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Who wants to school me on paint gun basics?

I haven't painted anything that moved with a spray gun for about 10 years and that was I think a forklift with enamels. I think I painted a conveyor about 5 years ago. So I need some tips for spraying 1K and 2K acrylics on aluminium and steel car panels.

What's the story with gravity feed vs suction feed? I've only ever used suction feed guns.
How many CFM is required in a compressor to comfortably spray?
Can 1K produce a durable finish or will it have issues over time with no mechanical damage?

Go ahead and hit me with any other advice. I want to get something done over Christmas.
 

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I was planning to use 2k on my 46 Dodge project until I started looking at the health risks. Unless you have a booth and a forced air supply mask, I would recommend having a pro spray it for you. Isocyanurate poisoning is nasty!
 

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Yes the risks of isocyanates are a factor to weigh up. I have access to the breathing gear and open spaces to paint. But if 1k acrylic will hold up it might not be necessary.
 

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Who wants to school me on paint gun basics?

I haven't painted anything that moved with a spray gun for about 10 years and that was I think a forklift with enamels. I think I painted a conveyor about 5 years ago. So I need some tips for spraying 1K and 2K acrylics on aluminium and steel car panels.

What's the story with gravity feed vs suction feed? I've only ever used suction feed guns.
Modern painting is done with HVLP (High Volume Low Pressure) guns. From what I have seen they all appear to be gravity feed. My guess is the low pressure air cannot create enough suction to run a suction feed. Anyway, I spray with an old, but expensive at the time, DeVilbiss suction-feed conventional if the paint job has to be first-rate. For primers and routine painting I have a cheap HVLP (gravity feed). It doesn't spray as nice as the DeVilbiss, but it wastes MUCH less paint and still does a respectable job. I've got my eye on a DeVilbiss TEKNA Pro, but not sure if I can justify spending the money (about $800 US) when I only paint a few times a year tops.

Also, base/clear and single stage are usually sprayed with 1.5 tips, while high build primers are usually sprayed with 1.8-2.2 tips. However, if you're like me and don't have multiple tips you can just thin down the high build to clearcoat viscosity and spray more coats.

How many CFM is required in a compressor to comfortably spray?
Not really sure. Go to a spray gun manufacturers site (DeVilbiss, Iwata, Sata) and see what they recommend for their HVLP guns. Conventionals (or a modern gun with a conventional-type air cap) use more air vs HVLP. At least, that's the case I have found with my two guns.

FWIW, I have a 5HP single-stage compressor and it keeps up fine.

Can 1K produce a durable finish or will it have issues over time with no mechanical damage?
1K covers a whole spectrum of paint types. Old-style lacqeurs, synthetic enamels, and uncatalyzed acrylics are not as durable as 2k acrylic enamels, let alone 2k urethanes. Some of the moisture-cured paints are quite tough, but they are slow-curing and don't give the shine of an automotive finish. They are more of an industrial paint.

My recommendation is to stick with 2k urethanes for paint, and 2k urethane or epoxy/urethane hybrid for primers. Most paint manufacturers have several lines: the cheaper paints like PPG Omni, Western (Sherwin-Williams) Dimension, Axalta's (formerly DuPont) Nason brand, and BASF Lemco are fine paints but they will succumb to UV in 5-10 years. The better stuff like PPG Deltron, Sherwin Williams Ultra, Axala Imron (single-stage) and Chroma (2-stage) and BASF DM or Glasurit are higher end paints that should give a long-lived finish. These are all urethanes BTW - I haven't shot acrylic enamels in decades.

Oh, and I agree with canlib: get a forced air supply hood. Isocyanates are powerful sensitizers and they WILL screw you up. I actually use a dual cartridge respirator, but unless you KNOW the respirator will work with isos AND you change the filters frequently I wouldn't recommend one. The main hazard with them is that if the filters get loaded up you will get exposed to isos BEFORE you smell the paint solvents and realize you are being exposed. I store mine in a zip-loc bag and change the cartridges after only an hour of spraying. When I buy a new gun I plan on buying a fresh air hood at the same time. The cartridges I use cost $80 a pair, so the hood will pay for itself after only a couple hours of painting.
 

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Thanks guys, that's a great help.

So for this job the car restorer down the road said if I prep them then he'll be able to paint them with the 2K quick and easily. The 2K is Axalta Centari. I'm after a finish that looks okay from 6 foot. Previously it was 60 foot and only if you squinted. So that's an easy way out for me.
One corner of this vehicle was touched up with Glasurite by a panel beater about 10 years back and that paint has held up fine. We have particularly harsh UV but the vehicle is off-white which probably helps. The original 30 year old paint is completely buggered and these are the two worst panels.

So next question.
What would be recommended for paint and application method for a shipping container? Colour will be something like the light stone or earth yellow, essentially a sandy yellow brown: https://www.e-paint.co.uk/Lab_values.asp?cRange=BS 381C&cRef=BS381 361&cDescription=Light stone


Looking for matte finish with the least special prep.
 

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Thanks guys, that's a great help.

So for this job the car restorer down the road said if I prep them then he'll be able to paint them with the 2K quick and easily. The 2K is Axalta Centari. I'm after a finish that looks okay from 6 foot. Previously it was 60 foot and only if you squinted. So that's an easy way out for me.
One corner of this vehicle was touched up with Glasurite by a panel beater about 10 years back and that paint has held up fine. We have particularly harsh UV but the vehicle is off-white which probably helps. The original 30 year old paint is completely buggered and these are the two worst panels.
You may want to price out a mid-grade 2k single stage urethane like Nason. I haven't priced out acrylics in a long time, but I can't imagine them being that much cheaper than a mid-grade urethane. I could be wrong though :confused:

[question]So next question.
What would be recommended for paint and application method for a shipping container? Colour will be something like the light stone or earth yellow, essentially a sandy yellow brown: https://www.e-paint.co.uk/Lab_values.asp?cRange=BS 381C&cRef=BS381 361&cDescription=Light stone


Looking for matte finish with the least special prep.[/QUOTE]

All paint manufacturers have industrial lines. Make sure it is UV stable though; not all industrial paints are designed for outdoor use.

Prep wise, no idea without seeing it, but I'd guess having someone to sandblast it? Application can be done with a regular spray gun (assuming the paint viscosity is compatible with your tip) but you will quickly tire of filling the cup. Best bet would be a pressure-fed gun that uses an external reservoir. It's possible some types of industrial paint are even usable in an airless sprayer like the type used for spraying house paints. I'm pretty ignorant on industrial painting so that's about all I have...
 
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