Spray Gun: Beginner's Guide

Using a spray gun can give you a smooth as silk surface finish. It's perfect for doing faux metal or even just painting a straight color really fast. But, it can be a bit intimidating as a beginner. When I was first starting out, I couldn't find any online sources that addressed all aspects of spraying. So, this tutorial will walk you through: the parts of a gun, mixing paint for the gun, how to properly hold your gun while spraying, trouble shooting, cleaning your gun, and safety. Don't get overwhelmed; there's a lot of information. But, hopefully by the end, spraying will feel a lot less scary.

Note: All the illustrations I have posted are images I've collected over the years. I'm not claiming artistic ownership, just trying to create a space for comprehensive learning.

Supplies:

spray gun

air hose

compressor

paint

thinner for paint

cleaning tools

gun holder

paint strainer/cheese cloth

stir stick

well ventilated area for spraying

respirator

nitrile gloves

safety glasses

long pants

long sleeve shirt

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Step 1: The Gun

If you don't want to jump into buying a $100+ gun, a cheap alternative is a gun from the Harbor Freight store. You can get the CENTRAL PNEUMATIC® 20 Fl. Oz. HVLP Gravity Feed Air Spray Gun for $15! If you clean it properly, it'll last a decent amount of time. You can always invest in a nicer more expensive one once you feel comfortable and know you'll use it often. As the saying goes, "you get what you pay for," but that doesn't mean you need to go broke to learn a new skill. This sentiment goes for pretty much anything purchased at HF.

This particular type of gun is called a gravity feed or cup gun. It means the paint cup is above the gun and gravity allows the paint to go into the gun. There are a few different types of guns, but this type is my favorite (I'm honestly not sure why lol. I think starting out it was the easiest one for me to use).

It's important to familiarize yourself with all parts of the gun. The most important are the air cap, fluid tip, fluid needle, fluid knob, air pressure knob, and some guns have a fan knob (I recommend getting a gun with a fan knob).

The illustration of the gun is not a gravity feed gun, nor does it have an air knob (so don't let that confuse you). I posted it so you can see the inner workings and parts of the gun.

***If you decide to buy the Harbor Freight gun, you will also need to buy a 1/4" plug to screw on to the gun for connecting to the air hose.

Step 2: Air

The gun we are using needs to be attached to an air hose which is attached to an air compressor. Air pressure, also known as PSI (pounds per square inch of pressure), can vary depending on the gun and material being used. Make sure to read the paint can and gun instructions to see what the recommended PSI is. Usually, water based paints need less air than lacquer or enamel paints. The average range used is 40-80 PSI. You can set the PSI on your compressor or with an air regulator that can be attached to your gun or air hose.

Step 3: Fluid/Material

All paints need to be thinned down to be able to make its way through the gun. Thin the paint with whatever material the paint can says to use to clean up (e.g. latex/acrylic thin with water,laquer w/laquer thinner, automotive acetone based with acetone, etc). You want it about the consistency of milk.

A good way to test consistency: Dip a stir stick in the paint then hold it up. If you see 3 drips of paint come off the stick, you're usually good to go.

Too diluted and the paint will run, not diluted enough and it will spray out speckles of paint.

Step 4: Fan/Pattern

Sometimes the fan is refered to as a spreader, but most people call it a fan. The fan determines the width of the spray. Set the gun to a wide fan for larger pieces to be sprayed and smaller fan for smaller pieces. If you use a wide fan for a small piece, you'll have a lot of over spray which wastes paint and money. Likewise, if you use a small fan for a large piece, it will take a lot longer because you'll have to do more passes with the gun and there's a greater chance of spraying unevenly.

Remember, when you change the fan, you need to change the amount of fluid that comes out and PSI too.

As pictured: Orientation of air cap: If the two pieces that stick out from the cap are vertical, you'll get a horizontal spray. Horizontal equals vertical spray. Just remember that it's the opposite of what it looks like it should be.

Step 5: Setting Up

Now that you know what the consistency of the paint should be, you are ready to pour it into the gun.

***Important! Always use a paint strainer to pour the paint into the gun.*** Even if your paint looks clean and smooth, it probably has a booger or two that the strainer will catch. If you don't strain, the boogers (boogers being clumps of dried paint, dirt, whatever else falls into the paint) will clog your gun. Remember: a clogged gun is no fun! You can buy cone shaped paint strainers at just about any major hardware store. If you can't find any strainers, fold up some cheese cloth and use that instead.

Place your gun in the gun holder (if you purchased one) so you can pour your paint in. Fill the cup 1/2-3/4 full. Don't fill it to the top because it will definitely splash out; plus the gun will be heavier and your arm will get tired faster. Place the lid on and make sure it's tight, you don't want paint dripping out from under the lid and ruin your work.

Turn your compressor on. Attach a coupler to the plug you added to the gun. I recommend a quick connect to the end of your air hose. This will make a HUGE difference. It allows you to easily and quickly connect/disconnect your gun from your air hose. You can also attach one to the other end of the air hose to make connecting to the compressor easy too. Set ithe compressor to the proper PSI. Make sure there are no air leaks from the hose or the gun. If there is, see the Troubleshooting page.

Step 6: Safety

No matter what type of paint you are using, it's important to protect your health while doing so. Always read the paint can and/or Material Safety Data Sheet (MDS) and follow their safety instructions. You are spraying paint particles into the air and they can easily get in your lungs, on your skin, or even in your eyes. Don't be a tough guy, where safety gear! Your future self will thank you.

To be the safest, wear:

  • NIOSH approved respirator w/ organic vapor cartridges (pink)
  • protective clothing to cover arms & legs
  • nitrile gloves
  • safety glasses

At the very bare minimum, wear a respirator.

Also, it is important to work in a well ventilated area no matter what material you are using.

Step 7: Testing Before Spraying

You always want to do a test spray on a piece of paper/cardboard/wood so you can adjust your air, fluid, or fan knobs. Also, this gives you the opportunity to make sure your paint was mixed properly before you jump right into your project. Additionally, you can check the spray pattern to make sure it's coming out even. I'll address any issues on the Troubleshooting page.

Step 8: Time to SPRAY!

When you are happy with the quality of spray during your testing, it's time to SPRAY for real! You want to hold the gun about 5-8" away from the surface you're spraying (that's about a fist or spread out hand's distance).

Hold the gun perfectly perpendicular to the surface. If it's tilted, you'll get uneven coverage.

With the fan oriented vertically, you'll start at the top and work your way down in rows. Point the tip of the gun at the edge of the surface. You'll have a bit of over spray, but this will give the edge the same amount of coverage as the rest. As pictured: working left to right, you'll pull the trigger and move your hand and arm left to right (like a typewriter, NOT like an oscillating fan). Don't keep your arm in one place and just move/tilt your hand (pictured in image 1); this will cause uneven coverage. You want to keep your arm and hand perpendicular to the surface at all times. At the end of the row, slightly release the trigger, but only enough to stop the material, not the air. Move down to the next row and repeat right to left. Picture 2 illustrates how you will overlap your rows. Always point the tip of the gun at the bottom of the last row.

It will take a lot of practice to get even rows. If it's too dry between rows, aim your gun closer to the previous row to prevent any gaps.

Step 9: Tips

*Before starting to spray your piece, always pull the trigger away from the piece's surface first. This will prevent any dried up boogers on the nozzle from getting on your piece.

*When you reach the end of a row or column, lightly release the trigger just enough to stop the fluid from coming out when you move your hand down to the next row or over to the next column. This helps keep the edges from getting unevenly heavy with material. (If you've ever sprayed a spray can, I'm sure you've noticed the ends of what you sprayed are always the heaviest because you're basically doubling up on material there when you move your hand down/over.)

*Keep your finger down on the trigger just enough so the air is always coming out; even when you aren't releasing paint. This will maintain your air pressure at the same consistency. When you release the trigger completely, shutting off the air, this could cause air pressure fluctuation and allows time for the paint to dry on the tip (which causes boogers when you start the air up again).

*Always spray with the lowest air and fluid pressures possible while maintaining finish quality.

*If your first layer is sprayed in rows (side to side), then spray the second layer in columns (down to up) and vise versa. This will help get complete coverage.

Step 10: Clean Up

Cleaning your gun is a bit of a pain, but definitely necessary!

Some instruction manuals say you should only clean your gun with mineral spirits, although I haven't met anyone who sticks to this. Most people will clean their gun with the material they used to thin their paint (e.g. water, lacquer thinner, paint thinner, acetone).

Remove the needle, air cap, fluid cap, and paint cup. The fluid cap is usually difficult to remove and requires a wrench. An adjustable wrench works fine on some guns, but they do make spray gun wrenches that have standard hexagonal shapes to make it easier and prevent slipping. You may also need a spray gun wrench if a standard wrench is too fat to fit.

You'll want to clean all of the gun parts individually. I use a variety of tools (as pictured). You'll figure out what works best for you. Make sure all paint is removed from inside the gun, the air holes, needle, cup, etc.

Before reassembling, squirt a small amount of lubricating oil on all the threads to maintain the integrity of the threads. Reassemble gun.

To make sure the gun is 100% clean inside, reattach it the the air hose, fill the cup with a little bit of the material you used for cleaning, and spray air through the gun. This will help push out any clumps you may have missed while cleaning.

Spray gun wrench:

Set of cleaning needles, wire, and brushes:

Step 11: Troubleshooting

Unfortunately, there isn't one clear cut answer for a problem you might be having. It's just trial and error.

Fluid leaking from packing nut

  • packing nut loose
  • packing worn or dry

Fluid leaking from front of gun

  • packing nut too tight
  • fluid tip worn or damaged
  • needle worn or damaged
  • needle spring broken
  • wrong size needle or tip

Spray is fluttering

  • material level low
  • fluid passage obstruction (clog)
  • loose or damaged fluid tip
  • material too heavy, needs thinned
  • air vent clogged

Gun spraying out odd shapes

  • I attached 2 illustrations that will help with this problem

Paint is coming out dry and dusty

  • holding gun too far from surface
  • didn't mix in enough thinner, add more thinner
  • air pressure too high
  • moving gun too fast while spraying
  • not letting enough fluid out, loosen fluid knob

Paint too runny

  • holding gun too close to surface
  • Mixed in too much thinner, add more paint
  • letting too much fluid out, tighten fluid knob

Step 12: After Learning the Basics...

After you learn the basics of spraying, then you can dive deeper into the more complex parts of spraying. There is so much more information out there about types of guns, fluid tip sizes, air hose length/sizes, ventilation systems, building a spray booth, regulators, pressure loss, CFM, temperature, humidity levels, etc.

I hope this tutorial was informative enough to get you started. Feel free to leave any questions in the comments section.

Step 13: Images of My Spray Work

Lastly, here are some images of things I've used a spray gun on. Now you know I'm not a hack and a fraud lol.

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