Question for Barry & the other pro's about surface prep before epoxy

S

Senile Old Fart

What I am wondering is once a piece of carbon steel has been cleaned back to bare metal what is the correct process to confirm it is in a neutral state and ready for epoxy.

On my SN65C there is iron oxide corrosion in areas that sandblasting will not get to,for example the roof rails on the interior side of the roof skin.

Call me crazy, but here is what I am thinking.

I method I am considering is using a chelation process to remove the corrosion. Most likely using molasses (cuz I am cheap and have not found a chemical I can afford).

Another option I am considering is using citric acid, which is supposed to not cause much hydrogen embrittlement.

I think the molasses will a: stink, and b: draw flies.
I think the citric will avoid those 2 problems


I was thinking of building a dipping tank long and wide enough to fit the 65 body shell in to a level of 1 foot deep.

The box need be nothing more than 3/4" plywood ripped into 2' strips and forming a box lined with vinyl pool liner ( walmart, etc.)

Using a rotisserie I could soak one side at a time and the roof in another soaking. ( 3 soakings)

By using a small water feature pump flowing thru a water heater and some pvc tubing I can easily make it a heated circulating bath and speed up the cleaning process.

The end result will be a clean body in all the nooks and crevices and 500 gallons of wash to get rid off.
Glad we have a free hazmat dump for households.
Only take me a trip a week for a year to get rid of it,LOL.
Actually just let it dry out via evaporation and get rid of the solids at the hazmat dump.

SO: back to the question, how do I properly prep the fresh metal for epoxy, another chemical application?
OR?

remember the objective is to get into those inaccessible places so scrubbing with a scotch brite and some Purple Power won't work.

Thanks, and be sure to point out any flaws in my plan
 
Am, I missing something here? If you can't sandblast, can you treat it with an acid? I'm totally lost here, maybe someone else can relate better.
 
There are areas that have corrosion that I do not see how it is physically possible to blast, like the top side of a roof bow unless you removed the roof skin, does this help with my poor description? But it is possible to soak via submersion and chemically remove the corrosion. My concern is the neutralization after the citric acid bath.
 
[QUOTE='68 Coronet R/T;3373]Are you reinventing the wheel here? Why not just have it chemically dipped and neutralized at a facility that does such things?[/QUOTE]

That would be an option if there was a facility within a few hours driving time and it was affordable. To miss 2 days work, travel 800 miles twice, and then spend a $1000 for the dip process just is not in my budget.
 
shine;3377 said:
there is no reason to worry about those areas. if it is that bad it is terminal anyway.
Click to expand...

Always blunt and to the point. I like that.

SOF, Some guys use POR15 or some other rust converter and actually try to fill the channels with it and rotate the car to effectively cover all sides. May take a gallon or two but it is cheaper than your other options.
 
surface rust is best left alone. it will never get worse. if you cover it with dirt, debris or por15 it will grow. ever notice how a plow can set in the field for 20 years and the only damage is the part in contact with the ground. the part above drys out. this is the only draw back on lizardskin . it is encapsulating the rust. this is why i blast inside as much as i can and then epoxy it . but i dont worry about those areas i can not hit. they dont get covered either.if you have caustic action going on you will never stop it. period.

by the time a car rust again we will all be dirt anyway. and 40 years from now guys will hate those who used por15 . just like i hated those idiots with their undercoat .
 
I agree with Shine. My neighbor is the smartest man in the world. He knows all about bodywork and painting......... really anything.

I turned him on to a '46 ford coupe. He bought it. The paint was sunburnt off of the roof. He asked what I would do if I was going to paint it. I told him sandblast it. He does all of his own work and you can tell.

A couple weeks later he comes over and says he's ready for me to paint the body. He and I block the primer he put on it. Cheap primer..... and I paint it a baby blue acrylic enamel. He takes it home. 2 weeks later he's back and says the paint has small bubbles in the roof. He takes his pocket knife and pops the bubble and there's rust on the bottom of his primer. I asked how could that be you sandblasted the surface rust. His buddy the second smartest man told him about POR 15. He put 2 coats of that on there to really seal it off then primer(cheap) on top of it . I told him that was the problem. No way. Yep look at everything else we painted on the car is it bubbling....nope. 3 days,a razor blade, sandblasting, primer(cheap) and he was back ready for me to paint the roof again. Amazingly 6 years later no bubbles.

Now he builds a 54 ford p/u. He comes over and asked what primer he should use because it is going to be a primered driver (rat rod yuk) I told him SPI epoxy. How much $$$$. told him. A week later a red/orange oxide primered 54 ford p/u pulls in the drive. He says did you know you can buy quarts of rustoleuom at the tractor supply store and brush it on or mix 50/50 with laquer thinner and spray it. I looked at him and said isn't that enamel primer? Yep, why didn't you use enamel reducer. 2nd smartest man in the world said it would dry faster this way.
 
The problem with removing corrosion from inaccessible areas by dipping, is that primer then needs to be applied the same way, by dipping. Otherwise, the bare steel that is out of sight will begin to rust again at an accelerated rate. (Think in-between pinchwelds.)

There is at least one outfit that does this in the South, I keep forgetting their name.
 
shine;3379 said:
surface rust is best left alone. it will never get worse. if you cover it with dirt, debris or por15 it will grow. ever notice how a plow can set in the field for 20 years and the only damage is the part in contact with the ground. the part above drys out. this is the only draw back on lizardskin . it is encapsulating the rust. this is why i blast inside as much as i can and then epoxy it . but i dont worry about those areas i can not hit. they dont get covered either.if you have caustic action going on you will never stop it. period.

by the time a car rust again we will all be dirt anyway. and 40 years from now guys will hate those who used por15 . just like i hated those idiots with their undercoat .
Click to expand...

I know,
old thread.
And probably something that has been asked a million times;

So I shouldn't do anything in between metal panels that can't be reached with a blaster?
For example; what about an old 65 Chevy truck tailgate? If someone suggest dunking it in phosphoric acid and then instantly to a dunk of fresh water to neutralize, how would we now get primer in there between the panels? dunk it in primer and then paint?

We know that tailgate is going to get moisture in between the panels the first rainy day drive.

So the consensus is to leave alone the inside of places we can't get to with a blaster?

I noticed someone posted above to take the cab to someone and have it dipped.
But then again, if we can't get in between the panels to scuff it with some 80 grit, nothing is going to stick in there anyway.

So,,
to recap;
Don't try and clean or spray anything into these cavities we can't get to blast?
If you can't cut it out, and you can't get a blaster in there; don't do anything?
No waxoyl, No Rustoleum Rusty Metal Primer.

So that I've covered all possible options;
What about having it acid dipped then instantly rinsed (neutralized), then a dipped in self etching primer so it sticks to those inside panels, and then dipped in paint to seal everything all up?

I know, some of you have probably answered this so many times that you're blue in the face.

I am just having the hardest time wrapping my head around the idea that unless we plan on tearing every roof skin off to get access to these areas, then don't do anything.
 
If you can block the substances that feed corrosion you can stop the rust growth. It's impossible to clean every seam and when seams are to far gone the only option is repair. For seams that can be opened up and cleaned-do it. Sometimes you can work open seams between the spot welds enough to clean them out, coat, close and seal. Other areas that can't be opened up need to be coated to stop the rust growth. If the seams are swelled with rust growth they'll need to be repaired. Door bottoms on the older cars and some new ones-they started rusting on the first rainy day, same with your tailgate. If the tailgate seam isn't swelled there's a good chance you can stop the corrosion by blasting the exterior, epoxy it, seam seal it, and saturate the inside of the seam with a cavity wax and make sure the drains stay open. To soak a seam you need to mask closed any drain areas and hose the inside down and then give it some time to soak the entire seam before opening up the drains-let it set a few days. A soak in acid is a bad move-the rust will start up again at a faster rate. For new parts soak the seams with epoxy letting it fill the voids then top it off with a self healing cavity wax as a secondary layer of protection in case there's fractures down the road. Dipping-Im not impressed with what it does within the seams. The inner structures on these older cars are usually all covered with a layer of surface rust-they weren't Ecoated in the old days and if the painter couldn't get primer on areas they were left bare metal-on a total rebuild you can properly coat the inner structure as the car is assembled, on other jobs you'll just have to do your best to coat every area you can get to. Flexible wands with 360* spray heads work well and there's some inexpensive ones for use on aresols-check out Transtar's Amber coat-excellent stuff and they offer the spray wand. Or there's also professional sprayers available-Eastwood has a decent one. Rustoleum rusty metal primer-a good friend of mine swears by it for inner panel coating and he reduces it with WD-40, his stuff does hold up. Bottom line do the best you can.
 
Only time i see dipping as a good thing, is if there were 3 or so tanks like on an assembly line. it goes into the acid bath, then the clean tank...another clean tank, then the epoxy tank.

There is a company in the midwest that does this with a phosphoric type primer solution (there may be more companies, this is just one i know of). I can imagine that gets pretty expensive though, and unless i could stand there and watch with my own eyes i would not trust it.
 
Just posted on the other thread but Bob, your post is just what I'm dealing with today. 58 GMC, I cut about 2" of the bottom of the inner panel which gave me access to do some phosphor prime. Just the lower part of the panel has any rust, and of course the cancer was at the very bottom, the top half is still factory primer. I felt before I started replacing the rot I'd do what I could to halt the rust thus the PP. So if I understand you correctly I should next apply a sealer? I have some of that rustolem on hand from another project and the inside of the door seems a good place to use it. But WD-40? I guess it might help penetrate the pores, is that the rational for it?
 
I think Shine suggests not trying to do anything in those areas you can't access to prep properly.
 
Thanks -65, I agree and wasn't intending to do anything in there until I saw I had to cut the bottom of the panel out anyway. At that point since I could get to it I felt it was worth doing. I've used the Phosphor Prime and feel using it on the inside of the panel is the best practice I have in my arsenal since I don't have a sand blaster. Also if it was simple surface rust I'd be less concerned about it but since its an area just north of where I'm having to replace rot I felt extra attention is warranted. At this point my real question is if I need to take any additional steps with the chemical stripper on the outer surface of the panel other than washing it off good before I start sanding. Besides... it'll give some extra time to figure out just how I'm going to fab the piece I had to remove:confused:
 
when i blast i get to everything i can . surface rust is not the rust that kills. it is the pockets where dirt collects and stays moist that eat through. dipping is the only way to get to those places and unless they rinse and ecoat it just makes it worse..
 
shine;10750 said:
when i blast i get to everything i can . surface rust is not the rust that kills. it is the pockets where dirt collects and stays moist that eat through. dipping is the only way to get to those places and unless they rinse and ecoat it just makes it worse..
Click to expand...

Is there a method of dipping that can be done by the hobbiest?

For example; the tailgate on my 66, what method of dipping and rinsing and ecoat would you recommend that can be accomplished in our backyard?
 
mo way that i know of. dealing with caustic chemicals . if your that worried take it and have it done. my self i would blast it and epoxy it.
 
I'm honestly wanting to trust Shine's knowledge and experience, and yet we have been so conditioned to believe the contrary.
I've been searching and searching and reading.
So much push for these Rust products.

I did find one post in another forum where a guy said he poured one of these POR products into either his door cavity or tailgate or something - I can't remember - what I do remember is him saying within a little over a year the rust pushed itself out to his outside finished panel.
He said he was convinced that the rust needed to push itself out somewhere and it took the route of least resistance.

But, then again; the bottom of my doors were rusted through. So I just keep thinking/wishing/hoping there's a solution to protect these areas we can't get to to blast - and an option other than taking it to have everything chem dipped.

I see Bob suggested Cavity Wax.

Does Shine, or anyone else see an issue with that?
 
You must log in or register to reply here.
Back
Top