When a Coating Starts to Fail
Three Finishes, Three Failure Modes
Most gates around here carry one of three finishes. Powder coat is hard, even and very durable until it is breached, at which point moisture travels sideways underneath it and lifts a wide area. Wet paint is softer and chalks visibly as it ages, which is unattractive but honest, because you can see it going. Hot dip galvanising sacrifices itself slowly and gives the longest life, though the surface is not to everyone's taste.
Why Powder Coat Fails Suddenly
A powder coated gate can look perfect for years and then present with a large blister. The reason is that the coating is an excellent barrier and a poor patch: once water gets behind it through a stone chip or a drilled hole, it cannot evaporate back out. The corrosion spreads under an intact looking surface until the surface has nothing left to adhere to. This is why a small chip on powder coat is worth touching in on the day it happens.
Where Breaches Happen
Almost never on the flat faces. The vulnerable points are edges and corners where the coating thins during application, the bottom of every vertical member where it meets the rail, any hole drilled on site after coating, and every weld made after the gate was finished. Site modifications are the largest single cause, because a hinge relocated or a bracket added leaves bare steel behind a bolt where nobody looks again.
Spot Repair Against Full Recoat
A handful of isolated breaches on an otherwise sound finish are a spot repair: grind back to clean metal, prime with a zinc rich primer, and topcoat to match. It will not be invisible and it will hold. Once the failures are numerous, or once the coating is lifting in sheets, spot repair becomes an endless job and stripping the gate for a full recoat is the cheaper path over any reasonable horizon.
Preparation Decides the Outcome
The most common reason a recoat fails early is preparation that stopped at wire brushing. Any remaining corrosion under a new coating keeps working, and the new finish lifts within a couple of years. Blasting to bare metal is the only preparation that reliably resets the clock, and it is worth asking a contractor which preparation their quote includes.
Recoating Is a Good Moment for Other Work
A gate that is coming off its hinges for stripping is also a gate that can be squared, have thin sections let in, and have drain holes added, at a fraction of what those jobs cost as separate visits. Bundling the structural attention with the finish work is how a twenty year old gate ends up with another twenty years in it.