easily. 180 would be fine in wet n dry or silicon carbide (which is the between coats stuff). There's also aluminium oxide but i only use it on runs and sags as it scratches quite easily.
Primers these days are thought of as being more than just something to take care of porosity. With oil and water based coatings being common now we think of a primer as a bridging coat to promote adhesion between different surfaces. A common acrylic wood primer would be of little use over a badly prepped gloss surface but a high grip primer like zinnser bin will happily stick and promote adhesion to subsequent coats of paint. However good solid prep is always best for a good finish.
Sikkens BL primer/uc is excellent and the Johnstones aqua is probably second best but be warned acrylic paints are far harder to achieve a good finish with than oil based but come with the bonus of not yellowing rapidly.
I personally have a reluctance to go into much detail with anyone in single figure posts because a lot of people never bother to come back and read the answer to their question.

There is a ton of information on here, some of it does contradict a bit or is open to misinterpretation because everyone has a view. Have a read, digest and then come back with anything you don't understand.