Best way to remove surface rust on sandblasted sheet metal

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Bill Crowell

Bill Crowell

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Just suppose that some guy [(not me; I would never do a thing like that) yeah, right!] sandblasted some fenders and then Life Got In the Way so he didn't prime them right away, and they picked up surface rust from sitting around. Would you sandblast them again, go over them with a Roloff disc, or de-rust them some other way?
 
I wold use the DA on ths with some 120 grit, careful with 80 leaving scratches maybe. I would then wipe then down with Ospho ( neutralize it with some water ) to be safe if topcoating with a epoxy, or a pro paint metal cleaner.
 
Roloc is good . 180 is good . brushblasting is good . chemical dipping is good . dustless blasting is good . I have done everything but dustless . chemical dipping leaves the best finish IMO
 
barbee6043 said:
Sandblast that old 40 year old fender a few more times, ...what is left!!??? lol I agree sandblasted metal I best, but even the guy in Ca. needs to to let it sit!!
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I did not read where the fenders had been sandblasted more than once and that they would be blasted more than once again or that they are 40 years old which should have no effect on them other than if they were left to rust. For all I know from the post it could be a tractor fender. He asked a simple question, I gave the simple answer to the choices that were provided. :)
 
Blasting is the best. Use some other form of media. Walnut shells will remove rust with no damage to the metal. So will glass bead, aluminum oxide.......and a lot of other choices, but blasting is the best method.
 
Hopefully they didn’t warp the fenders by sand blasting them. one time I hit just the underside supports of a hood and it warped the hood badly hopefully you will be ok.
 
RustyRatRod said:
Blasting is the best. Use some other form of media. Walnut shells will remove rust with no damage to the metal. So will glass bead, aluminum oxide.......and a lot of other choices, but blasting is the best method.
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Agreed. As a generalization I should have referred to it as "abrasive blasting"
 
All I was saying was this old car metal we are dealing with here is what 40-45 yr old. Seems like it can rust from the inside usually and is therefore thinner. Sand blasting makes it thinner yet no doubt. . Maybe his fenders were not blasted with sand, I forget.
I had a guy way back in th 80's that blasted with sand and was a master. He talked me in to letting him do a 68 roadrunner hood. HE did not worp it one bit, but he was a master. He had a boon truck and would raise my cars up by one end, lay under it on his back and blast, then do the other end!! I never heard a man cuss like him either! Made me even blush.
 
KB9GIB said:
Hopefully they didn’t warp the fenders by sand blasting them. one time I hit just the underside supports of a hood and it warped the hood badly hopefully you will be ok.
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That happens when you concentrate the nozzle in one area for too long. Blasting causes friction which equals unwanted heat. Back off a few inches and make wider passes -- it will cool off before you get back there again.
 
CudaChick1968 said:
That happens when you concentrate the nozzle in one area for too long. Blasting causes friction which equals unwanted heat. Back off a few inches and make wider passes -- it will cool off before you get back there again.
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there is a straight answer by someone who has done this several times.
I have blasted my valiant Twice for the same reason, was doing some metal work and well **** happened. so I blasted it again.
both times with black beauty. the second time was pretty much a dusting pass to clear off the surface rust.
 
Here is where I found it beneficial to use Ospho. On pitted metal, unless I can sand it completely down the get rid of the pits. If I DA it and do not get rid of pits there will be rust in that small pit hole YES Soutern Urethanes said using Ospho ,water it down while wet. They caution the use of the Ospho. I have used the DuPont acid preps, worked great, but expensive like all pro auto paint products.I have always let the Ospho dry over nite clean, and use a DTM epoxy. I have never used Southern Urethanes product but I did order some of their epoxy, but have not chance a chance to use it yet.
I have used Ospho on countless cars for probably 7-8 years and only time I ever saw a reaction was where I simply applied Rustoleum directly over the bare metal cleaned with Ospho. No neutralizing. In a few spots the enamel wrinkled some I had a hard time DA ing that paint off with 80 grit! I always do filler over epoxy primer.
I bought a 6 cuda from a ar bud, the PO have DA ed it to bare metal , all of the CAR! Been sitting out side in the weather for 8 months when I traded for it. I DA ed it , wiped it down with the Ospho, only because it had me very minor pits, BUT pits. Used as usual TCP Global epoxy, sanding primer topcoats etc. I sold it 2 1/2 years later, NO issues. !!
I hav e been told by paint people smarter than me, IF the epoxy primers are acid base, that is when problems tend to arise if cleaning with Ospho.. There are probably more to this a chemist could explain.
I have no dog in this race, just discussing what I have experienced.
 
Here is where I use Ospho a lot. The insides of doors will have at minimun, surface rust. Yes it would be great to pull the doors, take out all the glass and tracks, send them off to be blasted with a non worping method, but......I clean off the loose rust, use Ospho, let it dry a full day, use Rustoleum enamel over it, or second coat of Ospho, wash it off with water while still wet,. epoxy prime or Rustoleum. Sealed great. Other areas like the insides of door are the inner wheel housings, any inner structure that can not be sanded down to clean, bare metal.
I don't like rust!
 
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