In this article we explain what overspray is, its causes and how to reduce it.
There are several ways to reduce overspray. Changing your spraying technique, choosing the right pressure and selecting the right tip all contribute to reducing overspray. In this article we will look at what overspray is, the main causes of it and how to minimise it.
What is overspray?
Overspray is the fine paint particles that collects on nearby surfaces. Fundamentally overspray is any material that doesn’t land where you want it to.
Overspray can also create a mist as the material is dispersed into the air, creating a cloud of material.
Overspray is an issue for four main reasons:
1. Overspray creates a mess, leaving flecks of material everywhere. You will have to spend more time protecting areas that you don’t want to be covered by overspray if you don’t take the correct precautions to avoid it.
2. You will lose a significant amount of material to overspray. This means that you will have to use more material thereby losing money.
3. Overspray will affect the smoothness of the sprayed area, creating an uneven and unprofessional look.
4. Overspray is a hazard to your health and dangerous to breathe in.
Causes of overspray and how to prevent them
Adopting the right techniques of spraying reduces overspray considerably and results in a fine and even coating. Some rules to follow to ensure a smooth application include:
- Keep the gun 25cm-30cm (4” to 10”) away from the surface you are spraying. As the distance between the spray gun and the surface increases, so does the width of the spray pattern causing overspray.
- Hold the spray gun perpendicular (a 90-degree angle) to the surface. As the angle decreases, the material will ricochet off or miss the surface causing overspray.
- Keep moving the spray gun at a constant speed. Make sure to also move your feet and body to maintain the correct spraying distance and angle.
Optimal spraying pressure is crucial to help reduce overspray so that there is not an excess of paint particles being released into the air. It is best to always try to use the best the lowest PSI possible.
Selecting the right pressure for the job requires a combination of understanding the factors that can influence pressure as well as what visual cues to look for when you are spraying.
If your spray pattern is too low, the spray pattern will appear uneven, there will be more material towards the edges of the spray pattern, forming thin bands at the top bottom and bottom (when horizontally spraying). When the pressure is too high, the material is being forced out of the tip office at greater force, creating more overspray, the paint will then begin to run, with drips running down the spray pattern.
These are some factors that will also influence your working pressure:
- Higher viscosity material (e.g. spray plaster, water-resistant exterior emulsion paints) require much higher pressure, low viscosity materials (e.g. stains and lacquers) require lower pressure.
- The delivery rate of the machine.
- Spray tip selection.
- The temperature of the material. Heating material reduces its viscosity, meaning it requires less pressure for the same fan pattern.
- The longer the hose the lower the working pressure at the tip/gun.
- Diameter of the inlet pipe. Smaller sizes can reduce the flow of material.
How to find the correct Spray pressure
Ideally, you want to be spraying at the lowest pressure possible, this gives the user the greatest control.
To find the optimal spray pressure:
- Start with the lowest possible pressure.
- Check the spray pattern for uniform coverage with no visible segments.
- Gradually increase the pressure by increments of 20 to 36 bar until there is an even coverage.
Selecting the incorrect spray tip can result in too much material and increased overspray. Spray tips come in a wide range of sizes. Selecting the correct spray tip will ensure the best quality finish. The spray tip you choose determines how much fluid will leave the gun, as well as the size of the spray fan.
Read our article about how to select the right spray tip here.
In conclusion, you should expect some overspray. You should generally expect 20 to 40% of your material to be lost to overspray. As overspray is unavoidable you should always prep the area that you are going to spray. Make sure to cover everything close by to where you’re spraying with plastic covering, as well as masking fittings and fixtures. Ensuring you followed all the steps above will reduce the need for covering every surface, saving you both time and money.
Need more help?
If you need help picking the correcting overspray please call 0113 231 0500 or use the contact form here.
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