Oldblue

Ahh, earth humour. Selective .
People do use common products for their car.
tooth paste , clean plastic head lights, clean bug guts, polish billet aluminum .
used to use coke syrup to make the track sticky , indoor 1/4 midgets .
Fun stuff like that.

donbrew

I was wrong. Phosphoric acid is the favoring in Coke that makes the taste of 7-UP. Carbolic acid is what they use for carbonating at the tap.

geg

just to dot the "I" cash ...
finally, it was possible to finish the job, There is no rain, no snow, no urgent matters.
In short ... Some time ago I visited a car painter and got a piece of fine sandpaper, polishing felt and a couple of tips.
The whole procedure took about 15 minutes. I just removed the bumps and splashed fresh spray paint on top.
I didn’t take a photo - the process seemed simple and routine to me. It turned out all the same is not very beautiful, but a little better than it was.

geg

Hi guys.
A year has passed. What are the results?

Well, no reason to brag. My attempt has not stood the test of time. Rust appeared under the paint, the blue coating peeled and fell off.
You have to start all over again.

I don't know the reason, but there is an assumption:
1. I did not protect the coating with clear varnish, as Blue_SS advised;
2. I didn't wash the acid off completely. Once under the paint, the acid went over to the evil side and began to eat the metal.

Perhaps there is something else, but nothing else comes to my mind.

In any case, I have gained some experience and will try to avoid mistakes in the future.

tiapetra

There are dedicated products specifically for painting that are primarily phosphoric acid.
Take a look at OSPHO or a much cheaper version from Homey Depot made by Kleen Sritp called Metal Prep.
It is approx half the price of the professional OSPHO
.


Both products contain a bit of glycol to thicken the mix a tiny bit.

These products can be used in 2 different ways.
All waxes, oils and dirt must be washed off first.
They can be applied, left on and rinsed off with water BEFORE they dry. This will leave a surface so clean and etched that it will flash rust almost immediately.
This can be redone multiple times until all rust is removed

To paint an etching 2 part primer should be used along with a good 2 part urethane paint for best results.
Spray bombs won't cut it.

The second method is to apply the phosphoric acid and let it dry completely, preferably overnite.
This converts the rust and neutralizes it leaving a black and white powdery coating.
The loose areas can be lightly wire brushed off and then painted with the same 2 part method as above.

Any acid including vinegar, citric acid or even muriatic will work but will not convert the rust.
The phosphoric in Coke will work, it just takes much longer and the included sugars will have to be dealt with.

There are many other rust converters out there, but the Metal Prep is about the most cost effective.

Powder Coating works so well because if done properly a serious acid washing is done to prep the metal

Smash

Love that half panel, and love the advice. I'm close to literally rebuilding the bottoms of mine, the calcium solution they use on the roads up here is vicious stuff, I've fixed the bottoms of mine 3 times in 8 years, and they need it again.. I'm gonna run out of material. I was thinking to clean the bajeebuz out of it like our OP did, and then fibreglass over it.... and then fill the very bottom of the door pocket with expanding foam to keep water away from the insides. Obviously I guess I need some new door seals.....like all of them....

Oldblue

Clean up the door as you did before and apply POR 15