Maximum paint viscosity 60 din. Features of diluting paint for an airbrush

16.06.2019

What affects the thickness of the paintwork material during painting? How to determine the viscosity of the paint for the spray gun? What are its optimal values? What should be the spray gun for viscous liquids? Let's try to answer these questions.

What does viscosity affect?

The concept itself, I think, does not require explanation.

But what it affects is probably better explained.

Excessively viscous dye is difficult to spread over the surface in a thin layer. Excessive thickness will lead to long drying and ... a decrease in the final strength of the coating.

In addition: thick paint will not fill the small irregularities of the base. Thus, its adhesion to the surface will significantly deteriorate.

Due to the large thickness of the layer, streaks are inevitably formed on vertical and inclined surfaces..
Finally, most inexpensive spray guns simply can't handle material that is too viscous. The principle of operation of a pneumatic sprayer is based on low pressure in the air stream and suction of paint from the tank into it. At the same time, the pressure drop, by definition, cannot exceed one atmosphere even in the ideal case (we dare say, absolutely unattainable).

If the difference is not enough to push the paint through the siphon and nozzle, the result is a little predictable: the spray gun will have to be completely disassembled and washed with a solvent; about painting speech, of course, will not go.

Too much, however, when applied in a thin layer, neither the tool nor the surface to be painted will become unusable. However, the total number of layers to obtain a coating without unpainted areas will increase, which, taking into account the drying time, will lead to unreasonably high costs time.

A typical cause of streaks is paint that is too thick.

Viscosity measurement

Units

Domestic manufacturers indicate the viscosity of the dye in seconds; for imported materials, another unit of measurement is characteristic - DIN. What do these units of measurement mean?

Just the time (yes, yes, exactly in seconds) for which a fixed amount of dye or varnish will flow through a hole of a known diameter. It is clear that more liquid paint will leave the container faster, thicker - more slowly.

Methodology and tool

Viscosity is measured with a special tool called a viscometer. Under the frightening name lies a small funnel with a capacity of strictly 100 milliliters with a 4 mm hole. The price of the device, the accuracy of which is sufficient for domestic purposes, is 200-500 rubles.

Nuance: laboratory rotational and vibrational viscometers are much more expensive. The cost of these devices is sometimes measured in hundreds of thousands.

How to measure the viscosity of paint with your own hands using a capillary viscometer?

The instructions are ridiculously simple:

Fill the funnel by plugging the outlet with your finger.
At the same time, open the hole and start the stopwatch.
We register the time elapsed until the container is empty. Drops, of course, do not count.

Exclusively important point: measurements are carried out at a temperature of paint and ambient air of 18-22 degrees. When the temperature drops, any paintwork materials thicken; with an increase, their viscosity decreases, which reduces the value of the experiment to zero.

Optimal values

The optimal viscosity of the dye, primer or varnish is usually indicated by the manufacturer on the packaging. In extreme cases, information can be found on his website.

For automotive enamels, 15-20 seconds are considered the norm of viscosity.
For texture paints (which, however, are usually not applied with an airbrush) - 15-25 seconds.

For primers - 15-30 seconds.
For glaze - 20-30 seconds.
- 35-45 seconds.
For enamels and oil dyes - 15-25 seconds.

In the absence of a viscometer, it is useful to remember a simple rule: most household paints, unless otherwise specified by the manufacturer, before painting with an airbrush, they are diluted to the consistency of fat milk. The type of diluent must correspond to that indicated on the package: it is obvious that it is not worth diluting nitro enamel with water.

A special case

Two-component dyes stand apart - acrylic on organic solvents, epoxy, polyurethane and some others.

How to dilute these materials to working viscosity?

First, the paint is mixed with a hardener. Of course, strictly in the proportion indicated by the manufacturer: both the lack and excess of the hardener will adversely affect the strength of the coating.
Then the viscosity of the resulting dye is checked with a viscometer and, if necessary, diluted to a working consistency.

How to measure the required amount of base and hardener?

With a small volume, this can be done using measuring utensils.
In bulky cylindrical containers, it is easier to use a measuring ruler. If the height of the paint level without hardener is 40 centimeters, then to obtain a ratio of 1: 4, it is enough to add it to the level of 50 cm.

Do not forget: this method will give an accurate result only in a cylindrical container. An ordinary bucket has the shape of a truncated cone, which will distort the proportions.

Equipment for viscous materials

How is the spray gun for viscous paints arranged?

How to distinguish it in appearance?

In industrial environments, airless spray guns are used for high viscosity materials. piston pump does not supply air to the nozzle, but the paint itself under pressure up to 200 atmospheres. This type of equipment is characterized by a high percentage of dye transfer and a cost corresponding to the annual budget of a small African country.

At all times, paint has been used as a universal remedy for interior decoration. However, when working with oil formulations, the coating dries for a long time, and the mixture itself emits bad smell. What can not be said about water-based solutions. In this article we will describe what water-based paint is (technical characteristics, advantages and method of producing the composition).

Method for the production of water-based paint

The whole process can be conditionally divided into several stages. The first is the combination of a solution of an aqueous polymer dispersion with a pigment and a filler. The second - the resulting mixture undergoes dispersion (grinding of solid and liquid bodies). The third is the addition of additives that are necessary in accordance with the specifications. The fourth is the packaging of the finished material in cans.

Dispersion of ingredients is carried out in special dispersers (mills). These devices have several chambers, and they have a shaft with disks. It is with the help of it that grinding occurs. The resulting mixture is placed in the capacity of the dissolver (mixer). Thorough mixing takes place there, components are added according to specifications.

The timing of mixing all ingredients depends on the properties of each component, the total volume of the mixture, as well as the technical capacity of the dissolver and dispersant. As a rule, 30 minutes are enough for each operation. In this case, all work must be carried out at a temperature of +5 °C.

At the last stage, containers and strainers are prepared. It is through them that the finished paint will flow.

Advantages and disadvantages of water-based paint

Water-based paint for walls and ceilings has several advantages over oil-based paints. First, she dries faster. Sometimes, just a couple of hours is enough for the coating to dry. Secondly, absolutely safe and harmless to humans and environment. This means that during painting work there is no need to urgently leave the premises.

Thirdly, the paint does not have a strong odor, which usually lasts for several weeks after completion of work. Fourth, the coloring composition can be given almost any shade, while adding special pigments. For this, a special colorless composition is even sold. In hardware stores, as a rule, a catalog of colors and pigments suitable for them is offered.

Fifth, the process of applying paint is quite simple, and all tools are easily cleaned with plain water. You don't need to use any solvents. Of the shortcomings, only a few can be distinguished: work can only be done at a temperature of +5 ° C, the material is not cheap. For outdoor work, you need to choose the most expensive paint, because the conditions on the street are significantly different from those indoors.

Water-based paint: technical specifications

Water-based paint for ceilings and walls has the appropriate technical specifications. These include: composition, consumption, specific gravity, viscosity, storage conditions and shelf life. The composition of water-based paint: latex, thickener, fillers, antiseptic. Consumption on one layer about 150-200 ml/m 2 . The number of layers depends on the absorbency of the substrate.

Viscosity water-based paint is determined by a viscometer and should be equal to an average of 40-45 s (when applied with a brush), 20-25 (when using a paint sprayer). In fact, viscosity is an indicator that determines the degree of dilution of the paint with water. That is, water is added to the composition to a certain level, and then they are measured with a viscometer.

Specific gravity water-based paint is about 1.35 kg / l. Adhesion the average is 2.0 MPa. Drying time is from 2 to 24 hours. It all depends on the temperature and humidity of the air. The desired temperature is about + 20 ° C, and humidity - 65%. Keep the paint in a dark place (away from sunlight).

Water-based paint: technical characteristics and production method
Water-based paint, specifications - how do they affect the work process? What material parameters are important to know? About this in the video tutorial.

High-quality coloring is not only the result of the correct use of the coloring composition, but also a combination of certain material characteristics that determine solutions in this direction. When painting and varnishing, the key to success is the selection of such an indicator as the viscosity of the paint in DIN. The table of optimal values presented in this article will help in this matter.

What depends on viscosity?

The very concept of viscosity hardly requires further explanation. But, here are some other characteristics that conditional viscosity itself can influence:

If the dye is too viscous, it is difficult to evenly distribute it over the entire surface. Excessive layer thickness will lead to the fact that it will take too long to dry. The final strength of the coating, on the contrary, decreases.

A solution that is thick in consistency will not fill the irregularities on the surface. This means that the adhesion deteriorates.

A large layer thickness is the reason for the formation of smudges and other similar defects.
An inexpensive spray gun, finally, simply cannot cope with materials that have too high a viscosity. The main principle of operation for pneumatic sprayers is low pressure in the air stream, suction of paint from the tank. They help those who are interested in how to determine the viscosity of the paint.

If the pressure drop is not enough, then the fixtures will have to be disassembled and then thoroughly washed. Harmful and paint, diluted with additional efforts. The number of layers required for high-quality processing increases. The time costs for this or that work are growing, including those in which the spray gun is involved.

Measurement Features

In what units?

For domestic manufacturers, an indication is typical given parameter in seconds. But imported materials suggest the use of a different designation - DIN. What is the meaning behind these combinations? And how is the characteristic measured?

They are only needed to indicate the time (in seconds) after which the composition passes through holes of a certain diameter, previously known. If the paint is more liquid, then it leaves the container faster. In the case of a thick composition, this takes longer. This does not affect how the viscometer is used.

About methods and tools

A viscometer is a special tool used when measuring liquid, a small funnel that strictly has a capacity of 100 milliliters. There is also a hole with a diameter of up to 4 millimeters. Devices with sufficient accuracy for effective use in everyday life cost from 200 to 500 rubles. With the help of them, normal measurement viscosity. Devices used in laboratories are much more expensive. Sometimes the cost reaches hundreds of thousands of rubles.

Instructions for using this device are as simple as possible:

First you need to fill the funnel by plugging the inlet with your finger.
The stopwatch starts as soon as the hole opens.
It remains only to record the time elapsed until the tank is completely empty. Individual drops are not taken into account for the ink viscosity in DIN, the table confirms this.

The temperature of both the paint itself and the surrounding air should not exceed 18-22 degrees. Any formulations will thicken at lower temperatures. And at elevated rates, on the contrary, it decreases. Because of this, the experiment about the viscosity for the paint will not be as effective.

What values are considered optimal?

The manufacturer usually writes on the packaging about which indicator is considered optimal in certain conditions. But information is easy to find on the official website, including for viscous liquids.

Definition of paint viscosity in DIN and table of recommended values
The viscosity of the coating material in DIN, shown in the table, is a key parameter when carrying out repairs. What values are considered optimal?

Water-based paints are currently a very popular, high-quality, affordable and promising repair material. They are easy to apply on cleaned surfaces (concrete, gypsum concrete, wood and pre-plastered), are environmentally friendly and very practical. And in combination with the color scheme, you can always choose the color scheme necessary for the interior.

Advantages of water-based paint

Water-based paint is in demand due to the following characteristics:

no peeling for a long period of operation,
no cracks and bad smell,
ease of application,
fast drying process
acceptable cost.

Besides, water-based paint allows you to get almost any shade by adding special pigments. Often, hardware stores provide a catalog of colors and corresponding pigments that match them.

The main disadvantages of water-based paints

Such paints have practically no flaws. At the same time, it should be noted that it is extremely undesirable to apply them to metal and glossy surfaces, due to the presence of a large amount of water in the composition of the paint.

Today, obvious fakes of “water emulsion” are increasingly appearing on the market, which disappoint consumers. They fit very poorly on the surface to be painted, are overused, get dirty during the drying process and are washed off in case of water ingress.

Technical characteristics of water-based paint

Water-based paint has the following composition: latex, thickener, various fillers and antiseptic. The average consumption of water-based paint is 250 grams per square meter. The number of layers applied will directly depend on the absorbency of the surface to be painted. The viscosity of the paint is determined by a special device - a viscometer. This indicator should be within 45 s. (when using a brush), and 25 s. (using paint sprayer). By definition, viscosity is an indicator that characterizes the degree of dilution of the paint with water. The specific gravity of the paint is approximately 1.35 kg/l. Adhesion is 2.0 MPa, the final drying time is from 2 to 20 hours (depending on temperature conditions). It is necessary to store the paint in a dark and cool place (away from sunlight).

The main types of paints

Depending on the polymer present in the paint, there are four main types of water-based ( water-dispersion, latex or emulsion) colors:

Even among such a small variety, a potential consumer involuntarily raises a question: "So which water-based paint is better?". Let's take a closer look at the characteristics of each of them.

Acrylic water-based paints - quality first

This type of paint is most popular among both professional craftsmen and ordinary consumers who are trying to master the repair on their own.

Based on the name, it becomes clear that acrylic resins are in the composition of the paint as the main component. Such paints are applied to surfaces made of brick, wood, glass, concrete and plaster. The most common representative is veak 1180 water-based paint.

The main disadvantage of such paints is the expensive cost. Therefore, analogue paints with acrylic copolymers have become widespread. Their price is much cheaper than real acrylic, and the quality is not much inferior to the original. Sometimes, to increase the elasticity index acrylic coating, latex is added to the paint, due to which there is an effective resistance to moisture.

Painted coatings can be safely washed with water without fear of spoiling the applied paint. Manufacturers in the technical characteristics of water-based paint indicate that it is able to withstand up to 5,000 washing cycles with water. When applying a double layer of acrylic-latex paint, cracks on the surface (up to 1 mm thick) can be masked. And they dry at room temperature in just a few hours.

Silicone water-based paints - ideal for rooms with high humidity

In silicone paints, silicone resins predominate in the composition. They are a universal coloring and masking agent for all surfaces, hiding two-millimeter gaps from prying eyes. Silicone paint is also expensive, but it has a vapor barrier property, ideal for damp areas of the house that tend to form moisture. Thus, the paint will also actively fight the fungus that has appeared, preventing its reappearance.

Silicate water-based paint - an indicator of durability

Silicate water-based paint is a mixture of liquid glass, water with the possible addition of colored pigments. It is characterized by weather resistance and long service life (up to 20 years). But for excessively wet surfaces, it is better to use a different type of paint.

Mineral water-based paints

In the process of making mineral water-based paints, slaked lime or cement is added to their composition. They are used for any surfaces in the process of painting walls and ceilings. Their main purpose is Painting works with brick and concrete surfaces that are subject to significant hydraulic loads. Distinctive feature Mineral paints have a short service life, so they gradually cease to be in demand.

Types of water-based paints: advantages and disadvantages
Advantages of water-based paint. The main disadvantages of water-based paints. The main types of colors Technical characteristics of water-based paint

The viscosity of the paint most clearly characterizes its suitability for use and its characteristics - color saturation, uniformity of coverage, brightness. The material should flow well, but not drip. This property also determines the technical features of the application. There are several types of viscosity:

Newtonian. This type does not depend on the shear stress, but on the nature of the substance, its temperature and pressure.
Effective plastic. For systems with an internal thixotropic structure.

Viscosity can be different, the optimal one is when the paint does not drain, but lie down evenly

Viscosity can be absolute (dynamic), relative and conditional.

Viscosity is a characteristic property of liquid materials to resist the movement of one part of them relative to another during flow. Viscosity is one of the distinguishing qualities of drying oil.

Depending on the composition and method of application to the surface (brush, roller or spray gun), paints must have a certain consistency, which can be determined using a viscometer. It is a cone-shaped funnel open from above, turned downwards, which has a hole of a certain diameter at the bottom.

This instrument measures the flow time of the amount of the test liquid from a vessel with a special, calibrated orifice.

The higher the viscosity of the drying oil or paint being tested, the more time the viscometer shows and, accordingly, vice versa.

The process of measuring the viscosity of paints and varnishes

Before checking, it is necessary to add 10-15% water (or solvent, depending on the type of paintwork) to the enamel. We immerse the measuring device in a container with liquid and, simultaneously with raising the device, note the time. The time during which the enamel completely flows out of the vessel through the hole is an indicator. As a stopwatch, you can use a regular phone or watch.

The orifice size of the viscometer used depends on the type of coating. As a rule, it happens from 2 to 8 millimeters. In total, there are about 40 types of these devices in the world, with different area, hole size, geometry and volume.

The most common viscometers are Shell, Zahn, B3-234 (they are used both for building enamels, paints or varnishes, and in the printing industry).

Good viscosity of high-quality drying oil and paint is considered at 22-24 seconds, but different types materials, these indicators may differ, this information can be found on the packaging (if not, you can check with the seller). So, a viscous drying oil can dry in 12 hours, and a more liquid one in 24.

Viscosity for thicker materials is determined with a ball viscometer (type 83). In this case, the time it takes for the steel ball to pass from the mark to the mark inside is measured. glass tube containing the material under test. How to measure viscosity old drying oil, if she is very thick.

It is better to measure the viscosity of drying oil and paint in a room with an air temperature of 20-23 0С, since in very hot or cold conditions, as well as in high humidity, the material can change its properties.
It is necessary to carry out measurements several times during painting and, depending on the results, control the consistency (in case of thickening, add solvent, in case of too low viscosity, increase the enamel content).
Do not take measurements when the enamel is foamed, as this will not give an accurate result.
If it is necessary to use a primer before painting, then the conditional viscosity of the primer is checked using a viscometer (it is better to use a device of the B3-246 series), the diameter of the meter hole in this case should be 4 mm, and satisfactory indicators should be 12-18 seconds.

Deviations from the norm

For any discrepancy with the parameters specified by the manufacturer, difficulties may arise with the application of the material. If the liquid has too high a viscosity, it will make it difficult to pass through the spray gun opening, and the enamel will be applied unevenly to the surface. If the values are too low, the enamel will drain from the surface, stains and unpainted areas may appear.

Too high viscosity of the paint will not allow it to pass through the spray gun opening

Thanks to the measurement of viscosity, it is also possible to check the quality of the material - whether some solvent was added to the paint by the manufacturer or distributors, or not. Since some dealers may mix the paint with cheap low quality thinner in order to lower the cost of the material as a good competitive advantage.

Viscosity, or internal friction, is the property of a fluid, which manifests itself in the resistance to the movement of its particles under the influence of the forces acting on them.

Viscosity and its reciprocal - fluidity are one of the important characteristics of paints and varnishes. It is the viscosity that determines such properties as the ability to be applied by various methods, the tendency to form streaks and other defects.

There are dynamic, kinematic and conditional viscosity.

For water-dispersion materials, dynamic viscosity (Brookfield viscosity) is most often determined, for organic-soluble materials - conditional viscosity according to the VZ-246 funnel.

In the SI system, the unit of dynamic viscosity is the newton-second per square meter (N-s / m2), which is the viscosity of a liquid in which, when moving with a velocity gradient of 1 m / s, a liquid of 1 mg area experiences a resistance of 1 N. Tenth part of N.s/m2 is called poise. True dynamic viscosity in poise can be determined with capillary viscometers. In technology, to determine viscosity, methods and instruments are usually used that give "only a relative characteristic of viscosity, expressed in arbitrary units.

Kinematic Viscosity

Kinematic viscosity can be obtained as the ratio of dynamic viscosity to the density of a substance and owes its origin to classical methods viscosity measurements, such as measuring the time it takes for a given volume to flow through a calibrated orifice under the action of gravity.

For the conditional viscosity of paintwork materials with free fluidity, the time of continuous flow in seconds of a certain volume of the test material through the calibrated nozzle of a VZ-246 type viscometer is taken.

Viscometer VZ-246 (according to Russian GOST 9070-75), European analogue of DIN (DIN 53211-87) The most commonly used viscometer is VZ-246 with a nozzle diameter of 4 mm and a funnel volume of 100 ml. The temperature of the material to be tested shall be 20 ± 0.5°C. The method is intended for paints and varnishes with a conditional viscosity according to this viscometer from 12 to 200 s.

To determine the viscosity, paint is poured into the viscometer, the nozzle opening is opened and the stopwatch is turned on. At the moment of the first blockage of the jet of the test material, the stopwatch is stopped.

For the value of conditional viscosity (X) in seconds, take the average

arithmetic value of three parallel definitions of time

flow (T) of the test material and calculated by the formula:

where K is the correction factor of the viscometer.

The most common for measuring the viscosity of paintwork

materials is a DIN4 viscometer - with a diameter

calibrated hole 4 mm.

- Filling funnels ISO

Compared to DIN, this funnel is equipped with a longer nozzle, has a less pointed

body and other internal dimensions. This provides different expiration times.

The extended measuring range makes the ISO funnel a useful addition to the DIN instrument.

The ISO funnel holds 100ml ± 1ml.

- FORD (ASTM D 120087) for American products. These are cups in the form of a truncated cone.

with a wide neck and a narrow opening of a certain diameter located below.

According to the European standard, there are five cups of the same shape with a capacity of

100 ml, but with different diameters of the lower opening - 2, 3, 4, 6 and 8 mm. FORD cups have different

from this row of holes, for example, a Ford #4 viscometer (nozzle diameter 1/6 inch or approximately 4.2 mm).

you can use any of them with equal success: all these devices are built according to the same principle,

and for recalculation of indications there are special graphs and nomograms.

However, the exact viscosity of thixotropic materials cannot be determined by this method, as they liquefy very easily when stirred. After the cessation of exposure after a while, their viscosity rises again. The viscosity of thixotropic materials can only be determined using special viscometers.

Brookfield method

Brookfield viscometers are included in a large number of international standards and specifications. All Brookfield viscometers use the standard principle of rotational viscometry: the measurement of viscosity is carried out by converting the torque required to rotate the instrument's spindle with constant speed when immersed in the investigated environment. Each Brookfield viscometer model can be used for a wide range of viscosity measurements, thanks to selectable speeds and interchangeable measuring systems.

Measurement accuracy: +-1% of full scale, reproducibility +-0.2%

The determination of the apparent viscosity according to Brookfield is carried out according to GOST 25271-93 and the standard ISO 2555-89 This standard establishes a method for determining the apparent viscosity according to Brookfield Viscometers allow measurements of viscosity from 0.02 Pa.s (20 cP) to 60000 Pa.s (60.10 cP ).

The products to which this International Standard applies are generally non-Newtonian fluids and therefore their viscosity depends on the shear rate at which the measurement is made.

For all three types of viscometer, the shear rate at different points of the spindle is not the same. Thus, for a non-Newtonian fluid, the result obtained is not "viscosity at a known shear rate", as a result of which it is conventionally called the apparent viscosity. To determine the viscosity, a cylindrical or appropriately shaped spindle (disk) is rotated synchronous motor at a constant rate in the test product.

The resistance of the liquid to the rotation of the spindle, which depends on the viscosity of the product, determines the torque, which is recorded by the corresponding meter. This measurement is based on the relationship of the tension force of the coil spring with the amount of torque, fixed by the movement of the arrow on the scale.

Brookfield apparent viscosity is calculated by multiplying the scale reading by a factor that depends on the rotational speed and characteristics of the spindle.

To determine the relative viscosity of thickly ground paints, putties, highly viscous primers, etc. it is possible to use a method based on the immersion of a metal cone into the material under study and the determination of the depth of its immersion per unit time. The essence of the method (GOST 5346) is to determine the depth of immersion in the test material of a standard cone in 5 seconds. at 25°C and with a total load of 150 g expressed in integer tenths of a millimeter on the penetrometer scale.

The control of the obtained relative viscosity is carried out by an express method using a VZ-246 viscometer (Russia), Ford-4 (England, USA), DIN-4 (Germany). The method is based on measuring the duration of the outflow of a known volume of liquid from a funnel and a hole of a certain diameter. The expiration time is a measure of the viscosity of the coatings and is determined using a stopwatch in seconds (GOST 8420).

In all cases, the viscosity largely depends on the temperature, and therefore, before use, it is advisable to heat the paintwork material to the temperature of the room where the painting is performed, since a sharp change in viscosity during the use of the varnish due to a large temperature difference (warehouse shop) can lead to thickness variation and the appearance of defects in the coating.

The viscosity of varnishes is considered satisfactory if it does not create difficulties for a certain method of application. An even film, having the same thickness over the entire surface, can only be obtained when using paints and varnishes with optimal viscosity.

High viscosity makes it difficult to use paints and varnishes, since too viscous materials pass with difficulty or even do not pass at all through the spray nozzle and cannot be distributed evenly over the surface of the product to be painted.

If the viscosity is too low, the paints will run off vertical or inclined surfaces to be painted, leaving too thin a layer of material on the top and forming streaks on the bottom of the surfaces. Thus, each coating material must have an optimal viscosity, depending on the method of its application.

The viscosity of coatings when applied with a brush should be 30 - 40 seconds according to the VZ-4 viscometer, when applied by spraying - 18 - 22 seconds.

To bring to the optimum viscosity (working viscosity), thinners are used, which are introduced into the coatings before use.

After adding a thinner to the paintwork material, its viscosity is significantly reduced.

In addition to reducing the viscosity of the material, this also leads to a reduction in its dry residue and, consequently, the thickness of the paint film.

Manufacturers indicate the amount of thinner to be added (by weight or volume) required to give the coating material the working viscosity for application by equipment of a certain type in technical description for paint material.

This amount of thinner specified by the paint manufacturer is valid under standard conditions, which include an ambient and paint material temperature of 20°C and an air humidity of 50%. In practice, these conditions are met very rarely, therefore, the specific amount of diluent to be introduced is determined individually, depending on the conditions for applying the coating.

It is important to take into account the change in viscosity with temperature. If the specifications provide measurement data at 20 ° C, then the viscosity must be controlled strictly at the specified temperature. Before measuring the viscosity, it is necessary to mix the test material well, especially in case of long-term storage. If the temperature of the coating material decreases, its viscosity increases and therefore more thinner is required to give the product the necessary workability.

It is recommended to regularly measure the working viscosity of the product, usually it is convenient to do this with a DIN4 cup. Only in this case it is possible to determine the necessary degree of dilution of the paintwork material, regardless of temperature conditions.

In pigmented systems, viscosity largely determines the rate of settling of pigments under the action of gravity. The density of pigments significantly exceeds the density of the film-forming. When deposited, the pigment particles form a precipitate. The particle settling rate is inversely proportional to the viscosity, i.e. the higher the viscosity, the slower the formation of sediment.

During long-term storage, pigmented coatings may form a significant dense precipitate, therefore, before use and measuring the initial viscosity, paints and varnishes must be thoroughly mixed.

Possible defects in the paintwork in case of violation of viscosity indicators:

streaks
Wrinkling of the varnish film
Boiling (bubbles)
Shrinkage
Loss of shine
Variation in hue
Drying violation
Deterioration of adhesion
cracking paintwork
Swelling paintwork