How to dilute paints and varnishes for airbrushing?
Tools such as airbrushes are used in bodywork when creating any drawings or patterns, that is, for precise application of paint. Usually these works are carried out by professionals, and to do them yourself you need to know the features. So, first of all, not all materials used for spray guns are suitable for airbrushes. This article discusses what paints can be used for an airbrush and how to dilute them with your own hands.
Types of paintwork materials
The following are the paints that are needed for an airbrush:
- acrylic water soluble;
- urethane base;
- multistage multicomponent.
The features of the work depend on the type of paintwork material. So, the compositions of the first type are applied in 1 or 2 stages, urethane base - in 2 stages, including varnishing, multi-stage multicomponent - in 3 stages.
Water soluble materials such as gouache are not suitable for body work as they do not hold varnishes. Therefore, they are used only for training. Among the substances of this type for body work, you can only use water-based acrylic, and finely dispersed, intended for airbrushing. Such paint is most suitable for airbrushes with a fixed needle and external displacement of air flows.
The main advantages of these water-based paints and varnishes are considered to be low cost, non-toxicity, good miscibility among themselves, and resistance to chemical and physical influences after drying.
An important feature that must be considered when painting with your own hands is very fast drying. As a result, it is impossible to correct the applied pattern. However, this feature can be eliminated in two ways. First, you can add alcohol to the water used to thin the water-based paint. However, if its content exceeds 20%, the formation of paint clots on the surface, called run-up, is possible. Secondly, you can completely create a water-based mixture with your own hands, choosing the components in the required amount. In this case, the drying time is adjusted by changing the amount of polyester resins. This method is more advanced than the first one.
Polyurethane paints and varnishes are represented by polymer emulsions, consisting of stabilizing and coalescent substances, coloring insoluble pigments, resistant to solvent resin solvents. Pigments are presented:
- titanium white (white color);
- iron oxides;
- carbon black powder (black);
- chromium oxide;
- iron azure;
- umber (various colors);
- tin disulfide;
- silver (metallized).
Such paints can be brought to the consistency required for an airbrush with filtered water with your own hands. In addition, there are compositions of transparent candy paints designed for layer-by-layer glazing.
To obtain a "candy" color, you will need to use a binder solvent that keeps the viscosity of the enamel at a constant level. Airbrush paints are usually diluted 1:1.
Nitro paints are "bases" with medium hiding power. The main advantage of such paints and varnishes is the possibility of their layer-by-layer application without mixing. In addition, they are characterized by a very small size of pigments, which allows you to work with lines less than 0.3 mm thick and transparent halftones.
At the same time, the compositions under consideration have many shortcomings. The main one is toxicity. In this regard, it is unacceptable to work with them in residential premises, and during the application process it is necessary to use personal protective equipment. In addition, nitro paints are characterized by low light reflection. To increase their brightness, a white primer background is applied. In addition, to correct the mistake made, all applied layers will have to be removed, since they cannot be separated.
Blending requires the use of color indexing according to the manufacturer's palette in order to avoid the appearance of unexpected shades. Solvents 646 and 650 are suitable for nitro paints. It is unacceptable to suspend work until complete, that is, applying varnish, as the material fades. For application, airbrushes designed for contact with the material should be used, without rubber gaskets.
Principles of dilution of paints
The paint should be diluted with exactly the solvent recommended by the manufacturer. This will achieve the best quality coverage and avoid various problems. It is possible to achieve better results with other thinners, but this requires a lot of experimentation based on experience.
There are no exact recommendations for diluting the paint: the material is diluted individually in each case. The implementation of this operation with your own hands will allow you to form an idea of the properties of paint diluted in various proportions, and proceed on the basis of this in the future.
In the dilution process, they are guided not by the airbrush model, but by the outlet air pressure. In this case, they operate on the basis of the principle of matching high liquid to low pressure.
Normally diluted material requires a pressure of 1.5-2.5 bar, and fine work is carried out at 0.3-0.5 bar. However, it is important not to overdo it, as excess liquid paint will spray in the form of webs even at 0.3 bar.
There is a well-known rule according to which normally diluted paint is similar in consistency to milk. However, it should be borne in mind that it applies only to PF enamels and NC nitro-paints. For water-based acrylic, this is not the case.
- First, the pressure at the compressor outlet with the airbrush valve open is set to 19-20 psi (1.5 bar).
- The paint is stirred and dripped into the device, without diluting, in a small amount (1-2 drops).
- Then they watch how it flows down the wall of the tank, blow it off and listen. If the material does not puff, increase the pressure.
- Next, the paint is mixed in a container with a solvent in a ratio of 1: 1, poured into an airbrush, slightly reducing the pressure, and changes in the behavior of the substance and the transparency of the layer are observed.
- The behavior of the material is then examined when diluted 1:5 in an airbrush at 10 psi (0.8 bar).