My Media Blasting & Priming Lessons

There have been several discussions here about the pros and cons of stripping, blasting and dipping. I thought I wanted to strip until I got advice here on the Zone and after I did a test area. I was given a small sample of commercial stripper by a body shop acquaintance. I put the stripper on and the paint bubbled up fast. However, what a mess and it only works well one layer at a time. Since I have up to 5 layers, it took several applications to get to the metal. Next, find a blaster that did automotive work. No luck in the phone book as all of them did sand or aluminum oxide, but an industrial blaster gave me a lead in a town 30 miles away. Called and sure enough, he only does plastic media and can take the truck in the blast room. Not being familiar with plastic blasting, I did not know what to expect. So since I had most of the bolted items off the truck I took them there to have them blasted first. The results are not what I expected. Sand blasting removes metal as well as the coating so metal is usually pocked but very clean. Plastic only removes the paint but no metal. The steel looks polished and is very smooth. Whatever the steel looked like prior to its painting is what it will look like after blasting. If you had rust, you still have rust but it is now polished rust. You need to take a wire wheel to clean out the rust pits prior to priming. Those first parts were primed the same day they were finished and the truck taken over the following week. He required all the lights and dash panel removed to prevent blasting damage and static electric damage. We had to get a roll back hauler to take the truck over since now we could not drive it.

We did the wheel wells, frame, axels and wheels. Plastic media does not damage rubber, hoses or glass. The hood was not blasted as we are replacing it. The blasting uncovered more repairs we must do as there was body filler in a few places on the doors. Also, a few pin holes opened up that were rusting from the underside of the wheel wells. We also discovered the painted over registration numbers on the tailgate do not match those on the hood.

I taped up as much I as could to keep the dust out. Media still is everywhere, in every crack and crevice. My shop is full of it even after I air gunned and vacuumed over and over. It just keeps falling out. There is some media in spots in the first prime coat that I must sand out before the next priming.

Priming became another learning experience. Since I was using epoxy primer, the blaster guy told me to take the blasted items home, lightly sand if necessary, clean and prime. Not necessary to do it the same day. Several other folks, including the paint store, said I must etch or phosphate coat within hours. The blaster showed me a car hood that he blasted a year ago that the guy never picked up. Still no rust on it. After tons of conflicting advice, I contacted the PPG rep for my area. His advice was clean and prime ASAP as no prep coating was necessary. Turns out the primer has an etching agent in there. Also, since the steel was plastic blasted, the metal is not really “opened” in his words so it will not rust very fast. Just don’t set it outside (advice I didn’t need!)

The truck was returned late in the day Tuesday so I began taping for primer the next day. Next day, the guy who was to prime for me did not show up. So, I spent Wednesday sanding, cleaning and priming by myself. Never did a whole vehicle so a new experience for me. A very long day but one coat of primer all over the bare steel by nightfall.

These comments are not meant to be the only solution. It's just the path I chose.

Ready to go;
http://img147.imageshack.us/img147/17/img2602ez3.jpg

http://img390.imageshack.us/img390/2199/img2605qg7.jpg


Take offs primed;

http://img390.imageshack.us/img390/6673/img2609ti1.jpg

In the blaster;
http://img147.imageshack.us/img147/7341/img2621ee2.jpg

Naked truck home again;
http://img371.imageshack.us/img371/9621/img2633ez0.jpg


See How Clean?
http://img390.imageshack.us/img390/3750/img2626qf0.jpg

Primed;
http://img371.imageshack.us/img371/5082/img2636mj2.jpg
http://img147.imageshack.us/img147/9770/img2640wq2.jpg

That's pretty neat. It's like a fresh start. I'm interested in the approximate costs associated with the blasting done by a professional outfit after the truck has been disassembled, as you had done. It sounds like they had it done in a day.

We had a truck done about 60 days ago. (Northern KY area) We delivered and picked it up afterwards. Our total costs for the job was 600. That included the frame, cab, bed, doors, hood, tailgate and some other smaller items. Everything was blasted and primed on all reachable surfaces.

I recently got a quote here for about $700 for a soda blast

Cost to do the truck was $600 without the underside. Another $370 to do that. Plus roll back service!!!

After seeing how good that looks, I think I'll have to look into getting that done to mine when the time comes. I assume it's best to blast it, then do any body repair, then sand the repaired areas, and then prime. I have some rust holes in the cab that must be replaced. Thanks for posting the pics.

wrecker;
I am not an expert in body work but all the folks that are told me to do it in this order;

1. weld in new panels and any other welding required (if sitting awhile before stripping, prime these areas to prevent rust)
2. strip paint
3. prime one coat
4. body filler where required over the primer
5. prime again
6. paint

May be other ways but this was consistent advice.

Hey Roy, what media did your guy use? I'm wanting some work done on the wrecker. Thanks.

Quote:

---

Originally Posted by rboltz

wrecker;
I am not an expert in body work but all the folks that are told me to do it in this order;

1. weld in new panels and any other welding required (if sitting awhile before stripping, prime these areas to prevent rust)
2. strip paint
3. prime one coat
4. body filler where required over the primer
5. prime again
6. paint

May be other ways but this was consistent advice.

---

That is interesting about applying filler over primer. I was always told (not formally trained) to rough the metal with 36 grit then apply filler to bare metal. Methods may be a bit different now though...

Most filler sticks best to metal. Problem is, any water (humidity) between the filler and the metal starts to rust. Any flash rust on the metal continues to rust. As it usually takes a few days (or in my case, a month) to fill and sand body putty, there will be flash rust that needs to be removed.

When I did my 914, I put the filler over (rust free) metal. When I went to seal, I had to sand the entire vehicle to get the flash rust off. If I were to do it again, I would seal as soon as I stripped the vehicle, and then fill the low spots.

Now, I live in the humid east. In areas of the country with dry air, YMMV.

Zach

Steps may only apply to epoxy primer, which is what we used. Don't know if different for regular primer. The epoxy seals the metal. Really tough.

Living in the tropics of Fla, I prime as so as I get done blasting, then worry about filler. On humid days (Sun - Sat) the metal will start rusting almost immediately. even if I only get part of it blasted I will still prime what i have done, If I dont It will be rust the next day. I once blasted a horse trailer that took two days to blast, I wrap it in vesqueen (?) (construction plastic wrap,)
To keep the dew off the bare metal, it seem to work.

rboltz -
Great report!! Just about to do the same thing - buying my media this weekend.

Snuffy

After I had all my parts sandblasted I sprayed Ospho on them. That keeps the rust off great. I could spray them and they could sit for days with no rust, this was in NC. Just for fun I sprayed a set of needle nose that I blasted and then set them outside to see what would happen. After two weeks there was no rust on them. Stuff works.