I want to learn to paint with a spray gun

[szacsi72]

I need to repaint my engine bay and I want to do it properly. Of course I will try on something else first, but still.
It's zinnober, meaning one stage (acrilyc?) paint.
Could anyone recommend me nozzle sizes, pressures, thinning ratio? Does it matter where I buy my paint from?

Thank you.

[York]

A recent innovation in automotive paint supplies is the
Made to order spray can.
These are not the old fashioned rattle cans from Home Depot
A good supplier can make any color and place in spray can.
They also have cans with two component, bases and clear coats.
Nozzles in wide or narrow that turn fan direction you want
Plus spray upside down.
My sorce is Glue Products, Inc in west Palm Beach, Florida

[szacsi72]

I did try them, but it's just not the same quality. There's not enough pressure and I get too much orange peel.

[Federico]

As for nozzle sizes, base coat/clear coat usually ranges from 1.2-1.4, single stage 1.4-1.6, primer 1.8 usually.
Thinning ratio: usually you start at the manufacturer's recommended ratio and then add if necessary. i.e: you can totally spray single stage with a 1.3 If you add some extra thinner. Heck! I've airbrushed base/clear for smaller repairs, LOL.
The drawback of cheating by adding reducer is you have to make thin coats and it takes time.

[Chimi-Changa]

If you do try the cans, i always heat them up in a bucket of hotter water for a little while. Paint comes out as a fine mist and less globing potential.

[EuroShark]

I've painted a few motorcycles and some race car body parts using cheap HVLP guns and it went pretty well. I remember shooting at about 30psi with a 1.4mm nozzle for primer and 1.2mm for the base and clear, but depending on the gun and the material you're spraying you may need to make adjustments. You can make adjustments on the gun to the shape of your spray pattern and the mixture of paint vs air.

For an engine bay you probably won't need a massive compressor, but if you've got a small compressor you will end up spraying for a bit and then pausing while it catches up. This may not be a big issue but keep in mind you want to maintain a "wet edge" while you're spraying a coat of anything, especially color and clear. There are products that can be added to the paint to speed up or slow down the curing process if necessary.

You will need a decent filter. Any oily blow-by or moisture from the compressor will cause big problems so you need to make sure you have a very clean and dry supply of air.

Prep is genuinely 95% of a good paint job. You'll spend twenty times as long on prep as you will shooting paint, but its worth it because the paint will amplify any ugliness underneath. If you're using clearcoat you can sand and polish lots of mistakes out of it. Single stage is trickier.

Autobody101.com is a great forum with tons of valuable information. I learned just about everything I needed to know from the members there. I can't claim to be an expert but I think my projects turned out pretty well.

[szacsi72]

If you do try the cans, i always heat them up in a bucket of hotter water for a little while. Paint comes out as a fine mist and less globing potential.

That's a good tip! But unfortunately I'm still not satisfied. Plus, it's "just" an engine bay. That's a good place to learn, I think.. better than the roof!

I've painted a few motorcycles and some race car body parts using cheap HVLP guns and it went pretty well. I remember shooting at about 30psi with a 1.4mm nozzle for primer and 1.2mm for the base and clear, but depending on the gun and the material you're spraying you may need to make adjustments. You can make adjustments on the gun to the shape of your spray pattern and the mixture of paint vs air.

For an engine bay you probably won't need a massive compressor, but if you've got a small compressor you will end up spraying for a bit and then pausing while it catches up. This may not be a big issue but keep in mind you want to maintain a "wet edge" while you're spraying a coat of anything, especially color and clear. There are products that can be added to the paint to speed up or slow down the curing process if necessary.

You will need a decent filter. Any oily blow-by or moisture from the compressor will cause big problems so you need to make sure you have a very clean and dry supply of air.

Prep is genuinely 95% of a good paint job. You'll spend twenty times as long on prep as you will shooting paint, but its worth it because the paint will amplify any ugliness underneath. If you're using clearcoat you can sand and polish lots of mistakes out of it. Single stage is trickier.

Autobody101.com is a great forum with tons of valuable information. I learned just about everything I needed to know from the members there. I can't claim to be an expert but I think my projects turned out pretty well.

Thanks, lots of good information here!
I've got a really big, 80L V2 air compressor. I think it's pushing something like 400-500 liters per minute..?
I've done tons and tons of rattle can jobs, so I'm already good with the preparion. I just never held a gun in my hand. Probably won't be that much different...

I have a spare front wing, might try that first.

[mewherman]

I have painted several cars and motorcycles but am not an expert by any means, autobody has a very steep learning curve. That said I think if you are considering painting it with rattle cans It is definitely worth the upgrade to use a spray gun, if you paint lots of things it is cheaper in the long run, as long as you thin your paint out you can simply buy cans of paint at the hardware store and thin it with lacquer and spray it. It's how I've painted my last few engine blocks and it's worked out much better than $100 worth of rattle cans.

If you are using a spray gun you need a compressor to match it, the gun you choose will have specs as to what CFM is needed and you will be best off exceeding that CFM to spray appropriately. You will also need dry air, so you will need filters for your gun as well as an air/water/oil separator set up, it's no good spraying paint full of oily water. Buy the best spray gun you can afford, the difference in finish quality for a cheap gun vs even a semi-pro gun is massive, some of the cheap guns I've tried are no better than brushing the paint on.

Most quality paint guns will come with several different tip sizes, the tech sheet of your paint should have a recommendations of tip size, typically larger tips are used for primers and smaller ones for clear and top coats. The same goes for your mix ratios, your paint supplier will have all the information about how the paint is to be mixed and applied.

[Mike W.]

I have painted several cars and motorcycles but am not an expert by any means, autobody has a very steep learning curve.

That is the understatement of the year. I too have painted several cars and parts on others, but my spraying technique leaves much to be desired. I finally broke down and bought what I think is a decent gun, and at first I thought, wow, what a difference, but still disappointing. I'm great with rattle can, my prep is super, but my spray technique is not. Maybe it's still my gun, some say it's easy, but I don't think so. Might just be me...

[mewherman]

I have painted several cars and motorcycles but am not an expert by any means, autobody has a very steep learning curve.

That is the understatement of the year. I too have painted several cars and parts on others, but my spraying technique leaves much to be desired. I finally broke down and bought what I think is a decent gun, and at first I thought, wow, what a difference, but still disappointing. I'm great with rattle can, my prep is super, but my spray technique is not. Maybe it's still my gun, some say it's easy, but I don't think so. Might just be me...

I find the prep work to be the most difficult part, I am terrible at sanding and masking at least in my own opinion. I just don't have the patience to follow through on the prep work. I prep until I get bored and then paint things. There are some issues I've had consistently that I just don't know how to solve or what I am doing wrong. I almost always have some sanding marks on some minute part in the final product despite sanding to 400 exactly as it says and I find it impossible to get all of the fine scratches out when polishing, I have to choose between some orange peel or some fine scratches.

Generally I find that I make small mistakes every step of the way and then try to cover for those mistakes instead of starting over because who wants to start a 50 hour process over again and this compounds upon the final product. That said I am probably being hard on myself and I've had compliments on my paintwork, but I know to an actual pro it probably doesn't look great.