Prepping a shell for paint

[Thomas]

Hi guys,

Did a quick search and no bites so here goes.

I'm reviving an old project of mine, a TA22 shell, now that I have the time. I am in the process of sanding and prepping the shell for a lick of paint as the first job on the list.

1. I'm using a sheet sander at the moment. What is the best way of using such a sander? circular motion or long strokes?

2. In some places I have gone back to bare metal. How do I protect the metal from rust if I have to shelve the project for a few days?

3. Is it recommended to bare metal the whole car, or is it okay to sand off a few layers (there's heaps of layers in some places) with some bare metal peeking through in patches? I'll get a photo to show you guys soon.

4. Any sanding and prepping tips? I've never attempted such work before and I'm open to any and all suggestions. The glass has all been removed, as has the boot lid, one guard and most of the trim.

Cheers.

[Mr Ed]

2. In some places I have gone back to bare metal. How do I protect the metal from rust if I have to shelve the project for a few days?

I am also interested the answer to this one

[Screamn_Sleeka]

You should wash all exposed metal areas with detergent, then iron phosphate, then wipe of and then primer.

Most people i know that have taken a car back to bare metal all regretted it, and most sold it as it was for a very cheap price.

[glytch]

I only have my experience from painting my own car to draw from and I am in no way a professional.

1. I didnt' use a sheet sander - but I guess its more a matter of whatever works for you. more important to be consistant. maybe circular is a bit easier for that?

2. I used a can of spray on primer/filler. its fairly cheap and bonds fine with whatever primer/filler you will use. and you can cut it down later on.

3. Make sure you get rid of all the crap old paint. if the paint is in ok nick then you can just cut it down and go over the top. if it has any cracks etc best to take it back to metal to be safe.

4. its 90% prep work. Get it as smooth as possible - use a dust coat of cheap dark paint over the primer and cut it back to see any irregularities in the levels. Best to use a hand sanding block for that - the larger and flatter it is the better.

Tips - Remove all the bodywork thats bolted to the car. paint the insides first. (bay, underside of bonnet, inside of door and anywhere you cannot sea with all the bodywork on. Then put everything back on and paint the rest. There is nothing worse than a nice freshly painted car where you lift the bonnet and the bay is still crappy old paint.

anyway just my 2c.

[Thomas]

Awesome, thanks for the replies.

screamn: What the heck does iron phosphate do, and where can I get some? Is it some kind of anti-rust treatment? The shell's gathered some surface rust gathered from the 4 or so years that its been sitting there so I think some anti-rust will be a good idea.

glytch: the original paint is/was still in good nick, still really thick in some places, but I'm stripping off that layer and about one or two underneath. The problem is that the car has lots of layers in some parts and only a few in others. That's where I'm getting the patches of bare metal peeking through the paint. I don't really want to go bare metal all the way (really can't be f*cked!). Agree also with the inside paint, I want a black interior paint to go with my chosen outer colour

Any more tips guys? I'm learning as I go here.

[Mr Ed]

What the heck does iron phosphate do, and where can I get some? Is it some kind of anti-rust treatment?

Exactly

[Dale]

If you go back to bare metal I'd just brush (note; brush) on a bit of primer to protect it until you get back to it.. primer is porous though so it will absorb water if left long enough, as is bog, water will seep through it and then eventually get trapped between it and your new paintwork if you're not careful. Which in the end just promotes the rust which you spent all that time getting rid of.

One area I would go back to bare metal would be around the windscreens, use an angle grinder and some sanding discs to clean them right up.

There's really a mountain of tips to be given, there was a good thread a while back about spray painting and body work which was full of excellent tips. As with everything.. everyone will tend to have slightly different methods and contrasting opinions.

Although one tip.. it will be easier to paint the whole car with all the panels already hung on the car!

[thechuckster]

also - if you do go back to bare metal, use an etch-primer. Its needed to allow the paint to better adhere to the metal anyway and prevent surface rust leeching thru any primer (if stored for a significant period of time).

[Screamn_Sleeka]

Iron Phosphate is a rust treatment, its a must for bare metal thats been exposed, because although u cant see any rust, its there, and it will stay under the paint and with the smallest amount of oxygen it will continue and make bubbles in your new paint. All those commercial "rust repair" chemicals are what im on about. What i listed above is a standard procedure ever car manufacture in the world follows when painting cars. Oh, wait, chev corvette's, fibreglass...

[chaRwie]

Wow, this thread came up at the right time

Iam currently sanding mine down with a sheet sander, in a circular motion seems best
don't go to slow either as u'll get patches, RA28s are really curvy lol

[love ke70]

orbital sander for the win

standard primer does work fine on bare metal

no you dont have to cut it all to bare metal, just get rid of the worst. when i did mine i went back to factory base coats.

quick spray of primer over bare bits should stop surface rust. if not it sands off easy peasy from bare metal

[chrismiass]

Before you apply the final coat of primer you shoukd put de oxidine on it to get rid off all the rust you cant see .
Doing the same thing to my ke10 its alot of work but is worth it .

[Alex]

Orbital sander for sure, it will eliminate edges so you dont end up with a ripple effect at the end result when it's all painted and shiney, if you cant get an orbital, use your sander in a circular motion and just keep it moving all the time

Deoxidine is a good idea to be used on any surface rust, use it with scotch brite (scourer), ask for either at any auto paint supplier

Etch primer is definatley the way to go as it is cheap and non pouress and is also meant for bare metal, normal primer being pouress will not sheild your metal against moisture for more than a few weeks, even in a dry garage, so if you dont know when you're going to work on your car next (as time and motivation can be sometimes lacking) go for the etch primer

[infotechplus]

1. I'm using a sheet sander at the moment. What is the best way of using such a sander? circular motion or long strokes?

--> Don't use a sheet sander - unless you are an expert spraypainter you will regret it. Neither circular motions nor long strokes. Get an orbital sander (the Bosch PEX from Hard-to-Find-House is a good one).

2. In some places I have gone back to bare metal. How do I protect the metal from rust if I have to shelve the project for a few days?

--> Don't go back to bare metal unless you really have to. Remember if your project has its original paint then you will probably be going over 2pac with Acrylic (if you are doing it yourself). You only need to scuff the shine off the original paint and then prime it. Preparation is 99% of the job so a thorough clean first with soapy water then rinse then wax'n'grease remover then dry off with a clean towel. As stated primer will absorb water and when you use filler don't wet sand it. You should aim to cover the primer ASAP. A few days is okay but if its wet or humid a light sand will remove any spots.

Use an etch primer. It's usually a yellowy colour whereas primer / primer-surfacer is usually grey or a creamy colour. In the can etch primer is usually a dull grey.

3. Is it recommended to bare metal the whole car, or is it okay to sand off a few layers (there's heaps of layers in some places) with some bare metal peeking through in patches? I'll get a photo to show you guys soon.

--> See above. You only want to sand or feather out enough to achieve a smooth finish. A black acrylic overspray and rub back will reveal high/low spots which can be filled with spray putty and then re-sanded. Don't ever sand with paper in an open palm - all that will happen is that your palm will follow the contours of the panel. Use a cork block and paper.

4. Any sanding and prepping tips? I've never attempted such work before and I'm open to any and all suggestions. The glass has all been removed, as has the boot lid, one guard and most of the trim.

--> Remove as many panels from the car as you can. Remove all badges, trims, liners, plugs, etc Mask up everything else using good quality masking tape. Cheap tape will show paint lines and if left too long will leave a sticky gum on your panels, especially when hit with paint.

And don't be tempted to rush. Rushing the job is Public Enemy #1.

Get the correct spray gun for the paint you will be using. Larger tips for acrylic will be somewhere around 2.0mm and set the pressure right on the compressor, which should be flushed before each job, and at the start of every day to remove moisture from the tank. Also use a moisture trap between your comprerssor and hose to catch anything else (especially on a hot day).

Don't paint in direct sunlight. Acrylic will dry too quick and not spread. Warm the panel slightly in the sun and then remove to the shade, allowing it to cool a little. A cold panel promotes runs, a too-warm panel evaporates all the solvents before the paint can fully spread.

Depending on what colour you use, you will probably put a clear coat over the top. It will need to be cut and buffed to bring up the gloss. Use a good quality buffing compound from an auto paint supplier not the dept store stuff.

I've always used VG Auto Paints at Girraween if you're looking for a recommendation.

Best of luck,

Peter

[Wiggles]

Get a tack rag (open weave cloth covered in sticky stuff) and gently wipe the over spray dust off between coats. Gives a smoother finish - especially when painting in warmer weather outside (Warm air dries solvents quicker and creates more dry spray).

[Thomas]

Thanks for all the tips. I think I'll hunt for some iron phosphate and etch primer on monday. It's been dry here lately so I think it shouldn't be too bad to leave the shell under some tarps?

And on the note of sanding, is it ok to focus the sheet sander on sections to remove a patch of paint then go in long circular motions to even things out? Would the primer coat fill in any deep patches that are left if I focus on a particular area?

[LeeRoy]

On the note of hand sanding it is good and bad. Generally you will find that there is alot of stuff that you cant get with a block - even a tiny one and will end up having to use the tips of your fingers and sandpaper. Places such as door jams, door handle recesses, and other parts. Just be careful as if you do a bit of sanding by hand the shape of your hand will cause an uneven surface.

Also the problem with block sanders is that generally you use them with 360 grade paper which is fairly course. As such you will notice that after youve sanded, depending on how hard you've pressed, lines from the sandpaper. If you dont give a good wet rub - or two after youve dry sanded the primer/hi fill youll see these lines under the paint when its finished.

I'm a lil confused by your last q so can't help you there but in regards to primer its quite thin so no it wont cover what youve described as deep patches. Depending on how straight and wobble free your panels are you might want to consider giving it a few coats of hi fill. If you dont know what this is its like thick primer. Good for covering imperfections not covered by primer and you can put a good few mm of it on there.

- LeeRoy

[LeeRoy]

Heres some reading for you
Here for spray painting tips
Here for rust repair
Here for cleaning that unsightly engine bay
Here for bead/sand blasting
Here for acrylic paint help

- LeeRoy

[infotechplus]

Thanks for all the tips. I think I'll hunt for some iron phosphate and etch primer on monday. It's been dry here lately so I think it shouldn't be too bad to leave the shell under some tarps?

And on the note of sanding, is it ok to focus the sheet sander on sections to remove a patch of paint then go in long circular motions to even things out? Would the primer coat fill in any deep patches that are left if I focus on a particular area?

Putting an unprimed car under a tarp will promote moisture overnight, especially if you leave it for a few days. If you have dry weather make sure air can circulate under the covering. This is especially true for those poly car covers you buy from SupercheapAuto, Repco, etc.

The short answer to your second question is No. Modern paints are mostly water based - this is for legislative and OH&S reasons, it is only microns thick, so it won't compensate for heavy sanding in one area. I tried to feather out stone chips on a bonnet and even though it looked and felt smooth in primer when I did the colour coat you could see all the sanded areas.

You could use what's called HiFill, its a spray on putty. Also there is a skim coat filler that's easier to work with than normal body filler. It's used for final levelling, after you've sanded the guide (black) coat.

Again, it all boils down to patience and preparation.

But don't be put off because when you are finished there is a great sense of satisfaction when it comes up looking good

Peter

[Thomas]

doh. so no tarps? Whats a good way to store the shell outside then? At the moment I've got some tarps covering the metal, held in place by one of those dodgy supercheap car covers.