Aluminium corrosion ?

In article <[email protected]>, "Bob Hobden"
<[email protected]> wrote:

> "frodo" wrote about "Penetrol"
> >
> >> Have you got a website for them as I can't find one.
> >>
> > Just had a look in 'Google"... there're a swag of 'em there. Take your
> > pick!
> >
>
> Still can't find anything in the UK though, all either US or Oz.
>

>Hirsty wrote..
>likewise

THEN....

>Pittsburgh Pete wrote:--

>By the way, I forgot to add that Flood's Penetrol is also called Owatrol Oil.
>Geedon used to distribute it in the UK, but now it's coming via Igoe.

http://www.wdiyc.org/flood.html

http://www.geedon.co.uk

http://igoe.ie/products/whenyoupaintormaintain.htm

>Pittsburgh Pete


There ya go ! ) ......Thanks for the info P.Pete.

I was going to drop into the local place where I buy it to find out some
'background' info in the light of the probs outlined above.... but you've
covered it.


Sorry about the confusion Bob and Hirsty. It hadn't occurred to me that
'Penetrol' might have a 'name change' when sold in your part of the world
!!

As well, there's a product sold down here in Oz called "Lanotec" ( made in
QLD)..... it's based on 'lanolin' (from sheep's wool) . On accounts I've
heard it _is_ fantastic for corrosion protection, but it's about _four_
times the price of 'Penetrol', so I've stuck with the Penetrol. And, as
I've related, ( for me) Penetrol _works_, over a long period.---- I might
add that I live just a short walk from coastal salt water which crumbles
roof gutterings in just years !! ( Took all my guttering off years ago, a
few little modifications for drainage and I got away from that one !!
) ) ... My trucks 'sit' in this environment, but Pen. seems to work
well !!

Good luck with your stuff ( of whatever name in your part of the world !! ) .

..... frodo.

"frodo" wrote .
>
> http://www.wdiyc.org/flood.html
>
> http://www.geedon.co.uk
>
> http://igoe.ie/products/whenyoupaintormaintain.htm
>
>>Pittsburgh Pete
>
>
> There ya go ! ) ......Thanks for the info P.Pete.
>
> I was going to drop into the local place where I buy it to find out some
> 'background' info in the light of the probs outlined above.... but you've
> covered it.
>
>
> Sorry about the confusion Bob and Hirsty. It hadn't occurred to me that
> 'Penetrol' might have a 'name change' when sold in your part of the world
> !!

Thanks for mentioning it at a very fortuitous time, just about to start
sorting out the 90's paintwork having check most of the oily bits.
Now I can get some to sort out those doors and the painted steel bits that
on the S111 are galvanised.

--
Thanks and regards
Bob
In Runnymede, 17 miles West of London

Steve Taylor <[email protected]> wrote in message news:<[email protected]>...
> Hirsty's wrote:
>
>
> >Once breached the aluminium underneath reacts very quickly.
>
> Yes it does, but it should react with oxygen instanneously to form
> aluminium oxides again - so summat is keeping the channel open. It's
> road salt of course that keeps conditions sufficiently conductive that
> the film is broken down electrolytically.
>
> No, I haven't tried the electrolytic method on a vehicle, but it works
> well enough on ships ( protects the propellers) and pipelines.
>
> Like you say, its hard to see just how to implement it. I have just
> enquired in sci.engr.metallurgy.
>
> Steve

Steve and other Land Rover fans and fanatics:

The last few days we have been having fun kicking around the idea of
cathodic protection in another thread over at sci.engr.metallurgy.

The idea of automotive cathodic protection is a fatally flawed
concept, since you don't have a good way to protect the surface unless
you almost completely coat it (which is what is done with zinc on auto
body steel panels). See specifically:
http://www.corrosion-doctors.org/Car/carCP.htm

which points out that you have a nearly impossible task to get the
current to go everywhere you want it to, unless you keep your car
buried in damp soil or dunked in salt water.

You also could start at the more general Corrosion Doctors heading of
http://www.corrosion-doctors.org/Car/Car.htm
for a longer discussion which will tell you that what you want to do
is to

1. keep the drain holes clean
2. keep the little nicks you can see on the surface coated
3. coat the inner surfaces you can't see (if you know what you are
doing!)

In fact, your aluminium probably is helping to sacrificially protect the steel
but you wish it would not. If you coat with an inert barrier, then you
had better coat the cathode (the steel) as well as the aluminium (the
anode). Otherwise you may wind up with a small anode area and a large
cathode area, which is not a good situation.

Texas Instruments spent a lot of money doing research on automotive
cathodic protection years ago, and wrote up a technical paper saying
that cathodic protection was not practical. If it had been, then they
would gleefully have sold all the auto companies heaps of integrated
circuit control systems and impressed current anodes to do it (and made
even larger heaps of money).


Pittsburgh Pete
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Pittsburgh Pete wrote:
> Steve Taylor <[email protected]> wrote in message news:<[email protected]>...

Pete,

Thanks very much for all your contributions to this thread. Interesting
to see helpful inter-group traffic !

Steve