High Volume Low Pressure (HVLP) spraying is a technological solution for applying large amounts of paint or coatings to surfaces.

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1 High Volume Low Pressure (HVLP) spraying is a technological solution for applying large amounts of paint or coatings to surfaces. large areas with the same colour or spray intricate surfaces such as mouldings and fancy plasterwork, with a lot less fuss. As a painter and decorator, you may need to use spray equipment at some point in your career. This chapter will cover the following topics: Selecting and setting up equipment Preparing areas for spraying Preparing and applying water-borne coatings Maintaining and storage of spraying equipment. These topics can be found in the following modules: CC101 CC202 CC219 CC220 CC222 CC223 CC

2 Painting and Decorating NVQ and Technical Certificate Level 2, 2nd Edition PSI per square inch, a measurement of pressure Atomise break up into very fine particles, that is, mist Overspray paint that does not hit its intended surface, floating away and being wasted There are various methods of applying paints and coatings to surfaces, as you will High Volume Low Pressure (HVLP) method of applying paint is becoming more this technology uses a high volume of air at low pressure (0.1 to 10 PSI) to atomise paint. Advantages of HVLP HVLP paint systems are light, mobile and easy to clean, and can greatly increase roller or brush marks, using HVLP reduces overspray (85 per cent of the paint or coating lands on the surface), improves the transfer of coatings, and reduces the total volume of paint that is used. This in turn results in reduced emissions of two solvents found in paint: volatile organic compounds (VOCs), which are associated with the formation of smog hazardous air pollutants (HAPs), which are most associated with an increased risk of developing cancer. Spray guns are designed to be easy to handle, and they need to be: the gun will hours at a time, so comfort is essential. Spray guns Like many spray guns, HVLP types have nozzles with large diameter openings, is sometimes known, is the most important part of the spray gun, as it forms the various spray patterns, directing the air into the paint stream to Two types of spray gun are used in spraying: the bleeder gun, bleeder gun, where both the air gun are controlled by the use Figure 15.1 Paint being sprayed from tip of spray gun 314

3 Chapter 15 High Volume Low Pressure spray application An HVLP spray gun (electric) A typical air-fed HVLP spray gun of a trigger. The paint or coating is typically contained in a pressure vessel and fed to the spray gun using compressed air, usually supplied by a compressor. The compressor or motor drives air into the vessel or container to pressurise the paint. When the trigger is pulled, the paint or coating is released and atomised. The Airless spraying systems Airless spraying (high pressure) is very popular in the shipbuilding industry, with many painters carrying this skill over to the construction industry. Airless sprayers do not use compressed air to apply the paint: instead, the paint or coating is forced through the small tip opening of the gun at very high pressure to atomise it. A piston pump moves up creating a vacuum to suck up the paint or coating into a hose and along to the gun. Piston-pump airless paint sprayers are the most versatile systems to use in this category as they can spray a variety of paint thicknesses. However, because of the high pressures used, these are also some of the most dangerous systems to operate. An electric spray system An air compressor 315

4 Painting and Decorating NVQ and Technical Certificate Level 2, 2nd Edition Spray tip Bounce back of paint Nozzle Figure 15.2 Bounce back of paint when spraying Masking Figure 15.3 Masking light fittings and switches 320

5 Chapter 15 High Volume Low Pressure spray application a g e b j c f i h d Figure 15.4 Masking larger items Masking paper comes in three different widths 150 mm, 225 mm and 300 mm and masking tape comes in 25 mm, 50 mm and 75 mm widths Masking aids Figure 15.5 Spray shield 321