Why is HVLP preferred over conventional spray guns for metalwork?

HVLP systems achieve around 30% better transfer efficiency than conventional high-pressure spray guns. Because paint particles leave the HVLP gun at roughly half the velocity of conventional spray, the majority of the coating reaches and adheres to the surface rather than rebounding. This reduces material waste, cuts airborne paint particle levels, and produces a consistent, fine finish on architectural metalwork including shopfronts, window frames, and roller shutters.

What are the HVLP application dos and don'ts for metal?

For HVLP application on metal: do mix correct air-to-liquid ratios; do spray in elliptical overlap patterns; do add a small amount of additional thinner since turbine warm air dries paint slightly in transit; do use experienced operatives for consistent film build. Do not use halogenated hydrocarbon solvents or cleaning agents such as trichloroethane or methylene chloride. Always relieve air pressure when leaving the gun unattended.

Application Methods & Equipment

Why HVLP is the Preferred Choice for Painting Metal

Q: What does HVLP stand for?

HVLP stands for High Volume Low Pressure. The system uses a turbine or compressor to deliver a high volume of air at low pneumatic pressure, typically below 10 psi at the air cap, to atomise liquid coatings into fine droplets. The lower exit velocity of the paint particles means more of the coating reaches the intended surface rather than bouncing off or becoming airborne overspray.

Q: What coatings can be applied with an HVLP gun?

HVLP guns are compatible with a wide range of coatings including water-based and solvent-based systems, primers, 2K acrylic topcoats, lacquers, varnishes, and contact adhesives. They are suitable for RAL and BS colour-matched finishes across metallic and standard colours. Viscosity should be adjusted to the gun manufacturer's recommendation, too thick a coating will prevent adequate atomisation at low pressure.

Q: What causes orange peel finish with HVLP spray?

Orange peel, a textured surface resembling citrus skin, is typically caused by incorrect air-to-liquid ratio, insufficient thinner in the coating, incorrect gun distance, or too-low air pressure. Because HVLP turbine units deliver warm air that slightly dries the coating in transit, using a small amount of additional thinner is recommended to compensate. Spraying in elliptical patterns and maintaining consistent gun distance prevents orange peel from forming on the surface.

Q: What is transfer efficiency and why does it matter?

Transfer efficiency is the percentage of paint drawn from the gun that actually reaches and coats the intended surface, versus what becomes airborne as overspray. Conventional spray guns achieve around 30–45% transfer efficiency. HVLP systems achieve 65–90%. Higher transfer efficiency means less material waste, lower coating costs, reduced airborne VOC levels for operatives and building occupants, and less overspray contamination of surrounding areas, all of which matter significantly on occupied commercial sites.

How HVLP spray guns work, why they achieve superior transfer efficiency versus conventional spray, the correct technique for architectural metalwork, and what makes them the professional's choice for shopfronts, window frames, and architectural ironwork.

Anthony Jones, Vanda Coatings Updated February 2026 7 min read Application Methods Equipment Technical Guide

The spray gun is only as good as the atomisation it produces. Atomisation, the process of breaking liquid paint into a fine mist of tiny droplets, determines everything that follows: how evenly the coating lands, how well it adheres, what finish quality is achievable, and how much material is wasted as overspray.

HVLP (High Volume Low Pressure) spray technology produces superior atomisation characteristics to conventional high-pressure spray guns on the surfaces most commonly encountered in commercial metalwork refurbishment: shopfront frameworks, aluminium window profiles, architectural ironwork, roller shutters, and fascias. This guide explains why, and what correct HVLP technique looks like in practice.

What HVLP means and how the system works

HVLP stands for High Volume Low Pressure. The system delivers a high volume of air at low pneumatic pressure, typically below 10 psi at the air cap, to atomise the liquid coating into fine droplets. This contrasts directly with conventional (or "high pressure") spray guns, which force paint through the nozzle at much higher air pressures.

The power source in an HVLP setup is either a dedicated turbine unit, similar in principle to a vacuum cleaner motor running in reverse, blowing warm air rather than sucking, or a compressor configured to deliver high volume at reduced output pressure. Turbine-based systems are common for on-site metalwork because of their portability and the warm, dry air they produce, which aids paint flow and atomisation consistency.

The defining result of the low-pressure delivery is reduced exit velocity of the paint particles as they leave the gun. Where conventional spray guns project paint at high velocity, causing a significant proportion to bounce off the surface rather than adhere, HVLP particles arrive at the substrate with enough energy to wet and adhere, but without the rebound losses of high-pressure systems. This is the mechanism behind the transfer efficiency advantage that makes HVLP the preferred choice for commercial metalwork application.

Turbine / compressor

Delivers high volume of air at low pressure, below 10 psi at the air cap

→

Air cap

Low-pressure air meets liquid coating at the air cap, breaking it into fine droplets

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Spray fan

Fine droplets form a wide, even fan pattern, lower velocity than conventional spray

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Surface transfer

Up to 90% of coating reaches the substrate, significantly less overspray and waste than conventional spray

30%

better transfer efficiency than conventional high-pressure spray guns

65–90%

transfer efficiency range achievable with a correctly set-up HVLP system

<10 psi

air pressure at the air cap, roughly half the exit velocity of conventional systems

29 yrs

Vanda Coatings experience applying HVLP coatings to commercial architectural metalwork

Transfer efficiency: the critical metric

Transfer efficiency measures the percentage of paint drawn from the gun that actually coats the intended surface versus the proportion that disperses into the air as overspray. It is the single most important performance metric for spray application on occupied commercial sites, influencing material cost, contamination risk, VOC exposure for operatives and building users, and the amount of masking and containment required.

Conventional high-pressure spray guns typically achieve 30–45% transfer efficiency. The high velocity at which paint particles leave the nozzle causes a significant proportion to rebound off the surface rather than adhering, or to disperse as airborne mist before reaching the substrate. This is both wasteful and creates significant overspray contamination risk on occupied sites.

HVLP systems achieve 65–90% transfer efficiency. The lower exit velocity of the droplets means the majority of material reaches and wets the surface. On a commercial metalwork project, spraying shopfront frameworks, window profiles, or curtain walling, this translates directly into reduced material consumption, lower coating cost, and significantly less overspray to manage and contain.

Atomisation quality and finish consistency

The aim of any spray application is to convert liquid coating into droplets small and consistent enough to form an even, continuous film on the surface. The size and uniformity of the droplets produced at atomisation directly determines the quality of the applied finish.

HVLP produces finer, more uniform droplet sizes than conventional high-pressure spray. Finer droplets settle more evenly, coalesce into a smoother wet film, and produce less texture on curing. This is why HVLP is the preferred choice for architectural metalwork where finish quality is paramount, the smooth, factory-quality appearance achievable on shopfront aluminium and window profiles with HVLP is not practically reproducible by conventional high-pressure spray.

Proper atomisation also prevents a range of finish defects. Poor atomisation, from incorrect pressure, wrong air-to-liquid ratio, or contaminated air, produces orange peel texture, uneven coverage, and poor adhesion. The additional control that HVLP's lower operating pressure gives the operative makes these defects easier to diagnose and correct during application.

What surfaces HVLP is suited to

HVLP is particularly well-suited to the surfaces encountered most frequently in commercial architectural metalwork refurbishment:

Shopfront frameworks, aluminium and steel extrusions with complex profiles and rebates that require consistent coating in recessed areas
Aluminium window and curtain walling systems, profiled sections where finish quality is visible at close range and consistency is critical
Roller shutters and steel doors, large, flat or lightly profiled surfaces where even film build is straightforward to achieve
Architectural ironwork and fascias, ornate or complex shapes where HVLP's fine atomisation and lower overspray reduce contamination risk on adjacent surfaces
Office furniture and interior metalwork, smaller, intricate items where transfer efficiency and finish quality are more important than application speed
Signage and fascia panels, where a smooth, defect-free finish is essential and overspray must be tightly controlled

HVLP is less suited than airless spray for very large-area, high-speed application of thick coatings, such as high-build primers on industrial cladding, where raw application rate is the overriding requirement. For that class of work, airless spraying is typically the method of choice. See our companion guide on airless paint spraying for a full comparison.

Compatible coatings

HVLP guns are compatible with a wide range of coating systems. The key variable is viscosity, the coating must be thin enough to flow through the air cap and atomise fully at low pressure. Coatings that are too thick will not atomise adequately, producing orange peel or spatter rather than a smooth film. Where necessary, the coating should be thinned to the manufacturer's recommended viscosity for spray application, with cup viscosity checked using a flow cup before loading the gun.

Coating systems compatible with HVLP include:

Water-based and solvent-based primers
Two-component (2K) acrylic topcoats, the standard system for commercial architectural metalwork recoating
Lacquers and varnishes
RAL and BS colour-matched finishes across metallic and standard palettes
Contact adhesives
Vinyl fluids

Note on coating systems: Vanda Coatings specifies and applies non-isocyanate 2K acrylic coating systems for commercial architectural metalwork. These systems deliver the durability, colour fastness, and long-term adhesion performance required for external architectural metalwork without the additional health and safety complexity of traditional hardener chemistries.

HVLP versus conventional spray, a direct comparison

Factor	HVLP spray	Conventional high-pressure spray	Brush / roller
Atomisation pressure	Low, below 10 psi at air cap	High, 30–60 psi at air cap	None, manual application
Transfer efficiency	65–90%, best of spray methods	30–45%, significant overspray waste	Near 100%
Finish quality on metal profiles	Excellent, fine, even atomisation	Good, can produce orange peel	Visible brush marks on profiles
Overspray	Low, 10–20%	High, 50–70%	None
Material waste	Low	High	Minimal
VOC exposure risk	Reduced, lower airborne particle levels	Higher, more airborne mist	Lowest
Application speed	Good, faster than brush	Fast	Slowest
Suitability for thick coatings	Moderate, viscosity limits apply	Good	Good
Portability on site	Excellent, turbine units are compact	Good	Excellent
Best suited for	Architectural metalwork, profiles, intricate work	High-speed industrial application	Touch-ins, small areas only

Advantages and disadvantages of HVLP for metalwork

Advantages

30% better transfer efficiency than conventional spray, less material wasted as overspray
Fine, consistent atomisation produces a smooth, even film on profiled metalwork surfaces
Lower VOC levels in the working environment, reduced airborne paint particle concentration
Less masking required than high-pressure spray, reduced preparation time on occupied sites
Excellent control, lower pressure gives operative more time to adjust and respond during application
Compatible with a full range of 2K acrylic, water-based, and solvent-based coating systems
Turbine units are lightweight, compact, and well-suited to on-site access conditions

Disadvantages

Lower application speed than airless spray, less suited to very large-area high-build application
Viscosity limits, thick coatings require thinning to atomise correctly at low pressure
Turbine warm air slightly dries coating in transit, requires additional thinner to compensate and prevent orange peel
Not suited to very high-build coatings such as industrial mastics or intumescent systems
Regular cleaning required, air cap holes block easily if coating is allowed to dry in the cap

Correct HVLP technique for architectural metalwork

Using an HVLP gun correctly on architectural metalwork requires attention to preparation, gun setup, and application motion. Incorrect technique, even with a well-maintained gun and a quality coating, produces orange peel, runs, thin areas, or inconsistent colour.

Coating preparation and viscosity check

Mix the coating to the correct air-to-liquid ratio for the specific product and application method. For 2K acrylic systems, mix base and hardener thoroughly and allow the induction period specified by the manufacturer before loading the gun. Check viscosity using a flow cup, if the coating is too thick for adequate atomisation at low HVLP pressure, add the recommended thinner in small increments until viscosity is correct. Strain the coating before loading to remove any particles that could block the air cap.

Add additional thinner for turbine warmth

Turbine-based HVLP units deliver warm air, typically 10–15°C above ambient temperature, directly into the atomised coating droplets. This warming effect slightly dries the coating in transit between the gun and the surface. To compensate, use a small amount of additional thinner beyond the standard mixing recommendation. The correct amount depends on ambient temperature and the specific coating product, start conservatively and adjust based on the finish produced on a test surface before applying to the main area.

Set gun distance and angle

Position the gun approximately 15–25 cm from the surface for typical architectural metalwork profiles. Hold the gun perpendicular to the surface throughout the stroke, tilting the gun produces an uneven fan with heavier deposition at one edge. Do not arc the wrist; keep the gun tracking in a consistent straight line parallel to the surface. On profiled sections such as window frames, maintain consistent distance around all faces of the profile rather than allowing the gun to drift closer on the flat face.

Spray in elliptical overlapping passes

Apply coating in smooth elliptical (slightly curved) patterns rather than rigid straight lines. Each pass should overlap the previous by approximately 30–50% of the fan width. Elliptical technique produces more even film distribution at the edges of each pass than straight strokes alone. Begin moving the gun before pulling the trigger, and release the trigger before stopping at the end of each stroke, this lag technique prevents paint build-up at the stroke extremities which would cause runs or heavy edges.

Recesses and profiles first

On profiled sections, window rebates, door frames, shopfront extrusions, spray the recessed faces and inside corners first before applying the main face passes. This ensures adequate coverage in the areas most prone to thin film, and allows any build-up at inside corners to be feathered before the face coat is applied. On architectural ironwork with intricate detail, apply a light preliminary pass across all surfaces before building up full film thickness.

Two coats, adequate flash-off between

Apply coating in two coats rather than attempting to achieve full dry film thickness in a single heavy pass. A single heavy coat increases the risk of runs, sags, and slow cure, particularly on vertical surfaces. Allow adequate flash-off time between coats as specified in the product data sheet. Flash-off time varies with temperature, humidity, film thickness, and coating type, follow the manufacturer's minimum recoat interval and extend it in cold or high-humidity conditions.

Clean gun thoroughly after use

Clean the gun immediately after use, do not allow coating to dry in the air cap holes, needle, or fluid passages. For water-based coatings, flush with clean water followed by gun cleaner. For solvent-borne coatings, flush with the appropriate solvent. Disassemble and clean the air cap separately using a soft brush, never use metal tools or wire to clear air cap holes as this damages the precision-machined orifices. Turn off the air supply and relieve pressure from the system before any maintenance.

Safety and solvent guidelines

HVLP spraying operates at low air pressure and therefore does not present the injection injury risk associated with airless spraying. However, appropriate PPE remains essential, particularly respiratory protection rated for the coating system being applied, eye protection, and protective overalls. Ensure adequate ventilation in the working area to prevent build-up of solvent vapour.

Prohibited solvents. Do not use halogenated hydrocarbon solvents for thinning coatings or cleaning HVLP equipment. Specifically, trichloroethane, methylene chloride, and similar chlorinated solvents must not be used in HVLP systems, they attack seals and internal components and create unacceptable exposure risks. Use only the thinners and cleaning agents specified by the coating manufacturer for the product being applied.

Frequently asked questions

Q What does HVLP stand for?

HVLP stands for High Volume Low Pressure. The system uses a turbine unit or compressor to deliver a high volume of air at low pneumatic pressure, typically below 10 psi at the air cap, to atomise the liquid coating into fine droplets. The lower exit velocity of paint particles means significantly more coating reaches the substrate rather than bouncing off or becoming airborne overspray, giving HVLP its characteristic transfer efficiency advantage over conventional high-pressure spray.

Q Why is HVLP preferred over conventional spray for metalwork?

HVLP achieves around 30% better transfer efficiency than conventional high-pressure spray guns. Because paint particles leave the gun at roughly half the velocity, the majority reaches and adheres to the surface rather than rebounding as overspray. This reduces material waste, cuts airborne paint particle levels, and produces a more consistent, fine finish on architectural metalwork. On occupied commercial sites where overspray contamination is a significant concern, this efficiency advantage is particularly valuable.

Q What coatings can be applied with an HVLP gun?

HVLP guns are compatible with a wide range of coating systems including water-based and solvent-based primers, 2K acrylic topcoats, lacquers, varnishes, RAL and BS colour-matched finishes in metallic and standard colours, contact adhesives, and vinyl fluids. The key requirement is that the coating must be within the viscosity range the gun can atomise effectively at low pressure, most coatings require adjustment to spray viscosity before loading.

Q What causes orange peel with HVLP spray?

Orange peel, a surface texture resembling citrus skin, is typically caused by incorrect air-to-liquid ratio, coating that is too thick or too thin, gun distance that is too far from the surface, or insufficient additional thinner to compensate for the warming effect of turbine air. Since HVLP turbine units deliver warm air that slightly dries the coating in transit, a small amount of additional thinner beyond the standard mixing recommendation is usually required. Spraying in elliptical overlapping passes at a consistent gun distance of 15–25 cm also prevents orange peel formation.

Q What is transfer efficiency and why does it matter?

Transfer efficiency is the percentage of paint from the gun that actually reaches and coats the intended surface, as opposed to becoming airborne overspray. Conventional spray guns achieve around 30–45%. HVLP systems achieve 65–90%. Higher transfer efficiency means less material waste, lower coating costs, reduced airborne VOC levels for operatives and building users, and less overspray contamination of adjacent surfaces, all of which matter significantly on occupied commercial sites with sensitive surroundings.

Q When would you use airless spray instead of HVLP?

Airless spray is the better choice when application speed and film build rate are the overriding requirements, particularly on very large surfaces, when applying high-viscosity coatings such as high-build primers or mastics, or when the project scale makes HVLP's lower output rate impractical. HVLP is the preferred choice when finish quality, transfer efficiency, and control are the priority, particularly on the profiled and intricate metalwork surfaces most commonly encountered in architectural recoating work.

Anthony Jones

Director, Vanda Coatings, 29 years experience

Anthony has been specifying and supervising HVLP and airless spray application on commercial architectural metalwork across the UK since the late 1990s. The transfer efficiency advantage of HVLP over conventional spray is not theoretical, on the shopfronts, window frames, and curtain walling systems that form the core of Vanda Coatings' project workload, it translates directly into better finish quality, less masking time, and lower material cost per project.