resto_d1 said:

Looking amazing as always. May I trouble you for some info around the correction of the alli corrosion on body panels? I’d like to paint my panels myself but know I need to get a really clean base to start. I’ve noticed you’ve used a couple of aerospace products and clearly know your onions. If you got a sec, please could you pm me a bit of a dummy step by step? I was going to go epoxy 2k with nisacoat 2 top coat…

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heli_madken said:

Hi, Tried writing a PM for you but it was more than 420 characters (I waffle on far too much!) so thought I might as well reply here.

This is my process and I know there will be other opinions and alternatives.'

The problem with alloys like Birmabright is that they start corroding very quickly building up a layer of oxides if they are left untreated or unpainted in our normal garage environment for any more than a few minutes so it is very important to get the surface clean then seal it before applying paint.

I use Deoxidine 624 made by a company called Bonderite to clean and prepare the surface for treatment. It is very expensive unfortunately but I think its worth it as it prepares the panel for treatment with Alocorm 1200BR again made by Bonderite and again unfortunately expensive. What it does is sink into the pores of the alloy and sets up a barrier to corrosion it also provides an excellent base for painting or filling which is very important as getting either to stick to Birmabright long term is very difficult. My car was repainted at some point in the past in various locations and you can see in the early pictures I took the paint is simply peeling off because they didnt make sure the paint adhered correctly.

Land Rover interestingly dont recommend stripping back to bare alloy during repairs for the above reasons but sometimes you have no choice.

So the whole process I use is -

Strip off all paint, I dont use paint strippers for this to avoid any contamination of the surface. Nylon based stripping discs are ideal for this by the way as they dont damage the surface of the alloy, dont use flap discs or DA/Orbital sanders
Clean initially with panel wipe to get rid of any greasy finger prints
Clean with neat Deoxidine and a stiff brush working well into corroded areas, leave to dwell for 5 minutes and rinse off with hosed cold water, dry immediately.
As quickly as possible apply a coat of Alocrom which is a two part product. I use a clean sponge to apply it liberally and let it sit on the surface for 20 minutes. Wash off with hosed cold water and dry off.
Do any filling you need to get the panel straight then repeat the process above for any areas of metal you have sanded through around the perimeter of the filler.
Before painting use panel wipe again and tack off.
For painting it is very important to use an etch primer first. I use a very light dust coat of ProSpray A-514-2/3 but any good quality 2K etch primer will do. Concentrate on painting the bare alloy at this stage avoid spraying too much on the filler as it will react, another reason I apply a very light coat.
After that yes Epoxy primer is a great idea as it isnt porous. Be careful if you are not in a heated garage though at this time of year as Epoxy is very sensitive to temperature when setting, if it doesnt set initially it will never cure properly.

Incidentally I use UPol 'D' Metallic filler, seems to work really well on Birmabright and resists the etch primer well.

After the priming stage just treat it the same as any metal panel for painting processes.

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heli_madken said:

No Problem, one other bit of advice from my experience with the non-isocyanite paint you are going to use.

I can understand why they are used if you dont have an air fed mask and take lots of care isocyanites are nasty particularly if you have asthma or other breathing problems. But it is the isocyanites in 2K paint that are largely responsible for their hardness and durability.

So non-isocyanites need more care when painting and curing to achieve a good degree of hardness. Firstly keep coats light and allow sufficient time between coats for flash off. The paint should be tacky like a postage stamp before applying a second coat. If possible only apply two coats. Use a panel heater at this time of year to warm the part first and help with its curing. Be prepared to wait several days for the paint to harden.

If the manufactures instructions allow it after a couple of days flatten with 3000 grade wet and dry and leave in this state for a few days before polishing.

If you apply too heavy coats too quickly or build up too high a thickness the paint will never cure properly leaving it soft. Chances are you will also get sags and runs.

The idea of flatting after a couple of days is to open the surface of the paint to allow it to cure.

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heli_madken said:

Yes it does seem to get good reviews and is very fast drying which will help. Let us know how it goes on your thread

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heli_madken said:

Yes I have a note of the number of shims used and the position of the hinges. I will probably have to do some more tweaking but the idea is to reduce the amount of fitting and removal which could ultimately damage the finished paintwork.

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heli_madken said:

Probably not by the sounds of it?

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