SC 430 Roof

[Boomer54]

So ,being borderline obsessive when I get interested I started looking around. I found the roof of the SC430 is supposedly Aluminium. Also being borderline stupid I thought hold on rust on the roof is a common problem on these cars, but Aluminium does not rust, wrong. Confirming the stupid diagnosis actually Aluminium does rust, BUT importantly not in the same way as Iron etc. Rusting in Aluminium actually makes the base metal stronger ! So, in effect get that car cover off and pray for rain !. No, seriously read the article, it's interesting and particularly the part about you treat rusting Aluminium. My take is if you had a rust problem on your roof and it recurs then in all likelihood the coat of Aluminium Oxide probably was not removed well enough. On the plus side if you ever sell and your roof is showing evidence of rust then in all honesty you can tell your buyer you will not charge them extra because the roof is getting stronger.

Link.

Does Aluminum Rust? - The Craftsman Blog

[Boomer54]

Actually ,this a a better article on Aluminium. However, it is also 'muddying'

Does aluminium rust. Click to find out more. thyssenkrupp Materials (UK) (thyssenkrupp-materials.co.uk)

First rusting is not the right way to describe the roof problem. It is corroding. However, what follows is confusing. Apparently the Oxide formed from corrosion is stronger than the base metal, but unfortunately is a not a surface that will bond well for paint ! One guesses that perhaps that is why the paint on your roof may 'bubble' ?

I shall look further into this.

[Boomer54]

Hmm, better and better. So ,who thought 'rusting' and 'corroding' were the same thing ? Not so.

link

Does Aluminum Rust or Corrode? Aluminium Corrosion Resistance (theworldmaterial.com)

If roof corrosion occurs most commonly at the very edges abutting to the cars body. It would be interesting to know what metal those parts were made of, because perhaps we have a reaction occurring?

I imagine ideally you want your aluminium roof to be oxidised for strength ,but to be then treated with some form of bonding agent to seal it completely and form a suitable surface for coating.

I shall look into this further.

[Malc1]

in earlier times the pinnacle of avoiding rust was to manufacture panels in aluminium stuff  ......  the very praiseworthy Rover 2000 of some 60 years ago ..........  they just corroded and melted away into oblivion ....... rare to see a nice Rover 2000/2200 these days ..... .  they've all melted away

Malc

[Boomer54]

Gulp, LexiGirl is going to 'melt away' ?

[Boomer54]

On a more serious note I am having to think about the car cover a little more. Twice this week I have taken it off and found a decent amount of condensation to remove. Would guess that is a function of heat disparity between the temp outside the cover and beneath it, but it does beg the question just how much can we rely on this cover being 'breathable'. When the weather get's colder that issue probably diminishes, but by how much. At this point that cover comes off certainly a couple of times a week. The last thing this roof probably needs is to remain constantly wet. Although reading the article it isn't moisture per se that causes corrosion. It's moisture with salt in it ! Still I will err on the side of caution with this cover. It's only a couple of years ago I converted my carriage house and horse stable into a Garden kitchen Dining space. Very nice, but today I could do with that back !. May be have to look to build something to keep the weather off.

Beginning to remind me when my daughter won a goldfish with a 50p ticket at school. Cost me £150 to tank it and all the rest of the gubbins. Oh well , we love what we love.

[Malc1]

My 1932 Triumph sits in a very loose fabric covered metal framed “ garage style “ unit with space all around to even walk etc 

This didn’t require any PlanningPermission

Not inexpensive but of course allows plenty of draught etc

I’ve never used a close cover ever on a car …… I think condensation would readily start the rot process throughout 

Good luck

Malc