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Spraying 2-Pack 

 

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 Post subject: Spraying 2-Pack
Posted: Sun Dec 05, 2004 10:08 am 
Oompa Loompa
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Location: Cheltenham
VIC, Australia

I've sprayed a couple of cars before in good old acrylic, but know nothing about 2-pack except that its toxic s**t. I guess thats why I can't find anything useful on google. Can anyone give me some tips or point to a web site.
i.e. do you mix 2 parts together and then spray(if so how long have you got etc.) or spray 1 part then the other on top? I'm confused because I've seen it on the web in spray cans- how do u get 2-packs in 1 can? (or do you drink 2 packs of cans then start spraying)
Do you need to sand between coats or after final coat before clear coat.etc.

I told you I know nothing
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Posted: Sun Dec 05, 2004 4:47 pm 
Getting Side Ways
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OK I've sprayed 2k before and its much easier than acrylic to spray. The only caveat is you must get it right first time or you may have to sand the panel back and do it all again if you make a blunder.

Some tips-

Acrylic is like goo - its thick and does not run easy. If you make one single acrylic run if respraying an entire car, you should not attempt spraying 2k until you've perfected your acrylic spraying technique. 2k paints are thinner than water, the first coat is a 'dust coat' - it means just that, dust the paint on, do not attempt to cover the whole surface with paint with the gun. Since the paint is so thin, it will spread and evenly cover the surface.

For the second coat, lay it on a tiny bit thicker. It is difficult to see how thick you're putting it on though. You'll find after the dust coat has had a few minutes to settle on the panel, it will form a solid color and the dust effect will go away. This will now give you more surface area to cover with the second coat, hence needing more paint.

Acrylic usually needs a 1.8-2.0mm nozzle, most people choose suction feed. For 2k, you need a 1.2mm or 1.4mm nozzle, I prefer the 1.4mm gravity feed - this means the tank is on top of the gun. Have a bloody good air regulator, set it to about 35psi. Have a water trap installed in the line from the compressor. If you dont have a water trap, hopefully you'll have a hose thats around 30m long from the compressor, run that as high as possible, over a branch on a tree - this also helps reduce condensation spitting out of the compressor. I do all of this, the water trap and the hose 5m up over a tree branch then back into the shed.

2k contains the isocyanites and they are cancerous. When I spray, I have the compressor hose attach to a double adaptor on my belt, one hose goes to an air mask with an activated charcoal filter (about $60) and the other goes to the spray gun. Most auto paint shops have filters that you can buy, they look like the sound absorbing material you put in speaker boxes. I use thermofans to suck air through my filter.

If you have ever contaminated your car with any silicone based products, whether its on the dash, wheels or anywhere, not going to mention any names like armor something :) then you'll need silicone drops to prevent fish-eye in the paint. Silicone migrates, say you've polished your dash and made it all shiney and 'protected' it (if you beleive our mate Brock), you touch the dash, then you touch the paint and that panel is now contaminated. Check the link below for what fisheye looks. When you've mixed the paint up, put two or three drops of silicone drops per 500ml of paint in the gun and stir it up bloody well. Even if you have never used it, chances are some has made it to your car through the air or on other peoples hands so always use silicone drops.

For the primer/highfill, use a 2mm gun such as an acrylic suction feed gun. For the basecoat (and clear if the paint is a COB (Clear Over Base) type) use the 1.2 or 1.4mm gun. Get a 1.2mm nozzle to begin, it makes life easier since you dont have to be as quick.

For the air pressure, if the pressure is too low, the gun wont atomise the paint and it will 'spit' the paint onto the panel. If the pressure is too high, you'll waste far too much paint and it will end up in the air and as overspray on other parts of the car.

The gun should have a nice oval shaped pattern as your spraying, the subsequent strokes should overlap the original strokes about 30-40% depending on each situation. Always test spray a panel off the car (or the garage wall :) )

Wet the concrete - it reduces dust but dont wet the car. Spray the walls with water as well but dont get any on the roof or some may fall onto the car, do this before pushing the car into the garage.

I can not overstress - painting is very easy once you've got the hang of it but 95% of the quality of the final result comes from the preparation work. If you need to spend another hour sanding a panel, spend that extra hour sanding it. Acrylic is very forgiving to poor preparation because you need to sand and buff it to make it nice, 2k is perfect off the gun, often it needs a buff a day or four after you've done the spraying but do not sand 2k after spraying it!!

Do not spray if the ambient temp is below about 23 degrees. Give it 25 mins between coats at 23 degrees and drop one minute per degree increase in ambient temperature between coats, to a minimum of about 12-13 minutes. Dont spray if its above about 35 degrees.

Acrylic paints harden by evaporation, such as most glue. 2k paints harden by chemical reaction such as a 2 part epoxy. They also evaporate but not to the same extent as acrylic which can dry in seconds after spraying. This means you HAVE to keep the place very dust free. Get the gurney onto the shed/garage the night before spraying.

The basecoat paint is mixed typically about 60% paint, 40% reducer, the clear is typically 60% clear, 35% hardener and 5% reducer. Increase the reducer if the temperature is hotter than 23 degrees, to a maximum of about 10% and 30% hardener. Measure each mixture to the last millilitre, get it spot on or your second batch of paint will have a different texture or color to the first batch. An assistant washing and mixing is a huge help, my GF hates me because she gets high on all the fumes :)

Cleanliness is your friend. Do it right and the result will be right. Take shortcuts and the result wont be bad, it will be terrible.



I'll post more when I think of it, on the other hand, ask questions...

Last edited by Bozz on Sun Dec 05, 2004 4:55 pm, edited 1 time in total.

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Posted: Sun Dec 05, 2004 4:47 pm 
Getting Side Ways
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Here is my first attempt at 2k -

www.fullysikmate.com/bozz/respray/blah.htm
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Posted: Sun Dec 05, 2004 4:51 pm 
Getting Side Ways
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More info I just thought of.

In addition to what I wrote before about acrylic hardening by evaporation and 2k hardening by chemical reaction, you may be aware you can leave acrylic paint in the gun for days without it going off, dont do this with 2k, it will harden into a solid mass in the gun. You have about 90 minutes to spray the contents of the gun.

Always wash the gun thoroughly, get heaps of gunwash, about $10 for 4 litres, use at least a litre per wash. Each time you clean the gun, disassemble it (most are easy and only have less than a dozen parts or so that you need to pull apart to properly wash them), then reassemble it and add a little gunwash to it and spray some gunwash as if you were painting, this gets the last traces of other stuff out of the gun.

Prepsol (was & grease remover) is your friend. Use heaps of it when prepping the body....
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Posted: Sun Dec 05, 2004 9:52 pm 
Smokin em up
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Hey Bozz I hope you covered your head and eyes while spraying 2 pak. It is a real deadly cancer causing lollipop smelling paint and if the windows of the house are left open it gets in and into the curtins. Its actually a EPA infringment to spray in backyard sheds . There is a place in Bayswater vic that hire spray booths. But yes its a hassel getting the car trailed there to spray. But at least the dust and bugs won't stick and if a neighbour dobbs you . A heavy fine might be on the cards or a warning 1st time. But otherwise the job came out well. The Buick in my avatar was sprayed in the shed 2 Pak. But one of the neighbours was complaining about a mist and smell. So the cars nowdays a trailered down to the booths when ready to be painted.

ghiaman
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Posted: Sun Dec 05, 2004 9:54 pm 
Getting Side Ways
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And you can get isocyanate free 2 pack paints as well, they are OK-ish to spray but are more expensive.

I wouldn't go near it otherwise.
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Posted: Sun Dec 12, 2004 11:08 am 
Parts Gopher
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Joined: 25th Nov 2004

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Location: Cental coast
NSW, Australia

I m resprying my rims silver metalic i wanted to spray them in 2pak but you cant get 2pak in metalic would i be able to spray the acrylic metalic on the rims then put a coat of 2pak clear over it would this make it nice and hard to with stand the elements of knocks and weather.

Thanks Dazza :lol:
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