Choosing a spray gun for water-based paint

 

The device and the principle of operation of a pneumatic spray gun

The very name of this type of spray gun implies the use of compressed air during their operation, therefore, a compressor (mainly with an electric motor) with a receiver will necessarily be present in the design of the entire device. The spray gun itself is a spray nozzle in the form of a gun, on top or bottom of which a paint tank is attached.

The receiver and the sprayer are connected by a flexible rubber hose, through which air is supplied under pressure. Also, paint is supplied to the sprayer, which is broken into tiny particles by a stream of compressed air and blown out of the nozzle of the gun. Its shape is made in such a way that the flow of air and paint is not straight, but forms a so-called torch that diverges at a certain angle to the sides.

In order for such a device to work without failures, its components must be made of high-quality materials and precisely matched to each other. All this affects the final price, so pneumatic spray guns are mostly used by professionals.

Types of spray guns

It is impossible to imagine any type of repair, whether it is small or capital, without painting, works. Painting walls and ceilings using brushes and rollers require a lot of time. In such a case, it would not hurt for a home master to have a spray gun at hand. It will not only save time but also allow you to create a very high-quality coating.

The only thing that is required from the contractor is to determine the type of sprayer and choose the appropriate nozzle diameter for the spray gun. To do this, it is necessary to take into account the area of the treated surface. The stores offer three main options for paint sprayers: manual, electric, and pneumatic.

Manual spray gun

If you want to avoid large financial costs when carrying out repairs in an apartment or in the country, then it is best for you to choose a piston manual spray gun. Such a tool looks like a large outdated car pump. Let's get acquainted in more detail with its design:

• At the bottom, the tool has two valves — an inlet and an outlet. A special hose is connected to the first one, which is lowered into a container with paint.
• Through the outlet, the paint and varnish material enters the tube, and already through it, bypassing the nozzles, it gets to the treated surface.
• The working length of the nozzle, as a rule, does not exceed 4 m. Above the handle, which is located next to the base, there is a ball valve. It is used to stop the supply of paint.
• Such a tool has fairly high productivity, which can be up to 200 m2 / h. Manual spray guns are easy to maintain and are inexpensive.

They have the only drawback — after coloring, the surface acquires some roughness. It is possible to reduce the manifestation of this disadvantage by using benign formulations. Also, a lot depends on the viscosity of the paint.

Electric unit

This type of paint sprayer looks like a regular screwdriver. It differs from the latter only in that the nozzle of the spray gun is located in place of the rotating head, and a vessel with paint is installed under it.

• The compressor is located in the body of the electric spray gun. During vibration, its membrane creates a certain pressure, under the influence of which the paint from the nozzle is evenly sprayed on the surface to be treated.
• This tool can only work when connected to the power supply or with a charged battery.
• The unit has a capacity of 240-250 m2/h. Among the disadvantages of electric sprayers, we can note a significant weight, which in some models can reach 25 kg. Before painting the surface using such aggregates, it is necessary to dilute the paint with water, which helps to reduce its viscosity. As a result, the covering ability of the paint material deteriorates and it becomes necessary to paint the surface in several layers.

Pneumatic device

The operation of such a unit is based on the principle of using compressed air. In its appearance, it resembles a pistol with a trigger.

• The main working part is the spray head. The paint container can be installed in the lower or upper part of the gun.
• A high-pressure hose departs from the handle, through which air enters. Its other end is fixed to the compressor.
• Professional models of pneumatic spray guns for water-based paint are bulkier, although they have sufficient mobility. Their household counterparts are more economical and easy to operate. Such paint sprayers have a capacity of no more than 400 m2/h.

Choosing a pneumatic spray gun

There are many disputes on the topic of what should be chosen first of all – a spray gun or a compressor. You can give different arguments, but it will be most correct, depending on the planned types of work, to choose a spray gun, and to select a suitable compressor for it.

Paint application technology supported by a spray gun

The spray gun can be equipped with one of three paint application technologies that differ in working pressure and the volume of air required for this, which the compressor should give out. The technology used is directly displayed in the abbreviations of the names of the spray guns – HP, HVLP, LVLP.

Each of them copes in its own way with the main disadvantage of pneumatic spray guns – the formation of"colorful fog". It appears due to too much grinding of paint particles, which become very light, and on the way from the nozzle of the gun to the surface to be painted, they are simply slowed down by air and remain in it in the form of a suspension.

1 HP (High Pressure) – high pressure.

This technology is used in devices of a low price range. It has quite a lot of disadvantages, because of which it is used less and less and gradually fades into the background, but with a limited budget, such spray guns are still in demand. The main advantage of such devices is the fast painting of surfaces due to a large airflow, but their disadvantages are also associated with it:

• A high percentage of paint that does not get on the painted surface is about 50-55%, and this is significant overspending of paint and varnish materials, plus high air pollution. We have to buy paint more often and change respirators with protective suits – a mandatory attribute for such work.
• High air pressure requires the skills of using such equipment – if you bring the nozzle of the gun too close to the surface to be painted, the airflow will simply inflate the already applied, but not yet frozen paint.
•  Although the spray gun working on HP technology is characterized by a budget cost, the need to create high pressure and high air consumption requires a sufficiently powerful compressor.

If you do not pay attention to the question of economy, then high–pressure spray guns are inexpensive and versatile devices that can be used in the vast majority of types of paint and varnish works.

2 HVLP (High Volume-Low Pressure) – a large volume of air, low pressure.

The nozzle of the gun of such spray gun is designed in such a way as to lower the high pressure from the compressor at the outlet. Accordingly, the paint, although it flies out at a lower speed, in a larger amount per unit of time.

Since the airflow is lower, this allows you to keep the gun closer to the surface to be painted, which gets more paint, due to which the losses of paint and varnish materials are reduced – the transfer coefficient can be over 65%.

Such devices are noticeably more expensive than high-pressure spray guns, but saving paint over 15% allows them to pay for themselves quickly enough.

3 LVLP (Low Volume-Low Pressure) – low volume of air, low pressure.

Premium class devices, with a transfer coefficient of up to 80% of the paintwork. This technology does not require a high–pressure air gun at the inlet, respectively, a powerful compressor is not needed-it is enough to produce about 200 liters per minute.

It would seem that with lower air pressure, the speed of work should fall, but this does not happen due to a higher transfer coefficient. The quality of painting under such conditions only increases, since less control is required over the distance from the gun to the surface to be painted.

Although LVLP spray guns are the most expensive, they are irreplaceable devices when working with premium segment paint coatings. Even if the paint savings increase by only 5-10% compared to HVLP, with regular work, the purchase will quickly justify itself.

Diameter of the nozzle of the pneumatic spray gun

Depending on the density of the paint, its viscosity, and grain size, nozzles with an outlet diameter from 0.8 to 7 mm can be used. Also, this size depends on the size of the part to be painted – for example, in the ship repair sphere or in car construction, the ability of the spray gun to apply paint to a large area in one pass comes to the fore.

Many manufacturers make spray guns with replaceable nozzles, but completely monolithic tips for one size are not uncommon – the same professional devices for painting ships are unlikely to need additional nozzles for nozzles.

The diameter of the nozzles of professional devices is selected depending on the paints that you will most often have to work with, and the size of the parts to be painted. For household needs, nozzles with a diameter of about 1.5 mm are most often needed – they are suitable for the vast majority of varieties of paint and varnish materials, representing a reasonable compromise between the speed of work and the quality of the painting.

As a result, if a set of additional nozzles does not particularly affect the price, then it is stupid to refuse to expand the functionality, and otherwise, it is already worth estimating how much they will be in demand.

Paint tank

A mandatory detail of the entire structure, which is not always possible to remember when choosing a spray gun, although the convenience of work largely depends on the material from which it is made or the location:

1 Plastic or metal.

Here it is necessary to take into account such nuances as the weight of the tank and its transparency. The first depends on how much faster the hand will get tired during prolonged work, and on the second – control of the level of the remaining paint. According to these indicators, plastic containers are definitely leading, and sellers note that they account for a larger percentage of sales.

However, metal also has its own buyer – sometimes the requirements for strength outweigh everything else.

2 Upper or lower locations.

When the tank is located on the top, the paint is fed into the gun by gravity, and when it is located at the bottom, it is sucked due to the air supplied from the compressor. Placing the tank on top or bottom does not give any improvements in the quality of painting, so the choice between them will only affect the convenience of work.

When the container is fixed on top, the spray gun will have a slightly better weight distribution, but during breaks in work, you will have to think about where to put it.

When the tank is located from the bottom, it forms a distinctive stand, plus, if you often paint the walls near the ceiling or surfaces with a similar configuration, then the spray gun can be raised higher.

Availability of adjustments

Each manufacturer can equip the spray guns with various adjustments, the presence and quantity of which is not regulated by anything.

It is mandatory to install a needle stroke regulator, which determines the amount of paint supplied. There can also be installed limiters for the amount of air supplied, settings for the shape and size of the paint torch, as well as additional adjustments that can affect the painting process in different ways, depending on the paint materials used.