I have been working over the insides of my doors the last few weeks, repairing rust-out on my drivers door and preventing further rusting on both doors. I did use the RUST911 again for this and actually just ordered yet another (4th gallon over time). I REALLY like this stuff! Since you get 16 gallons for about $60...and it works so nicely, I haven't bought any other product for this job since my first gallon 2-years ago!
I just thought I would add a detail I feel will help other restorers dealing with the potential of rust-out down the road in the "hidden" areas.
So, my original doors look to have been galvanized steel, like the hood, fenders and probably most of the car sheet metal. Once the ZINC is off the metal, future life of the metal will be shortened. I learned this the hard way on my drivers door I am afraid. I thought I FIXED it back in 1985 from getting worse when I found a tiny blister in the front corner way back then.
Being from Ohio, I knew rust in 1985. I was then living in Palm Springs area, my 67 Mustang had been initially from the High Dessert area and I lived in the Low Dessert so the car was always HOT & DRY, why then RUST in the front corner of my original drivers door?
It's a TRAP! There is a trap in the front corners of our Mustang doors that retain dirt, debris and MOISTURE. In '85, when I cut my door open to expose the cause of my paint blister, I found this out. I sandblasted the opening I cut into the door skin, removed ALL of the rust I could reach, removed the door panel, cleaned everything inside the bottom of the door off, blasted whatever was rusty and shot undercoating on everything bare that I could see. The outside skin had already been "brazed" in so I simply body-filled the corner and repainted just the driver door. (no signs of any issues on the passengers door back then).
Fast-Forward to about a month ago and I stripped my doors down to the shells to clean then up and to get ready for paint. What I found next was SHOCKING!
I had already noticed another blister in my driver door, in the same area I had patched. The passengers door still looked pretty good but I could make out a faint, tiny blister there, in the same area. Not surprising, but what WAS surprising was when I removed my driver door lower weatherstripping, the whole front corner came out with it! All of what I THOUGHT I had protected so many years ago, was what looked like a TOTAL LOSS, but WHY? The passengers door I had never touched was all but perfect on the outside surfaces and I never did anything to it so many years ago, that and THAT door came from another parts donor back in 1978 so history of that door was anyone's guess!
I figured it out. I CREATED MY OWN PROBLEM! I "sandblasted" it to remove rust but without the original galvanized (zinc) coating, some areas were now BARE STEEL and the same garbage I took out of the TRAP so many years ago had returned too so the dirt was holding moisure on bare metal probably 99% of the time! You know, car washes, dessert dity blowing around getting car dirty, wash cat again, and again what 1-2 times a week?
I HAVE A SOLUTION! Recently, we have been discussing repairing textured surfaces on the INSIDES of our door assemblies so even though I thought my original door was probably rusted too bad to fix, I DID HAVE ANOTHER DRIVER DOOR that, though off a wrecked car, dented worse than I wanted to fix also, it had a section I could cut out of it to graft into my original drivers door. That was the easier part. NEXT, I need to get all the rest of the RUST OFF everything but more importantly, to PROTECT THE HIDDEN AREAS AS MUCH AS WHAT CAN BE SEEN AND COATED. Those front corner traps are just that, now after media-blasting now BOTH doors, I needed something to 100% coat them so that no water, moisture or dirt or debris can get in there ever again...The SOLUTION: Fiberglass resin (and gravity)!
Between the pictures below and the YouTube links which videos are only about a minute or so long each it explains a lot more then what words can say. Obviously I still need to move on to fixing the textured surfaces and such but I'm almost where the insides of the doors are done ( once I get another can of the RUST911 to finish the 2nd door)