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MG MGA - Dipping vs Sandblasting

I'm hoping some of the fine folks on this forum can help out. I was in the process of rebuilding the sills and rockers on my 57 roadster when I realized I had a dilemma. I am planning on acid dipping the car to clean up/remove paint and rust, but I realized if I install the sills (with the inside painted) then dip the car, I'll lose all of the paint inside the sills and then I won't have a good way to repaint inside.

I see two options, 1) take the body off the frame in two pieces, dip it, then put it back on the frame for the sill repair or 2) repair the sills and sand or soda blast the car.

I would appreciate comments and suggestions on the above options, or alternatives that I haven't thought about.

Thanks folks!
MGA Larry

It won't really help you for getting paint in there, but this kit should help you spray some preservative inside the sills.
Del Rawlins

It would probably help if I posted the link....

http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=21509&itemType=PRODUCT&iMainCat=373&iSubCat=376&iProductID=21509
Del Rawlins

Thanks for the info Del, that's the kind of tip I was looking for.

You made a good point about paint, I should have said preservative/sealant or something along those lines.
MGA Larry

I am not a fan of acid dipping. I did it once and as they say "Never again" The acid gets between every panel where layers of sheet metal are spot-welded together. No matter how well the shell is rinsed and neutralized there will remain acid residue between the panels. This residue promotes further rust and can bleed out later and damage final paint. The white 57 was the first frame off restoration that I did. I used acid dipping on it. After the acid dip I did the rust repair. I found that the rust/acid residue was still between the layers of sheet metal when I drilled apart the spot welds. The four MGAs that I have done since were all media blasted. http://users.telenet.be/mga/MG-Owners-Gallery/MGA/album/slides/Randy_Brown_Coupe_Project.html
My first car a 58 coupe did not get a frame off restoration. It and the Iris blue 60 roadster are not pictured as I have no pictures of them that include me. I have one more MGA, another 60 rodster, to do.
I advise any contemplating this type of work to carefully study this website. http://www.eclecticmotorworks.com/body.html
I believe that Eclectic uses Media blasting not acid dipping. The work they do is amazing. As shown in their website all metal work should be complete and all body panels fit together before any paint is applied to anything.
Barney's website shows rust repairs done in situ prior to removing the shell from the frame. None of mine were rusted badly enough to need to do those repairs first. I used a fixture bolted underneath to the 4 frame mount points and braced across the top to keep it sturdy as I did the rust repair. If I were to do it again I would make a fixture to bridge each door opening and one across the top. These fixtures would be made by bolting plate to the hinge points and the latch point and then connecting them with square tubing. Making these 3 fixtures in place on the car would retain the original spacing of that particular car.
Chose a media blaster with care for if they do it improperly or with the wrong media they can warp body panels. I found that the heavy frame and suspension pieces that are not in danger of warpage don't require the same care as the body. I used Alpine monument, a maker of headstones, on those heavy items. The body would be destroyed by SAND. The company, Zero Blast, that I used for the body uses glass beads.
Good luck and hopefully "Have a Blast"
Randy













R J Brown

Media Blast, Paint, then waxoyl
WMR Bill

I had mine media blasted with plastic pellets. Be certain that they know which parts are aluminum as they must be treated with more care.
Ed Bell

I guess it depends on the quality the people doing the work. I dipped both my Jaguar E Type and Austin Healey 3000 with great results. I never had any problems with residual acid etc. Currently I'm on the frame of my '55 A roadster and plan to dip the body when I get to it.
GD Glenn

Surely it depends on how you blast, as much as with what media. Holding the gun further away, or with reduced air pressure, might make sand OK? And vice-versa of course.
A Pearse

I had the wife's A dipped in 1990, it was also in two pieces. They used a very thin blade and slid it into all the joints between the spot welds so the acid could get in do it's job and get out. As of today I have had no rust creep out from anywhere. The aluminum panels were blasted with glass bead. i worked for a molding company and they used glass bead to clean the molds, the cabinet was large enough I could get all the panels in and do it myself. no warpage problems.
J Heisenfeldt

I have to admit to farming this part of the restoration out. The shop sandblasted the steel and chemical stripped the aluminum doors, bonnet and boot by hand.

C Schaefer

Larry, I had the 4 wings, and front valance acid dipped and I didn't paint them immediately, in fact not for about 2 months but I stored them inside. They all developed a slight corrosion, which I sand blasted at home with 60 mesh sand using a 40 lb cannister blaster from Harbor Freight. I also sand blasted the entire Coupe tub in my driveway with the same set up and it came out great. You need a big compressor (5hp and 60 gallon tank minimum) and 1/2" hose. You can control the sand blast very easily and get a great finish at home. Cheaper than spending $1500 on a media job. I used chemical stripper (Jasco)on the bonnet, boot and doors which also came out great, just keep on putting it on and wear good rubber gloves. Finish cleaning with 4x0 wire wool.

Good luck.

Andy


Andy Preston

I had mine dipped by Redi-Strip 23 yrs ago with no troubles afterward.They did however dent in a new rocker panel and drill a hole in the roof to get out the air.I was more upset about hole tho. I then waxoyled after the paint.
gary starr

Has anyone had any experience with Soda Blasting? I came across it at a car show recently and according their info it eliminates the possibility of panel warping, as per other media.

Chris.
Chris Bond

Soda blasting is probably fine to remove paint but, like plastic media, doesn't work well to remove rust. It's just too soft. I've had the best results with White Play Sand. Works good on rust, but not too aggressive. Never had a warping issue. Even use it (carefully) on aluminum parts.
Cheers,
GTF
G T Foster

I had my doors soda blasted, and as Gerry says, it didn't do a good job on the steel door parts. No problems with the aluminum door skins, so I guess its a good choice for the aluminum bits.

G Goeppner

Andy, Using your setup how long did it take to strip the complete tub? My amateurish attempts to sandblast were painfully slow, admittedly with a smaller compressor than yours. Thanks Mike
m.j. moore

Mike, I sandblasted the whole of the exterior down to white metal and spent much time on the rust around the windows ensuring that I got it all down to the bare metal. I also did inside the boot and engine compartment. I did not sandblast the inside of the car because it's not seen. I gave it a good wire brushing and sprayed it with Endrust red primer.
I think it took me a whole weekend to do the tub, that's around 16 hours. It's not very fast even with a big compressor. It also helps if it's hot and dry and so the sand doesn't get stuck in the cannister. Here's the tub now.

Andy


Andy Preston

This thread was discussed between 02/12/2008 and 05/12/2008

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