In this article, we will show you how to use a HVLP spray gun and equipment to get started with your painting project.
What is a HVLP spray gun?
When you talk to people about spraying, most people conjure up the picture of a car sprayer. This is a classic compressor and spray gun system. The spray gun has the paint cup typically on top of the gun. This technology has been around a very long time and is a cheap way to get into spraying.
One of the drawbacks of this technology is that it creates a lot of overspray due to the high pressure needed to atomise the paint. This puts paint into the air and is, therefore, a form of pollution. When people began to get more aware of the possible damage to the environment in the 70’s engineers, looked at alternative ways to spray paint.
We all remember the Kirby hoover, and back in the 1930’s they had a spray gun attachment that worked off the hoover. The hoover could produce a high volume of air at lower pressures, and the gun could be used to spray thin liquids and water.
Fast forward to 1966, and an English company called Apollo sprayers took the technology and improved it to produce a professional sprayer.
The turning point came in 1984 when Apollo submitted a report to a Californian government agency to show that their sprayers had an 80% transfer efficiency and therefore created minimal atmospheric pollution.
The Government agency coined the term “High Volume Low Pressure”, and HVLP sprayers were born. They were promoted because of their portability and efficiency, and they soon became the mainstream.
HVLP systems are available in several “stages” common examples: the three-stage HVLP and the five-stage HVLP. The stage refers to the fans that produce the pressure, with each stage adding around 2 psi. For a system to be classed as HVLP, it cannot be more than 10 psi. Hence the 5 stage is the most powerful HVLP system available.
Why would you use a HVLP spray gun?
HVLP systems are ideal for the decorator because they are small, portable, and easy to keep in your van and take into a customer’s house. They can spray many types of paints that a decorator uses. They are good at spraying thinner products such as Zinsser BIN and Lacquers.
HVLP can be used to spray stains and glosses, but the paint may need thinning before they can be sprayed successfully. One of the great things about HVLP sprayers is that they are very controllable; you can control the fan width on the gun and dial it up to as much as 30 centimetres and down to as little as 1 centimetre. This is perfect for spraying things like stair spindles, and very little paint is wasted by being thrown past the spindle.
Another massive advantage is that the spray guns are easy to cleanout. If you are spraying an oil-based coated and the gun needs to be cleaned out with white spirit, then very little thinners would be used to clean the gun.
What equipment is used with a HVLP spray gun
A HVLP system is made up of three parts: the turbine, the hose and the gun. We will have a look at each one in turn. The turbine draws air in from the outside and compresses it, there is no storage tank, so the compressed air is sent immediately down the hose to the gun. The size of the turbine will determine the pressure. A 5 stage turbine will produce around 10 psi, which is needed to spray decorative paints.
This thick, inflexible hose is built to withstand the high volume of air that the turbine produces. The hose gets very hot near the turbine, so you need to be aware of this. Do not hold or touch the hose, especially the first metre of hose from the outlet. Because the hose is so stiff and inflexible, you will need to add a short flexible “whip hose” between the end of the hose and the gun.
These are available in 3 types.
1. Gravity feed this has the paint cup on top of the gun. These are nicely balanced and are great if you are working in a workshop or booth.
2. Suction feed has the paint cup below the gun, which makes the gun easier to put down onto a flat surface between spraying. These are better for onsite spraying.
3. Pressure feed. This has a separate paint container called a pressure pot. The pressure pot holds more paint, typically 2 litres. There are 2 lines from the pressure pot to the gun, which feeds the gun with paint and air. This setup means that the gun is light and can be turned to any angle when spraying. Once they discover this system, many decorators go for it.
How to use a HVLP spray gun
One of the great things about a HVLP system is that the turbine does need any setting up, you just switch it on, and you are spraying.
The gun can be a little trickier. There are 2 controls on the gun, one that controls the fan width and one that controls the paint flow. You need to set the fan to the desired setting, say a 4-inch fan and then turn the fluid flow up to match the fan setting.
Test the fan to make sure that enough paint is coming out to coat the surface that you are spraying evenly. This gets easier with practice. I have written a little book on this, and you can check it out here.
5 HVLP Tips
1. Buy a 5 stage turbine; the most common mistake that decorators make is buying a turbine that is not powerful enough.
2. Get a 1.5mm tip set. Most HVLP systems will come with a mid-range tip size, but it is worth checking before ordering. This site is a good all-rounder.
3. Get a whip hose. This is essential for comfortable spraying because the main house is so stiff and inflexible.
4. Clean the gun thoroughly after each use. Most problems you will encounter when spraying with HVLP are due to the gun not being cleaned properly. It is worth taking the tip and needle out once you have cleaned the gun to make sure that these are also spotless.
5. Make sure that the paint is not too thick. HVLP sprayers like thin paint. If you are spraying a paint that has been designed to be sprayed, then it will be fine, but if you are spraying an emulsion designed to be rolled, you may need to thin it before it will spray or find a better alternative.
This is the main mistake we see people make. They will try and spray a paint that is simply not designed to be sprayed, and when it splatters, they blame themselves when in fact, it’s the paint.