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MG Midget and Sprite Technical - Protecting Aluminium

My sprite still has the original windscreen but it is peppered with stone chips and needs to be replaced. I managed to buy a complete windscreen very cheaply so I am able to recondition this at my leisure. I have completely dismantled the whole unit (I have left the angle brackets screwed to the verticals though) and have spent a very pleasant afternoon polishing all the aluminium with progressively finer emery paper and the Fracella rubbing commpound. I did try buffing one of the castings with my bench mounted polishing machine but the fine emery did a much better job. The same applied to Solvol Autosol v Farecella. The issue now is how do I protect the aluminium from tarnishing. I know the originals were anodised but where could I get this done and how much would it cost. I think my best option is to use lacquer. I bought som two pack lacquer for my MG TF but I think it needs to be baked on. After four days it was still tacky but when left in the sun to warm up it was rock hard in 10 mins. I could use this and bring the parts indoors to warm up since it is late in the year to hope for heat from the sun. An alternative is to use an aerosol but I wonder about the durability. Has anyone got advice or comments?

If anyone would like to see how the windscreen frame fits together I have taken some photos.

Cheers

Jan
J Targosz

I would suggest it would also be worthwhile removing the brackets and refurbishing before reassembly using new screws following cleaning the tapped threads.
DO NOT USE COPPER BASED GREASE FOR REASSEMBLY but aluminium or zinc based antiseize would be suitable.
The problem with lacquer is that is is prone to damage so keep with using Solvol Autosol on exposed parts or just waxing.
I had to carry out weld repairs due to wiper arm wear on the bottom rail so after filing/sanding finished by fine bead blasting to achieve a uniform surface texture followed by waxing but not yet refitted to car.
S G KEIL

I've used Rustoleum clear lacquer on aluminium which has stood up well and it adheres well which can be an issue with aluminium. I've had anodising done in the past and the issue there is likely to be a minimum charge, the guy said I could have had about 10x the amount done for the same price but I needed it done and they did a good job of the black anodising.
David Billington

I used Everbrite on mine. Expensive and to be honest seems much like a laquer but their website makes strong claims for it. It hasn't yet been on mine long enough for me to judge it though.
https://www.everbritecoatingsuk.com/

That said, I would expect there to be several firms doing anodising in or near Glasgow. I am never convinced by companies that say your order is too small as if they wanted the work they would just batch up with other orders to make up the required quantity anyway.
GuyW

Jan,

I've managed over 50 years to polish through the anodised coating in a few places using Autosol.
I've left it bare as it's a much nicer finish IMO. An occasional buff with Autosol keeps it clean, shiny and doesn't allow it to tarnish. I do it about 4 times a year.
Jeremy MkIII

Something that I've done over the years for finishes that are slow to harden is to place them in the kitchen oven at the lowest temperature for about 20 minutes. Bakes out all of the volatiles and hardens the finish nicely. One caveat, make sure that SWMBO will be gone for a while.
Martin

I've never tried lacquering or coating aluminium but when I was painting my door off the car I used an infra-red heat lamp to speed up the curing process.
C Mee

I have now found an anodisers just outside Glasgow. Half their work is motor bikes and old cars so my frame is no problem. They also do zinc plating so my bonnet catch will probably be going there as well.

BUT anodising uses sulphuric acid so all ferrous screws, brackets etc. must be removed. From experience of my frame I suspect most owners would have problems unscrewing the brackets where they fit into the vertical stanchions. Mine were corroded, solid and difficult to get to. The screw heads quickly rounded off. The only solution was to drill them out - easy because they are soft metal. I suspected this would mess up the threads in the aluninium stanchion and I would have to drill and tap new blind holes close by the original ones. Fortunately I had a brain wave and before I attacked the screws I drilled two small holes through the bracket and into the aluminium. After eventually releasing the bracket I was able to use these holes as a pilot for drilling, taping and countersinking and maitained perfect alignment.

I will let you know how the anodising goes.

Any recomendations where I should puy the glass and rubbers from? I wonder if Autoglass have any screens at the back of their warehouse?

Cheers

Jan
J Targosz

I am with Jeremy. IMHO it does look better and over time I think any lacquer will start to peel and look a little yellow and shoddy. I'd be tempted to use wet and dry to obtain a nice even finish before applying Autosol/Mother's Aluminium polish or similar. Keeping it bright also gives you something to do over Winter..
Oggers

I have now reclaimed all the various brackets that hold the windscreen frame together, even the ones that fit into the vertical stanchions. Every single screw was solid and I messed up the screwdriver slots on them all and had to drill them out. I bought a pack of 50 stainless M5 countersunk screws from Toolstation for £2.5, drilled out all the all screw holes at 4.2mm and retapped at M5 and they are now perfect!!!!

Jan T
J Targosz

Even stainless will react with aluminium to some extent - suggest you search for a suitable assembly compound from either a classic car or yacht supplier.
AdrianR

2.50 for 50 M5 s/s c/s screws sounds awfully cheap. You sure it is stainless?
Oggers

Yes certainly stainless non magnetic. Go to the Toolstation site and search for M5 Stainless. You will see M5 X 16 stainless countersunk screws for sale at £2.27 for 50. They have Allen key heads so are easier to tighten / unscrew. I have had to shorten them though, didn't want to crack the glass as they were tightened.

Jan
J Targosz

I rubbed off the anodisation from my windscreen in 2007 and all I've done since is wash it when I wash the car. Still looks good.

I did change the glass a couple of years ago, a task made more difficult by the fact that you cannot obtain the rubber seal in the original profile or material, ( original is solid rubber, new ones are sponge) and I had to use plenty of screen sealer to fill out the space left by the smaller profile seal, particularly on the side members.
Bernie.
b higginson

Has anyone compared Autosol with Silvo? I used the latter (after 400/1000 paper and G3) because we have some but if Autosol is much better I'll get some.
Bill Bretherton

Autosol is very good. Mothers mag and aluminium polish equally so - if not a tad better. On bikes at least, I tend to apply both with fine grade wire wool and buff off. Produces a nice clean satin sheen. Works well on alloy engine casings and similar.
Oggers

OK thanks Oggers.
Bill Bretherton

Bernie,

what did you use to remove the lacquer? Mine still has stubborn bits which are resisting the Autosol treatment and I'd like a completely uniform (ie no lacquer at all) appearance?
Jeremy MkIII

Jeremy

IIRC - I used paint stripper, then wire wool/petrol to remove the residue. The trick is to use something that removes the lacquer but does not scratch the relatively soft metal substrate underneath.
Oggers

Thanks Oggers, yes that's my main concern as it's such a soft material it's so easy to scratch, Using only Autosol to remove the remainder will take another 50 years!
Jeremy MkIII

Jeremy

Agreed - it is indeed relatively soft metal. Not quite sure exactly what it is so take care. Vapour blasting would work but obviously rather impractical, and I have also has some success using a 6" sisal polishing mop on a drill - using the wax abrasive. It's a bit tedious but manageable.
Oggers

Oh that's interesting Oggers, hadn't considered a sisal mop and just happen to have a couple of mops and waxes handy so may try that.
Jeremy MkIII

I attach a couple of photos showing my windscreen frame after polishing. I spent a couple of hours removing all the anodising with emery paper and then finished the rails with a small polishing mop. To get the matt effect on the stanchions I swabbed a dilute solution of caustic soda on them (careful it is nasty stuff). I am taking them to the anodisers next week. They are not perfect and there are one or two nicks and craters which could have been removed with a file but this would have changed the shape of the frame. I did try spraying one of the stanchions with two pack lacquer and hardened this with heat from a readiator. It looked great until I noticed a corner of the lacquer lifting. I was then able to peel the entire coat off, just like a sheet of cling film. This was on a stanchion which had been thoroughly degreased and etched with caustic. There is no way the lacquer would have adhered to the smooth, shiny rails.

Jan T





J Targosz

Jan,

That's why I mentioned the Rustoleum clear lacquer works well on bare aluminium in my experience as I had read that most lacquers don't adhere well to it. I was using it to protect polished aluminium mould components from attack by the alkali nature of refractory castable and it did the job well. The abrasive nature of the aggregate in the castable and vibratory casting did damage the surface so it had to be re done after a few dozen casts but the lacquer never peeled off and was removed by soaking the mould components in thinners and then applying a new coat.
David Billington

Applying caustic soda to aluminium alloy - which I think the windscreen surround is or something like it amyways - will produce salts of aluminium on the surface and within the microscopic pores of the metal. - probably sodium aluminate or something. It will then proabably break down to aluminium oxide over time. No wonder any subsequent lacquer did not adhere to it.
Oggers

I used 1800s wet and dry to start removing the anodisation, then 320s, then 600s, then Solvol Autosol. It took some time, but I'm happy with the results.
b higginson

That should read 180s not 1800s.
b higginson

Cheers Bernie. Think whatever method is chosen, wet and dry or polishing mop, it's going to take a while.
Jeremy MkIII

I did much the same as others here; sucessive grade papers followed by polishing mops and compound. I did find that the original anodising seemed to have penetrated to varying depths into the metal, so it was a little different to my expectation that I was just removing a surface film, as one might with a paint layer. The only difference I think is that having got to a clean, shiney, bright finish, I then applied the Everbrite treatment rather than going for wax and polish.
GuyW

I do alot of motorcycle engine casings. The vast majority do not have any protective lacquer or coating, but if they do, solvent or paint stripper - which I think is mainly dichlormethane - another solvent - usually works well. Ensure you wash well afterwards. Certainly wet and dry is the way to go intially, and if the coating is thin, wet and dry usually removes it without the need for the stripper.

I have found that the trick is to obtain an even satin finish on the last wet and dry - 800/1000 grade or so - and to rinse it well before polishing with a mop. When polishing, do not rotate the mop too fast as it just melts the wax hard onto the metal. Basically you end up with black streaks which do not polish the metal surface. Wipe off and start again with brake cleaner/petrol. Polishing takes time. Patience is a virtue.
Oggers

Curiously it's only the driver's side where the coating has polished through, presumably as the driver has gripped the pillar whilst swinging into the car over the years.
Oggers, I polished the dashpots last year, one came out gleaming the other not so much. Think I made the amateur mistake of applying too much compound so will try again after using your brake fluid cleaning tip. Ta.
Jeremy MkIII

Jeremy

NOT brake fluid! Brake cleaner - the mild solvent in a can.
Oggers

Took the parts of the frame to the anodisers this morning. Quote is £40. Will post photos when they are done.

Jan T
J Targosz

Oggers, oops typo! I doubt the brake fluid I have would make much difference as its silicone.
I have a couple of brake cleaner somewhere...
Jeremy MkIII

I would not want you to get brake fluid anywhere near your shiny paintwork....
Oggers

Absolutement!


Jeremy MkIII

Jan T,
need an update please, when are they due back... eager to see the results as I have a B frame or two that need doing...
Can provide detail of who you entrusted with the work (assuming you can recommend their service!).

Best of...
MGmike
M McAndrew

Hi Mike,

They are at Able Platers in the Deans Industrial Estate in Livingstone. I told them I wasn't in any hurry and they said about two weeks so am expecting a call at any time and will certainly post pics.

I spent a full day preparing the frames using progressively finer emery paper and polished the two shiny rails with a buffing wheel but found Solvol Autosol gave a better finish. They were not perfect since polishing out some of the nicks would have left a hollow but I was very pleased with my work. I don't know if Able can do the prep work for you.

Jan T
J Targosz

Jan

Did you get a replacement screen? I might have one in the garage if you are stuck, but would need to check to see if it is OK.

Thanks
Mike

M Wood

Jan T,
Thanks that's good to know. Livingston is only 3 miles from my workshop!
Let me know when you're collecting them and I'll meet you for a show and tell ;O)

Best of...
MGmike
M McAndrew

The plater said they would be ready today (Fri) so I will probably go over on Tue next. I will let you know for sure but give me your mob number and I can let you know when I am nearing the place.

Jan
J Targosz

Oh bugg** I missed that! Not that I had any time to leave the office today :O(
How did the pick-up go and where are the pics :O)

Best of...
MGmike
M McAndrew

Now got the anodised frame parts back and I am a little disapointed with the results. I was not able to polish out every blemish without creating flat spots or hollows but I think I did a reasonable job. Anodising appears to have highlighted all the small pits I had left and maybe created some new ones. The finish appears to be a little granular. The frame on my car is very good but I wanted to build up a spare glass and frame and then fit this to the car. I will probably use the existing one. It is a pitty since I spent some time drilling out the old screws and retapping threads.

Looking forward to my visit to the NEC Classic Car Show next Friday.

Jan T





J Targosz

Jan,

Do you know if they've sealed the anodising? If not best not to handle it until it has been done.
David Billington

£40 that's a bargain, I tried several anodisers around the Midlands and they either would not take on a one off job or were far too expensive, I ended up polishing mine with polishing waxes on a bench polishing wheel and finishing it with Autosol, but it took many hours but was somewhat enjoyable seeing the dull piece of aluminium come to life.
Tim Lynam

This thread was discussed between 30/09/2021 and 02/11/2021

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