Painting 101

So I'm about to embark on one of the most terrifying automotive journeys I've ever been on - painting a car.  Until now I've never done anything other than rattle can or paint walls in my house.

Now, I have the "it's a racecar" excuse as a backup for when it turns out like crap, but I came here for sage advice.  I've done plenty of Googling, and plenty of reading, but I'd love some first hand experience, because there is a lot of info out there.  For example, just about every video or message board post I've found about spraying primer are shooting it at 20-40psi, but the tech sheet for my primer (Nason SelectPrime 2k 421-10 - http://www.axaltacs.com/content/dam/NA/HQ/Public/Nason/Documents/TDS/NSN-TDS-421-10-Eng.pdf) says 7-9psi.  See what happens when you read instructions?  I've also been consulting with the shop I got my paint supplies from, but I'm interested in even more knowledge.

I have built a booth in one half of my garage, and I've almost finished surface prep in accordance with the tech sheet for the primer.  I'm planning on adding fans and making it positive pressure, but that's mainly so I don't die or blow up.  I do have a decent respirator.  My compressor is good enough, I've got a dryer in-line, and I spent a whole 80 bucks on some paint guns that are more colorful than the ones at Tractor supply.

So give me your best tips, most massive failures, and anything else that you think could help me!  I'm excited, but terrified.

I've done it a few times.. Don't think about it and just try it.  Start at the low end (7 PSI) and play with a scrap piece of metal until the primer is laying down pretty nicely.  If it's coming out splotchy, you either didn't thin it enough or don't have enough PSI for your gun/thickness.  If it's coming out powdery and not really adhering, you've got too much PSI for your thinned-level (is that a thing?).

Primer should look like a nice shiny smooth coat for a minute or two until it starts to set up.   If you're dripping, you're going too slow.  If you're getting really light dusty coverage you're either too far away (drying in air) or  you're going too fast.

Take a deep breath, you'll be fine :)

Spray according to your guns requirements/instructions. Do you know what kind of gun you have? HVLP LPHV or an old school mist-maker?

I have pressure readout right at the gun. The gun specifies a pressure at the gun, and you need to set it with the trigger pulled.

There is fan control and paint volume controls on the gun. I use masking paper as a set-up  test surface and make sure that it sprays a nice cigar shaped  one second blast.

Your gun provider will give you ballpark tip values for primer , base and clear. I have a primer gun and a good gun for the paint.

You can learn a lot if you fill your gun with water and practice painting the  a car. If nothing else it will give you an idea of how you are going to move around and keep control of the hose. And it is free. Use distilled water if you do.

Mixing cups and paint filters are your friends

Buy the proper panel-wipe for the job it removes grease and silicone. I tried to get away with lacquer thinner for this job once and it did not work.

Don't try to get a full coverage on the first coat.

Don't overthink this, paint is easy compared to prep. If you mess up somewhere, just go back and re-do it.

It takes me a week-end to spray base and then clear.

Pete

Spend about 10 times more on bodywork than you think is necessary.  Vaseline on your face beforehand will help seal the mask.  Pull lots of air hose around the car first, so you're not dragging it with the gun. 

Practice painting on something first.  Get a junkyard hood or something, set it beside the car when painting, use it to adjust your gun moments before spraying on the car.  

Ask the guys at the paint store lots of questions- they'll know best.  Use a few drops of Dawn in your wet sand bucket. 

I use a Tyvek suit and mask my shoes, along with a balaclava.  But I'm now a clean freak.   

Make double sure you have all the paint supplies needed before starting.  

Spray the difficult areas first, even if it is just a dry coat.  

Don't let the car sit in primer for more than a few days.  If it sits too long, sand back to metal z and reprime.  Primer absorbs moisture.  Don't let a bad undercoat ruin your paint job.  

Don't be afraid to cut and buff mistakes to fix them.  Don't try to fix a mistake by over spraying a section.  

If you're using clear coat, then the color coat is just that-color.  The color coat doesn't need to be a heavy, protective coat.  That's what the clear is for.  Just get your color on uniformly and even.  

Wetting your floor may help prevent dust and dirt in your paint job. 

Lots of good advice.  Pulling out plenty of hose was a really good tip. I’ve seen more than one good job wrecked by dragging a hose through wet paint.

The low pressure is probably for an HVLP spray gun.  The higher pressure is for standard a paint gun. 

Be aware that although the HVLP gun requires low pressure, it requires a lot of CFM.   So I heard.   

I did this again couple years ago - lots of good suggestions so far. 

A good epoxy primer won't absorb water, epoxy is one of the few finishes in life that is waterproof. I like  Southern Polyurethanes primer, a favorite of the hot rod crowd. 

It is possible to substitute time and effort for skill - if its not right, sand and respray. 

I think I left more paint on the shop floor than the car the first time, I've figured out since how to avoid orangepeel.

Single stage or base clear?

I've been wanting to ask this for a little while:

For those who are doing a little bit of metal work , and then epoxy priming that much at the end of the day, what is the work flow for using a two part primer? How do you efficiently mix a little bit, spray, and clean up? 

I've painted four complete cars, and lots of other stuff,  but never got involved with the epoxy primer situation.

As someone who is preparing to paint a car soon I also have questions. 

As I weld in sections and do repairs I am coating with a weld through primer or zinc phosphate self etching primer. Can these be topcoated with a two-part epoxy primer before paint or do I need to sand everything down before shooting primer?

In reply to coexist :

If it is not going to be a topcoat, you can mix and brush on epoxy primer. This is handy when you are doing your block sanding since polyester high build is not direct to metal approved.

You can also buy spray cans of epoxy primer, but you have to use the stuff pretty much the same day.

The SP primer I mentioned above has a 48-72 hr pot life. Gun liners help cleanup. 

I purposely stayed away from this thread since I posted it so I could get a few responses.  Thanks to everyone so far for the help!  If others have questions, jump in.  Let's make this a mega-thread.

Gun-wise, I'm using a HVLP setup from TCP Global
https://www.amazon.com/gp/product/B001N1E9Y8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Because I am painting the underside of the car (without a rotisserie) and portions of the roof, I added a DeVilbiss DeKups kit
https://www.amazon.com/gp/product/B003JD5JQK/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

If you want to use that kit with those guns, you have to get a different adaptor directly from TCP Global
http://www.tcpglobal.com/DEV-DPC-11_2.html

I am shooting single stage for a topcoat.  There will be a layer of LizardSkin on floor pan/rear firewall panels too.  The actual plan is to prime the entire car, inside and out, and then topcoat the underside/chassis/interior, leaving the outside in primer.  I'm going to then assemble the mechanicals and make it a running driving car before painting the outside.  I know this means more sanding and a re-prime, but there may be tweaks to the outer body before it's "ready" for paint.

I know I'm totally overthinking things, but you've already caught some stuff I didn't think about.  Shooting distilled water, for example, is a great idea!

Keep it coming!

Biggest mistake i see people even some pro's do  is not keeping the gun nozzle even with the surface, unless your trying to feather in repair work you don't want to lok the wrist and swing from the elbow.  Doing so will caise heavy coating in the middle and light on the sides. Yuo want to use your wrist to maintain the parallel and distance to the panel.

Buy a roll of brown paper and hang it up and practice, this will help you set the gun flow and nozzle setting up as well.

2nd)  If your doing a whole car try to mix your paint  and you've sett aside 2x the time you think it will take.

3rd) If you bought paint in quart cans mix both quarts in to one larger can so there's no variation in the color.  A new 2.5 gallon gas can works good this way you have room for the thinner  and hardner.

I have another stupid question!

It was mentioned earlier that I could spray distilled water through the spray gun to get used to using it/set it up.  What about spraying wax and grease remover through it, and having someone else wipe it as I go?  That would help me prep the surface, and give me practice.  Thoughts?

In reply to Gimp :

I don't see this as an issue. I was more thinking that you could be practicing on the DD sooner rather than later. If you maybe want to strip the wax off and put a new coat on, even better!

What you want to be getting the feel for is what 44 Dwarf mentions, keeping the gun a fixed distance from the work and not doing a curved sweep.

The other thing to practice is the half overlap; every time you make a pass with the gun you want to half overlap the last one. I was trying to figure hour to use a laser pointer to guide me in this.

Knowing how you are going to be working around the car is a good idea, best not to be making it up after you start spraying product. If you are going to need a step to do the roof, figure it out ahead of time or find a tall friend.

I have been told to ground the car. Never tried it so I cant say if it is worth the effort. I could make an argument for doing so, but its just theory.

EDIT

If you DO use panel wipe to practice, you will have a great chance to qc your bodywork. Since the wet panels are going to look just like a clearcoat finish, if you check the panels with a reflected light you will see any imperfections the same as you would in the actual clearcoat..

coexist said:

For those who are doing a little bit of metal work , and then epoxy priming that much at the end of the day, what is the work flow for using a two part primer? How do you efficiently mix a little bit, spray, and clean up? 

What you will do is use a lot more paint and primer than you would if you did it all at once.   I painted my Spitfire a little bit at a time because I did it over a period of years.  If I was painting only a little stuff, I used a jamb gun.  I got pretty good and figuring out how much to mix up.  I used a larger gun when I did the exterior panels or larger parts.    

I would clean up using cheaper wash lacquer thinner, not the stuff you would actually use in paint.  The cup system will help immensely.   

From my limited, one time only experience painting a car, you're going to want more light and more sand paper. 

I spent more on sandpaper than primer, paint, spray guns, air dryer, simple green, and tack cloth combined. 

I took everything apart to prime, then put it together again before paint. That was really stupid, because there are places like the door side of your side mirror they are really difficult to paint properly when on the car. 

Practice first. A spare hood from the junkyard, the side of your carport, anything metal and not the car to find a good rhythm and pattern. 

Leave the windows in the doors and paper over them. Trying to hang paper over such big gaps sucks. 

And for big spots, try to do it all in one pass, because this seam is ugly. 

So, step one is done! https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1981-camaro-c-prepared-build/59501/page26/#post2505302

I have, in theory, successfully primed the whole car.  This was WAY harder than physically than I imagined, but I'm glad to have that bit done.  Now I'm moving on to the next bit and I have some questions.

I'm going to coat the floor and firewall panels with Lizard Skin.  According to them, as long as the primer is fresh, I can apply it right over top without sanding.

I'm also going to paint the chassis/interior after I do the coating.  The instruction sheet for the primer I used said I have to sand with 320-400 before paint.  Is that just so I smooth out the 2k primer, or could I have adhesion issues if I don't sand the primer?