The Spray Painting Thread

[hamgatan]

I'm seeing a little oxidisation here and there on the areas I've taken back to bare metal..(which is normal) It's taking me a while to get the car back to metal. In the interim is there sone kind of pressure pack rust inhibitor that I can spray on the surface and isn't going to affect it when I etch prime the whole thing later?

[love ke70]

as has been said earlier, de-ox-it or some other phosphoric acid thingo.
basically replaces the factory zincy type coating.

its a wipe on wipe off affair, and you can etch straight over it.


on that question, do you need to etch prime over de-ox-it, or standard primer?

[jeffro ra28]

Most PPG products recomend deoxidine 624 (similar to de-ox-it) as the substrate for their primers. So in saying that i think you could either etch it or just use your normal primer.

["Z" UTE]

I'm seeing a little oxidisation here and there on the areas I've taken back to bare metal..(which is normal) It's taking me a while to get the car back to metal. In the interim is there sone kind of pressure pack rust inhibitor that I can spray on the surface and isn't going to affect it when I etch prime the whole thing later?

Yeah, that is always going to happen when you scratch the paint off. Paint stripper on the other hand will leave the surface free of rust IF DONE PROPERLY. Live with the small amount of surface oxidisation untill you are ready to prep the entire car for paint. Most deoxidine type products call for primer to be applied within a couple of hours of their application.

Alternately you could buy some walnut oil from the supermarket, and wipe it over the bare metal as you go. The most non abrasive paint removal blasting systems actually use walnut shell, which leaves this oily deposit behind, and will protect the bare metal for a few weeks.

The most important thing is to keep your sweaty hands and those of your mates off the bare metal, it is the acids in the perspiration that starts the corrosion cycle. My son's TA22 has been sitting bare metal in his garage in Canberra for the past 11 months, and the only signs of surface corrosion are where his mates have put their freakin hands on it. Mutter mutter $%#@##$$ mutter.

cheers Chuck.

[GeneSPIDA]

Hi,

I can only tell you what I was told by my experienced restoration spray painter when I did a 6 week course at TAFE earlier this year, and what I'm planning to do with my Celica.

If you're taking the car back to bare metal, and not painting it with primer virtually straight away, you should metal condition it. This is basically using phosphoric acid to condition the surface, washing it off with water before it goes white, and then DRYING IT COMPLETELY. You need the water to neutralise the acid, but don't leave it wet as that will lead to rust.

You can do this procedure repeatedly if need be, if left for several days/weeks, until you get a chance to protect it with non-pourous primer.

On that front, you should use an Epoxy primer as this will protect the metal with a non-pourous coating, before you later apply other primer coats and paint.

One area I've heard conflicting details on is with regards to Etch primers. My lecturer said you should never "Etch an etch". Meaning, that if you treat the panel with acid as above, don't use an etch primer as it effectively contains acid, and the adhesion can be affected due to you having already "etched" it. However, various people seem happy to apply etch primer after using phosphoric acid. Unfortunately, it's one of those things only time will tell, and where you need to trust someone else's word/experience.

Gene

I'm seeing a little oxidisation here and there on the areas I've taken back to bare metal..(which is normal) It's taking me a while to get the car back to metal. In the interim is there sone kind of pressure pack rust inhibitor that I can spray on the surface and isn't going to affect it when I etch prime the whole thing later?

[GeneSPIDA]

Oh, and the hand prints, etc. is one of the reasons to keep cleaning your panels during the respray process. A book on Show Car preparation I have goes as far as to say use BOTH solvent and water-based cleaners as they take off different things.

While solvent based cleaners will take oily things off, the water based is good for removing salt.

The only problem, in Perth anyway, is that water-based cleaners are almost impossible to find (I've found somewhere), and are very expensive (why I haven't bought any yet).

["Z" UTE]

Oh, and the hand prints, etc. is one of the reasons to keep cleaning your panels during the respray process. A book on Show Car preparation I have goes as far as to say use BOTH solvent and water-based cleaners as they take off different things.

While solvent based cleaners will take oily things off, the water based is good for removing salt.

The only problem, in Perth anyway, is that water-based cleaners are almost impossible to find (I've found somewhere), and are very expensive (why I haven't bought any yet).

Gene, my cleaning procedure for a car getting a repaint is;

Wash car with high pressuure washer, degrease inside door jambs at hinges and door catch, and high pressure wash that area again,

Wash entire car with "sugar soap" in water,

Chamois off, and then proceed with any paint removal, sanding and body repairs.

When wet sanding, I use "sugar soap" in the water. Any slurry is also washed off with sugar soap in water. The final wash down before application of primer is done with a very very dilute solution of "sugar soap" ie. a couple of drops into a 5 litre bucket of hot water.

Many years ago I purchased aa dozen cotton tea towels, They were run through the washing machine and dried half a dozen times before I used them for the car sanding and washing.

You must use a high quality wax and grease remover, not the crap available at most auto parts stores. It is imperrative that you tip the prepwash/pespsol onto the cloth "WITHOUT LETTING THE CLOTH TOUCH THE LIP OF THE CAN", failure in this area WILL lead to contamination of the prepwash.

PrepWash and dry a panel at a time. Tack rag the surface to remove any lint from the prepwash drying cloths.

90% of a paint job is in the preparation.

cheers Chuck

[craig28celica]

hi great thread, very helpfull

just 2 questions, im currently getn my 23 (stuff all rust n straight) ready for acrylic paint, i wasnt planning on taken it back to bare metal, just a sand n primer etc..

there is a few blisters in paint, mainly on boot n roof, iv taken it back to metal in 1 bad spots, (just to have a look) n the metal has minor surface rust? (im not sure wot to call it, its not really rust??) it sands off once paint is gone, n metal is clean.

my question is do i need to sand all these blistered areas back to metal? im guessing this is wot caused the blisters?

the car has been painted a few times before, many layers of paint n primer n filler, on like the middle layer of colour, it has a heap of small... 0... small circles in paint (fish eyes?)
2nd question is do i need to sand them out as well, or will the spray putty fill it?

im hope'n to finish sanding, clean n primer it before dark tomorrow. (last week of holidays ) so any help would be great
thanks

[o_man_ra23]

If in doubt, sand it out. Orbital sander, start with 60 grit, and work your way up from there. Once you have a flat surface, and all the rust worms, fish eyes, and other nasties are taken care of, then start laying filler, and sanding flatter with a long board. Unless of course you want it all to come back...

[VA61DETT]

Hi All,
This tread is a fantastic wealth of knowledge!

I just have a quick question regarding corrosion protection of ferrous metals.
Mainly relating to the steel tubes used for coil-over mods / suspension geometry adjustment, basically anything that's threaded & needs to be moved periodically.

I have noticed that a lot of factory steel parts have a greenish/gold colour to them which looks like a form of anodizing, of course this wont work with steel.

Any ideas as to what it is & how to source / apply such a coating?

Thanks,

-A

["Z" UTE]

G'day -A, the coating is actually plated on in an electrolosis bath. Can be any colour you want. For the life of me I cannot think of the name of the plating material, it is something like cadmium. Cadmium was banned from fridge shelves years ago, as unsuspecting peole were getting cad poisoning when they used the fridge shelves as BBQ grilles.

Any plating works will be able to do the job for you.

Another method of protecting steel, is to pickle it. Essentially the parts are immersed in an extremely hot bath of chemical salts.

cheers Chuck.

[VA61DETT]

-"Z" UTE

Cheers for the info.
Cadmium sounds somewhat familiar, I remember some one saying you had to be careful not to breathe in any fumes from welding such coated materials for that reason, but the BBQ fridge grille, would have never though of that one!
Was hoping there is a less toxic / caustic way of protecting the metal in this day and age

-A

[o_man_ra23]

You could try nickel plating. You can purchase a 'kit' to do it at home, and it looks like chrome with a bluish tinge when you are done. That will provide corrosion protection.

Failing that, for threaded parts you can use a heavy grease, and just ensure that any time you pressure wash under the car, you re-apply.

[SilverRA23]

For parts fabricated and or machined at work we "blacken" them.

We have a cold bath system for nuts and small pieces we manufacture, but that doesn't offer a great deal of corrosion resistance, though does slow it down.

For fabricated suspension components we send them out for the hot process.

An overview here

http://en.wikipedia.org/wiki/Blackening_(chemistry)

[VA61DETT]

Thanks for the info ppl,

From what I have gathered there is no simple process for a lasting protective coating.
For now I think ill use o man's idea & slap on some grease for the time being.
If I am feeling rich Ill look at getting the parts professionally coated down the track

Cheers
-A