Morris Minor Owners Club

This is probably a stupid question, but how necessary is the etch-priming step of a bare metal respray? I wound up taking all the paint off Fenchurch's passenger door because it had been poorly sprayed in the past. I don't have enough etch-primer to spray it all so would have to order some more. Can I get away with just spraying zinc primer onto the bare metal or would that not adhere well enough?

Also, is the correct order of application etch-primer first, then the zinc-primer over that? How about if you need to use filler? I've been putting filler over zinc primer (figuring it won't be able to do its rust-prevention stuff if it's not in contact with the metal), but I'm not sure if that's the right way to do it.

I'm just looking in envy at your rust free door!!!

I expect paint experts will be along, but it depends what type of primer and top coat you are using. With rust free bare metal, fill over that sand it perfectly smooth with feathered edges. Then in the past I have etch primed (one coat) and used celly primer (several coats flatting them smooth) before the top coats.
I only tend to use zinc primer on the underside of the car or in box sections to protect it a bit more. This is what I personally do- methods vary- especially if using 2-pack or water based.

I think this door has been replaced at some point, hence why it didn't have the original factory paint finish. The passenger-side rear wing was obviously replaced at the same time as it has the same dodgy finish. I'm using cellulose primer and topcoat.

just laquer it and put it on like that looks lovely.
I see I have some competition in the strip it to shiney metal stakes

oooh look a door without a welded patch strip along the bottom!!!

isn't the point of etch primer that it actually etches itself into the metal, thus providing a sensible base for subsequent paint and filler?

I don't actually know, I'm just pondering!!

ps alex do get something onto it quick, even if it's just a "holding" coat of red oxide. the rust starts to grow as soon as the metal is exposed to damp air.

Most 2K primers are etch primer and filler primer in one product, so the need for a dedicated etch layer is no needed. However I always spray a thin layer on bare steel then prime onto of this when sure that it is perfectly dry. Some filler primers do not like etch at all and will react.
You can apply zinc primer, then etch and primer, however always apply the filler to roughed up bare metal. Personally I'd go etch, filler primer and top coat

Great, thanks a lot

I'll order some more etch-primer. I've wiped a thin coating of Duck Oil onto the door to protect the bare metal until I'm ready to paint it (should wash off OK with panel-wipe).

I'm a bit unclear on why you would spray etch-primer over zinc-primer instead of the other way around.

Zinc before etch as the zinc has better protective properties and needs to be on the metal surface, the etch then adheres to the zinc.