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secrets of surface rust removal revealed

309K views 178 replies 91 participants last post by  MARTINSR 
#1 · (Edited)
Hi Hotrodders,

I see several posts regarding surface rust and what to do about it. In this post, I will reveal how I go about removing surface rust from automotive body panels. It's a bit time consuming, but not too terribly bad. I prefer to have Redi-Strip do it for me, but there are times when I have to resort to doing it the old way. This is a very inexpensive process that provides excellent results.

Let's start with a materials list. You will need a DA sander (any type will actually work, or you can sand by hand if you wish)
80-180 grit sandpaper, steel wool (any grade will work), Naval Jelly, a squirt bottle w/warm soapy water and a roll of paper towels.



The first step is to sand the entire surface rusted area with a DA sander fitted with 80-180 grit paper. We're not trying to sand off the rust entirely, just get the majority of the heavy rust and make the panel somewhat smooth.



Working in an area about 12"-16" square, apply a fair amount of naval jelly and start scrubbing with the steel wool. It's wise to wear rubber gloves, as the phosphoric acid in the naval jelly may affect your skin!!
It is important to keep the area wet at all times. Do not allow the naval jelly to dry. A few shots of water from the squirt bottle will help to activate the acid and may aid in quicker results. Depending on the severity of the rust, you should start seeing shiny metal within a few minutes. You may have to rinse the area and re-apply the naval jelly several times to get it all, but it WILL remove the rust eventually. When you're finished working an area or you need a break, wipe off the excess naval jelly with a paper towel, squirt a health dose of the warm soapy water on the work area and immediately dry it thoroughly. This will neutralize the acid and leave a bluish colored film on the metal.

I did this 16"x16" area in about 15 minutes. More extreme rust would have taken longer, but the end result would have been the same.



Repeating this process over and over in workable size areas will yield a rust free panel that is ready for a good coat of epoxy primer that will last years, with just a few hours of good old hard work!!!

This '40 Willys roof panel has more than 90% of the rust removed. One more application will get it. I have a little under three hours in it to this point.



The last picture was taken just after wiping the panel with a wax and grease remover. I did this to clean it up and also to help highlight the dents. If you look closely, you will notice several half moon shaped creases in the roof. This all gets repaired in the next step. I will submit a tutorial on that tomorrow night.

Randy Ferguson
Ferguson Coachbuilding
(618) 544-2972
www.metalmeet.com
 
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#4 ·
When I did the roof on my 64 Nova I used a product called Captian Lees that I got at the paint store,but when I couldnt find it anymore I tried an experiment.I went and got some electrolite or battery acid at the auto store and it did the trick.I did the floor in my wagon and it got rid of all the surface rust and left virgen metal.The secret here is you have to keep the area wet,once it dries it stops working.Brush it on the area,get some cotton shop rags,lay this on the surface,get wet,brush out all air bubbles and let it set for a few days.It will eat all the rust and leave fresh,rust free metal.But you got to keep it wet.
 
#6 ·
Nah, I stold that picture from Byron's Gasser Mandess! web site. Posted the pic to get Randy's juices flowign so he will finish his Willys project. If you love gassers, you MUST visit that site.

Don't need to clean off the navel jelly or other phosphoric acid metal treatment. It creates an iron phosphate coating that enhances paint adhesion. Just do the wax & grease wash thingie and paint.
 
#7 · (Edited)
The naval jelly will etch the surface, but I've found I get better results by sanding the metal with 80-180 grit prior to applying the epoxy. If you use a high quality epoxy primer, such as this one from Southern Polyurethanes, Inc. you shouldn't need to apply a metal conditioner.

http://www.southernpolyurethanes.com/images/epoxy_gallon.JPG


I've found their products to be second to none!!



Willys36,

The '40 Willys Coupe belongs to a client. The metalwork is scheduled to be completed in May.

I'm using this one to make the necessary bucks, patterns and forms for the '37-'42 Willys replacement panels. I sell a complete line of inner and outer sheetmetal parts for these.

I am also working with a gentleman with a '35 Willys coupe, who is interested in letting me use his car to make all the bucks, patterns and forms from it to start producing the '33-'36 Willys sheetmetal as well.

Also in the works is Porsche 356 panels as well as a few others!!

I'll be a busy boy, eh!!!

Randy
 
#9 ·
How do you feel about the use of muriattic acid. I have used is several times. I take and sand the surface with like 80-120G paper on my DA and the soak a towel..(not the wifes.. BAD Idea.. If it looks pretty.. you'll get in trouble..) in a bucket of acid and water the lay it on the surface to be cleaned up, then keeping it wet it cleans to the point you had shown.

BUT WAY more hazardous
 
#10 ·
My experience with muriatic acid in this application is very limited, but I do seem to recall that it will make the metal very brittle.

I spent 6 years as a plumber (my father's business) and once had to leave the sewer auger in a clogged drain overnight. The owner had dumped a couple gallon of muriatic acid down the drain prior to me getting there. The next morning, I went to pull the auger out of the drain and it snapped. I was only pulling it by hand, and as I recall, it didn't take much of yank to break it. These things are made of some pretty tough stuff, about 3/16" coil spring is what it looks like. We've had to tie to them with a backhoe to get them loose and they haven't broken, but one night in muriatic acid and this thing was done for!!! I could bend it only slightly and it would break like a pretzel.

Perhaps a bit off topic, but I would hate to see that kind of embrittlement in your cars body panels. Stress cracks would surely appear, I would think.

No doubt it will clean up the rust though!!!

Randy Ferguson
 
#11 ·
Muriatic acid is another name for Hydrochloric acid. Dilution depends on what you buy but it can be very strong.

Depending where you work or what industrial supply is near you, it can also be very cheap, and can be diluted to the strength that is easy to work with .....BUT NOT IF YOU DON"T KNOW WHAT YOU ARE DOING! YES I AM SHOUTING ON PURPOSE! It's strong stuff.

If you haven't worked with it before, don't try without someone who has, and read the instructions and warning labels.

That said -- and I have worked with the stuff -- naval jelly is probably easier and certainly safer. Thanks Randy for the great article.
 
#13 · (Edited)
I don't understand!

We have one of a very few top notch leaders in his field here trying to teach us something (and he is, me anyway)
and were clogging this up with wily cars and acids and I'm sure next some one will tell him to por it and be done with it.

There are 100's of threads here covering all that stuff, so can we keep this one clean and on subject.

Were lucky a guy like this is doing what he is as you don't see Boyd on here trying to teach anyone anything!

If I offended anyone I am not sorry and feel free to blast me with a PM, just keep this thread clean.
 
#15 ·
If I remember correctly, the active ingredient in naval jelly IS phosphoric acid. As I said, there are many ways to do this, but the beauty of the naval jelly is that it is a thick base that will stay put, rather than running all over the place like most rust removal treatments. As others have said, it's very important to keep it wet.
Rust can be removed by soaking your parts in molasses too, but that take several days.
They's many ways to skin a cat!!

Randy
 
#18 · (Edited)
I agree with Randy on this solution. I don’t trust any of the rust converters that I see so many people bragging on. These converters may seal the area well enough to stop the rust, and they may convert a little of the flash rust, but I don’t believe that they are a miracle cure. Say you have rust pits that are .030” deep and you spray on a generous coat of say .015” of this converter. The converter would have to be 200% effective by volume to convert the rust. I am using naval jelly in a similar manner to Randy, and I am positive that the rust is gone. If I am going to put all of this time and money into an old car, I am not going to skimp on the ground level to save a little time and a few pennies. Rather than steel wool to scrub the jelly, I am using a small wire brush that is a little larger than a toothbrush to get down into the pits and dislodge the rust. Do use rubber gloves because this stuff does burn. I have attached pics of the roof of my car mid process and after all of the rust was removed.

pics are not cooperating. Oh well.
 
#22 ·
Once the naval jelly has removed the rust and you're left with a pitted but clean surface like on Kev's roof, will body lead stick to the converted surface?

On deeply pitted areas that are nearly black and very hard, what is this material? The naval jelly doesn't seem to clean that at all until it's been dislodged with a wire brush like Kev is using, no mater how patient one waits.
 
#23 ·
firstgenbird,

I suspect is just more lodged rust!!! Kev did a great job cleaning up the rust on his roof.

Rather than using body solder, which takes heat and will cause severe warpage in a roof, or any other low crown panel for that matter, I would recommend two coats of epoxy primer, followed by 2-3 coats of high build primer. I've found Southern Polyurethanes products to be the best available. check them out on the web www.southernpolyurethanes.com

Remember that the metal used on cars of this era is normally 19ga. which I believe is around .042 thick. The primer will those rust pits with no problem. Much better and easier than working lead!! The epoxy will actually seal out moisture, stoping the rust for good. Back when these cars were built, lacquer primer was the norm. Very porous stuff.

Randy Ferguson

Willys36,

When I find a little time, I will!!
 
#24 ·
Hi
Randy
im restoring my car that had freshly sandblasted floors inner outer
we recently lost our shop lease and for a while im going to start working on it at home
i had it in my front yard applying epoxy to the floors but a neighbor was complaining , so i stopped spraying ,well it started raining. i went out the to check and now there is surface rust all over ,nothing to serious,
well my ? is ,whats the best way to remove this rust,
will this process work also. i got a little rust spots coming from the firewall seams, i had them primered already but the water went through , im going to have to seam seal everything but want to remove the rust first
i had the car covered but the wind riped the cover,now im screwed

any advice
 
#25 ·
Hi Hoss,
The naval jelly will work on the rusty surfaces just fine.

As for the seams, I would have to look at them to get an idea of what to do. My best guess would be that you should use a two part seam sealer. SEM #39777? if I remember correctly is a good flowable seam sealer that will set in about 5 min. It's sandable if you want a really nice finish. I use it in drip rails, as it flows out great and sanding it lightly with 320 has it ready to accept primer OR sealer.

Randy
 
#26 ·
Firstgenbird,

The black material that you are referring to is iron oxide (rust), and you are correct, it is pretty hard. I probably should have went into a little more detail on what all I did to remove the rust in those pics that I posted, so here is the process that I used. First, I used aircraft stripper to remove the old paint. Next, I went over the pitted areas with a wire brush on a 4-1/2 grinder held at about a 60 to 90 deg angle to the surface. NOTE: I use a crimped wire brush with small diameter wire, not a knotted wire brush. I feel that the knotted brushes are too aggressive and will cause more harm than required. Be careful not to heat the metal too much – do not sit in one spot. The wire brush on the grinder will not remove the rust, but I feel that it helps loosen or scratch the surface to allow the jelly to get in a little easier. I apply the naval jelly with el-cheapo paint brushes, and allow it to sit for about 10 or 15 minutes. I then scrub with the little wire brush that is a little larger than a tooth brush. Buy a good brush ($2.00) and it will last a little longer. I work the brush in small circles, sometimes at an angle to allow it to work into the pits better. Let the acid sit for another 5 or 10 minutes and repeat. After 2 or 3 brushings I clean off the acid, apply a new coat, and repeat. Sometimes between coats I hit it with the brush on the grinder to help knock loose any scale that has freed up. It also helps to take a pocket knife or pick and dig into any pits that are troublesome. The scale will fracture out if you dig at it. Once I have gotten every little black spec that I can see out of the pits and have cleaned off the metal, I slap some wax and grease remover on it, let that dry, and hit it with the DA and some 120 or 80 grit. Wax and grease remover again, PPG metal cleaner and prep stuff (basically more acid), and 2 coats of epoxy. I am not going to lie, it is a pain in the rear and a lot of scrubbing. It took me 2 days to strip the paint, remove the rust, and prime the roof of my Buick. Call me anal retentive, but I know for a fact that the metal is clean. I inspected every square inch of the metal and if I did not like the color of it, I slapped on some more jelly and scrubbed.

Kevin
 
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