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MG MGB Technical - time to paint

I think it's time to consider the paint on the car which is in need of some TLC. Or rather stripping off and starting again. I have been told that as the paint is microblistered in places that it needs stripping right back to bare metal. so some questions.
1. How to get the paint off? Nitromoors? Some sort of abrasive wheel?
2. When the paint is off I want to get the bare metal covered as soon as possible. Do I use something to remove any residual microscopic rust before I spray on some etch primer?
3. Whats next after the etch primer? I shall be using cellulose as a top coat. I don't want to kill myself with 2 pack!

I shall try the boot lid first as it is a managable size to test my skills on.

Anything else I need to know. I have a HVLP gun (Sharpe) and a small compressor witha access to a bigger one if mine is not man enough.
Steve Church

I removed the paint from my B using a multi speed buffer polisher. I kept it on the 2nd speed out of 5 and used 100 grit sanding discs. The polisher I have is set up for velcro discs. The top layer tended to clog up the discs, no idea what it was, the factory paint under was not too bad coming off. I used minimal down pressure and changed the sanding discs often.
Kelvin Hawkins

May be a good question to ask a body shop. It may be that just a good sanding is all that is needed, with attention to the blister areas.

I had blister areas on the roof and these were the only spots that needed to be taken down to metal. Sanding to where the under primer is showing through the paint normally will give a good base, but again that is a question I would pose to a good paint shop.
Bruce Cunha

Hi Steve,

My 2c. If you can, always go back to bare metal as you can be sure the paint will be reliable based on what you do.

For bare metal you can use paint stripper and/or an abrasive wheel.
Scotchbrite has a number of abrasive plastic wheels that are really good for attachment to an angle grinder and make removing paint and rust really quick. Just not cheap. you would prbably go through a few of them. They are less messy than stripper. I use a brand called brumby which is like a cut off disk with blue plastic pad attached. They work well and I get two panels per disk sometimes more. The benefit is they work really fast.

You should wear a mask when doing either. The surface can be wiped down with phosphoric acid to remove micro rust. all MG's will have small amounts of rust like little worms sitting under the paint in a number of places. They generally wipe off with the acid. Next you would acid etch the bare metal. Once this is done you usually high build prime the car and sand and fill any small imperfections.

When your happy you would shoot top coats then clear or just polish after top coat.

I find this part or restoration very rewarding. As stated though I would talk to your local paint shop as they can help you choose a paint process to suit both your budget and the desried outcome.
Allan
A J Ogilvie

I took "Rocky" , my TD , to a body shop the other day, just to find out what they would charge to media-blast, (glass beads), if I bring them the various body parts....
They said it would be $1000....
Sounded like a lot, but when you consider how many hours, and how much sandpaper, to either grind it or hand-sand it, it's not such a bad idea....
Eastwood has several treatments for bare metal, that will keep it from oxidizing....
There is one that mixes up 7 quarts, from a dry powder...You spray it on with a hand sprayer bottle, and it keeps it from rusting for up to three weeks....
You can prime right over it , after it is dry.
I am seriously considering this....I hate sanding car bodies....I've done several paint jobs, and sanding off the old paint, is , by far , the worst part of the job.
Edward
E.B. Wesson

I would have to agree with EB Wesson, I too have had a modest amount of experience with sanding and painting, but I tell you it is an awful lot of work. Quite frankly I am quite happy to pay some-one to do it. So Steve, if you enjoy that sort of thing go ahead. Mike
J.M. Doust

Steve,

What you take the paint off with may be a function of what tools you have and what time of day you work at (if you have neighbours).

I have found a wire brush in my 115mm angle grinder to be best. It is quick, does not damage the steel, but makes alot of noise and the particles of stripped paint go alongway.
I have used paint stripper, it takes along time, the mess lands in a fairly consentrated area so is easliy swept up, it does not make much noise.
I have used a sanding disc in the angle grinder, it is easy for the disc to make gouges in the steel, alot of noise, the dust goes everywhere. The dust is finer than the particles from the wire brush.

The bare steel should be coated with some kind of metel prep solution to stop flash rust as soon as possible after stripping. I use one of the products from www.rust.co.uk/surface-preparation.cfm

If you are dealing with one panel at a time in a dry then proceeding to etch primer, high build, cellulose top in fairly short order should be fine. What you need to bare in mind is that of those it is only the top coat that is water proof. So if left for a long time in primer rust can start under the primer. I have used Upol Acid 8 etch primer in these circumstances without any problem. Clearly what represents a long time depends on the dryness of your garage.

For panels that will be left along time epoxy primer is better than etch. It is water proof so you can leave the primed panel outside in the rain! However, it is 2 pack and should never be used in an enclosed space without an air fed mask.

I have used epoxy primer outside with a normal cartridge mask. (but you do that at your own risk) After that I sprayed cellulose based high build and colour coat in the garage.

A good contrast between the colour of your first primer and your high build is important as it helps you to avoid sand through.
David Witham

Dave,
Thanks for the comprehensive reply, just the sort of info I need. I appreciategoing back to bare metal is going to be time consuming. I originally thought that just flatting back the top coat would be sufficient but a paint guy I know advised against it (he also offered to prime and top coat the car which I may consider but I am over budget already by quite a way!!)
I am considering doing the car in stages as I can't get round all the car with a spray gun in the garage. So boot lid first maybe along with the bonnet (these can come off the car easily). Then the rear of the car up to the front of the sills. Then the doors...are these easy to remove and replace? Then the front wings and valence. Doing it in small(ish) chunks means I can get stripping and painting done within a reasonable time frame for each section.
Steve Church

David, epoxy primer may be "2-pack" but it does not have isocyanates, so not as supposedly poisonous. A simple cartridge respirator is OK.
Art Pearse

I've just trying out a couple of abrasive wheels. Both from Screwfix. One is a surface preparation wheel which is like an inpregnated nylon honeycomb. The other is an 80 grit Zirconium disc for the angle grinder. A quick test tonight shows that the surface prep wheel is ok but will probably get the panel too hot. The Zirconium disc is a little too agressive unless used very lightly but will not get all the paint off without compromising the metal. However taking the majority of the paint off with the Zirconium disc and then finishing off with the surface prep disc seems to work the best. The latter tidies up the remaining paint and also polishes the metal to a better surface.

Out of interest I have painted brake fluid onto a square foot of painted surface to see is it softens it up!
Steve Church

This thread was discussed between 16/08/2011 and 26/08/2011

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