[Closed] Oil or water based paint for exterior sash windows? Number of coats?

personally I would be oil based undercoat, primer and gloss and at least 4 coats in total. I am not a painter tho

Are they bare wood and installed? For our new ones they were build, dismantled, sprayed in a shop then assembled again. Better coverage and finish that way.

I'd make sure they are using knotting solution as well as priming etc.

I'd not worry about the number of coats or type of paint if you are looking at specifications and guarantees. You should be asking how it will perform. When will it need repainting, will it lose gloss, will it yellow etc.

Paint manufacturers will have recommended schemes for their products. You'll probably be able to find them. Johnstone's and Dulux would be a good start (or one of the other Akzonobel brands specific to wood, Sadolin?)

You need enough to get coverage of the final coat. There might be a minimum thickness to protect the wood but I don't think that is as important as it is with steel coatings.

There are good and bad paints that are oil or water based. The technology alone isn't the decider in terms of performance.

Water based is more sensitive to environmental conditions during drying as water evaporates slower than most solvents and is more sensitive to humidity and airflow.

Satin is better than gloss in my experience. Gloss drops over time and starting at a lower gloss level will reduce the percentage change. I also think it looks nicer and is more tolerant to an imperfect finish - gloss shows every brush mark and imperfection.

Linseed oil based paints or they'll eventually rot due to the moisture trapped by modern paints

If I was starting from bare wood I'd use a linseed-based paint (edit - jinx!)

They are 125 years old original oak, so I think all the moisture has long since gone, so hopefully shouldn't rot. They'll need rubbing down and some re-puttying in places, but the timber is generally sound.

I wouldn't paint them in a modern paint

Alternatively Sadolin superdec white satin - not a paint system but an opaque stain, that soaks in and lets the wood breath. Really easy to use and clean up (water based) and has lasted v well for me. My only query is how much it would soak in to oak that old...

Had ours painted about 3 or 4 years ago with water based paint. Think it was a Dulux paint. Still looking good now.

Just so much easier and quicker to get them painted and dried properly.

I've had mixed results with water based paint in the past, but since come to the conclusion that you get what you pay for.

Water based is fine.. Unless you're painting on a hot day in which case it's a nightmare. I think Dulux Weathershield is about the only paint that states two undercoats and only one top coat rather than the other way round but I could be wrong.

Alternatively Sadolin superdec white satin – not a paint system but an opaque stain, that soaks in and lets the wood breath. Really easy to use and clean up (water based) and has lasted v well for me. My only query is how much it would soak in to oak that old…

Sounds similar to Dulux quick dry opaque. How does a stain based paint work on wood that has already been painted? Would you need to remove all the old paint. I’m guessing when they have been rubbed down there will be patches of bare wood but also the existing gloss so if it is an opaque stain it might not soak in too well on the existing areas of paint and give an uneven finish?

Bedec Barn Paint, finishes in gloss, semi-gloss and posssibly matt. It’s water based, flexible and hard wearing.

My usual go to is oil based for exterior, like the Dulux Weathershield system.

Dulux Weathershield for the last 30 years in my 110 year old Sash windows.

Dulux Weathershield is water based surely

Sadolin Superdec fan here too.

Dulux Weathershield is water based surely

Not the last time I used it. Though they might now do a water based weathershield?