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Rust control inside cavities
tegwin - 2/9/15 at 10:24 PM

I am trying to stop the spread of rust along a seam on my tin-top. I think water has been leaking into the cavity behind the panel and has caused damage where the side panel meets the top of the sill.

I can get to the outside of the seam with a rust converter and then paint it so thats good. However getting to the inside is a bit harder. I'd like to be able to spray the entire cavity with something that reacts with the rust and provides a protective layer to stop further water getting to the metal. I don't want to put anything in the cavity which might trap moisture and make it worse.


I know eastwood do a product called "heavy duty anti-rust" which sells in the US in spray cans with a long hose for the job. I can't find it in the Uk... Is there anything similar that would work?


I also want to add a bit more under-seal in the wheel arches as the factory stuff has worn down a bit, I don't want gooey shite... any suggestions on that front?

The number of products available from different manufacturers boggles the mind!

[Edited on 2/9/15 by tegwin]

mike2704 - 3/9/15 at 12:42 AM

My Dad used to swear by waxoyl cavity wax reacts and kills rust as well sealing heard nothing but good about this product.
No I'm not a trader or a rep.
Cheers Mike

Bluemoon - 3/9/15 at 06:53 AM

Waxoyl will not convert the rust but will stop moisture getting to it.

Down side is can burn when welding (think wax candle)..

plentywahalla - 3/9/15 at 07:56 AM

Rust converters like Fertan or Kurust will only work on surface corrosion. When sheet steel is rolled it creates a stratified grain structure in the steel and corrosion propagates along the grain boundaries. The effect is to create layers of corrosion product which eventually flake off. This is known as lamellar corrosion or 'pancake rusting'.

Rust converters simply react with the iron oxide to convert it to iron tannate which is inert. To be effective it is necessary to remove the 'pancake' layers until you reach the surface of good steel as the converter cannot work through layers of corrosion products.

So it depends on how bad the corrosion is as to whether it will be effective... Good luck.

tegwin - 3/9/15 at 08:02 AM

quote:
Originally posted by plentywahalla
Rust converters like Fertan or Kurust will only work on surface corrosion. When sheet steel is rolled it creates a stratified grain structure in the steel and corrosion propagates along the grain boundaries. The effect is to create layers of corrosion product which eventually flake off. This is known as lamellar corrosion or 'pancake rusting'.

Rust converters simply react with the iron oxide to convert it to iron tannate which is inert. To be effective it is necessary to remove the 'pancake' layers until you reach the surface of good steel as the converter cannot work through layers of corrosion products.

So it depends on how bad the corrosion is as to whether it will be effective... Good luck.


Thanks, I had s feeling that was the case.

I can see the back of the seem using a dentists mirror and it doesn't appear to have any corrosion visible which is odd. The outside is on a tight return just before the seam weld with the sill. It's a strip of rust about 3-5mm wide just enough to bubble and crack the paint. Bloody annoying given the fact that body was galvanized from new.

Not sure why it's rusting where it is... I'm hoping that converting what I can get to and then sealing the rest will slow it down sufficiently to give me another 5 years or so before I consider more dramatic approaches

CosKev3 - 3/9/15 at 08:20 AM

http://www.bilthamber.com/cavity-waxes/dynax-s50

Bilt Hamber products are good.

Stay away from Waxoyl,it's old technology,hard to get it thin enough to go into tight spaces and cracks/splits if you apply it slightly too thick.

theconrodkid - 3/9/15 at 08:42 AM

i spray old engine oil in,it,s free and seems to work.
did all my suspension arms as well,the oil is still on there a year later and the surface crustyness is gone

SJ - 3/9/15 at 09:43 AM

quote:

i spray old engine oil in,it,s free and seems to work.


+1 all the old cars I've had with a decent oil leak rusted much less than those that didn't

dhutch - 3/9/15 at 11:58 AM

quote:
Originally posted by plentywahalla
Rust converters like Fertan or Kurust


Not for this purpose, but while it might be slightly off topic, I use Vactan over Fertan as it doesnt need rinsing before overpainting.

Expect you could do a lot worse than a rust converter followed up be engine oil, but I understand that is effectively what Waxoyl is intended to do.


"The thick waxy liquid is saturated with a very powerful rustkiller and it chases out moisture to form a flexible weatherproof skin that wont crack, dry or wash off in the rain.
The rust-inhibiting molecules in Waxoyl cut through films of oil, grease and dirt in seconds and cling to metal surfaces and unlike chemical inhibitors used in ordinary rustproofers, they stay active indefinitely. If the skin is scratched or punctured Waxoyl creeps back and reseals itself.
Waxoyl is ideal for the insides of doors, behind sills, chassis and anywhere that water is likely to collect."

Daniel

dhutch - 3/9/15 at 12:03 PM

http://www.honestjohn.co.uk/forum/post/index.htm?t=81647

MikeRJ - 4/9/15 at 10:02 AM

quote:
Originally posted by CosKev3
Stay away from Waxoyl,it's old technology,hard to get it thin enough to go into tight spaces and cracks/splits if you apply it slightly too thick.


You just need to get it hot, by e.g. standing the can in a bucket of hot water. Waxoyl gets pretty thin if you get it hot enough.

CosKev3 - 4/9/15 at 10:07 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by CosKev3
Stay away from Waxoyl,it's old technology,hard to get it thin enough to go into tight spaces and cracks/splits if you apply it slightly too thick.


You just need to get it hot, by e.g. standing the can in a bucket of hot water. Waxoyl gets pretty thin if you get it hot enough.


No point though,as there are better products available that offer better protection and don't need heating up etc

coyoteboy - 4/9/15 at 04:51 PM

IME once corrosion has started you're screwed.

tegwin - 4/9/15 at 08:09 PM

quote:
Originally posted by coyoteboy
IME once corrosion has started you're screwed.


Well thats true.... but its like saying once your born your as good as dead... Slowing the rust down or hiding it from view until the car falls appart is the way forward

Irony - 4/9/15 at 10:18 PM

quote:
Originally posted by SJ
quote:

i spray old engine oil in,it,s free and seems to work.


+1 all the old cars I've had with a decent oil leak rusted much less than those that didn't




True, Rover did this for years. Look at the percentage of defenders still on the road. my