Let's talk RUST

J

JonC

Well-known member
Can you really get rid of it, and how. I recently started to get all the parts sorted for my 31 std. Roadster. Many parts were stored in a dirt floor barn by the PO. All the floor pans were new at one time but now are covered in rust, not deeply pitted but covered in rust so that a wire cup wheel on a grinder pushes it around but not clean enough for paint of any kind I think. Many other parts are like that as well, the rumble lid I sanded down had rust areas that when wire brushed after sanding appear as dark pitted spots or areas. So what do you do, if I grind with a 36 grit pad I can remove them Maybe but most of the metal is gone too. Has anyone had experiance in dealing with this sort of thing.
 
ya take it to a GOOD sandblaster - make sure they know how to properly blast sheetmetal without warping it.
 
I have been in the same situation as you. I use a cup brush on my 4" Dewalt right angle grinder. After I have most all of the rust removed, I treat the metal to an overnight soaking of Ospho. It is a phosphoric acid that converts iron oxide into iron phosphate. Works good. After removing the white powdered iron phosphate, the metal looks new again. The iron phosphate can be painted over if you would like.
 
Sand blasting I think will warp the panel, I would like to know if anyone has painted over the phosphoric coatings on a panel that is finished painted and has it held up?
 
There are a number of chemical processes to treat rust. They range from Phosphoric acid mentioned above to tannin which converts the rust to an inert and stable black substance which can be painted over or there is even molasses. The key thing is to make sure all of the rust has been removed before painting.
 
Get yourself a sandblaster and learn how to sandblast properly on some sheetmetal of similar or lighter than what you want to do. You need to keep your media coming quite heavily, your pressure down, keep moving, blast at an angle so it glances off. Sandblasting REMOVES the rust. A wire wheel leaves it in the pores of the metal and it WILL come back to haunt you. I myself have not had very good luck with converting rust, eventually it always came back. That's my experience anyway. On delicate pieces I use glass beads, I use black slag on sheetmetal.
 
eagle said:
Get yourself a sandblaster and learn how to sandblast properly on some sheetmetal of similar or lighter than what you want to do. You need to keep your media coming quite heavily, your pressure down, keep moving, blast at an angle so it glances off. Sandblasting REMOVES the rust. A wire wheel leaves it in the pores of the metal and it WILL come back to haunt you. I myself have not had very good luck with converting rust, eventually it always came back. That's my experience anyway. On delicate pieces I use glass beads, I use black slag on sheetmetal.
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yup 100% agree - like I said take it to a GOOD sandblaster and decide what will happen in the event the guy screws up the panel BEFORE he starts and have it in writing. I say that generally because the guy writing the workorder is usually not the guy that does the blasting.

ive always had rust come back unless sandblasted or chemically removed first before paint.
 
I also like Black Beauty sandblasting media. I hold my 1/8" nozzle 1 to 2" from the metal, and use 40 pounds pressure at the nozzle.

Only a few parts with very light rust will clean up with a wire wheel. The sandblast also leaves a good gripping surface for the paint.
 
Dustless blasting works well. It's sand (or glass) blasting in a stream of water to prevent heat/warping. Something to consider is to undercoat everything with rustbullet https://www.rustbullet.com/ Read the FAQ and it will tell you everything you need to know about it. If you DO use rust bullet, you could in all likelihood get away with just the wire wheel, no blasting.
 
On the really rusted body for my 29 coupe I used a 36 grit 3 inch flexible pad on a hand drill and took down all the high spots then followed by brush on metalprep and wiping with steel wool, after drying and wiping down I sprayed on good old Rustoleum rusty metal primer then after drying for a few days sprayed on primer surfacer. This procedure I used in 1981 and after a top coat of acrylic enamel there are no rust spots or peeling.
 
An important part of stopping rust on sheet metal is to use a coating after rust removal that stops air from reaching the metal to cause new rust. Paints like PPG's DP epoxy primer make an air tight seal. POR15 does so also.
 
JonC, I know a very inexpensive method for removing rust, you can mix 1 to 1 ratio of white vinegar with water,(1 gallon of vinegar to 1 gallon of water for sheet metal: 1 cup to 1 cup for smaller parts)Let the parts soak for 1 to 3 days..depending on the severity of the rust, all the rust will disappear and you will be left with clean original metal.
Wash the parts in clear water and dry then prime.

I have done this with wrenches that were rusted shut, original spark plugs, tools, nuts and bolts that wouldn't come apart, sheet metal, dist parts and shafts, old springs.
Good luck ~~ Michael...
 
gypsycandle said:
JonC, I know a very inexpensive method for removing rust, you can mix 1 to 1 ratio of white vinegar with water,(1 gallon of vinegar to 1 gallon of water for sheet metal: 1 cup to 1 cup for smaller parts)Let the parts soak for 1 to 3 days..depending on the severity of the rust, all the rust will disappear and you will be left with clean original metal.
Wash the parts in clear water and dry then prime.

I have done this with wrenches that were rusted shut, original spark plugs, tools, nuts and bolts that wouldn't come apart, sheet metal, dist parts and shafts, old springs.
Good luck ~~ Michael...
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Thanks I will try that.
 
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