How to paint a car with a spray gun is something you should have first on your “to Learn” list. Why is that so important?
Well, we often look at cars and admire their appearance in design, brand, shape, upholstery, suspension, etc.
However, the first thing you’ll always notice about a car is its color; it often makes the car look sleek and refined.
The color is obviously due to paint, and the painting process is an art in its own right.
There are numerous methods of car painting, but we’ll take a closer look at how to paint a car with a spray gun.
The process involves putting on safety gear and removing materials not needed around the working area to create more room for ventilation.
You should follow the above step by sanding the body of your car. Taping to protect areas that won’t need paint should follow next.
The next step is to set up the spray gun to work effectively and per your needs.
After you have set up the spray gun, start by first priming over your sanded body. Have your paint mixed and ready then do the painting.
Normally, I advise that you spray paint as per the manufacturer’s guidelines on the paint label.
I’ll give detailed information about the procedure a few paragraphs down the article.
Before then, I’ll give you a smooth transition into the above topic by defining a spray gun, the types, and its advantages.
After the procedural segment, I’ll give a brief writeup on the following:
- The most optimum spray gun pressure for painting a car
- The number of cans you need to spray-paint a car completely
- The best compressor size for spraying cars
- How to paint a car without a compressor
- The practicality of painting a car with a 30-gallon air compressor
- How to mix paint for a spray gun
I urge you to stay focused throughout the discussion; it’ll serve you well in all your car painting projects, and you’ll be able to handle all related situations with panache.
What Is a Spray Gun?
There are various ways of applying paint. They include brushing, dip coating, spraying, rolling, flow coating, etc.
In congruence with the article’s heading, let’s look at a paint spraying machine called a spray gun! What exactly is a spray gun?
A spray gun is a device that disperses coating materials (varnish, paint, ink, etc.) into a mist that lands on the targeted surface.
The most common models use either pressurized/compressed air or hydraulic pressure systems to disintegrate and channel the paint.
Spray guns are an improvement of airbrushes; you can tell the two apart using their size, handling, and spray patterns produced.
Airbrushes are handheld and ideal for detailed painting jobs, as in fine arts and photo retouching.
Spray guns are bigger and often cover large surfaces like car bodyworks, kitchen cabinets, metal sheets, walls, etc.
Spray guns have interchangeable heads/tips that produce varying spray patterns and can be handheld or automated.
Pros of Spray Gun
There are many forms of spray painting; the spray gun is more popular due to its unparalleled benefits.
Here are some of the advantages of a spray gun:
- The technique is less messy
- Spray guns produce even coatings and leave no brush marks
- This tool allows you to dial in your desired pressure for painting
- It leads to low production costs
- Spray guns need less effort than other painting tools because it is motor-driven
- The atomization of paint by a spray gun speeds up the drying times
- It can easily paint on rough and smooth surfaces
- The machine covers large surface areas per unit of time; this enhances timely project completion
- A spray gun enables you to achieve several spray patterns by changing the tips and manipulating the fan control
- The machine is ergonomically designed for comfort and a delightful user experience
Cons of Spray Gun
- The machine results in an orange peel finish from excess paint application, incorrect machine setup, and rapid solvent evaporation.
- It wastes paint and pollutes the air due to overspray.
- Spray guns are efficient only under calm weather; wind or even a light breeze exacerbates the overspray problem.
How to Paint a Car With a Spray Gun
We’re now at the article’s focal point that arguably needs utmost attention.
If you’ve skipped the preceding segments, I advise you to scroll back up and read them; they contain crucial introductory information that will simplify your understanding.
Here, I’ll give a step-by-step guide on how to paint a car with a spray gun.
- Sandpapers: 80, 180, and 240, 320, 400-grit
- Sanding machine: orbital sander, disc sander, or palm sander
- Body filler
- PPE: gloves, respirator, safety goggles, protective suit
- Painter’s paper: 18″ by 750 ft roll
- Painter’s tapes: three-quarter inch roll and two-inch roll
- HVLP or an air paint gun and filter
- Compressor and regulator
- Mixing cup and paint filters
- Paint, reducer, & catalyst
First, remove all the materials you don’t need in your working station or garage; this creates more room and aids ventilation.
Then, wear your PPE (personal protective equipment). For now, you can only put on the respirator and safety goggles.
Start the first sanding phase using 80-grit sandpaper on a handheld or disc sander. Wipe off or vacuum the accumulated debris.
Using a sanding machine will save you a lot of time and effort, given that you have four sanding cycles.
Next, mount 120-grit sandpaper and sand the car body again. Remove the accumulated debris.
Continue changing the sandpapers as you move the grit size to the highest grit number.
When using the 400-grit paper, do wet sanding to avoid obstruction from the resulting debris. It enables the abrasive to work smoothly.
Wet sanding also cleans the car in readiness for the next stage.
Dry sanding at this stage is challenging due to obstruction from accumulated dust.
Next, wipe down the car to remove any residue in preparation for the next step.
Taping Off the Car
Cover up all the exterior car parts that don’t need painting.
These include all the headlights, windows, taillights, and mirrors.
Use the large painter’s paper to cover and the smaller painter’s tapes to hold the paper cover in place.
Cover the larger seams directly with the two-inch tape and use the three-quarter-inch one for small seams.
Mask the wheels using hard polythene papers, if present, or just use the painter’s paper roll.
Also, cover the surrounding garage equipment and floor to prevent accidental splatters/paint spills.
Setting Up the Spray Gun
Before preparing your spray gun, I’d like to share some vital information; a siphon-feed spray gun wastes a lot of paint.
It is due to its operating mechanism.
The paint holder is located below the nozzle; the machine sucks up paint and delivers it to the nozzle directly.
I, therefore, contraindicate it for spray painting.
Instead, I encourage you to use an HVLP spray gun for the above undertaking.
The paint cup sits above the nozzle, so it’s gravity-fed. Its operating mechanism ensures less overspray, less paint wastage, and minimal environmental pollution.
The spray gun has four key adjustment knobs that you should set up for correct usage.
They are the horn/nozzle adjustment, fan control, paint volume control, and air volume adjustment.
I’ll cover the above controls in the test-run section that’s only a few steps below. It’ll make more sense when they come after paint mixing.
The only control dial I can highlight here is the regulator. It isn’t always a part of the spray gun.
The regulator is usually attached to the air compressor, bought separately from the spray gun.
Regulators control and measure the air pressure that comes from the compressor, and they are calibrated in PSI (pounds per square inch).
Other than the one that comes with the air compressor, I advise you to purchase an external regulator and attach it to the air inlet valve close on the spray gun handle.
It enables you to know the exact air pressure used for paint atomization.
I say so because the air pressure measured at the compressor usually is lower when it reaches the spray gun, especially when using long hoses (50 feet and above).
The second reason to buy an external regulator is that it enables you to attain air pressures specified for the spray gun if the air compressor operates at high pressure ranges beyond the HVLP gun.
Attach the external regulator to the spray gun inlet. This attachment obviates the need for using the air volume adjustment.
Next, connect the spray gun to the air compressor and power the machine.
Tune the pressure to the recommended range for painting cars.
You can only make this adjustment when the machine and compressor are running.
The optimum air pressure range for most HVLP sprayers is 20 to 30psi.
When you get to the specific mark, switch off the machine and don’t interfere with the setting because you’ll use this pressure for the final painting.
If the pressure is too high, there will be too much overspray and a high paint rebound effect, leading to paint wastage.
If the pressure is too low, there will be insufficient atomization, and the machine will discharge larger paint globules.
It results in droplet-like patterns, which are pretty unsightly on a supposedly painted car.
The next stage involves mixing the paint. Let’s march on.
Before handling the paint, ensure you have on the respirator, safety goggles, and gloves. Put on the safety/protective suit as well.
Open the paint can and pour it into a mixing cup/container.
Remember always to close the original paint can to avoid loss of solvents or contamination from outside sources.
Add thinning agents or reducers as you stir to get the most optimum consistency for your project.
Then, strain the resulting mixture through the paint filter into the spray gun’s paint cup and close with the lid.
The next stage involves testing out your spray pattern!
The Dry Run
Use a scrap piece of material for the test run, preferably a metal sheet, but you can use cardboard if the metal sheet isn’t nearby.
I prefer a metal sheet because it resembles the target substrate, i.e., the car’s bodywork.
Mount the paint-filled cup to the spray gun to begin the trial. Fine-tune the following controls/adjustments when testing out:
The nozzle control/horn: It’s found in the airhead area (front part of the gun).
Adjust it to control the orientation of the paint stream; it lets the paint spread out horizontally or vertically.
Fan control: This is located behind the paint cup at the rear end of the gun. It regulates the shape and broadness of your spray pattern.
If it’s closed/screwed in, you’ll get a concentrated and narrow circular pattern.
The further you open/screw it out, the wider or more fanned out the paint pattern gets; the finish also goes on lighter.
The fan adjustment determines the paint coverage. If you are painting the broad parts of the car, you should pull the control further out.
When you get to the smaller or intricate parts of the car, tighten the fan control for a narrow pattern.
The paint/fluid adjustment knob: It’s located immediately below the fan adjustment.
It controls the amount of paint that comes out of the paint holder. The further out it is, the more the paint is released.
If you screw in the above adjustment too tight, little paint comes out. It leads to disproportionate air mixing and will go lightly on the surface.
Consequently, you’ll need to go over the surface several times to get a decent coating, which wastes time.
Loosening the knob too much will lead to excess paint discharge; this gives you less control, paint runs, and causes wastage.
From experience, it’s always better to add paint than to remove the excesses, so I urge you to tune the control from tight to lose.
The air adjustment knob is found at the lower part of the HVLP gun handle. It regulates the air supply.
Since we’ve bypassed the air control with an external regulator, it won’t be useful.
Do not adjust the regulator pressure because we had already dialed in the required settings earlier during the spray gun setup.
It’s best to make the above adjustments when testing on scrap metal, not on the car. After you’ve tuned everything to perfection, proceed to paint the car.
Hold the HVLP sprayer 8 to 12 inches from the substrate when spraying the car’s bodywork.
Ensure the machine’s nozzle is perpendicular to your target.
The best spraying technique is moving your hand a few seconds before pulling the trigger and staying in motion a few seconds after releasing the trigger.
It prevents the collection of paint on the surface at the end/beginning of each painting cycle; the paint collection is due to paint spitting by the machine when you pull or release the trigger.
I also advise that you do 50% overlaps when painting to avoid missing any part and for sufficient paint-substrate interaction.
For the first coat, I recommend that you go lighter. It enables you to prevent paint runs and makes it easier to correct any mistake.
Remember, making amends on a lightly painted surface is easier than on a heavily painted one.
After spraying the first coat, let it dry for the recommended time, then apply a second and a third coat.
Lay down the last two coats a little thicker than the first and let them dry too before the next step.
Afterward, remove the painter’s paper and tape from the car and other covered materials in the garage.
That’s it! Just follow the simple steps above, and everything will pan out well; you’ll have a newly-painted car with an excellent durability profile.
Critical post-painting management practice is cleaning up. It’s a different ball game that needs a detailed approach because you’re dealing with a spraying machine.
Take a look at the abridged process in the following segment.
It’s best to clean the HVLP gun immediately after painting. During the said time, the paint has not yet dried/hardened in the cup and the internal parts.
The paint removal agents (mineral spirits and water) can easily detach the paint residue.
First, you need to empty the paint cup, pour the paint into a clean, empty container and close it.
Store this residual paint for future use. Do not discard by spraying into the air, pouring to the ground, or drainage systems.
It causes environmental pollution, and you may be culpable for breaking your local waste disposal regulations.
If you don’t need the paint, it’s a good idea to give it to neighbors/friends, take it to paint recycling plants, or seek counsel from the waste-disposal department of local authorities.
Next, fill the paint cup halfway with an appropriate solvent (warm water if the paint is water-based or mineral spirits if it is oil-based).
Swirl the liquid in the cup and pull the trigger to release some of it through the nozzle. Pulling the trigger cleans out some of the paint stains inside the gun.
Pour out the remaining liquid in the paint cup into an external drainage system; you can dispose of it in the said manner because it contains highly diluted paint material.
Next, unscrew the paint cup and wipe the inside and outside with a rag soaked in the same paint thinner you used above.
Then, undo the gun’s external air cap (the horn) and dip it into the mineral spirit.
Afterward, unscrew the paint volume adjustment to remove the gun needle and immerse the said needle into the mineral spirit-filled container.
Be careful not to lose the spring that moves the needle back and forth; set the adjustment knob and the spring aside.
Next, remove the internal air cap using a wrench; most guns will always come with a wrench meant for the above undertaking.
Dip the above air cap and what’s left of the gun into the paint thinner.
Let the machine and its parts stay submerged in the cleaning agent for about 40 minutes.
Then take s specialized brush for spray gun cleaning and scrub the parts and their internals lightly as you rinse with the paint thinner.
The special cleaning brush is widely available in a kit that contains several sizes and designs that are pretty cheap.
The kit also contains a special liquid for lubricating the needle and other parts when reassembling the gun.
Lastly, wipe the gun and its parts with a paper towel and put it back into one piece. That’s all it takes.
Cleaning up is a relatively simple process that doesn’t take much time and is often disregarded.
It’s, however, quite crucial as it maintains the integrity of the gun for subsequent projects.
If you store the gun uncleaned, the paint will dry inside, clog the tip and undermine the spray quality the next time you use the machine.
Here’s a Video On How to Paint a Car With a Spray Gun:
Best Spray Gun for Car Painting
If you care about your car, it’s good to give it top-grade treatment in every aspect, including painting. Here is my recommendation for the best spray gun for car painting:
DeVilBiss STARTINGLINE HVLP Spray Gun
The above is an HVLP spray gun manufactured by DeVilbiss Automotive Refinishing Company.
The company manufactures airbrushes, spray guns, and associated products. It was founded in 1907 and is headquartered in the US state of Arizona.
The spray gun in question comes with these exceptional features and advantages:
- It has an excellent paint transfer rate (above 80%)
- The machine produces minimal overspray, thereby economizing the paint.
- DeVilbiss spray gun has a 600-milliliter plastic cup that holds enough paint to cover an entire car without refilling.
- It has four adjustment knobs that enable you to tune the machine for the best spray pattern; the controls also make the sprayer easy to use.
- This air sprayer comes at a pocket-friendly price relative to its output.
- DeVilbiss air sprayer uses low pressure to discharge sufficiently large paint volumes for a top-quality finish.
How Many PSI Do You Need to Spray Paint a Car?
We measure spray gun pressure in PSI (pounds per square inch).
Spray painters’ regulators have a scale that indicates the above reading and helps you control the amount of pressure you need for painting.
All the extreme ends of spray gun pressure (too high or too low) are detrimental to painting.
Therefore, how many PSI do you need to spray-paint a car?
It’s impossible to pinpoint a psi value that’s the universal best for spray painting cars.
They differ based on paint viscidity, hose length, project size, and the spray gun type/model.
For an HVLP gun, the best pressure range is 20 to 30 psi. The lower half of the above range is ideal for the following circumstances:
- When using paint of low viscidity
- If you have a short hose (less than 25 feet)
- For a narrow spray pattern
- For small car painting projects
The upper half of the range, i.e., 25 to 30 psi, is perfect for the following situations:
- Whey applying thick paint
- For longer hose cords (above 35 feet)
- If you want a broader spray pattern
- For faster paint application (bigger projects)
An airless spray gun operates at a higher pressure than the HVLP and air models.
Its optimal range for spray painting cars is 40 to 50 psi.
In a nutshell, many dynamics are involved in determining the spraying pressure you need.
I advise you to check and follow your machine’s specifications and always test on scrap material before working on the main substrate.
How Many Cans Does It Take to Spray a Car?
Any bonafide painter or paints expert will tell you that their biggest nightmare is falling short of paint when painting a car or anything.
After finishing your project, a second but less dreadful situation is when you’re left with too much paint.
You need to purchase paint in quantities that will see you through the entire project.
Similarly, you need to take an economical approach when purchasing to avoid paint and money wastage.
That said, how many cans does it take to spray a car?
Averagely, it takes 20 to 30 rattle cans to paint a car. It could go to as many as 40 cans depending on the number of coats you’ll use, the paint type, and the capacity of the aerosol can.
Spray cans work quite well on cars, but I discourage their use because you’ll need to purchase many.
Plus, it takes a lot of effort and time to use them. I’d rather you get a proper spray gun, buy paint in gallons and mix, then apply to the car.
The rattle cans are ideal for painting smaller car parts or if it’s just a single car.
However, the one thing I acknowledge is that spray cans give excellent car paint finishes; the paint adheres quite well, and there is minimal wastage.
What Size Compressor Do I Need to Spray a Car?
A compressor stores and releases pressurized air to aid in the atomization of paint in air spray guns.
You need to fit your spraying machine with the right size for work convenience and attain the right PSI for spraying. In that respect, what size compressor do I need to spray a car?
My opined best air compressor capacity is 50 to 60 gallons. However, smaller-sized compressors will suffice, but not lower than 30 gallons.
The compressor’s volume directly affects its CFM and PSI efficiency. CFM is the air flow rate, i.e., the volume of air in cubic feet per minute that the compressor pumps at a given pressure.
Both small-sized and large-volume tanks can achieve high CFM values; however, the smaller tank will quickly run out of air, and you’ll need a refill.
The immediate consequence is you’ll have to stop painting the car midway; this is pretty inconvenient, especially if you had dedicated your time to spraying your car.
Even after refilling the compressor, the cascading negative effect is uncoordinated paintwork; the initially-applied paint shall have dried by the time you’re using the refilled tank.
It’s also difficult to match your initial painting rhythm, paint mix consistency, speed, etc.
The overwhelming domino effect will lead to an uneven paint job.
To be safe, use large compressor tanks between 50 to 60 gallons, as I’ve mentioned. The tanks will sustain your project in one go.
If you’re operating on a fixed budget, or if you feel financially constrained, try not to go below 30 gallons.
How Can I Paint My Car Without a Compressor?
We’ve seen the role of a compressor in a spray gun.
But what if I’m in no mood for buying and setting up a compressor, or what happens if it’s inaccessible?
To be direct, how can I paint my car without a compressor?
The best way to paint without a compressor is by using an airless spray gun!
This paint has a different working mechanism that doesn’t rely on air compressors.
It uses hydraulics instead to move fluid at high pressure; this provides a force that atomizes and discharges jets of paint from the nozzle.
The above machine is ideal for medium to high-viscosity paints, has high paint transfer rates, and produces a bolder finish.
Since an airless paint sprayer does not have an air compressor, it operates at a much higher pressure than air sprayers and HVLP spray guns.
It’s because it solely relies on the hydraulic system for pressure.
On the other hand, spray guns attached to air compressors rely on pressure from the compressed air and the machine’s paint feed system.
For the above reason, airless spray guns work optimally at pressures between 50 to 60 psi, while HVLP and air-assisted sprayers operate pretty well at 20 to 30 psi.
The procedure for spray painting cars using an airless spray gun is largely similar to the air and HVLP models. The only differences are:
The airless machine doesn’t have a paint cup attachment. Instead, you’ll mix the paint in a bucket and immerse the sprayer’s hose.
You can also paint directly from the paint gallon or container as the machine can handle most viscous paints.
The airless sprayer releases paint at a higher pressure, so you must keep your control in check.
This sprayer has a low paint transfer efficiency resulting in high oversprays. However, it works faster than the other machine models, so you’ll complete your car painting faster.
For the painting steps, follow the same procedure for the HVLP sprayer as detailed a few segments up the article.
Remember to start on a scrap piece of metal before proceeding to the primary substrate and clean up the airless tool immediately after finishing.
Regarding the best machine brand, I recommend you use the PowerSmart Electric Airless Paint Sprayer!
The PowerSmart label is a registered trademark under Amerisun Inc., based in the US state of Illinois.
The company makes power tools of great renown. Its electric airless paint sprayer has the following eminent features and advantages:
- The gun body and motor are separated to lighten its head; this is convenient for mobility when painting.
- It has a piston pump made of stainless steel, which is strong enough to push thick paint and is rust-resistant for improved durability.
- The machine has a pressure adjustment knob to give you better aiming and general control.
- PowerSmart spraying machine has a flexible hose that enables you to work directly from a paint bucket or gallon.
- This tool has a simple design that makes it easy to use and clean.
- It’s pretty easy to assemble and disassemble the sprayer in question.
- The spray gun consumes less electrical power from AC sources.
Can I Paint a Car With a 30 Gallon Air Compressor?
I’ve already discussed the most appropriate compressor size for spraying a car; it’s 50 to 60 gallons.
But how far can you stray from the above range in the event the qualified compressors are inaccessible?
For instance, can you paint a car with a 30-gallon compressor?
Yes! However, I emphasize that this should be your lowest limit.
Otherwise, you risk running out of compressed gas before you finish painting.
Remember that you need more than one coat for a successful paint job.
A 30-gallon compressor can sustain three coats in one go.
By comparison, 50-gallon tanks will do four coats, leaving you with more air for the next project.
However, the 3-coat sustenance of a 30-gallon produces a good enough finish.
Another situation that could warrant using 30-gallon air tanks is a spray gun that operates under low pressure, e.g., the HVLP models.
Low pressure reduces air utilization for paint disintegration, so the compressor in question is sufficient.
30-gallon tanks also work perfectly for car painting when the compressor itself has low airflow rates ranging between 5 to 12 cfm.
These compressors also use small air volumes for paint atomization, so you won’t run out of pressurized air.
The other point regards compressor-spray gun compatibility. Certain air spray guns or HVLPs have specifications that only work well with a specific range of air-tank capacity.
If the 30-gallon value falls within the said range, you can use it to paint your car.
Lastly, the above compressor capacity is ideal for small-sized cars. It’s because these cars have small surface areas for painting.
Best 30-Gallon Air Compressor For Painting a Car
If you are looking for a wonderful 30-gallon air tank for the above painting project, here is one for you:
The Campbell Hausfeld VT6271 30-Gallon Horizontal Tank
The above air compressor is manufactured by Campbell Hausfeld Company based in Harrison, Ohio.
It was founded in 1836 and initially manufactured farm implements.
The company has since evolved to make air tools, winches, air compressors, spray guns, generators, pressure washers, painting systems, and related products.
The Marmon Group acquired the above company in 2015.
The VT6271 model makes the perfect 30-gallon compressor due to the following benefits and features:
- It’s made of steel alloy that makes it strong and capable of holding pressurized air indefinitely
- The compressor comes with a 25 ft air hose that enhances mobility and wider reach when painting the car
- This tank delivers a decent air flow rate of 10.5 cfm for efficient paint atomization
- It relies on a corded electric power source for operation
- The tank is equipped with a cast iron twin cylinder pump that is oil-lubricated
- Its horsepower rating is 3.7 hp
To conclude, there’s a seachange in car painting techniques lopsided towards spraying. The technique has swept painting professionals, DIY enthusiasts, and amateurs off their feet.
It’s because of the comfort, affordability, and efficiency that it accords us.
A spray gun is one of the many machines used to effect spray painting. This is the best time to learn and know…
How to Paint a Car With a Spray Gun
I’ve highlighted all the steps, and the clarity is as good as it gets.
If you follow all the protocols and use the products I’ve mentioned, I guarantee you nothing will go wrong.
Your car will come off smooth, classy, and as good as new.
As I’d promised at the beginning of the article, I’ve also covered the following issues:
- Required spray gun pressure in PSI for car painting
- The number of paint cans that are sufficient to paint a car
- The best compressor size for car painting
- How to paint a car without a compressor.
I’ve given you all there is to know about spray painting a car using a spray gun.
I now leave the decision-making and action part to you. If you have any questions, comments, additions, and related content, feel free to interact with me in the comments section.
Otherwise, I wish you the best spray painting experience going forward.