Sealing rust "forever" is possible? 1

[waingroo]

Good Day,

As I am new on the eng-tips.com , I'd like to present myself as someone who try to do research and find experts concerned answers to my questions about sealing iron corrosion. The target is to learn how to deal with the rust on my own car (Vito VAN) and perhaps to others.

Many times, on car forum/rust debates, some claim that once the iron rust attacked is impossible to stop it, sometimes comparing it with cancer which in my opinion is improper. As cancer is a complicate DNA "malfunction" , I believe that iron corrosion is just an oxidation process who take place in the presence of both water and oxygen according to Wikipedia.
In my case, the corrosion begin from interior to exterior of the car, especially to the wheel arches where maybe water condense or perhaps rain it went through outside rims clips.
But, as I've found almost impossible to clean interior side of rust, I'm looking to find a way in sealing it from oxygen and water. For this, I did some research in sealing old art pieces rust patina where some recommend using linseed oil combined with wax or just simple linseed oil.
Of course, there are some other phosphoric acid based treatments who convert the rust, but I find them not trustful as long I know that they won't seal the rust but just lengthen the oxidation process.

My auto tinkers who will prepare in the next days to repair the outside of the car (wheel arches) told me that from his experience will not keep longer more than three months as the interior rust will crack again to outside.
So, I became to do research in battle with rust by sealing it. For this, I think I need expert advices not from car forums ,but from engineers.

I do believe it is possible to seal rust forever by sealing it, but I must know how to proceed.

Thank You!

 

[MikeHalloran]

If you figure it out, protect and monetize the knowledge, and you can buy a new car every week.


Mike Halloran
Pembroke Pines, FL, USA

 

[swall]

"Sealing Rust" is a misnomer. What you are doing for the most part is bridging the rust deposit. Even the best coating applied over rust will eventually be compromised and the moisture will find its way through to start the rusting process anew. Some automotive body rust does indeed start from the inside. Other rust starts on the exterior when the top coat has been chipped or nicked. In the refurbishment of a rusted auto body, ALL rust needs to be removed by chemical means, mechanical means or both. To do a proper job generally is cost prohibitive unless you are doing a no holds barred restoration and have the financial resources to undertake such a project.

 

[waingroo]

Thanks for the answers!

I know I exaggerated by asking to seal rust "for ever". Mostly I want to keep at this stage as much possible. Perhaps, purring from time to time linseed oil or cavity wax spray, I will extend the life of the car. It is quite difficult to arrive with any mechanical tool as there is a "V" shaped velding and the rust over there can only be stopped, not cleaned.

I attached a scheme and an image... not my car, but I did marked the rust on outside, bubbled paint and how it looks on outside arches. On inside, there is a thin crust of rust all over the arches.

The V shape, where the plates are welded, cannot be reached by mechanical.

 

[moltenmetal]

You can convert iron(III) oxide to its tannic acid salt with a "rust converter" primer.

Is that better than removing the rust completely to clean new steel and applying a non-conversion primer directly to the bare metal? That depends on exactly how much sound metal is left underneath the oxide, how adherent the oxide layer is, and whether or not you can get to both sides of the repair.

Can you "seal" rust permanently so that it will never start again? Not really. But you can do your best to seal out water and other corrodents. You can also try to add an anode to protect areas where the coating is damaged, by using a zinc-rich primer. Those primers in my experience are not of any use except when applied to bare steel, and even then they have been less effective than I'd have liked.

The approach I've used on my own classic car is removal to bare steel where possible, followed by proper surface prep and a highly adherent base coat (typically a surface tolerant epoxy). I don't bother with the zinc rich primer any more unless it's a location where I can leave it as a finish coat. Any areas that are inaccessible, i.e. the insides of hollow structural sections, inside doors, places where panels are overlapped or spot welded together etc., are coated with a "cavity wax" type rustproofing material- a self sealing, self-healing coating of oil/wax that is reapplied every spring after the car has spent the entire winter indoors drying out. The one I use is "Rust Check" but there are many others. It's messy, and every seam looks dirty after a while, but it's really effective.

 

[waingroo]

Thanks for good advices @moltenmetal.

The truth is that I did a mistake by using wax cavity spray (from Teroson-Loctite) without using first a rust converter that I already had in my house (Kelfos rust converter).

Now, I know that the cavity wax already sealed rust in it's thin crevices and using now rust converter is useless in that arches area as will not penetrate as should do.

For the other parts I will not do the same mistake and I will use first rust converter.

But, for arches area I bought one liter of boiled linseed oil which I will combine with acetone to make it as thin as possible then, pour into the arches cavities. The acetone will dilute the wax too and will go deeper into the rust along with linseed oil.

 

[Andrew1974]

We use a Moisture Cured Urethane in our facility over rusty surfaces. It's the best I've seen at sealing it, but it doesn't last forever. All we do is knock off mill scale and apply coating to tight rust. We use Gulf Coast Paint MCU-100 Aluminum.

http://www.gulfcoastpaint.com/products/mcu-100-rust-primer-finish-coat/

Andrew

 

[waingroo]

Thank you for your kind answer, Andrew!

Unfortunately, in Western Europe is hard to find this product... I must find a handy alternative. From all my research results that Penetrol is the best in sealing rust fallowed by linseed oil. I will use linseed oil combined with thinner/acetone to make it penetrate the rust capillary as best as possible. I will use this cure each year because I still believe that as long oxygen is stopped the oxidation can't take place. A
example: a half rusted nail/screw dropped in oil or wax will still "forever".

I also believe that the cars of this days are especially made to rust at one point after a few years of use.

 

[moltenmetal]

Linseed (flax) oil is just an alkyd (drying/hardening) oil. You would be better served in my opinion using the cavity wax/oil which is intended for rust prevention, rather than a drying oil which will form a skin or film where it settles out. The cavity wax some self-sealing, self-healing capability that the alkyd doesn't.

 

[waingroo]

Thanks @Moltenmetal

I just thought to this too. Using cavity wax Teroson/Terotex made by Henkel who says that contains also rust inhibitor!? In fact, I already used it from the first time. I wrote above that I can't use rust converter as I used cavity wax and rust converter will no longer do the job. But, I decided to use cavity wax, then, after a few days to apply one more coat of linseed oil.

Linseed Oil seems to be very recommended for preserving rust patina on art objects both outdoor and indoor.

So, for my peace, I will use first Terotex Cavity Spray and Linseed oil over it. More than that I really can't do. Where I haven't used nothing and for future interior rust, I will use rust converter, then cavity wax.

The interior rust is the most dangerous and take place in winter and in the summer when A/C is used... This result in condensation of water allover inside a the car.