To sandblast or not to sandblast?
OpelGT.com is the premier Opel GT Manta Ascona Kadett Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 15 of 15

Thread: To sandblast or not to sandblast?

  1. #1
    Opeler SpaceMonkey1313
    Join Date
    Nov 2002
    Posts
    2
    Downloads
    0
    Uploads
    0

    To sandblast or not to sandblast?

    Hi everyone. This is my first post here, but I've been watching the forum for a while. I've got a '69 GT that I started to restore back when I was a freshman in high school, but had no time and money, so it sat. I'm starting up again, 7 years later, with new enthusiasm. I've got 2 '69's. One with an almost flawless body, but with no parts, and the other has the bottom almost completely rusted out, but has everything else intact. I bought both for $100.

    Anyway. I'm wondering if the opel can withstand sandblasting. I've seen a couple people on this site do it without problem, but then I've read stuff from auto body specialists who say that you should never ever sandblast a car. They say it can make it look like ripples on an ocean. Any advice on what to do would be great. Thanks.

    David

  2. Remove Advertisements
    OpelGT.com
    Advertisements
     

  3. #2
    Member Site Supporter My location N61WP is on a distinguished road N61WP's Avatar
    Join Date
    Mar 2002
    Location
    New Orleans, La
    Posts
    648
    Real Name
    James
    Downloads
    0
    Uploads
    0
    DON'T SANDBLAST SHEET METAL!

    I learned this the hard way a few years back with the hood of a MGB. The sand blasting warped the sheet metal, ruined the hood.

    I have seen good results on classic cars with media blasting. It's like sand blasting but they use a plastic bead that's alot kinder to the metal.

    There is all so a process that uses backing soda, but I have not seen the results. It was being marketed as being safe enough for airplane aluminum.

    Bestus,
    James
    Headless 70 GT

  4. #3
    Code Goober Geek
    Join Date
    Aug 2002
    Location
    Northern Virginia
    Posts
    243
    Downloads
    0
    Uploads
    0
    In addition, it seems to me that I recall reading that someone had sand blasted their hood only to find that you could begin to see the supports. It is pretty thin metal.
    No, that's not a defect, that's a feature.

  5. #4
    crazy opeler My location opelgt73 opelgt73's Avatar
    Join Date
    Nov 2002
    Location
    Atlanta, GA
    Posts
    549
    Downloads
    0
    Uploads
    0
    I don't think there is a problem with sandblasting as long as it is done right, I have never blasted an entire car but I have done doors, hoods, the headlight buckets, and parts of the fenders where they had rusted. Wayne torman had his whole car sandblasted.
    What is this metal warping that you guys are talking about? I blasted my parts with a commercial grade blaster fed by a 120CFM tow behind compressor. The same setup that I used to remove paint from our barn from 5 feet away, and I didn't get any metal warping.

    You must use a metal primer immediatly after doing it so that rust doesnt start. Also as Wayne had once said, be prepaired to find sand shaking out of the car for years afterwards.

    But why dont you just transplant all of the parts from the bad body to the one with the good body?
    The only time that you really NEED to sandblast is when there is just too many layers of bad paint. As a rule of thumb a car should only be repainted twice, after that you will have problems with cracking, and an increased threat of paint incompatiability.
    plus parts look soo much newer with just one coating(primer, color, clear) of paint on them.
    Last edited by opelgt73; 12-17-2002 at 04:30 PM.
    Chris
    Shanghai, China

  6. #5
    Opeler SpaceMonkey1313
    Join Date
    Nov 2002
    Posts
    2
    Downloads
    0
    Uploads
    0
    I am going to transplant all of the good parts from the rusted out one to the new one, but I'm going to give it a new paint job. The one I have still has the original paint. If not sandblasting what is the best way to take off the paint? Hand sanding, grinding, if sanding what grit paper? My dad owns an automation/machine shop, so resources are not a problem. Thanks for all of the help so far.

  7. #6
    crazy opeler My location opelgt73 opelgt73's Avatar
    Join Date
    Nov 2002
    Location
    Atlanta, GA
    Posts
    549
    Downloads
    0
    Uploads
    0
    If it still has the original paint I would sand and paint over it. If the sun hasnít ruined it then it will serve as a good base for a new paint job. It really isn't worth all the time and the effort to sand off all of the paint when it is the first time the car is being repainted. Plus you still have to apply the metal sealer primer immediately after you sand it.
    Chris
    Shanghai, China

  8. #7
    Project 1450 supporter... Site Supporter My location RallyBob has a spectacular aura about RallyBob has a spectacular aura about RallyBob has a spectacular aura about RallyBob's Avatar
    Join Date
    Mar 2002
    Location
    Pleasant Valley, CT
    Posts
    10,640
    Real Name
    Bob Legere
    Downloads
    0
    Uploads
    0
    I agree with opelgt73, the old paint is an excellent foundation for new paint. You should completely wash the surfaces to be painted first with a degreaser/cleaner before starting to sand the old paint. Otherwise, old wax and grease/oil can get 'rubbed' into the old paint surface, and may create adhesion problems later on. Sand down the old paint just enough to eliminate any surface imperfections. If you need to use filler, make sure that you sand down to bare metal for good filler adhesion, and clean the metal before applying filler (not with lacquer thinner, it leaves a film). Try to minimize filler use by using a hammer and dolly to 'bump' as many of the low spots or high spots as possible first. Seal all bare metal areas with a product designed for that purpose, and prime the body with a good high quality primer, such as a high-fill epoxy primer. In this day and age, there's no reason to use lacquer-based primers! The final surface can be block-sanded and all the slight imperfections and sanding scratches removed. If you want to make it REAL good, then wait aty least a month for the filler/primer to completely shrink and then resand the surface. Some scratches are bound to have 'reappeared' after a while.

    Bob

  9. #8
    crazy opeler My location opelgt73 opelgt73's Avatar
    Join Date
    Nov 2002
    Location
    Atlanta, GA
    Posts
    549
    Downloads
    0
    Uploads
    0
    Bob,
    that whole wait a month thing.....is that common?

    When I was painting my car the body shop friends that I had told me that I needed to apply the color before the primer had dried to ensure good adhesion.

    Chris
    Chris
    Shanghai, China

  10. #9
    Site Admin My location Gary will become famous soon enough Gary will become famous soon enough Gary's Avatar
    Join Date
    Mar 2002
    Location
    Swansea, MA
    Posts
    7,579
    Real Name
    Gary
    Downloads
    4
    Uploads
    2
    When I did my '69 GT over 10 years ago, I had it sandblasted, undercarriage and all. The 2 lacquer paint jobs over the original paint made it necessary to strip it. They used Black Beauty media and it was not too abrasive. Pictures of the process are in my album in the members photo gallery.

  11. #10
    Project 1450 supporter... Site Supporter My location RallyBob has a spectacular aura about RallyBob has a spectacular aura about RallyBob has a spectacular aura about RallyBob's Avatar
    Join Date
    Mar 2002
    Location
    Pleasant Valley, CT
    Posts
    10,640
    Real Name
    Bob Legere
    Downloads
    0
    Uploads
    0
    Originally posted by opelgt73
    Bob,
    that whole wait a month thing.....is that common?

    When I was painting my car the body shop friends that I had told me that I needed to apply the color before the primer had dried to ensure good adhesion.

    Chris
    It's not uncommon for some restoration quality paint jobs to sit around for 6 months to a year after topcoating so the paint can shrink. The paint will be wetsanded about one week after painting, then the car is put into storage while other parts are worked on. Then, after the waiting period, all the paint has shrunk, and the car is wetsanded again, with finer and finer grits (they have 10,000 grit and finer paper!). Then final buffing and the paint is usually flawless. But yes, especially with lacquer primer, the stuff should be allowed to thoroughly dry first. It takes a while for all the solvents to evaporate out. It can then be scuffed for paint adhesion and the vehicle then painted. This is NOT usually done with non-show quality paint jobs BTW.

    Bob

  12. #11
    Opeler My location George
    Join Date
    Mar 2002
    Location
    Jacksonville Fl.
    Posts
    248
    Downloads
    0
    Uploads
    0

    body repair

    What product do you use to clean the body before using body filler?Also while sanding the paint of I noticed that there were three layers of paint brown white and blue.I know the brown is the primer and the blue is the top color but what is the white for?

  13. #12
    crazy opeler My location opelgt73 opelgt73's Avatar
    Join Date
    Nov 2002
    Location
    Atlanta, GA
    Posts
    549
    Downloads
    0
    Uploads
    0
    That is probobly the sealer.
    Painting systems differ depending on brand. When I painted my car, there were
    2 coats of gray primer
    2 coats of white sealer
    2 coats of color
    4 coats of clear

    they told me for coverage purposes that I could mix a litte color in the whilte sealer layer to tint it.


    HTH
    Chris
    Shanghai, China

  14. #13
    Member My location Stanley_P Stanley_P's Avatar
    Join Date
    Mar 2002
    Location
    Kentucky
    Posts
    257
    Downloads
    0
    Uploads
    0
    I sand blasted my entire car. The only problem I had was on the hood. My brother did it and held the nozzle to close to the metal and you could see the reinforcing bars from top of the hood. (Had to buy another hood )Other than that everything turned out well.....I think with the sand blaster you will find more holes, rust, etc....I'm going to do it again on my next car.

    Stanley P

  15. #14
    Detritus Maximus opelbits is on a distinguished road opelbits's Avatar
    Join Date
    Jul 2002
    Location
    St. Louis MO
    Posts
    1,691
    Downloads
    0
    Uploads
    0
    The metal warpage is from too much sand blasting in small area. As the sand eats away the paint/rust alot of heat is generated by the friction. A shop I worked at had a car sent out for sandblasting, it came back ruined. All the panels were kind of 'puffed out' and warped.
    The next car went to a place that used 'plastic media', gentle but effective. The glass and rubber can be left on the car as well as stainless trim. The plastic media doesn't hurt it, in fact, in cleans it. Very nice. A shop that is really good can even do Corvette bodies and take it down no further than the gelcoat.
    "No, it's not fiberglass."
    "No, the motor is not in the back."
    "No, your friend in high school did not 'peg' his speedometer."

  16. #15
    Opeler cougar6
    Join Date
    Aug 2002
    Location
    Sierra Vista, AZ
    Posts
    26
    Downloads
    0
    Uploads
    0

    Be careful what you wish for

    I had my 73 GT sandblasted by a guy here on post some time ago and it didn't affect the body. However, that being said, it would be VERY hard to do any more damage to my car than the PO. Sandblasting has the nasty habit of uncovering the many blemishes that bondo and paint so nicely cover up; be careful what you wish for and be prepared to watch your small $2,000 project morph into a $10,000 white elephant. In retrospect, I would sooner drive my car in ignorant bliss than leave it in the carport needing paint and LOTS of bodywork. Of course, I didn't buy the car for its resale value and fully knew that I was getting a project from which I would never recover my expenses but I was not prepared for the significant damage lurking underneath that blue paint. You can go to the member's photo section and find cougar6 to see what my car looks like.

    Richard
    73 GT w/ A/C - parked patiently in the carport awaiting my return from being deployed to the big sandbox in the Middle East

+ Reply to Thread

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts