Aluminium corrosion repair (advice sought)

[daveo-r8v8]

Hoping for some advice here...

I've done some minor bodywork repairs over the years, but this is a potentially a new level...

I have an aluminium body with some corrosion over a rear wheel arch:



I sort of think that the process is thusly

1) sand down the corrosion to bare metal
2) mask and spray with an Acid 1k Etch Primer (I have one from paints4u)
3) flat
4) do I spray grey primer now?
5) I spray the colour coat, blending it in so a soft mask not a hard line.

From here I'm soldidly in need of proper advice - do I need to wait for this to dry to machine off any overspray before the clear coat goes on? Do I need a number of layers of colour?

If any one has done this (it's a very small spot repair) and has useful advice I'd love to have it, particuarly if it's with an aluminium body car.

[V8covin]

You don't flat the etch primer,let it flash off for as long as the data sheet says then spray primer over that,flat that primer before you go to the colour coats....as many as it needs to cover,no hard n fast rules here

[paintman]

Pretty much what you've said.
If the etch primer leaves an orange peel surface you may need to flat it - just be careful not to break through to bare metal or you'll need to re-apply.

Apply sufficient colour coat to fully cover the repaired area - so you can't see the primer etc.

You must mask off the area you wish to paint including a blend area as you DO NOT sand or do anything to the colour coat as it will affect its appearance & you will then need to apply more colour coat to cover it. If you can work to a swage line on the panel then you can backtape along the swage & paint to that.
If no swage line you need to blend the colour out onto the panel & then take the clear out further than that. Be aware that if it's a dark colour you may finish up with a visible edge to the clear & painting either to a swage line OR the edge of the panel may be the only option.

You should get the Technical Data Sheets for the paint (colour and clear) you are using as that gives you all you need to know including flash-off times before applying the clearcoat. Ask the paint supplier for them.

I do a lot of caravan body work so much involvement with aluminium panels.

ETA I should add that my own car is a 1986 RRC so aluminium (strictly speaking 'Birmabright') corrosion & I are old adversaries

Edited by paintman on Friday 4th May 19:01

[daveo-r8v8]

OK, this makes sense... so "thank you very much"...

Now I've got another problem... YouTube has told me that I can't use spot putty (I have a 1K Lechler product) over etch primer... my plan was Sand, Etch Primer, Putty, Primer, Colour, Clear - but there is almost an implication that if I use the putty then no etch primer?

Sorry this all used to be so simple when it was just fibreglass and resin (;

Dave

[steveo3002]

id say it wants sand blasting , sandpaper wont remove the pits

then epoxy primer would be my choice

[daveo-r8v8]

Ah - ok... so the putty could be a primer...? How do I know if *my* putty is a primer... does it go onto the bare aluminium?

[V8covin]

Why do you want to use putty ?
The procedure would be body filler if needed followed by etch primer..... don't sand.....folliwed by primer filler (what you called grey primer ) and then flat that and if there are any pin holes then you can use putty

[Cookiedough]

Use your swage line as previously stated to keep the repair local. Get yourself a tak rag to wipe the panel before lacquering. If it were me, and I was keeping the car, I would go either epoxy or at the very least, wash primer before basing. 👍