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Help with case corrosion

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First post, by The_Red_Fox

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So, i recently bought this old dell optiplex and turns out it has this white corrosion all over the botton and some on the sides of the metal case, i dont have any idea what caused it (it was like this when it arrived home) and in some points its aleardy turning rusty, a friend of mine told me that i should try rubbing it of with isopropyl alcohol and then use car wax on it and other told me to use rust removing chemicals (Ferox and kaol) but i think that would be too overkill, does anyone know what i should do ? im worried that it may get worst with time
https://imgur.com/a/eaczU
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Last edited by The_Red_Fox on 2018-04-15, 03:53. Edited 1 time in total.

Reply 1 of 27, by TOBOR

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That white stuff you see is mostly zinc oxide and rust. Zinc is the plating over the steel base metal. The acids in your skin and moisture in the air are the main culprits in its destruction. If you want to paint over it you should use a paint that has a rust inhibitor in its ingredients.

If the truth hurts, tough shit.

Reply 3 of 27, by Dominus

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Hey now, hey now now, sing this corrosion to me
Hey now, hey now now, sing this corrosion to me
Hey now, hey now now, sing this corrosion to me
Hey now, hey now now, sing

(Sorry, saw the subject and the song was playing in my head)

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Reply 5 of 27, by cyclone3d

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Can't see your pics because they are on photobucket.

But the generally good idea is to clean and the paint with rustoleum.

I recently did some case repair where some of the insert was rusted very badly. I even had to remove some of the metal it was so bad.

The gray rustoleum primer seems to be a lot hardier than the paint itself.

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Reply 6 of 27, by PCBONEZ

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@ OP, your pics are not working.
Try uploading them here instead of using photobucket.

I've restored a few cars.
Just sanding and painting don't work well if there is any pitting.
Slows it don't. Doesn't stop it. Rust will grow back from the bottoms of the pits and bubble the paint
If there is pitting you either need to use one of those toothbrush style SS wire brushes to clean out the pits completely or go the chemical route.

The cheap red-neck chemical route is to use something like tobacco sauce + the SS wire brush.
It's very acidic and it works better than you'd think.
I use a brand called Valentina because it's potent, cheap and comes in a big bottle.
This won't stain you plastics (but it might give you clean spots).
The down side is the process is messy and you'll probably have to give your case a hot shower before you paint.
It's not a good choice is you have a large area to cleanup. Great for small spots.
Using a plastic (vs SS) toothbrush this works pretty good to derust the metal around d-sub ports or to clean slot contacts.
Even for that it's messy and the cleanup is more work than the job itself.

The middle chemical route is the automotive converters.
Some of those work very well but most will stain plastics black if you are not careful.
Seems you have plenty of guidance there.

The most effective and way more expensive method is to use a marine rust converter product called Ospho.
Been around since 1947 and I dunno if you can even get it outside the US.
It's tough to find inside the US. True Value Hardware (or was it Ace?) will order it for you in 1 gallon size.
Treating a whole case would probably only take a pint. A gallon will derust a lot of cases.
For this stuff you want to do a complete disassembly down to just metal. Big job.
You need gloves and eye protection for that one and following the directions is not optional.
It's a phosphoric acid based concoction that leaves a paintable surface. Don't use on Aluminum.
.

Last edited by PCBONEZ on 2018-04-15, 04:05. Edited 1 time in total.

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Reply 8 of 27, by TOBOR

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The_Red_Fox wrote:

I was planing on using a toothbrush style wire brush and then painting it with anti rust spray paint, using chemicals isnt really a option due to my poor skills handling it

The problem with using rust conversion paints is that most contain some form of fish oil. The oil does the chemical conversion to stop the rusting process. That in itself is good but if used on a surface that does not have any rust (iron oxide) it will tend to "boil" the fish oil to the surface wich could lead to blisters, orange peel and fish eyes. Always test the type of paint that you are considering on some scrap material first and wait a few days before evaluating the outcome.

If the truth hurts, tough shit.

Reply 9 of 27, by PCBONEZ

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I've never used a rust conversion paint. Sounds like a hype product to me actually.

I have several times used full on rust converter (intended for car restoration) and then painted it.
I didn't have any issues with the paint later on.

Real rust converter is an oxidizer. It converts iron based red rust into black rust.
Black rust doesn't flake off exposing the new fresh metal underneath it like red rust does.

I tested the stuff I used by cutting a rusty piece of angle iron in two.
I treated one per the directions and sanded/wire wheeled the other.
Painted both then then put them into salt water for 3 months.
The untreated one was badly eaten. The treated one looked like they day I treated it.

Unfortunately the company that made that stuff changed hands and the product was altered.
The new version works but it's no where near as good as the original.
.

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Reply 11 of 27, by PCBONEZ

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There is a spray-on zinc coating available.
It's used to 'patch' repair? galvanized metal after it's been welded on or cut.
Usually near the chain-link fence stuff in the hardware store.
Sometimes by the galvanized roofing.

It does not require a primer IIRC.

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Reply 12 of 27, by TOBOR

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Plasma wrote:

Just leave it...the bottom of the case is not gonna show. It will look better with the factory zinc and a few very minor rust spots than covered with spray paint.

You must have been turned down for a job at Earl Scheib at onetime.

If the truth hurts, tough shit.

Reply 13 of 27, by Plasma

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TOBOR wrote:
Plasma wrote:

Just leave it...the bottom of the case is not gonna show. It will look better with the factory zinc and a few very minor rust spots than covered with spray paint.

You must have been turned down for a job at Earl Scheib at onetime.

You must be blind if you think spray paint can match the look of actual zinc plating.

Reply 14 of 27, by PCBONEZ

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.

Last edited by PCBONEZ on 2018-04-15, 07:31. Edited 1 time in total.

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Reply 15 of 27, by PCBONEZ

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Plasma wrote:
TOBOR wrote:
Plasma wrote:

Just leave it...the bottom of the case is not gonna show. It will look better with the factory zinc and a few very minor rust spots than covered with spray paint.

You must have been turned down for a job at Earl Scheib at onetime.

You must be blind if you think spray paint can match the look of actual zinc plating.

I have actually used the stuff hot shot.
The different brands have different looks.

No that the OP's photos have shown up so I can see the finish. One of them is a dead match.
I have actually used it on several cases with that finish for the same thing.
It's a WAY closer match to that than any of the other coatings that have been suggested here.
.

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Reply 16 of 27, by TOBOR

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Plasma wrote:
TOBOR wrote:
Plasma wrote:

Just leave it...the bottom of the case is not gonna show. It will look better with the factory zinc and a few very minor rust spots than covered with spray paint.

You must have been turned down for a job at Earl Scheib at onetime.

You must be blind if you think spray paint can match the look of actual zinc plating.

No not blind. Those factory zinc jobs are crap. They will continue to lose the zinc over time. After the zinc is gone then the steel will have nothing for protection.

If the truth hurts, tough shit.

Reply 17 of 27, by Plasma

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PCBONEZ wrote:
I have actually used the stuff hot shot. The different brands have different looks. […]
Show full quote

I have actually used the stuff hot shot.
The different brands have different looks.

No that the OP's photos have shown up so I can see the finish. One of them is a dead match.
I have actually used it on several cases with that finish for the same thing.
It's a WAY closer match to that than any of the other coatings that have been suggested here.
.

You and TOBOR need to calm down. We're talking about two extremely minor rust spots on the BOTTOM of a computer case. That nobody will ever see.

If you tore the whole thing apart, sanded and prepped it, masked all the labels, and painted it with your fancy "almost looks like zinc" paint, it might look "almost original."

Is OP gonna do all that? Probably not. Is it worth all that trouble? Definitely not.

Reply 18 of 27, by TOBOR

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Plasma wrote:
You and TOBOR need to calm down. We're talking about two extremely minor rust spots on the BOTTOM of a computer case. That nobod […]
Show full quote
PCBONEZ wrote:
I have actually used the stuff hot shot. The different brands have different looks. […]
Show full quote

I have actually used the stuff hot shot.
The different brands have different looks.

No that the OP's photos have shown up so I can see the finish. One of them is a dead match.
I have actually used it on several cases with that finish for the same thing.
It's a WAY closer match to that than any of the other coatings that have been suggested here.
.

You and TOBOR need to calm down. We're talking about two extremely minor rust spots on the BOTTOM of a computer case. That nobody will ever see.

If you tore the whole thing apart, sanded and prepped it, masked all the labels, and painted it with your fancy "almost looks like zinc" paint, it might look "almost original."

Is OP gonna do all that? Probably not. Is it worth all that trouble? Definitely not.

It seems like you are the one getting all exited not us. It is worth whatever the owner wants to put into it.

If the truth hurts, tough shit.