Painting advice

[HoSS]

Hi,

I need to paint my truck body. Its steel with Alu/Zinc coating and the flaky NATO paint on top.

I do have a spray gun & compressor, but i'm no expert. Could someone talk me through the process please?

I need to get the old paint off without damaging the Alu/Zinc, so i guess sanding is out. What should i do?

If the paint is sound, can i just key it with a scour pad or light paper, and then pain on top?

Which undercoat should i use?

I plan to use a matt or satin top coat something like this http://www.ebay.co.uk/itm/Military-Vehicle-Paint-2-5Ltr-5Ltr-Cans-All-Colours-/330894028228?pt=UK_DIY_Material_Paint_Varnish_MJ&var=&hash=item4d0ad22dc4

I dont have a paint booth, but can make a polythene tent in my workshop.

[Les Brock]

Heres a post I did on painting ...in my build thread

http://forums.lr4x4.com/index.php?showtopic=67196&page=17#entry728779

[Tom1809]

Perpetration is key to a good job. Invest your Time into that and you will get good results, make sure you buy proper panel wipe too.

[HoSS]

Excellent post.

But i just have a few questions stiil:

How to get down to the alu/zinc layer without damaging it? paint stripper & scotch brite?

I guess i need to use 2k etch primer on the Alu/Zinc? But do i need to put high-build primer on top of that?

[Cynic-al]

Are you painting the whole thing? With patience and the odd rubbing back of mistakes I can get a good finish but I've never managed a good colour match!

[C18RCH]

I used a wire knot brush on an angle grinder. Was the only thing that would touch the old military paint. Didn't damage the body work, it's tougher than you think. Just kept moving around so as not to build up too much heat in one area.

[HoSS]

I'm not exactly sure what technology my 'Alu/Zinc' treatment is. But using a wire brushing on a test patch seems to take it down to steel so i dont want to do that obviously. The same for sanding.

I've tried household paint stripper but that is only partially effective.

Any ideas? Is there a specific stripper that will be more effective on bodywork paint?

[studmuffin]

I'm not exactly sure what technology my 'Alu/Zinc' treatment is. But using a wire brushing on a test patch seems to take it down to steel so i dont want to do that obviously. The same for sanding.

I've tried household paint stripper but that is only partially effective.

Any ideas? Is there a specific stripper that will be more effective on bodywork paint?

The Alu/Zinc coating is a generic Hot Dipped Alloyed coating similar to HD Galvanised, with either 95%Zinc/5%Ali (ZA) or 55%Ali/1.6% Silicon/Balance Zinc( AZ). Either one will react badly with strong acids or alkalies.

If the paint is sound rough up as you suggest. Maybe a scotch brite pad? Try not to degrade the coating. Its what is underneath painted steel roof sheets as well as panels and is very effective as anti rust protection.

If its an area where heat doesn't matter possibly try a hot air gun.The coating should take a pretty high temperature.

I am no expert on coating but suspect an etch primer will work as its fairly mild.

Maybe look on the tech articles by the Galvanisers Association.

If you need the Euronorm/British Standard detail for the coating pls PM me.

Hope its going well

Barry

[discomikey]

i have always flatted back with an 80 grit to take the majority off, or smooth out any large imperfections,

apply a guide coat and then flat back again with a more fine grit, usually 180 then 240 if neccesary,

you dont neccesarily need to strip the paint, but where there is a transition between painted and bare ali, you dont want to see a defined point where the paint stops and the ali is bare, you want that feathered over as large an area as possible, you can feel things that you cant neccesarily see too.

i didnt go for a 2k etch primer, i used this stuff on the series 2, apparently its best you dont give it a thick coating of this stuff, i applied it so you can still see the changes in paintwork colour behind it, i thinned it with a 50:50 mix and just to give you an idea of coverage i managed to spray the full tub(series 2 88"), interior and exterior, seatbox, floor panels, and tunnel with 1l of the stuff

i didnt etch prime the underside of the seatbox or floor panels as they are bare from the factory and undersealed.

if you want to do this really really properly, then you ought to apply a sealer primer over the top of this, i would definately reccomend this in general as it evens out the paintwork where the etch primer is semi transparent you then have a solid colour to apply to.

one step better, on top of this apply a few layers of high build primer, guide coat and flat back until perfect, this will ensure you have the best possible starting block to apply your base coat to.

after this its the satisfying part, base coat you dont need it to be massively thick, first coat, dont worry too much if you can see very slight misconsistencies... (is that even a word?) but the second and third coat you should be looking to get complete and even coverage, (some poeple say the first coat should be like this too, others say no need) i would say that 3 coats should be plenty. you can actually make the paint too thick here which will make the paint more likely to chip.

after that, depending on what paints you have used, a 1,000 or higher grit wet sand, and depending on how good you want the finish put id say from 3 coats of clear upwards on, ive seen 7 or 8 coats of clear go on before but if you apply that much you need to wet sand and rubber block it all then because you dont want the clear to stay that thick either. although its advisable to apply thinner coats anyway.

after all this you might even be able to see yourself in the mirror.

most important thing with spraying though is enjoy it, take your time, and dont apply too much at once, and always remember, if your not happy with the way its turning out, dont worry, 90% of the time unless you have really cocked it up, you can flat back any imperfections such as excessive peel or slight runs between coats. you just need to make sure to let it dry properly first when your going to sand it, and then before the next coat make sure to key the paint, remembering that keying doesent neccisarily mean getting the 80 grit out and having a good go, keying for a clear or second/third topcoat layer works well with 1,000-2,000 grit paper, just make sure the paint is dull and not excessively glossy because thats what makes the paint not stick so well.

anyone can create a showroom finish even if theyre completely rubbish with the spraying itself as long as they are willing to spend the time in the prep stages (before and between coats) and also with the final finish. but just dont underestimate the time and patience required haha

[discomikey]

P.S. i would reccomend leaving the paint a good 2 or 3 to cure completely before doing the final cut and polish, assuming you are that bothered about the finish it is a LR after all.

and P.P.S. dust IS your worst enemy with painting a car.if you can seal an area off, and sweep out as much as possible, then damp the floor this keeps any dust down

[adele]

Yes. It will be more beautiful.

[HoSS]

In the end the best method i found to strip was using good quality paint stripper to soften it and then a plastic bristle brush on my angle grinder, that chewed it off without damaging the zinc.

[HoSS]

So i have got myself some 2k etch primer and a 2k top coat.

I did a first test dusting of the primer on the internal area (where things are not too visible) and it wasnt spraying too well, i think it may have been too thick. They guy in the shop didnt give me any thinners for that, just catalyst and told me to mix 1:1. I probably need to go back and ask about thinners. Products shown below for ref.

Do you think i should use some high build primer in between? I'm not going for a perfect finish, but i would like to take out the worst of the imperfections.

[discomikey]

its amazing the difference a high build primer can make, you can spend as little or as many hours as you like flatting it back its just one of those things, it will help to even out anything, especially if you might get slight runs in it or the etch coat

i would go for a sealer primer before that (But after the etch) as well in an ideal world. but 100% definately would if you had paint bubble anywhere like the bottom of your doors as if you dont it will be a matter of weeks, maybe months depending on weather before those bubbles return, on an otherwise very smart paint job. pop those bubbles and behind it is water. this is because behind each bubble there will be a pinhole in the aluminium, nirmally invisible to the human eye.

[studmuffin]

This is all good advice for me too, as I am looking to paint the back of my truck later in the year.

I want to keep it as original as possible so does anyone know the technique Land Rover use to get that lovely orange peel paint effect??

Barry

[discomikey]

all to do with the thickness of the paint applied, the pressure of the gun, and the speed in which applied. in order to get it to match you will have to do some trial and error on an old body panel