How to Spray Finish your Furniture Using HVLP Spray Guns

Spray gun setup and techniques

One of the most common questions I get on my YouTube channel is “What’s your go-to finish?” For me, it’s conversion varnish. That’s what I use on almost all my furniture pieces.  However, for this how-to-spray-finish article, I am using a Lacquer, a more approachable finish for most people getting into spray finishing.   So here is a guide to how I set up my spray gun to give me a flawless finish and a few techniques I have learned along the way.

Getting Technical

The first thing you need to figure out is what size needle you need in your spray gun, based on the viscosity of your finish. (I use a Fuji MPX-30 Gravity RP Gun ) You can find this info on the manufacturer’s technical data sheet, or you can measure it yourself with a viscosity cup. Basically, you time how fast the finish flows through the cup – that’s your viscosity.

For this lacquer, the viscosity is between 21 and 25 seconds. When I checked my chart for the Ford measuring cup, I found that a 1.3mm tip handles 15-19 second runout time, while a 1.4mm tip handles 19-23 seconds. My finish is 21-25 seconds, so it might be a bit too thick for the 1.4mm tip. That’s where thinning comes in.

I’m going to thin this finish to get it under 23 seconds, ideally between 19 and 23. The instructions say not to thin it more than five percent – if you need to thin more than that, you need a bigger tip.

The Retarder

Next up is deciding whether you need a retarder to slow down the drying time. There are a few reasons you might want this.

If you’re working in a hot, humid area, the finish can dry really fast and trap moisture inside, making it hazy – definitely not what we want. Slowing it down lets that moisture evaporate before the finish cures.

In really dry climates, the finish can set up so fast that you can’t maintain a wet edge, especially on large pieces. A little retarder gives you more blending time on those passes.

Personally, I almost always use a retarder regardless of temperature or humidity. It just gives the finish a little more time to settle and flatten out, resulting in that glass-smooth finish every single time.

Always Strain Your Finish

This is non-negotiable: always strain your finish. Even if it’s a brand-new can, strain it. It only takes one little particle to plug up your gun and ruin your whole job.

And here’s another pro tip – those strainers are one-use only. Once you pull it out, it starts drying on the outside, and if you reuse it, a dried, crusty piece will fall into your spray gun and plug everything up. So use it once and toss it.

Setting Up the Gun

Let me walk you through how I set up my spray gun. I start by installing the right cap size for my needle, pushing the needle in, adding the spring, and then threading on the fluid control knob.

I hold the trigger down and tighten the knob until I feel the trigger start to move and get pressure. That tells me it’s set at the maximum amount of fluid that’ll go through the gun.

My gun has a regulator that lets me adjust pressure on the fly – and if your gun doesn’t have this, I’d seriously consider upgrading. It’s incredibly important for dialing everything in.

Dialing In the Perfect Spray

I set up a black backdrop so I can see the fan pattern as I adjust it. Remember, I’ve got the fluid control at maximum, air dialed all the way down, and my fan set at its widest opening. My gun has a micro-adjust on the fan, which is clutch – if yours doesn’t, it might be time for an upgrade.

I turn the air all the way down to start, basically to zero, and then slowly add air pressure until I see that my spray pattern is fully atomized.  I then go do the opposite, I turn the fluid control way down so I am getting a minimal amount of finish come through the gun, and start the air pressure at zero, and slowly turn it up until I get a full atomization on my spray pattern.  Now that I have a feel for my minimums and maximums, I can play with the setting between until I find the sweet spot.  It is a lot about practice and observation. If it feels like it is going down too heavy, you need to readjust your fluid.  Just don’t forget to readjust your air.  The amount of fluid and air pressure go hand in hand.

Before hitting the actual project, I do test sprays to see how the finish looks. I’m checking if it’s too thick, too runny, if there’s a weird texture or orange peel. The key is staying parallel to your work surface – don’t swing your arm and create heavy spots in the middle with light areas on the sides.

Finding the Sweet Spot

Since I’m just spraying water for the demo, it’s running pretty quick, but the principle is the same for every finish. Once you know what maximum feels like, dial everything down to minimum and spray again. This helps you find that sweet spot somewhere in the middle.

If you’re at minimum and need more finish, open up the fluid control. If you’re at maximum with too much overspray or weird texture, dial down the air. It’s all about finessing the gun until you get a nice, clean, smooth finish that looks like perfectly clear glass going down.

Time to Spray

I’ve got all my cabinet parts laid out in my drying rack, my safety equipment ready, and my spray station set up with explosion-proof fans behind filters. If you don’t have a dedicated booth, just spray outside – and whatever you do, don’t put a fan in the doorway blowing air in. That just stirs up particles that’ll fall into your wet finish. You want the fan pulling everything out, not pushing air around.

I always spray edges first, then come back for the top surfaces. This prevents overspray buildup. I start closest to me and work toward the fan so overspray gets drawn out immediately, not across my fresh finish. I overlap each pass by at least a third to half.

First Coat Lessons

Since this is the first coat, I’m not being overly picky about exact settings. I’m using this coat to dial everything in because I’ll be sanding it back a little before the next coat anyway. As I spray, I’m noticing a lot of extra overspray, so I’m adjusting my fan pattern and reducing air pressure slightly.

I also need to replace my fan filters – they’re getting caked up and not drawing overspray away properly. That’s something I’ll handle before the second coat.

What’s Next

And that’s a wrap on the finishing process. Next up, I get this spray gun clean.  Thanks for sticking with me through all the technical stuff.