The Stovebolt Site Forums The Shop Area Paint and Body Shop What to do after Media blasting?

I am about ready to start into my 1952 3100. I can already tell I will need to replace the floor, cab corners, and passenger side cowl. I am trying to figure out the order of what I should do.
This is what I am thinking.

1. Media Blast
2. Primer (etching primer?) Any suggestions?
3. Replace bad metal panels.
4. Filler/Bondo
5. Filler Primer
6. Epoxy Primer

Any suggestions?

Thanks,
Brad

Use an epoxy primer.

Blast
Replace rusty bits
Epoxy primer
Body work /fillers what have yoi
Reduced Epoxy primer / sealer
Paint

I do all of my cutting, welding, and dent repairs (excluding filler) prior to blasting.
As a hobbyist, I can't get it all done at once, so there is bare metal exposed to the elements throughout the process. This is not a problem since everything will be blasted and epoxy primed once I have everything done. Once everything gets back, epoxy primed, I can begin high build primer and filler work on top of the epoxy without worrying about rust.
I never understood why anyone would do the blasting first on a rust bucket, unless they had the ability to knock out all of the repairs in a day or two.
Carl

Glad I asked. Lots of different opinions. The elements aren't an issue, as the truck is in my garage. As I watch different car shows, they all seem to do it in a different order. I am liking the idea of doing all the repairs first and then blasting. Thanks for the advice.
Brad

ansec66,

I see myself heading in the same direction. Unfortunately I don't have the luxury of keeping everything in the garage (small single car garage), so I have to do some planning. I also like the way that 52Carl has laid out his work. Thanks 52Carl!

After blasting or chemical cleaning, surface rust is going to be a problem unless your shop is in a very low humidity area like the desert. At least apply a "guide coat" of primer to limit how must rust you'll have to deal with later, immediately after media blast work. The old style lacquer-based primers will suck up moisture like a sponge, so be careful how long primed parts are exposed to humidity before they get a finish coat.
Jerry

Leaving the old paint on while working out the major dents and dings helps a lot. It enables you to see the high and lows spots quite effectively which you can then hammer and dolly out. Leave it, then blast in my opinion too.

Well, I dont mean to toss a wrench in the machinery here, but how do you know if you have made all the repairs if you don't blast it first? Over years and years of use, people do repairs, etc and paint over it. If it was a competent job, you have NO idea whats under there until you blast it.

Another problem is the thickness of the metal where rust occurs. Blasting can expose very thin areas that need repair. To get a really good look at what needs repair, I don't know of another way. Dents and dings I understand, but when metal gets really thin, and you have a patch panel ready to put in, you may need more repair and not know it.

I agree with Deve.

- Blast to clean metal and assess damage (and maybe find previous bondo/filler/poor-repairs that have to be removed).

- epoxy prime

- clean (remove primer) from areas that need metal replaced/repaired

- repair/replace metal

- prep part for priming (whole part or worked-on areas)

- epoxy prime (whole part or worked-on areas)

- prep/fill/seal/etc for painting

Here is what I did

Blasted
Banged dents
Welded patch panels
Clean with pre cleaner
Rage Gold where needed
Epoxy Primed
Filler primer (sand)
2k primed
I live in Arizona and it was stored indoors so I had time to do that.

Here is a Deve point of fact; Everyone has the exact same amount of TIME.

So, here is what I am driving at.. Blasting sucks! But after you have done that, plan on the day after blasting doing epoxy priming. Within 7 days, you also have to high build primer, or, you have to re-scuff the epoxy! So the procedure is...

1) Sandblast
2) Epoxy Prime the next day or within a reasonable period..
3) High build Urethane Prime within the 7 day required window.

Once you have done this, the clock stops. There is no windows to concern yourself with. You CAN put Rage Gold or a good premium body filler directly over metal. I choose to do that over the High Build Urethane at my leisure.

Where do repairs come in that ruin your primer jobs? Anywhere you want them to. You can fix everything, then reprime the area according to the above. Epoxy primer is not ONE and DONE. If you repair an area, its okay to shoot epoxy again. Just remember epoxy has a 7 day window. If you go to day 8, you get to spend the NEXT 8 days scuffing the epoxy! Instead, apply a single coat of Urethane high build to stop the clock.

I did the chemical strip to a nice metal finish. Had to leave the project for a year and gave it a coat of rattle can primer, now I wished I had covered the horizontal surfaces with plastic or some such. I think that would of helped reduce the rust that returned (live on the west coast with lots of moisture}. Now I'm back to stripping it down to metal and epoxy prime immediately the areas that I expose. I've been doing some research about roll-on epoxy primer, with a high build later. Anyone have any experience with that...cheers

The very first thing that I do is use Norton Paint Stripper discs to find all of the rust-thru and bondo areas. It goes very quickly and shows you where the work needs to be done just as well as media blasting.
If I were to blast and epoxy prime first, there is no way I can finish all of the patch welding, and body filler work within the 7 day no-scuffing-required time period (I need more like a 7 Month window). I don't like the idea of having to scuff every square inch of that rock hard primer.
Carl

I don't like the idea of having to scuff every square inch of that rock hard primer

Patience and determination.

I have primed parts that have waiting for attention for over three years. Scuff them and move on.

Just remember you don't have to scuff if you put a coat of high build Urethane over it in the 7 day window. Cause I agree! There is nothing worse than rock hard epoxy primer. I didn't mix my first frame right and had to scuff an entire frame, so it will NOT happen again. EVER!!

When you guys say scuff it after the 7-day window, what do you use?

Dennis

Thanks for the info guys; much appreciated!

I used a red scothbrite pad. Every square inch should be scuffed otherwise adhesion problems occur. This is why I avoid that process. The Epoxy Primer IN its 7 day window had super adhesion properties, but after that 7 days, it depends on the scuff job you do. Why not just clean your gun and hit it with High Build Primer to stop the clock? With the high build on it, you can put it away for a very long time and it will be as good as the day you did it.

Hi Dennis - assuming you plan on more 2k primer or another coat of epoxy, a quick scuff with 180 or 220 is all you need. For me at least, this is the fastest way to cut into the harder epoxies out there with the least amount of effort. If you are working on a very detailed area you may want to approach it differently but on big panels the scuffing really isn't that hard. Personally I like using the epoxy as a guide coat. I have stuff in epoxy that is over 10 years old and have no concerns about adhesion when the time comes.

Deve's point about the thin metal is very valid so my vote is to blast first and epoxy prime if you are going to be a while and presuming you aren't replacing half the metal in your truck to begin with.

Good luck

Good point Scott. Seems like all I ever have to work on is borderline basket cases. That's a big reason why I haven't considered blasting first.
Carl

Thanks Deve and Scott on what you use for scuffing. I didn't think much about the window when I started this little project. Now I shoot it again with the high build primer. It's only money.

Dennis

To add another option, my blaster applied a coat of zinc phosphate, Blastshield, after blasting. The claim is 5 mos indoor protection for flash oxidation. This should be enough time for me to fix the rot and get into primer. More info at classiccarblasting.com.