Film-forming paint on rough-sawn timber Coating damp or freshly treated wood Spraying on a windy day next to a car or a neighbour's garden

Which paint should I use on a fence?

A penetrating stain or fence treatment rather than a film-forming paint — and let new pressure-treated timber weather first.

Rough-sawn fence timber moves a great deal with the weather and has an open surface, and any coating that forms a continuous film over it will eventually crack and flake as the wood swells and shrinks — at which point recoating means scraping the whole fence. A penetrating stain has nothing to peel, so it simply weathers back and takes a fresh coat. New pressure-treated timber has a second issue: it is often still wet with preservative solution when delivered, and coatings applied to it will not soak in, so weathering it for several months is the standard advice. End grain and the bottom of each board are where rot starts, so those are worth treating twice regardless of product.

The options, ranked

Ranked best-first for the stated job. The third column is why the others exist.
Option	Good at	Bad at
Penetrating wood stain or treatment	Soaks in rather than forming a film, so it fades rather than peeling and needs no stripping to recoat.	Needs renewing every two to four years on a sunny elevation.
Solid colour wood stain	Much more opaque coverage while still behaving like a stain rather than a film.	Can begin to flake once the coat is thick after several applications.
Fence paint	Cheap, opaque and covers weathered and mismatched timber in one go.	Forms a film on rough timber that flakes, and once it flakes the only fix is scraping.
Sprayer application	Covers rough-sawn timber and gaps in a fraction of the time a brush takes.	Overspray drifts onto plants, cars and neighbours; back-brushing is still needed for penetration.

Technique that changes the outcome

Let newly treated timber dry out for a few months before coating
Brush off dirt and algae, and treat green growth with a fungicidal wash
Work in dry weather with two dry days forecast
Treat end grain and the base of every board generously
Back-brush after spraying so the treatment is worked into the surface rather than sitting on it

What goes wrong

Film-forming paint on rough-sawn timber
Coating damp or freshly treated wood
Spraying on a windy day next to a car or a neighbour's garden

Compiled practical guidance rather than a published standard. Product formulations vary by brand and market, so read the label — and where the work is structural, electrical or gas, the regulations that apply where you are govern rather than anything here.

Other paint questions

For	Use
Previously painted wood	Clean it, key it and spot-prime bare areas — and find out first whether the existing paint is oil or water based.
Bare wood	Knotting solution on the knots, a wood primer, then your topcoat — and prime end grain twice.
Plastic	Any paint, provided an adhesion promoter goes on first — and on polypropylene or polyethylene, the promoter is not optional.
Kitchens	A scrubbable acrylic eggshell or satin on the walls — and for cabinets, degrease, prime and use a proper cabinet enamel.
Bathrooms	A moisture-resistant acrylic in a satin or eggshell sheen with a mould inhibitor — but ventilation, not paint, is the actual fix.
Metal	Remove the rust, apply a rust-inhibiting primer the same day, then an alkyd or a direct-to-metal acrylic.
Ceilings	A flat matt emulsion — and if there is a water stain or nicotine, seal it with a shellac-based stain block first.
Tiles	Tile paint over an epoxy or adhesion primer on a thoroughly degreased and abraded glaze — and expect a limited life in a shower.
Floors	Two-pack epoxy on concrete after a moisture test and a proper grind; floor-grade varnish or floor paint on timber.
Radiators	A radiator enamel — water-based acrylic ones no longer yellow, which ordinary gloss on a hot surface always will.
Exterior masonry	A breathable mineral or masonry paint — and on an old solid wall, breathability matters more than any durability claim.
Galvanised metal	A mordant wash, a self-etch primer or a purpose-made acrylic primer for galvanising — ordinary oil-based primer peels off in sheets.
UPVC	A uPVC-specific paint or an adhesion promoter with an acrylic topcoat — and avoid dark colours, which can distort the frame.

Common questions

Which paint should I use on a fence?: A penetrating stain or fence treatment rather than a film-forming paint — and let new pressure-treated timber weather first.
What should I avoid?: Film-forming paint on rough-sawn timber Coating damp or freshly treated wood Spraying on a windy day next to a car or a neighbour's garden

Which paint goes over previously painted wood? Clean it, key it and spot-prime bare areas — and find out first whether the existing paint is oil or water based.
Which paint should I use on bare wood? Knotting solution on the knots, a wood primer, then your topcoat — and prime end grain twice.
Which paint sticks to plastic? Any paint, provided an adhesion promoter goes on first — and on polypropylene or polyethylene, the promoter is not optional.
Which paint should I use in a kitchen? A scrubbable acrylic eggshell or satin on the walls — and for cabinets, degrease, prime and use a proper cabinet enamel.
Which paint should I use in a bathroom? A moisture-resistant acrylic in a satin or eggshell sheen with a mould inhibitor — but ventilation, not paint, is the actual fix.
Which paint should I use on metal? Remove the rust, apply a rust-inhibiting primer the same day, then an alkyd or a direct-to-metal acrylic.
Which paint should I use on a ceiling? A flat matt emulsion — and if there is a water stain or nicotine, seal it with a shellac-based stain block first.
Which paint can I use on tiles? Tile paint over an epoxy or adhesion primer on a thoroughly degreased and abraded glaze — and expect a limited life in a shower.
Which paint should I use on a floor? Two-pack epoxy on concrete after a moisture test and a proper grind; floor-grade varnish or floor paint on timber.
Which paint should I use on radiators? A radiator enamel — water-based acrylic ones no longer yellow, which ordinary gloss on a hot surface always will.

Sources

Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked