What product to protect after media blast?

[78SCRSMAN]

I'm having the car body, door, hoods etc. media blasted. I would like to know what product should be used on the car immediately following this procedure. It may take me some time to do bodywork and so forth before I'm able to primer all of the parts. I would prefer to use something that can just be epoxy primed? with as little prep as possible when I'm ready. Most of the car will be blasted with plastic media with a few areas blasted using sand on those stubborn rust spots. The car should be free of any rust save for a few areas (seams that can't be reached by blasting) when finished.

Advice is appreciated.
Derek

[962porsche]

180 or 220 DA sand the body and panels down then using a good quality metal wash clean the panels . wipe the panels clean untill the wipe down rags are no linger looking dirty after cleaning . use any brand of a good chromated (etching) primer .

[78SCRSMAN]

Sounds good. Can Acetone be the wash? As far as the under side of the car goes, is the etch prime all that is needed or then use a good epoxy primer? I plan to put back the PVC under coating too.
Thanks for helping to clear this up.

[962porsche]

i only use products that are made for the tack there designed for . acetone is out as a cleaner ! get metal cleaner . 4 coats of etch primer is all thats needed for the under side of the car . but check the TDS on the product you pick to use . after it dryes you can red pad it and clean with a pre paint cleaner then chip guard . i opt for u-pol's gravi tex product #0721 chip guard.

[ix0ifan]

Even after bead blasting the surface of the steel will be very active and will oxidise very quickly. With normal levels of humidity it will visibly discolour in 2-3 hours and look quite ugly overnight.

The best thing to use is a good touch dry inhibitor such as Tru Chem 138

Tru-Chem

Failing that a coating of a commercially available 'fish oil' such as WD40 will work for a couple of weeks and is quite cheap. It is quite easy to remove with a good panel wipe.

I would vacuum out the residue of the bead blast media before applying any liquids or you can end up with a soggy mess.

Are you taking the heater silencers out of the sills? If you don't they will tend to hold quite a bit of media.

[78SCRSMAN]

I plan to cover as many cavity access holes as poss. The heater tubes being one of them. After exhaustive research and conversations with "Hot Rod Restorers" I've decided on SPI epoxy primer. I've found absolutely nothing negative about it. Apparently it can be applied over bare metal after wash and prep. (It etches) Then body work (fillers and such) can be applied directly to it... then 2K primer for sanding and a final sealer coat of SPI if desired. Sand with 600-800 grit and apply topcoat.
As far as the tub goes, it will be blown out with air and shop vac as much as poss. I also have a rotisserie that I can turn it on if need be.
I will look into Tru-Chem to see if it applies or is needed.
I live in the inland NW and we have VERY dry summers here so I doubt having much trouble with flash rust but I will do what is necessary to prevent it before applying the SPI.
I welcome any comments or suggestions if I'm way off base here.

[962porsche]

you should never have more metal blasted then you can prep and prime in a reasonable amount of time . what we do is send out all the bolt on panels and then the main body . some times we will have the blaster shoot one coat if his non catalyzed etch primer on . And as we prep and do the body work it just gets striped back off for our primers . he only hits me up for an other 125 bucks for priming .

[abisel]

On my project RSR, I have been using a product called Picklex20. It has been working great to keep any flash rusting from occuring on the bare metal. Long term too.

http://www.picklex20.com/

Be sure to click on the Picklex for Power Coating in the left navigation pane.

[78SCRSMAN]

How much did you buy/use? How have you used it? I mean what did you do to the surface before using the Picklex20 and what did you do to the surface after using Picklex20 and before priming? Looks like a great product and green too. I like that it can be just sprayed out of a spray bottle. Thanks for sharing everyone.

[abisel]

I bought a gallon jug and have used 3/4 of it so far.

With the metal bare, I would pour a little into a squeeze trigger spray bottle, spray an area, scotchbrite it for a little (wear latex gloves) to make sure it covered completely and then wipe if dry with a towel like those shop towel boxes you get from Home Depot. I also used an air hose to blow out any excess that seeped under weld flanges. That was all. I have not yet applied any paint as I plan to have the entire car dipped into an e-coat tank and when that happens, I am told the cleaning stage will remove the Picklex coating.

The product web site claims that a primer can be applied right over the Picklex coating, but I have not tried that. Maybe someone here can try a test panel to see how it fairs.

[xr4tice]

Common practice once a shell has been stripped is to remove all blasting media, dirt, undercoating, seam-sealer, and dust. Tape off any areas needing further attention and spray a coat of good quality epoxy primer (Glasurit has become our product of choice). It will protect the shell from rusting and is a great layer to work upon once you dig in on the bodywork/metalwork etc.

Nate Williams

[70SWT]

This thread and another recent one touch on a major question I have, now that I am digging into a project car with rust repair needed. It sounds like it works if you do the following, in order (correct?):

1) get the panels to bare metal
2) use epoxy primer
3) THEN, apply glazing putty or Bondo as needed OVER the epoxy primer

Should you grind off the primer as much as possible, or not? Is Bondo/putty better on bare metal, or the epoxy?

It seems like wherever I see Bondo on bare metal on cars I've worked on, I see rust.


Thanks

[78SCRSMAN]

You got it right... filler over/on epoxy primer.
Grind off primer??? Not sure what you mean.
If you use epoxy and have exceeded the 7 day window, (may be depend on brand) it needs to be sanded/scuffed before spraying over it.
So epoxy, then filler, then epoxy again to seal filler and where bare metal exists from sanding filler. Then move to high build primer (2K)... after scuffing.

To answer one of your questions: filler apparently bonds well to bare metal but it also trap/absorbs moisture hence the rust you see under old repairs. So now the process is to seal the metal from the filler.

[70SWT]

What I was getting at was, is the epoxy there just to protect the paint until final surface prep, or is it OK to leave it on permanently. You answered that very clearly - it should prevent the rust that you see under Bondo so often. Thanks!

[78SCRSMAN]

Epoxy primer is the prep. So yes, leave it on permanently. I'm no expert on this... everyone seems to have an opinion. I have chosen to go this route. I have decided to follow "The Perfect Paint Job" from the Southern Polyurethane site and also use their products. (except for the base color) You must order from them direct (no local stores carry it) That's the down side. The upside is: no middle man to double the price and made in USA! Many HotRod builders swear by their stuff and don't mind sharing experiences and info.

[RichF]

hey thanks for the link to southern. They have a lot of information and spell out the paint job procedures without the bull. Granted you still need to know a little about prep and what not but that is an awesome site. Do you like the products from them?

[78SCRSMAN]

I have the epoxy primer on hand (2 gallon containers mix is: 1 to 1) but have not used it yet. It requires the metal temp to be 60deg. and it only touches that for an hour or so here. The next step for me is to get the tub and body parts blasted but I'll need to wait til' the middle of April or so. I'll report how it works out if you like.

[70SWT]

Funny, I just talked to an experienced body guy about this issue. He says NOT to use epoxy primer under anything else. His recommendation was to use a thin skim of short-fiber fiberglass reinforced Bondo on bare metal, then further filler/glaze if needed, and THEN primer. His rationale was what I have been concerned about, that primer is essentially paint - it doesn't have the structural strength to hold filler/glaze in place, and becomes the weak link.

Yet another opinion, YMMV.

[78SCRSMAN]

I agree with him to a point actually. I have done exactly what he is talking about in the past with good results. On my car, there are two panel seams (one on each side) that were leaded from the factory that I plan to use some fibre strand filler on the bare metal to get it close. ( It will need to be about 4mm thick there) But I will definitely spray the epoxy and use filler on top of it. I have no reservations with this procedure due to the simple fact that there are no areas on MY car that will require anything more than a mm thickness of filler to be perfect. My belief is if you got to cake on the filler then you might want to consider replacing the panel or a section of it. My car has not been in any collision and the body is very straight. I will only be filling a couple door dings and a few other minor imperfections. Also, I believe you wont have any problems unless there is some sort of impact at the site of repair that will bend the metal. Obviously that would create a dent. Either way it will need to be repaired... again.

I don't know what is right or wrong... I've heard it argued both ways. In the end, it's your burger, have it your way.

Sorry, what does YMMV mean?

[70SWT]

Means the same thing as the last sentence you wrote - "your mileage may vary"...