Prepping the Shell for Media Blasting

[MikiK]

If you had your car media blasted, how much prepp work did you do?

What exactly did you do?

For example when you remove the windshield you have some of the black tar/sealant residue left over. Should I worry about that before media blasting?

From the search I did on the forums I found out that it is better to get the car media blasted and then perform the major rust reparations like replacing the floor pans and patch up the cancer sports.

What is your experience on this?

How much of rust would the plastic media blasting actually remove?

I found a local place that would gladly media blast my car. I talked to the owner and he has agreed to give me a fair deal since I have totally stripped the shell down to nothing. And if I do most of the prep work myself he might give me a better deal. Also he said he would coat the car with epoxy primer once he media blasts it.Epoxy primers are strong and durable so I would not have to worry about surface rust while the car is parked in the garage.

But would it mask some of the rust and make it harder for me to find?

Any other tips and tricks you guys can share with me regarding media blasting would be cool.

Regards,

Miki Kologranic

[ZSaint]

I would have him hold the primer until you remove the surface rust and w/s sticky. You will not have any problem finding the stuff after the media blasting. It will really stick out after it is blasted. The metal will look like new EXCEPT where there is rust or anything that absorbs engergy. If you have a small sand blaster and some thinner, you can remove the rust and the sticky pieces prior to his primering. Don't wait too long as this new metal surface absorbs moisture from the air in a hurry.

I had parts of my car media blasted and it looked great. The painter loved it, too!

[EScanlon]

...hold the primer until you remove the surface rust and w/s sticky. You will not have any problem finding the stuff after the media blasting. It will really stick out after it is blasted. The metal will look like new EXCEPT where there is rust or anything that absorbs engergy....

I disagree. If you are NOT going to tackle the shell IMMEDIATELY after it gets blasted, get it Epoxy Primered. By immediately, I mean the next day or two. If you are going to be more than a day or two----primer it. The amount of surface rust you will develop, and the hazzles to remove make this a no-brainer in my book.

The amount of headaches, hazzles and problems you will save are well worth whatever inconvenience you might have when effecting repairs over the primer.

If the media blast does the job it's supposed to do, you won't have ANY surface rust afterwards. Actual rust-through will be plain as day, and even heavily pitted rust will be obvious, those are the sections to worry about. When you have those areas addressed, whether by cutting and replacing with new metal, or grinding and brazing/welding an overlay patch, the primer will just be ground away from the repair area.

Weather strip glue, tar-paper, etc., you'd be best off to remove as much as possible before you go to him, and then let him know where you couldn't remove so he could pay special attention to. Lacquer thinner, MEK, are but two solvents that will literally dissolve weatherstrip adhesive, tar, and most of the gunk found on the car.

If you have areas that you already know are problems, rust-through, bondo, prior metal repairs, etc, point those out to him. He can then make sure that those areas get cleaned up well.

2¢

Enrique

[Ron Carter]

Depending on what media is used, (there are several different types). Will depend on whether or not it will effect the surface of the metal, if you use a media that does disturb the metal it will rust very rapidly. If you use a media that does not it will not rust for some time....regardless once it is media blasted you will want to keep the car in a dry warm location if possible to prevent rusting.

With my car I did all the rust repair, and some additional welding prior to epoxy priming the car.

In preping the car, your blaster will want to see the car as clean as possible because anything that comes off the car will contaminate the media. So the cleaner the better.

the one thing you want to be prepaired for is that the media will get into EVERY nook and cranny. I still have some media falling out of my car periodically. I would suggest blocking off some areas that will trap media and make it hard to get out.

Hope that helps.

R

[MikiK]

I was literally thinking of asking him to give me a call once he media blasts the car. I would come out and use laquer thiner or metal etching to sort of go over the whole car before he epoxy primes it, but it might be too much since media blasting preps the whole surface for primer pretty good. I like the idea of using MEK or Lacquer Thinner to remove the rubber stuff.

One more question, after I fix/patch the rust areas and ofcourse remove some of the epoxy primer what is the best way to protect it, can you get epoxy primer in a can so I can spray over it to keep the surface from rusting again?

[NZeder]

If you are NOT going to tackle the shell IMMEDIATELY after it gets blasted, get it Epoxy Primered. By immediately, I mean the next day or two. If you are going to be more than a day or two----primer it. The amount of surface rust you will develop, and the hazzles to remove make this a no-brainer in my book.

The amount of headaches, hazzles and problems you will save are well worth whatever inconvenience you might have when effecting repairs over the primer.

If the media blast does the job it's supposed to do, you won't have ANY surface rust afterwards. Actual rust-through will be plain as day, and even heavily pitted rust will be obvious, those are the sections to worry about. When you have those areas addressed, whether by cutting and replacing with new metal, or grinding and brazing/welding an overlay patch, the primer will just be ground away from the repair area.

Weather strip glue, tar-paper, etc., you'd be best off to remove as much as possible before you go to him, and then let him know where you couldn't remove so he could pay special attention to. Lacquer thinner, MEK, are but two solvents that will literally dissolve weatherstrip adhesive, tar, and most of the gunk found on the car.

If you have areas that you already know are problems, rust-through, bondo, prior metal repairs, etc, point those out to him. He can then make sure that those areas get cleaned up well.

2¢

Enrique

I agree with Enrique - my brother has a business here in New Zealand doing just what this topic is about - media blasting. He always recommends to his customers to paint in epoxy primer (he usually does this for them - some customers don't want it done so he will paint whatever primer they supply - he does not and very rarely lets blasted metal leave his shop in bare steel - usually because he does not what to argue a quote he once told me "what do I know I am only a panel beater and have been stripping and blasting cars for 15 years. But this customer who is a businessman know better than me so whatever. I wont do any more work for that idiot") One thing that my brother will do for customers is take photos before blasting, after blasting and then on with the primer. I know he has even had to had to call a customer to come a look at the car and make the decision to continue or cut their loses and find another body shell (very rusty + bog and poor smash repairs etc)

So like others above have stated - get it premiered ASAP, keep it in a dry environment etc.

Cheers

[AWC]

So then how long do you have with the body primed before the finish paint needs to go on? It goes:

Blast

Epoxy Primer

Bodywork

???

I guess you need to sand to provide some tooth for the next coat of paint because the primer will have dried and perhaps cured by the time you do the next coat. Would it be necessary to do another coat of primer or could you go straight to base?

[MikiK]

So then how long do you have with the body primed before the finish paint needs to go on? It goes:

Blast

Epoxy Primer

Bodywork

???

I guess you need to sand to provide some tooth for the next coat of paint because the primer will have dried and perhaps cured by the time you do the next coat. Would it be necessary to do another coat of primer or could you go straight to base?

AWC, here's a great site. I would say it has everything you need to know about painting.

http://www.lambolounge.com/Body/Paint/paint.asp

But to answer your question, once the car is covered with epoxy primer it should protect from rust as good as a paint job. Epoxy primer is non porous, and offeres great protection vs rust.

One thing on that site that I find very interesting is that it suggests to leave a little "skin" of the epoxy primer and do the final smoothing with body filler on top of that. Better adhesion. I can see that work out.