Being of metal, our cars are certainly not immune for the tin worm.
Eventually rust will get hold of every car, that is unless it is made of stainless steel
(lucky deLorean owners) or glass fiber (lucky Reliant, Corvette and kit car owners).
But us poor SD1 addicts will have to prepare ourselves in the battle against rust.
To defeat your enemy, you have to know him. So what is rust and how does it form?
Rust is the product that forms between a chemical reaction between the metal (in our case
steel or iron (Fe) and oxygen (O2). Normally Iron and Oxygen are not that
attracted to eachother . But boy can these two change when a third party gets involved....
named water (H2O) . Water gives iron a chance to ionize and the iron ions are
able to bind with the oxygen present in the air. So water is the receipt for a love affair
between water and oxygen.
For the more chemical interested ones.....see the article on the right.
So it is obvious water and oxygen makes our cars rust. Cars are especially vulnerable to
rust because they are made of thin sheets of steel. (Higher-grade steel costs the carmakers
too much money to be cost-effective.). So the solution seems easy to prevent rust...keep
water away. Sounds good but then water is everywhere, even in the air. This is what makes
cars rot so fast in wet countries like England, Holland and Belgium. And this is also the
reason they are in such a good rot free condition in California....the dry climate works the
miracle......So now you know how important it is to keep your car dry. Put your car
preferably in a garage and not outside on the street were the elements take their toll.
However....beware of damp sheds and garages...they can be even worse than putting your car
outside. As a rule of thumb....if the relative humidity exceeds 50% then rust can form.
Below 50% it's a slow process. This is why dehumidifier's are sold for garages.....oh and
Mmmm......come to think of it, this also explains why SD1 sills so seldom rust through!!...
the air flowing from the engine bay through the sills is relatively high in temperature and
thus has a low humidity. In this way the air won't contribute to the oxidation process it will
even absorb the moist which was built up there from the time the car stood idle......
A brilliant idea!!!
Now normally the paint provides the defense against rust by separating the steel and
water/oxygen. But when paint gets older it loses its defensive power by stone chips,
deteroration by the sun, cracks,high- and low temperatures,etc..... And through the cracks
and pores....rust slowly but surely forms.
This process already shows how important it is to keep the car clean and the paint in good
condition. If you spot a stone chip or crack....immediately treat the area before rust gets
a hold. And even more important keep your paint in good condition by regularly waxing your
car with a good quality wax.
All right, waxing is good....but what about the underside or the inner sides like the sills??
For the underside use a good quality underseal wich stays flexible over a long time and over
a long temperature range. For the inner sides a tectyle treatment should do the trick by
sealing the inside off with a sticky water retenting layer. At the factory the SD1 was
already treated with anti corrosion inhibitors in its hollow spaces. To keep the layers
intact this process has to be repeated at least every 1 to 3 years depending on the use of
the car. Shown here are some pictures which clearly show were the car was injected with
corrosion inhibitors. So when you start with an anti corrosion scheme this will show you
were to inject.
Click on one of the three images to enlarge
But sadly as much SD1's go through their cars live there is often a phase in which this this
anti corrosion treatment is neglected.....hence...rust appears....To treat a rusty car to an
anti-corrosion treatment has little or no use. But the state of a car is often not very
clearly visible from the outside alone. The hollow spaces can contain a lot of rust.
With an endoscope the hollow spaces can be inspected...unfortunately not many car
enthusiasts have one but perhaps an anti-corrosion center can help you here. If rust is very
clearly visible...outside or inside...this should be treated first.
First get rid of all the surface rust. On outside panels this is fairly easy....
On inside panels this can be very difficult. A possible solution is to clean the inside with
a high pressure cleaner (it can be necessary to drill holes to get the nozzle in).
Then inject a layer of Fertan. Fertan is a chemical product which converts rust to a black
layer. Fertan works best on moist surfaces so injecting Fertan after high pressure cleaning
is ideal. After 24 hours a 2nd layer can be applied. The rust is then converted into a
black-grey layer. After again 24 hours the inside can be cleaned again with a high pressure
cleaner. Preferably with hot water. Why not let the Fertan sit on its place??.......this is
because when the metal works the "Fertanised" layer can work loose as it is a very brittle
layer.....and so rust can form again...
So when the most of the "Fertanised"layer is cleaned out the inside panels should be left to
dry thoroughly. If possible you can blow dry air through the panel. After drying inject a
"Penetrant" into the hollow parts. This is a liquid which reaches all corners and welding
seams providing a thin rust inhibiting layer. It should be sprayed very thin however because
otherwise it cracks easily. Then a last layer of sealant is sprayed which forms an elastic
water retenting layer. Because a car body is never free from movement...cracks can slowly
form even in the elastic layer...therefore it is necessary to repeat this treatment once a
year for cars which are in constant use or every three years for cars which are ocasionally
used. Another thing to consider is the use of waxoil. As the name says it is a mix between
wax and oil and it sticks to your metal like glue but it keeps itself soft even during the
winter. In the summer it slowly flows into creaks which could have formed during colder
weather. A bit more expensive than tectile but excellent stuff.
Some points to remember:
- If you use a sandblaster on your car make sure all the "sand" is removed....it
gets everywhere even in the sills....If you don't remove it before the rust treatment....
water/oxygen still has a chance to do its devastating work.
- Don't forget to cover the disc's of the brake system and electronic sensors and
- Don't use a steam cleaner to clean the car....it can .....no worse!!...
it will crack your paint....And you know by now what this means....
- Don't use a steel brush to clean off rust before you remove all the grease and
dirt.......because otherwise you will bring all that dirt and grease into the pores
of the material before any corrosion inhibitor can do its work
- Many people treat the outer surface with Fertan and leave it there.....just don't.
Just use the Fertan to convert the rust...remove it as much as possible and then
treat it with zinc compound paint or other paint systems.
- Don't leave a surface for a long time with just a layer of zinc compound or
primer.....this layer is still porous so water may enter behind the layer and play
havoc with your precious metal later....
- When repairing sections of bodywork don't use overlaps!!.....
rust really forms between the gaps....so make your patches exactly the right size and
- When replacing your windows, watch out not to damage the paint! Later on this can result
in serious rust problems around the windows. So if you remove the windows be careful with your
screw driver or make sure you carefully repaint the damaged area. When the window is out
it is the perfect time to correct any corrosion and give the area some rust treatment!
How rust forms|
When a droplet of water containing a little dissolved oxygen falls on an iron pipe,
the iron under the droplet oxidizes:
Fe(s) Fe2+(aq) + 2 e-
The electrons are quickly snatched up by hydrogen ions and oxygen at the edge of the droplet
to produce water:
4e- + 4 H+(aq) + O2(aq) 2 H2O(l)
These equations imply that increasing the concentration of hydrogen ions will cause more iron to
oxidize. So a lower pH is expected to increase corrosion
so long as there is a sufficient supply of oxygen. If the pH is very low, and there isn't
enough oxygen, the hydrogen ions will snatch up the electrons anyway, making hydrogen gas
instead of water:
2 H+(aq) + 2 e- H2(g)
But where's the rust? The equations above tell only a small part of the story.
Hydrogen ions are being consumed by the process. As the iron corrodes, the pH in the droplet rises.
Hydroxide ions (OH-) appear in water as the hydrogen ion concentration falls.
They react with the iron(II) ions to produce insoluble iron(II) hydroxides:
Fe2+(aq) + 2 OH-(aq) Fe(OH)2(s)
The iron(II) ions also react with hydrogen ions and oxygen to produce iron(III) ions.
Fe2+(aq) + 4 H+(aq) + O2(aq)
The iron(III) ions react with hydroxide ions to produce hydrated iron(III) oxides (also known as iron(III) hydroxides).
4 Fe3+(aq) + 2 H2O(l)
Fe3+(aq) + 3 OH-(aq) Fe(OH)3(s)
These can dry to make plain iron(III) oxide, Fe2O3. This is the red,
powdery stuff we call "rust".
Since these processes involve hydrogen ions or hydroxide ions, they will be affected by changes
If you have other ions like calcium or carbonate present, they make a variety of precipitates that mix
in with the iron hydroxide precipitates to produce a crusty, gnarled coating which can slow corrosion
under some circumstances by cutting the iron off from the acid, water, and air supply.
Copyright © 1997,1998 by Fred Senese
SD1 rust spots|
- The edges of the sunroof panel and the roof. Also inspect the underside of
the sunroof panel. This can be very rusty without being visible from the outside.
- The front of the bonnet can become rusty from stone chips. But also check
the inside. Rust can form easily around the mountings and on the inner side of
the front lips.
- The area around the headlamps. The bracket can rust easily and spread the
rust to the bodywork.
- The area underneath the bumper can get quite rusty from stone chipping and
often this part is never thoroughly cleaned.
- The seal between bodywork and sill can crack thus giving rust a good area
to do its work.
- Ah the doors!!...the favourite rustspot on SD1's the rust forms especially
on the inner side of the edges. Treat the inside of the doors with good rust
inhibitors and such . Don't wait too long to eridicate rust on your doors.
New ones are getting scarce....i.e. expensive!
- The seal between rear bodywork and sill....can crack and stone chips do the
rest......The small spoiler from a Vitesse can help preventing this in the
future....though not original if you don't have a Vitesse
- The area underneath the rear bumper....gets seldom thoroughly cleaned and
stone chips do the rest....Make sure the rear spats are in good order
- Wheel arches. After the doors the biggest SD1 rust spot. Make sure to regularly
clean the wheel arches to prevent mud built up. Once you spot rust here....
treat it as soon as possible...it seems to spread very quickly in this area
- The rear hatch...This one can be quite rusty without immediately noticing it.
Just check the rear lip when opening the hatch. Also check the condition where
the air grille let's the air out. It can be quite rusty in that area too.
- Around the window. Rust spots here are difficult to repair so better treat
them as early as possible. Especially when you've got water leakage (water in the
glove box compartment) suspect leaking window seals and rust.