uncertain on technique for urethane topcoat on a car

[myredracer]

Will be painting a car in our driveway next month. The body is in primer (high-build over epoxy) and need to do a little touch up here and there where I sanded through to bare metal. I'll be using Nason 2K single stage urethane paint and an Astro Pneumatic HVLP gun with 1.3 mm nozzle. The car body is about the size of the new Fiat 500s and is the entire exterior (except underbody) and some of the interior.

https://www.axalta.com/content/dam/...ents/TDS/NSN-TDS-Ful-Thane-IS-Quality-Eng.pdf

I can't seem to find any info. on where to start on the body and where to keep moving the gun and what time I have regarding flash time and recoat time. I will be overlapping each pass 50%. The trunk & engine lids, doors and engine support panel will be painted separately.

Should I start on the roof? What happens as I move around with the gun - do I have to keep flash time in mind before I say move the gun from one end of the body to the other? Or can I just keep going as needed to get the paint on everywhere? Should I pre-plan where to start and have a pattern to move the gun so I don't apply paint over some of it before it has flashed?

Maybe I'm overthinking it? Maybe it's a case of just keep moving the gun and timing isn't really an issue? Is stopping say 5 minutes or so to mix more paint a timing issue? With the cost of paint I don't know if I should pre-mix more paint and risk having too much left over?

How long do I have before I apply a 2nd coat? Before the tack-free air dry time of 45-60 minutes?

Should I do the interior or exterior separately and mask them off so I don't get overspray where the paint has dried?

I painted our truck canopy a few weeks ago with the same paint so have a little experience of what it's like. Turned out sort of okay but I used a cheap HVLP gun and I need to sand out a couple of runs and some minor orange peel.

Thanks!

 

[astroracer]

Your paint supplier will be able to give you the spec sheets for both paints. These will include best practices for getting a good spray job. Also look on YouTube, tons of videos and how-to's out there.
Mark

 

[steveo3002]

id paint the interior let it dry then mask off the windows ...doing all of it can be too much and risk of dust blowing out onto the good bits or airline touching the car

i would start half way up the door pillars then work the center of the roof , go around the oter side carry on from the center down to the pillars ..carry on and do that quarter panel and go around the back of the car

wait times will vary depending if its hot as hell where you live , often you can refill the gun and keep going ...my test would be touch the masking paper , its ideal when you just leave a thumbprint and dont get color on your finger , 10-15 mins is typical in moderate climate

 

[astroracer]

Start in the center of the roof. Do both sides then start working downward from there. Starting in the center keeps the air hose out of fresh paint on the sides of the car. Also, looping the air line up, over your shoulders and then out to your gun hand will keep the line out of your way and off the paint. Control the rest of the line and keep it out of the way with your free hand.
Mark

 

[Jazz1]

First I paint door jams, fender arches and any other area where you cut in. Then start at center of roof where the rest of the coat will be long even strokes. Overlap each stroke
YouTube has many short tutorials.

 

[Wrench97]

Years back I did a lot of outside painting, spring and fall are the best around here, the sun, bugs, dust, birds and humidity are your enemy. Newer paints do seem to be as forgiving when you try to extend or speed up drying times. Do not premix what you can not use for a single coat if you run into trouble the timer on the paint keeps ticking, in the sun light the top(roof, hood, trunk) are going to set up a lot faster then the sides I have always divided the inside and the outside do not try to do both at the same time. I found that by the time I was done spraying the first coat and mixed the paint for the second the roof was ready to be recoated so basically I just kept on painting

 

[myredracer]

All excellent info., thanks. I'll do the interior and exterior separately. It's not like the paint doesn't dry quickly anyway. Starting on the center of the roof makes sense so the hose stays away from the surface.

 

[HMCFab9]

If it's Hot out....you're going to have a rough time keeping it all wet, especially if the sun is shining on it.
At the very least, I'd do it under some kind of canopy.

 

[myredracer]

If it's Hot out....you're going to have a rough time keeping it all wet, especially if the sun is shining on it.
At the very least, I'd do it under some kind of canopy.

Agree. I will be on the shady side of the house in late afternoon. I have a frame setup I've used for media blasting in the driveway and could use some sheet plastic on it. One thing I am concerned about is isocyanate and want plenty of ventilation since I don't have a self-contained breathing setup. Enclosing the area with sheet material could make it riskier.

I'm hoping for an overcast day with good temps.

 

[don long]

You will definitely want / need some type of respirator when spraying

You should do the interior one day and the exterior the next or even two days later so the masking tape will not mark the new paint. If you are not in a big hurry and are a novice painter you might think about painting the roof of the car separate from the rest of it so you won't be in such a panic to get the paint out of the gun.
When I paint a car I start at the Right 1/4 panel at the door edge.
That is the least looked at part of the car and so if you have a dull spot from paint drying too fast that is where you want it.

Most important thing to remember is to relax, make smooth even strokes and stay on one panel at a time.

Good luck

Don

 

[jiminlakela]

Do the jambs etc first then get the car ready to spray if it is hot you won’t have time to get around the car without over spray just paint the outside by itself if you don’t have a booth you will be working to get around it before it is dry pay attention to the mask you are using a real mask with good filters the 2 part paints can be quite hard on you in theory you should have a air supply respirator just take your time and be smooth




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[ncboat]

As an aside having painted large boats outside check the temperature of each side. Depending on the position of the car you can have different substrate temperature. The right speed on one side can be to fast or slow in the other side.