I know there's at least one chemist around here so why hasn't he posted?

Phosphoric acid reacts with iron oxide to create iron phosphate (that black stuff the naval jelly produces). Since its an acid, ordinary baking soda is good to neutralize it after the rust is converted. If you don't rinse it well nor neutralize it, it will continue to react and convert the iron in your panels to iron phosphate as well. That takes a whole lot longer than converting the rust, though.

Muriatic acid is hydrochloric acid (somebody pointed that out earlier in the thread) and is used (diluted!) to clean aluminum. It is definitely NOT suitable for cleaning steel or iron. The brittle drain snake that Randy described is ample evidence of that.

Very early on, somebody said they used battery acid to remove rust. That's nuts. Sulphuric acid will certainly take out the rust but it will also eat the steel, your hands, your eyes, and create some nicely flammable hydrogen gas while it's doing so.

I don't have an Air Compressor for a DA Sander, so would just a regular Oscillating sander work?

What about just spot blasting or grinding to fresh metal?

The pressure of blasting stretches the metal, creating a dent at best (a big wavy panel, worst case) grinding removes too much material and produces excessive heat, which can also lead to warpage, due to shrinkage created in hot spots.

Randy

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Diet-Pepsi that sheetmetal!!

I've begun body work on my 54 Dodge Panel truck and found plenty of surface rust on the interior. The interior is gutted except for the bed panels. Are there any special considerations for using the naval jelly technique inside? It sounds infinitely easier than all the wire bushing I've begun with. I should mention that there is paint on some surfaces but not others. I plan to upholster the complete interior so preserving the paint isn't essential. Any thoughts?

Navel Jelly works,it just takes some time.To speed up the process mix with some battery acid 50-50.The secret here is that you need to keep it wet,once it dries out it stops working.One way to keep the stuff on an incline surface is soak a piece of fabric and lay it on the surface.I did the roof of my Nova this way and it worked like a charm.

Come on z51Jeff, it has been discussed in detail in this forum.
You should never use hydrochloric acid on body metal.

Hey Chief,it works for me,you use what you want.

I would suggest following Randy's directions to the letter. If acid was needed, or recommended, for this project, I am sure he would have mentioned it. He is a metal working master! He doesn't just dabble in that stuff!!!

Aaron

As stated above,you can use what you want,Ill use what I know works.In the past Ive used a product called Captain Lees that I got at the auto paint store that was some type of acid,cant find it anymore so I thoutht Id try electrolyte-battery acid- and it works.Im sold on my method so thats what I use.

Randy, Excellent pictures and explanation of rust removal. Keep up the good teaching. Bud

I can't believe that a person would come on here and say throw battery acid on your car and save time. Comments like that should be kept to themselves cause some poor SOB is going to read that and in a few years his car will be falling apart. I've got a 52 Dodge in the shop right now that battery acid was used on and it looks like the sheetmetal worms had a party. It looked great for the first three or four years. It never stops working no matter what you do. Get some on your jeans and every time you wash them the holes get worse. You want to use battery acid on your car fine. Its your car. But dont come on here and steer a young kid into a total mess. Randy is one of the best in the business. Period. If you don't want to learn the right way fine. But start your own thread on how to screw up a car and leave this one alone.
Enough said.

Jeff, You may THINK it is working just fine but the problem is that the wrong chemical reaction is happening here. Phosphoric acid works because of the chemical conversion that leaves a phosphate coating that inhibits further rust but the battery acid will do just the opposite and once the metal is contaminated with that stuff it will set in motion a chemical process that will be very difficult to stop. I just cannot imagine someone intentionally contaminating their sheet metal with battery acid! If you have already used the battery acid the best thing to do at this point is to remove as much as possible, try to neutralize it as best you can and hope for the best but you have created a monster whether you believe it now or not. Do it if you want it is going to be your loss.