Sandblasting shell, but what to put down afterwards?

[Marine1342]

I have finally found the place where I'm going to get my 280z shell blasted ($400-$500) but still haven't gone to them simply because of flash rust fear. Little bit of info on what's going on:

 

I've stripped the car down to the shell, just recently finished pulling off the front and rear axle and putting it on a pallet with wheels. Structurally the car seems pretty good (granted this is before blasting....), only things that will need to be taken care of will be the floor pans, front engine rails and an outer wheel well.

The car is going to be blasted with a combination of black beauty and some other sand media, then air blasted clean.

The company that is media

blasting it said that they can put down a coat of primer down to keep the clean metal from flash rusting, but the guy I talked to didn't recommend I use their primer simply because they use an oil based primer and further painting would not work well.

So for the past almost three weeks I've been searching on this forum, painting forums, and calling S&W, debating on talking to NAPA, to see what primer they would recommend.

All the answers I've gotten are very conflicting but what I've found so far is that once the metal is bare and clean you need to coat it so that it won't flash rust (duh), except S & W recommends using a self-etch metal primer and they said it helped to etch the metal and bites into the metal so that its well attached to it. Then epoxy or some other coating paint etc.

Read online else that self-etching primer is only good for other layers to stick to the metal, doesn't offer good rust protection and that if the metal is already clean just put down epoxy and go from there.

Others said just go to NAPA and ask for car primer and thats it.

 

For those that have gone down to the bare metal for a restoration, what did you use or what do you recommend for the step after media blasting but before bodywork? I know that each metal reacts differently to different substrates and would like to know your guy's inputs on which step I should take from here.

 

I'm not going directly to painting once its primed, since I do need to cut out and weld pieces.

Also, the inside jambs of the roof and the roof are completely clean (no rust, although did find a comb from the 1970's judging by the color), so would it be best to have the blasting place not blast that area, since getting media out and getting it rust proofed in there would (at least seems to me) be a bit of a chore.

 

I'll be posting pictures soon, and more detailed ones as soon as I get to go back out to the shop.

Thanks for the input (helpful or flaming )

[palosfv3]

You have a couple of choices on how to protect the bare metal . You can coat it with Gibbs or other similar product or just spray a light coat of a zinc based etch primer. Each paint company makes a competative etch primer. Its just best to use one manufacturers line from start to finish for your paint and materials. A product like DuPonts 615s is a good choice for this step.

 

You want to be somewhat careful with sandblasting per say. You dont want to use sand to remove rust or paint. It leaves an embeded residue on the metal that should not be painted over. BlackBeauty or aluminum oxide is a better choice.

[rturbo 930]

You dont want to use sand to remove rust or paint.

I'm confused. If you don't want to use sand for removing rust or paint, then what DO you use it for?

[zgeezer]

You have a couple of choices on how to protect the bare metal . You can coat it with Gibbs or other similar product or just spray a light coat of a zinc based etch primer. Each paint company makes a competative etch primer. Its just best to use one manufacturers line from start to finish for your paint and materials. A product like DuPonts 615s is a good choice for this step.

 

You want to be somewhat careful with sandblasting per say. You dont want to use sand to remove rust or paint. It leaves an embeded residue on the metal that should not be painted over. BlackBeauty or aluminum oxide is a better choice.

 

 

 

I went out to my local sand dune, screened, and used about 75 gallons of very fine, very abrasive, silicon... ie fine blow sand as my media. Two days later, I had a very light coating of rust. Three days later, a very uniform coating of light surface rust had formed. I knocked that off with POR 15 metal prep in about three hours and then painted it using POR 15 silver, using a 2.5 inch brush and a small 1 inch brush. Took me about two hours, a six pack of Pepsi, and two tacos to finish. Threw the brushes away and let it cure. That was ten years ago (more or less). The Z carcass was stored outside in this low desert sun for nine years before I brought it in. No rust.... anywhere. Very smooth "glass like" finish, but POR 15 is photo sensitive: the silver turned to a crappy yellow/green dry heaves, vomit kind of color. To paint over POR 15 you pretty much have to use their "Tie-Coat" product that is a primer and accepts the usual paint.

 

I'm sure there are many other products out there that you can use, but remember lots of primers pass water and rust can develop under the primer.

 

G

[palosfv3]

There are many different types of blasting media. Walnut shells, aluminum oxide, glass beads, iron slag, plastic and yes sand. There are also different sizes of each material type, just like grit on sandpaper and different nozzles , pressures and volumes of air for each material. Its important that you use the correct material for the application . Some materials cut more aggeressively than others , some leave residue others dont. Using sand is also unhealthy and unprotected inhalation will result in silicosis.

 

Sandblasting is an often misused word that encompasses the use and application of these materials and processes. You should know what is the correct material to use for the application. Dont always rely on the blasting company to know whats best. If they recommend a particular material or process , ask why and what will the end result be like.

 

If you going down to bare metal there is no need for Por 15 and it can compromise the chemical integrity of the paint system . I'm not a real believer in this product . I've been repairing and restoring cars for over 40 years and have found nothing that works better on clean rust free metal than a Zinc (epoxy ) based primer. These zinc primers have the best adhesion and rust resistance properties known to man. Primer surfacers are porous and susceptable to moisture penetration to bare metal and should not be confused with zinc based primers.

Edited February 24, 2010 by palosfv3

[19762802+2]

There is also Dry Ice blasting which doesn't leave any material or residue behind except for whatever your blasting off. Few places do it and they sell Dry Ice pellets also. Just make sure you do it in a well ventilated place because the CO2 from the dry ice can kill you if you breathe in to much.

[Marine1342]

Clarification on things:

The media that they will be using to blast the car (the shell) will with Black Beauty (fine coal slag), and they said that if they need to (and with my permission) they would use aluminum oxide, but only on the very bad rust spots/holes.

 

That being said, the car will be media blasted with black beauty.

Checked for dry ice blasting, no one around the area that does it and doing it myself wouldn't be doable. Thought about buying dry ice to remove the sound dead-ner on the trans tunnel, but then figured 8 bucks for a torch worked just as good.

 

Palosfv3: What is the epoxy that you've been using or that you would recommend? I was thinking of going with an etching primer that Sherwin Williams recommended to me, I assume it has zinc and hopefully a good amount but then again when you assume things....

 

That Gibbs Stuff seams pretty freakin' cool though. Can you vouch for these claims Palosfv3?

Gibbs Brand Oil

 

Researched the POR-15 Rust Bullet Zero Rust thing, and still mixed reviews on it. Heard its great for 4x4 and off-roading, but that is not the case with this car. Maybe for parts underneath but paint compatibility is another issue with that.

 

So epoxy primer (with zinc) seems to be the solution to laying a primer over bare metal?

 

Now is it recommended to put down the zinc etching primer prior to the epoxy primer?

 

If I'm miss-understanding something in these steps please let me know. I'm a body work and mechanical guy, this paint stuff is quite new (and confusing to me)

 

Thanks again for all your help

[palosfv3]

The conditions and location of the area that you are wanting to get to clean bare metal will determine what method of removal is best. I would not recommend removing the paint on any exterior panels (hood ,roof ,doors.)with BlackBeauty . . It would be best to soda blast these areas. Use the BB on the real rusty parts, jambs(not underside of hood), eng compt, underside.

 

S&W 980/981 vynil wash primer is a zinc etching primer and would be an acceptable choice. You dont want to prime anything else until all metal work is complete. This application of zinc primer is preferred before an epoxy primer. Some may say its overkill but this is the best way for your situation.

 

Please explain your meaning of Media Blasting. Its been defined in the shop as removing the paint from sheetmetal or plastic with a hi volume low air pressure system with a plastic cutting agent. I have never heard of this system/method being used with BlackBeauty.

[Marine1342]

Ok

Well what I will be having blasted will be strictly the shell. No hood, no hatch, no doors. Hood and Hatch might be replaced with Fiberglass for ease of rust issues, but that depends on several factors.

Now the roof (since it is just a sheet of metal) outside has to be cleaned, and the company that is doing the blasting says that they work with metal thickness up to 22 gauge I believe.

Anyways, I digress.

The two other guys that took their Z there to be cleaned said they did a great job, adjusting pressure and nozzles for the appropriate thickness of the metal (solid to sheet etc.)

 

What I mean by media blasting, and maybe I'm using the wrong term, the term wrong, or using it too loosely, but what I mean (and what I'm having done) is using a media to strip rust and/or paint off of the surface of metal via a pressurized air system. The media that I would be using in this case would be the Black Beauty (coal slag).

So instead of using sand (as in sand blasting), it would be with BB.

Again, not sure if I'm understanding you correctly on this, hopefully I am.

 

To clarify:

On the primer that you suggested; its an etching metal that is applied after blasting the metal.

"You don't want to prime anything else until all metal work is complete"

You mean don't prime anything else with epoxy primer until all metal work it complete? Then apply epoxy primer over entire car, covering the zinc etching primer?

 

So steps would look like this:

 

Blast metal and air clean

Spray on Zinc etching primer on shell

Cut out bad metal, grind back primer (for clean weld) and weld on new metal)

Cover exposed areas with zinc etching primer

Spray epoxy primer over car (and therefor zinc etch primer)

[GOTHALOSISM]

I'm surprised no one mentioned Soda Blasting the shell? Also another good product to use after its to the metal is Lizardskin a waterproof ceramic that cuts down on heat as well as sound.

 

http://www.lizardskin.com/pages/ceramic.php

[Marine1342]

Well soda blasting has its ups and downs. I had considered it (spent 300 on a soda blaster...), but haven't found anyone in this area that will do it for the price I found to have my car cleaned with Black Beauty. Plus, cleaning the soda residue after-wards, didn't fine a clear answer for that and I need to have it primed ASAP.

So I figured lets do it how almost everyone does it, with abrasive blasting.

 

Only problem I had was which primer I needed to use right after I had the shell stripped down to the bare metal.

 

And I guess with the information I've gotten, best set up is to use an etching primer that has zinc, followed by an epoxy primer and then the rest of the steps.

 

I've heard about the lizardskin but never researched it. Really as resilient as they claim it to be? That would be great to use that instead of the heavy dynomat, but then again I can get dynomat for cheap...

[palosfv3]

The problerm with Lizard skin or similar products are that most are not repair friendly. If you have to weld, straighten or replace any metal you will find it very difficult to work around or patch in. Its fairly routine to replace a damaged pick up bed sprayed with this stuff. There are other products out there that work well for the application and are cost and user friendly.

 

T

Edited February 26, 2010 by palosfv3

[Marine1342]

Thanks for that tip palos.

Guess its dynomat for me then.

[fast-datsun]

Soda will remove paint but not RUST

[Marine1342]

Yup.

Soda blasting is great for getting almost everything off, down to the bare metal, but it will leave a coating of soda residue on the surface (which has to be cleaned off prior to placing anything down) and it will leave rust untouched.

Good for sheet metals or cars that just need to have paint removed, but in terms of helping to treat rust, its a no go.

[Brad-ManQ45]

If you have a place to store the car out of the rain, then coat it with OSPHO or PickleX. It will be ready for primer anytime after a rubdown after that.

 

There was one professional painter on this board that used Zero Rust exclusively on his own cars and any customers who didn't have a hard head about POR15.

 

He claims much cheaper and better results.

 

I have had extensive conversations both in PM's and on the phone with him.

 

He got tired of everyone arguing with him and no longer posts at all but you can look up posts by RacerX.

 

I have used OSPHO PickleX and Zero Rust on my ZXT project and am very happy with it.

 

As far as Zero Rust as primer - as long as you let it dry a good long while then scuff and do a light coat first with Xylene as the thinner (instead of Acetone), no problems with BC/CC or Single stage urethanes.

[redlinevo7]

I was in your position and did alot of research. Bought a ton of the POR15 stuff and more reading later decided the best solution was a high quality Epoxy Primer on the bare metal. These guys sell a nice one. Southern Polyurethanes I recommend you do some research on their Epoxy Primer yourself. There was a PDF I found on this site somewhere with national standards as to rust preventative coatings and they also recommended a good Epoxy Primer as the best option.

[Marine1342]

Haha, how funny I had found them (SPI) a while back and completely forgot about them. They sell epoxy primer, which from what I've read sounds very promising to use. Only thing I'm worried about is the compatability with other paints. I was planning on going with Sherwin Williams for the base/clear coat but if it works with this, who knows.