Oil based undercoat as an exterior finish paint?

I personally wouldn't leave and exterior oil based undercoat exposed to the elements. Oil based paints provide several finishes, eggshell/satin/gloss

Not really but you can get a different finish such as a satin finish which is much flatter then gloss if you painting exterior you need to be using exterior paint

Undercoat paint is not for finish. That's why they called undercoat. It will be damaged very quickly if you don't put a gloss or any top coat.

Best to use primer first then exterior paint never use primer for final finish recipe for disaster

Absolutely! Yes you can. Just ensure that substrate is well prepped, especially no residual emulsion paint underneath, and apply two coats. You can thin the 1st coat 5% with white spirits

No it won't last ,there are eggshell type finishes available

If you use an exterior sealer on top - but it will require regular maintenance , as all external paintwork.

If you get
Exterior undercoat
Would be fine
But getting exterior paint
Mixed same coulor would be better

you can but make sure it's exterior paint

Hi i would not use an oil base undercoat as a finish if you want the look i would suggest using a satin wood in the finish of the undercoat.

No you can't.

The short answer is NO. And NO again.

Masonry paint and oil is NOT breathable. The paint companies will tell you it is, but the bottom line is that anything made with plastic is not breathable. You wouldn't take your house out for a run in a plastic mac would you? It sweats.

Wataerproof masonry paint is a bit of a problem as a concept. Counter intuitive maybe - but old houses need to breathe. If you slop any form of plastic onto an old building, it will not be able to breathe. That starts to cause huge problems with moisture retention in the building fabric. When that happens, your masonry paint, that you thought was breathable, starts to peel and flake. Why? Because water vapour pressure is pushing it off the wall. Precisely because it is acting like bubble gum. Blow hard enough, the bubble grows, and then bursts... pop. And so the masonry paint pops and blisters as moisture finally manages to get out.

The worst culprit by far is Sandtex masonry paint. We have seen this again and again - thick layers of Sandtex built up over years of painting an old house, until it forms a horrible thick plastic sheet. Eventually it is so thick that you can lift an edge and peel big sheets off it - sometimes water actually runs down behind the paint sheet. When peeled off, the sopping wet wall behind will gradually start to dry out. I've seen old solid walled houses with Sandtex masonry paint covering them that have taken 18 months to dry out when the Sandtex was removed. My advice - steer clear of ANY masonry paint.

If you want truly breathable external paint - there is only one thing to use is - Limewash. It's been used for hundreds of years, and it WORKS! It's a shelter coat

There is external undercoat on the market and at most diy stores I wouldn't advise using any internal paint outdoors.

No reason why not, I'd.probably give it 2 coats just be on the safe side though

I'm afraid you cant. The properties of the undercoat are not made to withstand the weather it is set to endure without its top coat. Get the colour scanned at your DIY store and have it made into a top coa finish. Try an Eggshell as your finish coat. This is similar to the flat look with almost no shine finish that you like in the undercoat.

Buy a satin oil based top coat for the same effect

Not recommended to use undercoat as a finish.