What is moire and color distortion? "moire" - polymer powder coating for metal doors Painting moire.

Powder paints are now used for decoration big view surfaces. Sometimes we may not even notice that the structure in front of us was painted using powder paint. This, in turn, affects the wide range of products presented, each element of which has its own advantages and disadvantages. However, in most cases, the choice of powder paint type is determined by the scope of its application or, more precisely, the type of application surface. So, if you plan to place the structure outdoors, then powder painting with a polyester mixture is the best method, since it better protects the surface from sunlight and other weather conditions. In turn, epoxy analogues are suitable if increased resistance to chemical, acid or alkaline influences is required. Finally, epoxy-polyester combinations are great for indoor use. They not only lie very easily and evenly on the surface, but also allow you to create various types of textures that open up great opportunities for decorating a room and creating a unique interior. Despite such diversity possible options, is most popular among painting specialists today moiré powder paint, which after spraying resembles to the touch orange peel. This popularity is caused by several fundamental factors that distinguish this type of raw material from most of its analogues.

In general, the consistency of moire can be compared to very fine sandpaper. At the same time, the surface is velvety and shiny to the touch. In this case, the degree of gloss is adjusted by changing the saturation of the consistency of the paint composition. The minimum value is 20%, and the maximum is 40%.

The main advantage of powder paint for moiré metal is that it can easily hide any small defects on metal surface. This is often the decisive factor when faced with a choice between painting or replacing a particular part. Moiré gives the surface a matte tint, which appears already at a distance of only half a meter, which makes it a choice when there is insufficient funds for real matte powder paint. By the way, the price of moiré paint is on average lower than any other analogue, which again is an argument in favor of choosing this particular type of powder raw material. Another advantage is that moiré powder paint very flexible to mixing with various additives, which cannot be said about most other analogues. Thanks to this, developments are currently underway to create a special type of moiré powder paint, which will have anti-vandal properties. In other words, surfaces coated with this coating will have increased strength and scratch resistance. This discovery should be a breakthrough in the automotive industry, which is why today investors are investing large sums in these developments. In addition, the possibility of mixing significantly expands the boundaries of the use of moiré powder paint. True, experts note that in pure form this raw material is applied much better and creates a higher-quality coating, which cannot be said about its mixed modifications. That is why moire cannot yet compete at a decent level with other types of powder paint that are used in specific application conditions. In addition, this powder raw material still does not make it possible to create a smooth surface, which is so valued in the decorative arts. By the way, the roughness of the texture leads to another drawback, which is susceptibility to the rapid accumulation of dust, which complicates the process of caring for such a surface. However, in general moiré powder paint has the best characteristics of its kind, which make it so popular with many companies that specialize in coloring. Perhaps in the near future experts will find ways to level out these disadvantages of moire paint, and this

When two or more grids (rasters) consisting of lines, dots or other geometric elements are superimposed, a picture appears consisting of alternating dark and light stripes. This phenomenon is called moire effect. A moire pattern occurs if these two rasters are rotated relative to each other by any amount or have a slight difference in pitch (the distance between adjacent light or dark stripes of the same name).
What explains the phenomenon of moire? The human eye has limited resolution. A system of alternating dark and light stripes, the distance between which is visible at a viewing angle of less than 1A, is perceived by the eye as a solid gray field. When two systems of lines are superimposed, the intensity of light across the surface of the image changes, and this change in intensity is perceived as a moiré pattern.
The center of the light moire stripe coincides with point A, where the light lines of both rasters are combined. The center of the dark moiré stripe coincides with point B, where the dark line of one raster overlaps the light line of another raster.

Thus, the moire effect is an optical phenomenon that occurs when fine meshes are superimposed. The wavelength of the light does not matter in this effect, which is why the moiré effect is sometimes called mechanical interference. by analogy with ordinary light interference.
Interference is the addition of two periodic phenomena, which results in a third phenomenon with a larger period.
Moire stripes have the property of increasing movement.
Moiré stripe pitch

where a0, a1 are the pitch of the original and distorted rasters; φ - angle of rotation between raster lines.
From the analysis of the above equation it follows that small values ​​of the difference between the steps and the angle of rotation correspond to a large step size of the moire fringes, that is, small deformations that cause raster distortion correspond to large parameters of the moire pattern.
Let us determine the value of the relative degree of deformation εat φ = 0, if the step of the original raster a0 and the step of the moiré stripe n are known.

Where

The moire effect was discovered by Lord Rellay in 1874, but only in the second half of the 20th century, when it became possible to obtain sufficiently small and accurate rasters (up to 100 lines per 1 mm), this method began to be widely used in research practice.
The moire effect when studying the stress-strain state (SSS) of a metal is used in two directions:
- to study the stress-strain state by directly applying a raster to the surface of the model under study;
- to study the deflections of plates and shells by projecting rasters on them.

Study of stress-strain state when directly applying a raster to the metal surface

The raster is applied to the surface under study by scratching, etching or photo printing. The sample is then subjected to deformation, during which the raster is also deformed. Then a reference raster (the same as it was before the deformation) is superimposed on the deformed raster. As a result of their interference, a moiré pattern is obtained.
Moire stripes in in this case are lines of equal movements of metal particles. That is, all particles lying on the moire stripe received the same movements equal to the pitch of the original raster. Therefore, by selecting the initial raster with the required pitch, it is possible to obtain data on metal deformation with the required degree of accuracy.

Since the moiré pattern carries information about the movement of metal particles only in the direction perpendicular to the raster lines, to obtain data on deformation in the plane under study it is necessary to apply another raster with the pin direction perpendicular to the first raster. Usually if VAT is investigated; in any cross-sectional plane of the sample, then a raster with a longitudinal lineature is applied to one half of the sample, and a cross-section to the other half; if the model under study has an axis of symmetry, then rasters with mutually perpendicular lines are applied to the different halves of the section relative to the axis of symmetry.
Denoting the displacement in the direction of the x1 axis through U, and in the direction of the x2 axis through V, the deformations can be written:

Taking into account that the moire stripe is a line of equal movements, knowing its order and price, the movements at the points of interest can be determined as follows:

where n,m is the serial number of the moire band; a0 - step of the original raster.
To determine the sign of deformation (compression or tension), one of the properties of moiré fringes is used, namely, the original raster superimposed on the deformed surface under study begins to rotate. If the moire fringes rotate (shift) in the direction opposite to the direction of rotation of the undeformed raster, then the sample has been subjected to compressive deformation (the deformation has a negative sign); if the direction of rotation of the raster coincides with the direction of displacement of the moire fringes, tensile deformation occurs.

When determining the deformation at points not lying on the moiré fringes, the interpolation method is used with the assumption that the movement of line to line occurs according to a linear law. In this case, the movement at point B

Using the found components of the deformation tensor at a point, the intensity of the deformation can be calculated

Knowing the relationship between the strain intensity (εi) and the stress intensity (σi), the value of σi is determined. Then the components of the stress tensor are found.

When solving the problem for a plane stress state, these dependencies have the form:

As a result of processing the moiré pattern of displacements, it is possible to obtain fields of partial derivatives of lines of equal deformations, deformation rates, etc.
Thus, depending on the research task, a moiré pattern can provide large and varied information.

SSS study of thin-walled structures, plates and shells

When studying the bends of shells, two research methods are used using the moire stripe method:
- using reflection of the designed raster (bending study on mirror models);
- using a shadow image of the designed raster (on surfaces that do not have a mirror surface). The essence of the first method of obtaining moiré patterns is that a mirror plate 2 is installed in front of the screen 3, on which the raster is depicted, and through a hole in the screen, the camera 1 records the image of the raster on the surface of the undeformed plate.
Then the model is loaded and the raster image is photographed again, but on the surface of the deformed model.

The angles of inclination of the curved surface of the deformed model dφ/dx in this case cause a shift in the lines of the reflected
raster images at an angle of 2dφ/dx. Overlays of the reflected raster before and after loading form a picture of moiré fringes, which are level lines constant angles rotation of the normal to the surface under study. Knowing the curvature of the surface through the angles of inclination of the normal, we can
Obtaining a mirror moiré pattern, calculate the stresses acting in the plate.
The disadvantages of this method include:
- the need for double photography of the reflected raster, since it is impossible to visually capture the moiré pattern;
- special preparation of the mirror surface of the object under study.
A moiré pattern, which characterizes the amount of surface deflection, can be obtained in another way - using a shadow image of the projected raster.
To obtain a shadow moiré pattern, a translucent raster 1 (made on glass or made of stretched threads) is placed at a sufficiently close range above the model under study 2. With oblique lighting (light source 3) in a direction perpendicular to its lines, a shadow raster image is formed on the surface of the model. By observing the raster and its shadow in a direction perpendicular to the raster plane (or at some angle β to it), one can see the pattern of moiré fringes as a result of the interference of the original and shadow rasters. This picture can be photographed and observed visually.
Deflection value for moiré stripe points

where m is the serial number of the moire stripe; a is the pitch of the original raster; α, β-angles (see figure).
Thus, in this case, the moiré stripe is the geometric locus of points of the same distance from the plane of the original raster to the surface under study.

Advantages moire method:
- research on real materials;
- high degree accuracy in determining deformations;
- the method allows you to obtain an integral picture of the deformable state throughout the entire volume under study;
- the ability to study deformations regardless of their physical nature under static and dynamic loading.
The disadvantages of this method include the following:
- impossibility of studying large plastic deformations (more than 50%) and small elastic deformations (less than 1%);
- difficulty in obtaining small rasters (less than 20 lines per 1 mm).

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When two systems of contrasting stripes are superimposed, a pattern appears formed by their thickening in places where the stripes of one system fall into the spaces between the stripes of the other system. The occurrence of such patterns is called moire effect.

The simplest moiré pattern occurs when two systems of equidistant parallel stripes (lines) intersect at a slight angle. A small change in the angle of rotation of one of the systems leads to significant changes in the distance between the elements of the moire pattern.

A moire pattern is also formed when two non-intersecting systems of equidistant parallel lines are superimposed, when the step size of one of the systems is slightly different from the other. Moreover, the smaller the difference in pitch, the greater the distance between the moire fringes. This makes it possible to obtain a colossal increase (millions of times) in the difference in the width of the spaces between the lines. In other words, the moire effect makes it possible to visually detect, without the use of optical systems, minute deviations in almost identical periodic structures. Currently, the moiré method is widely used to control the accuracy of dividing devices for the manufacture of diffraction gratings.

Moiré appears in an electron micrograph of two crystals superimposed so that their atomic lattices are almost identical. Any defect that disrupts the regularity of the crystal structure is clearly visible in the moiré pattern. The magnification is such that it allows one to see displacements of atoms, the magnitude of which is less than the diameter of the atom itself.

If two lattices of equidistant parallel straight lines, slightly different in step size, are moved one relative to the other in a direction perpendicular to the lines, then the stripes of the moiré pattern will move at a speed much greater than the relative speed of movement of the lattices themselves. In this case, the direction of their movement coincides with the direction of the relative displacement of the lattice with a smaller step. Thus, a small movement of one of the gratings results in a large movement of the moiré fringes, which is easy to detect and measure.

Application example:

A method for determining deformations from a pattern of moire fringes, characterized in that, in order to increase the accuracy of measuring deformations, the ratio of the speeds of mutual movement of the deformed and reference meshes and the speed of movement of the moire fringe is determined, and the magnitude of the deformations is judged by the value of this ratio.

The described manifestation of the moire effect has long been used in all measuring instruments with nondus, such as a micrometer or caliper.

The moiré effect can be used to visualize minute changes in the refractive index of transparent media by placing them between gratings. For example, you can visually study the dynamics of the dissolution of two substances.

The same principle allows for express analysis of the quality of optical parts. The lenses are placed between the gratings; the presence of a convex lens increases the elements of the moire pattern, while a concave lens decreases them. In this case, both lenses rotate the pattern in opposite directions at an angle proportional to the focal length. In places where the structure or shape of the lenses is inhomogeneous, the pattern lines are distorted.

Another example of optical control:

An interference method for measuring the wedge shape of optical transparent plates, which consists in focusing a beam of light from a laser using a lens into the plane of a hole in the screen, behind which a controlled plate is installed, differing in that, in order to increase the accuracy and productivity of measurements, from the controlled plate with its In a fixed position, a transparent copy of the interference rings is obtained, the plate is rotated in its plane by 180, the interference pattern is superimposed on the copy, and the wedge shape of the platinum is measured using the width of the moiré fringes formed from the overlap.

A variety of moiré patterns can be created by combining lattices formed by a wide variety of lines, such as concentric circles, spiraling wavy or radially radiating lines from a point, and even families of evenly spaced dots. In this way, it is possible to simulate many complex physical phenomena, such as the interaction of electrostatic fields, wave interference, and others. Some problems of architectural acoustics are solved using similar methods.

In Japan, it has been proposed to use the moire effect to compile topographic maps of objects. The object is photographed through a grid of thin threads, casting a clear shadow on it. The shadow is deformed in accordance with the relief of the object and when it interacts with the real lattice, a moiré pattern appears, superimposed on the image of the object. In the photograph, the distance between the moire lines corresponds to the depth of the relief. This method is very effective, for example, in studying the deformation of rapidly rotating parts, in analyzing the flow of a surface layer of liquid around bodies in medical anatomical studies.

The versatility of the moire method, the ease of converting various quantities with its help, close to IFR, high resolution - all this suggests that inventors will turn to the moire effect more than once in their practice.

The specialists of the Neman company have perfectly mastered the technology of applying polymer powder coating both to finished doors and to non-standard structures. For this you have everything you need - knowledge, experience, strength and desire. Polymer painting is a waste-free and clean technology that allows you to obtain high-quality decorative, protective and decorative coatings.

Note that appearance is formed from polymer powders applied to the painted part of the product fabric. Next, the product is heated and held at a certain temperature for several minutes. The low polymerization temperature makes it possible to paint glass and metal using this technology. In the last decade, this technology has gained great popularity and is gradually replacing traditional methods of applying paint and varnish coatings.

One of the finishing options offered by the Neman company is Moire. What is this coating? This is the finish front door, offering a special powder coating structure. So, upon completion of the work there will be a special pattern on the canvas. Speaking figuratively, moire can be compared to the effect that gives sandpaper. The main advantages of this type are: practicality, aesthetics and versatility. Typically, such products are used in cases where it is necessary to obtain the maximum practicality possible. It is also effectively used to hide defects in the outer part of a metal door.

What benefits does a consumer receive when choosing moiré coloring?

• High resistance to aggressive environments (alkalies, acids, organic solvents);
• Resistance to mechanical stress;
• Increased adhesion. In this case, the adhesion of paint particles to the surface being treated is 500 kg/nm;
• High anti-corrosion resistance;
• Environmental friendliness. The paint does not contain organic solvents or other types of volatile substances.

The main point of the painting method is to spray on previously cleaned metal coating powder paint. You need to know that paint particles receive an electrostatic charge, which allows the particle to stick to a product that has the opposite charge. Particles that have not had time to settle are captured in the spray chamber and can be used again. After this, the product is placed in a polymerization chamber for subsequent baking of the paint at a temperature level ranging from 180 to 200 degrees Celsius. Thus, a reliable, high-quality and safe decorative and protective design for humans is created on the canvas. Metal doors painted with Moire can be used not only for installation in apartments, cottages, but also in industrial facilities.

Moiré pattern

The appearance of moire when two linear gratings are superimposed.

Moire pattern(moire, from fr. moire) - a pattern that occurs when two periodic mesh patterns are superimposed. The phenomenon is due to the fact that the repeating elements of the two patterns follow with slightly different frequencies and either overlap each other or form gaps.

The moire pattern is observed when different parts of tulle curtains are placed on top of each other.

The concept of "moiré" comes from fabric moire, in the finishing of which this phenomenon was used.

The moire pattern occurs when digital photography and scanning reticle and other periodic images if their period is close to the distance between the photosensitive elements of the equipment. This fact is used in one of the mechanisms for protecting banknotes from counterfeiting: a wave-like pattern is applied to the banknotes, which, when scanned, can become covered with a very noticeable pattern that distinguishes the counterfeit from the original.

Digital image processing

The appearance of moire during scanning

Most often in Everyday life Moire appears when scanning printed images. This occurs because the scanner re-rasterizes an image that already has the original raster in it. It can be more simply imagined this way: if you take a tracing paper with one ornament and put it on a tracing paper with the same ornament, but depicted from a different angle, then the resulting ornament will differ from both the first and the second. If you put them so that they coincide, then the first ornament will coincide with the second.

The round “rosettes” at the intersection of two rectangles result in image distortion, which is visible in the first picture.

The appearance of moire during the screening process

"Divers". The sky is painted with uneven horizontal lines, and at low resolutions the result is moiré.

Moire can also occur due to incorrect setting of angles between the lines of primary colors during screening. Both are, in fact, the interference of two sets of raster lines. There are several types of moire rosettes, by the appearance of which you can often find out the cause of moire.

Scanning, in fact, is the modulation of signals in the scanner grid nodes by the brightness of the typographic raster nodes. IN general view the result is the product of two modulated sinusoids (gratings) with different periods spatial fluctuations. One harmonic may have a larger period equal to the sum of the periods of both gratings, which causes moire. The second always has a period equal to the modulus of the difference between the grating periods and disappears because it cannot be implemented at a given scanning resolution.

Paints that affect moire

Moiré ribbon

When printing with any set of inks, the most intense (dark) ink, which has a value of 30 to 70% over a large area, can produce moire. That is, if in our CMYK photograph the black channel does not dominate (<10-15%) то вероятность возникновения различимого глазом муара минимальна. Таким образом можно почти не обращать внимание на жёлтый канал CMYK фотографии. Угол поворота растра между самыми проблемными каналами должен быть как можно ближе к 45°.

When printing “solid” (that is, with >95% coverage), the concept of “raster inclination angle” practically disappears (even if we're talking about about photography).

see also

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See what “Moiré pattern” is in other dictionaries:

The appearance of moire when two linear gratings are superimposed. Moire on the ribbon of the Order of St. Andrew the First-Called. Moiré pattern (moire, from the French moiré) is a pattern that occurs when two periodic mesh patterns are superimposed. The phenomenon is due to the fact that... ... Wikipedia