Sandblasting a Camaro shell

[BuddyP]

Well, original plan was to have it dipped. But now after talking with a local sandblaster I can get my '68 shell blasted for a lot less than I thought. He also is able to spray it with Epoxy primer afterwords. I just wanted to see what anybody had to say about the process or the epoxy primer. Anything I should watch out for or focus on when prepping it for him to blast it? Any need to wipe down the metal before it's sparyed with primer? I can't assume that he will do this.

Any info is greatly appreciated!
Thanks
Buddy P

[viper11]

hi buddyp
you can only sandblast the underside and jambs etc... don't sandblast any exterior sheetmetal apart from any rust (it will warp the hell out of it)
you can sandblast underneath and media blast the rest
you must get some coating on it asap after blasting or it will start to oxidize almost instantly
we use epoxy or etch primer
jason

[manicmechanic]

Yes, I agree do not sand blast the body panels. A friend of mine just had his 70 Camaro media blasted for $750, total car, top to bottom. Don't know what your dip estimate was, but don't sand blast.

[elcamino80]

Dumb question but what is the difference between media and sandblasting?

[viper11]

sand is very coarse and heats and warps the metal as it strips
media blasting uses walnut shells, plastic beads or other media ,
i'm not sure why it dosent warp the metal but i pressume it breaks down as you blast it, causing it not the damage the metal, it also leaves a very smooth surface, great for priming over
jason

[Hammered]

I've had cars dipped and blasted. It's not the courseness of the media so much as the pressure that is used to blast that will warp sheet metal. A knowledgable blaster can easily blast exterior panels without warping them. Reduced pressures and oblique attack angles are what's necessary. Still, I wouldn't use anything courser than brown sand. If the blaster is not experienced with cars/sheet metal, keep searching for one that is.

If the body is going on a rotisserie, you should have no problem with getting the excess sand out. Having dipped and blasted multiple times, I very much prefer blasting.

[BuddyP]

I've had cars dipped and blasted. It's not the courseness of the media so much as the pressure that is used to blast that will warp sheet metal. A knowledgable blaster can easily blast exterior panels without warping them. Reduced pressures and oblique attack angles are what's necessary. Still, I wouldn't use anything courser than brown sand. If the blaster is not experienced with cars/sheet metal, keep searching for one that is.

If the body is going on a rotisserie, you should have no problem with getting the excess sand out. Having dipped and blasted multiple times, I very much prefer blasting.

Why do you prefer blasting? Seems like dipping would get into more area's that blasting can't? As much as I hear how important it is to get every little spec of rust off the car, what about all those area's where panels are overlapped and such? Seems dipping would take care of that whereas blasting will not?

Also, just as a note, after blasting I need to replace the qtr's and such. The only panel that could possibly get warped would be the roof.

Thanks
Buddy P

[ProTouring442]

The problem I see with dipping is that many places, especially here on the east coast, don't know what to do to make sure ALL of the stripper is neutralized. I also don't know of anyplace over here that coats the body to ensure that it won't rust in the hidden areas. I stripped a hood a few years ago that later rusted out from behind a brace. I cut it open after having replaced it and found it to be VERY rusty under all of the braces. Just for giggles, I cut open a junk hood that I had taken off of a very rusty parts car and it had very little surface rust under the braces.


As for sand blasting, I had all of the inner panels on my 442 sand blasted, they were told not to blast the metal part of the dash or the rear body panel. It took a lot of work to fix the warpage they created when they blasted them anyway.


Shiny Side Up!
Bill
'72 442 "Inamorata"

[BADVELLE]

Ask your guy if he can soda blast the shell, this is what I am currently having done on a '67 Cougar I am building for a customer. The soda (which amounts to nothing more than baking soda) does not build heat, plus it will not damage any trim you may have on the car. I am having the surface rust spots shot with glass bead, since the soda will not affectively remove these spots. Anyway, just another idea, plus the clean will be easier than any other media.

[BuddyP]

The problem I see with dipping is that many places, especially here on the east coast, don't know what to do to make sure ALL of the stripper is neutralized.

I should note that this place that does the dipping, does an alkaline dip... Not chemical dip. So basically when the shell is pulled out of the tank, it's just water left on it I believe??

[Hammered]

Dipping removes the paint from every interior cavity, many of which you can't recoat. Insides of rockers, lower cowl, etc... Second, even the alkaline strippers leave residues in crevices that later mixed with water can cause paint bubbling. A pillar, c-pillar, quarter to deck filler seams, etc... Thoroughly rinsing with water just leaves you with a re-rusted body so that's not an option. I guess one could douse the car in pre-clean? Finally, remove your trim tag and aluminum vin tags or they're toast.

Blasting has none of those problems. Blasting does carry the risk of warping, but generally only in the hands of an incompentent person. Using glass or an other media that breaks down on impact makes it even harder to warp panels. You only strip the parts that you can recoat and the surface has a very strong tooth for primer. I have not found getting all the sand cleaned out to be a problem. Even if you miss some, it's been blown out during the priming stages anyway.

The primary reason comes down to confindence in the substrate that you'll be putting paint on. I've done each more than once, (alkaline dip every time), and won't dip again. BTW, the alkaline dip is a chemical, just not an acidic one, and has been the dominant stripper to my knowledge. The term "acid" dipping is erroneously used in most all circumstances.

John

[BuddyP]

John, thanks for all the info! It eases me a bit about the blasting now.

[ProTouring442]

Soda blasting works very nicely. A friend of mine had his Mustang race car soda blasted, they came to his house and did it! Didn't leave a mess either.

Shiny Side Up!
Bill
'72 442 "Inamorata"

[Hammered]

BuddyP: Always glad to help someone when I can speak on something that I have experience with.

I've read about soda blasting, but have never used it. It breaks down completely on impact, thus not peening or texturing the metal surface. I understand that it will preserve the coloration in metal where spotwelds were made, but does a poor job of removing rust. If you go this route, ask the blaster how it will do with the rust.

BTW, no media is good at removing resilient materials like caulk and body filler.

[BuddyP]

BuddyP: Always glad to help someone when I can speak on something that I have experience with.

I've read about soda blasting, but have never used it. It breaks down completely on impact, thus not peening or texturing the metal surface. I understand that it will preserve the coloration in metal where spotwelds were made, but does a poor job of removing rust. If you go this route, ask the blaster how it will do with the rust.

BTW, no media is good at removing resilient materials like caulk and body filler.

For the most parts, any panel areas don't have rust (except underside of roof). When you say no media is good at removing resilient materials, does that include sand?

[Hammered]

Yes, and even courser media. You should scrape undercoating, tar, glue and other rubbery materials off before blasting. Hard and brittle - no problem, soft and rubbery - you got a problem. The media will bounce off with little effect.

[BuddyP]

Gotcha, well there's not a whole lot of anything on the car, just some of the tar sealant around the interior floor pan. Are there any area's of concern that I should look at or take care of before having it blasted?

I was looking over the thing tonigt... whew... not sure how I'm going to get this thing done! I wanted to get the drivers side floor welded in place before I take it there but have a LOT of work to do to get it the rest of the way in. And being new at this I'm overly concerned as to whether or not I'm doing it properly. I'm trying to get as much advice as possible along the way but still unsure of myself overall.

What about seem sealer and such when I get it back form the blaster (like around the cowl, interior and underside panel joints, rear deck panel to qtr panel gap, etc.)?

[Hammered]

I think it's best to get it blasted before replacing any metal, but I've seen it done both ways. You can cut out some rusted metal if you are confident you know how it goes back together. If it's a convertible, make sure you put a brace across the door jambs and inside. You can see pictures on my website of where braces typically go. Dig the seam sealer out and scrape the tar off before you take it to the blaster.

Vacuum it out, blow it off, repeat these steps, wipe it down with precleaner and spray epoxy primer on it as soon as you get it home. Sealer can be reapplied much later.

Good luck,

John

[BuddyP]

This guy sprays on epoxy primer on the spot right after he blasts, so I won't have to worry about that.

[Todds69]

Hi Buddy, may I ask who you are thinking of taking it to?