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 Post subject: Removing Rust from Frame
PostPosted: January 10, 2017, 11:52 am 
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I'm sure this has been beat to death, but I'm getting close to the point were I'm going to paint my chassis. Its fairly rusty, and I'm wondering what the best way to remove the rust is? Due to the acute angles, as most of you are aware, its impossible to get in there with a angle grinder. Being the middle of winter, I'm not to keen on using a chemical that needs to be rinsed off as it will make a major mess in the garage. Not wanting to work that hard or take that long, I'm also not too eager to sand it by hand.

-Sand/media blasting seems to be my top option. Anyone that has paid to have this done, would you mind sharing how much it cost? If I get it blasted, is moving it from a warm shop, to -20C to transport it back to my shop going to cause rust issues if I don't seal it right away? I have a few items I'd like to change that require welding following blasting and wouldn't be sealing it for several days after blasting;

-Would electrolysis work/do a decent job? I think it would be fairly easy to jimmy rig a tub together that I'd be able to submerge the frame in, has anybody done this? Not sure what I'd do with the sludge afterwards, just trying to judge based off member feedback if this is a feasible option.

I suppose I could make some sort of tub and rinse the frame off by submerging in, just wondering what members have had success with.

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PostPosted: January 10, 2017, 12:22 pm 
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I'm a big fan of spray on rust converters. I think one brand is tannic acid based and another is a phosphating solution.

Both work well.

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PostPosted: January 10, 2017, 3:08 pm 
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I would just hit as much as I could with the angle grinder/wire cup. Then use the other styles of wire wheels and rotary tools like the 1/4" bit type tools. Then hit anything that's left (shouldn't be much) with sandpaper and then anti rust paint. Wipe off rust dust by hand prior.

Transporting the frame in and out of warm humid areas and into cold dry areas is asking for more rust. If the shop paint/blasting so much as blows the blasted frame off with an air gun, it will also get blasted with water/humidity.


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PostPosted: January 11, 2017, 8:27 am 
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The local business that sand blasted my frame also painted it with primer before taking it out of their shop. I don't remember the cost, but not very much, something in the $150 to $200 range total, maybe? Don't know if the sand blasting folks in your part of the world do the same primer painting, but it won't hurt to ask. Worst they can do is laugh at you and say "Hell no!" If you're married, you're probably used to that sort of thing... :mrgreen:

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PostPosted: January 11, 2017, 11:53 am 
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Hey Josh

What works for me is POR-15 Metal Prep, is converts rust, turns the frame a chalky white, ready for primer.

I've used it in the winter, just used a spritzer spray bottle to apply metal prep and keep wet; then a weed sprayer of distilled water to rinse the frame off. Just threw a bunch of soaker pads on the floor to soak everything up, don't think I used more than 2 gallons of water.

Paint is still hanging on both 7's.

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PostPosted: February 3, 2017, 1:23 pm 
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Just a quick update, I looking into both blasting the frame and utilizing a chemical agent. I'm going to go with the sand blasting. If using an agent, I'd probably use Evapo-Rust from Princess Auto with two jugs running about $56.00. Then there is the pads/tub for my floor to avoid getting chemical on the concrete/water everywhere. I'm guessing all said and done, it would be about $100.00 in material. I got quotes from three shops to blast it ranging from $200.00 to $450.00. I think I'd rather just take it to a shop than provide the necessary labor if the difference is only going to be $100.00.

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PostPosted: February 3, 2017, 2:18 pm 
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Make it clear to the sandblasting place that it's thin metal and you don't want to remove the good steel. Worst case you could take it to a place like that and when you go back they will say: "We don't know what happened, it's just gone!".. :rofl:

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PostPosted: February 3, 2017, 7:41 pm 
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It's true that sandblasting can do a LOT of damage to thin metal in a SHORT time. Of course, there are other types of media that aren't so aggressive, so they might be an option.

I'm almost at exactly the same stage in my build, with exactly the same dilemma. When I moved my frame out to the new (unheated) shop, it looked like a single, complex piece of polished stainless steel. Now, a few years later, it looks like old disused railway track.

The idea of sanding etc. to remove rust leaves one gigantic issue. When rust attacks steel, it creates millions of tiny pores in the metal, filled with rust. Sand them all you like, you will NEVER get all the rust out of the pores below the surface of the steel. Paint over the rust and, well, we all know how that will work out over time.

I'm leaning toward the idea of knocking off as much as I can (on my frame, it looks like a coating of orange dust), and go at it with one of the liquid "rust converters". I've been researching this for a bit now, and VHT's rust converter seems to have the best reviews. Theory is, this stuff gets right into all those little pores that you can't sand, chemically changes the rust to an inert substance, and seals the surface. Once that's done, you can fee free to paint the frame, knowing there's no source for rust to flare up.

I'm actually thinking of using Tremclad. I've had great success with the stuff over the years (far better than other rust paints I've used), it's cheap, touch-ups are a breeze, and you can get it both in rattle cans (for the main parts of the frame) and small paint cans (for brushing on, in those hard-to-reach places).

Just throwing this out there...

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PostPosted: February 3, 2017, 11:40 pm 
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I sanded/wire brushed the light rust off my frame after it sat in a shed for a few years, then cleaned with acetone and brushed on some Tremclad. It's not the most durable paint in the world and has a few chips, but the rust never came back. I even used Tremclad for painting the body, thinned with laquer thinner and sprayed with a cheap Princess Auto gun.
Kristian

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PostPosted: February 4, 2017, 9:04 am 
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You're more than likely past this point but as I build my frame I have been hitting the steel with weld thru primer from Eastwood. And any areas with finger rust on it I have been going over it with steel wool then steel prep acid to convert the rust. then prime.

When all is said and done i plan to have it professionally sand/media blasted. I guess I'm hoping the primer acts as just a good covering till that day comes. Then more metal prep and pro-15 or powder coat. not sure which yet.

:cheers:

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PostPosted: February 4, 2017, 12:14 pm 
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Electrolysis would work IF you submerged the whole thing in a tank. The problem is you have to turn the whole object you want to derust into a battery terminal. It is great for small parts (calipers, etc.). Getting rid of the sludge is no problem. It is washing powder and rust. Just dry it and bin it.

As an aside I wonder how those weld thru primers affect TIG welds ? I wonder about contaminating the bead in a typical TIG bead ?


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PostPosted: February 4, 2017, 2:59 pm 
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Heck, if I had the ability to completely submerge my frame, I'd dip-galvanize it like a garbage can! Imagine how long that would last? Considering how long-lived galvanized cans last when filled with rotting, acidic trash, water, etc., a nice dry frame would probably last virtually forever!

Ah well - as the expression goes, "If wishes were horses, then beggars would ride.."

I suspect there's a few rattle cans of rust converter & a half gallon of Tremclad in my future...

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PostPosted: February 4, 2017, 4:56 pm 
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zetec7 wrote:
Heck, if I had the ability to completely submerge my frame, I'd dip-galvanize it like a garbage can! Imagine how long that would last? Considering how long-lived galvanized cans last when filled with rotting, acidic trash, water, etc., a nice dry frame would probably last virtually forever!

Ah well - as the expression goes, "If wishes were horses, then beggars would ride.."

I suspect there's a few rattle cans of rust converter & a half gallon of Tremclad in my future...


I think galvanizing is over rated anyway. I am patching rust holes in a Toyota I can put my arm through. Under the paint and undercoating is galvanized steel... and rust holes :|


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PostPosted: February 4, 2017, 5:22 pm 
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zetec7 wrote:
Heck, if I had the ability to completely submerge my frame, I'd dip-galvanize it like a garbage can!


If you're serious about wanting to galvanize it, there's nothing stopping you from building a temporary plywood frame-sized tub. You could reuse the top of your build table and easily build some plywood sides. A coating of enamel paint and some cable supports strung across the top of the tub to stop the sides from bowing out and you'd be set to go. Or use a tarp for water-proofing like the picture below.

How hard would the chemical/electrical part of the galvanizing be to do? How long would it take to do a whole frame?

Attachment:
Screen Shot 2017-02-04 at 3.21.21 PM.png
Screen Shot 2017-02-04 at 3.21.21 PM.png [ 249.41 KiB | Viewed 249 times ]

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PostPosted: February 5, 2017, 12:59 am 
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To be honest, I have no idea how to do the plating process. I'm assuming it would involve some kind of electrolyte, some hunks of zinc (those I have, in abundance - I have a boat that needs new zincs twice a year, and I have a pile of partly-dissolved ones), and some amount of electrical current. I'm sure it wouldn't be too difficult, aside from the obvious issues of having a big enough vat to submerge something 12' long or so.

In order to do it right, though, the best way would be to drill holes in every single tube, so the electrolyte can get everywhere, including inside all the tubes.

Interestingly, Porsches from the late '70' onward were fully galvanized. Once the entire frame/body were built & "in the white" (no coatings etc., just raw steel), they were carried by an overhead rail down into a tank, fully submerged, and plated inside & out. Even here in the Pacific northwest, where salt & moisture are airborne 24/7, these cars simply never, ever rust...unless they've been damaged & had bodywork. Then, all bets are off.

Anyway, at one point galvanizing my Locost was a dream (okay, maybe a pipe dream...), but I'm learning that simplicity is a virtue. You might not know it from my build, but I'm learning.

My buddy insisted my cooling system wasn't going to work, that I needed a remote pressurized expansion tank, a remote filler neck, see-through bleed-nipple adapter, dual chrome-lined reverse de-coupling framulators, cooling-inversion gespatcho-stimulator modules, and a bunch of other stuff I didn't understand. :shock:

Then, I pointed out that my radiator cap is already the highest point in my cooling system, so if it worked in the original Ford Focus with nothing more than an overflow bottle, it ought to work for me, too, right? See - I'm learning!

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