The production of “moire”, hammer, crackling, and “antique” coatings is based on the ability of certain paint and varnish materials during film formation, form beautiful patterns in the form of wrinkles, embossing or tears. Such coatings based on liquid paints have long been used in mechanical engineering, instrument making, the electrical industry and other industries. IN Lately similar coatings are obtained using appropriate powder paints. Hammer coatings are especially popular, as they have a smooth surface that does not become dusty and weakly retains radioactive contamination.
Moire coatings (Fig. 11.5, A) obtained using epoxy powder paint P-EP-135 different colors. Similar
Paints are produced by many domestic and foreign enterprises. The corresponding wrinkled pattern is formed due to the presence of a special additive in the paint, which ensures different curing rates of the film former across the thickness of the coating. Paints are applied to the surface using electrostatic spraying; coatings (thickness 80-120 microns) are cured at 180 °C for 15 minutes.
Moiré coatings can also be obtained using liquid paints(MA-224 paint on compacted (polymerized) tung or oitis oil). The coating technology in this case is much more complicated. Paints are applied to a pre-primed surface, usually in two layers with an interval of 5-10 minutes. The formation of the coating is carried out in two stages: at the first stage, the pattern is revealed, at the second it is fixed. Identification of the pattern is carried out at 80±5 °C for 25-40 minutes, the fixing operation is carried out at 100-170 °C depending on the type of paint and its color.
Hammer coatings (Fig. 11.5, B) By appearance resemble the characteristic patterns obtained by minting metal. This effect is achieved by introducing into liquid enamels non-floating (low-grease) aluminum powder and pattern formers, which are organosilicon compounds - silicone oils, SKT rubber, Vaseline KV-EM-1. The latter, by changing the surface tension of the film former, contribute to its “contraction” (collection into drops) on the surface of the substrate and powder particles. In this case, violation of the continuity of the coating is not allowed.
To obtain hammer coatings, the industry produces melamine alkyd (ML-165 and ML-165M), nitrate cellulose (NTs-221), alkyd styrene (MS-160) and other enamels. Along with aluminum powder, they contain small quantities of covering mineral or organic pigments, which give the color shade coating. Enamels are usually applied by spraying (1-2 layers) onto a previously prepared and primed surface. Before use, a pattern former is introduced into them in the form of a 10% solution in xylene at the rate of 1-10 g per 1 kg of enamel. A drawing (pattern) is formed immediately after applying enamel to the surface. It is fixed (coatings are cured) in the case of ML-165 and ML-165M enamels at 120 °C for 1 hour, NTs-221 - at room temperature for 24 hours.
Powder paints (P-EP-258 and others) have also been developed to form hammer coatings. When using them, pattern formation occurs at the moment of coating formation due to surface effects in the film. They also contain aluminum powder. Depending on the type of color pigment, they form coatings of different colors and shades.
Hammer coatings made from liquid paints are used for finishing metal and wooden products: devices, movie cameras, sewing machines, cases for devices, etc. Powder paint coatings have the same purpose, but they are suitable for painting only heat-resistant substrates.
Cracked coatings (Fig. 11.5, IN) imitate the pattern of crocodile skin. To produce them, both liquid and powder paints are used. As liquid formulations Nitrate cellulose paints are used, which are highly filled systems that are diluted with highly volatile solvents, such as acetone. Cracking is caused by the low cohesive strength of the resulting films and large internal stresses that arise during the rapid volatilization of solvents.
Paints are applied over a background layer of cellulose nitrate enamels, the color of which is usually chosen to contrast with the color of the cracking paint. In thick layers the paint cracks with large tears, in thin layers it cracks with small ones. Cracking occurs immediately after applying paint to the surface. After drying from solvents, the coating can be covered with a layer of varnish or enamel.
Recently, these paints have practically lost their importance for environmental reasons and fire hazard. This niche has been firmly occupied by powder paints that are more convenient to use. They are obtained by introducing aluminum powder and special structuring additives into thermosetting powder compositions, which, by stretching the powder particles in the surface layer, imitate the state of a cracked film. Unlike liquid paints, powder paints practically do not create a surface relief (it remains smooth), which contributes to the non-contamination of coatings. The size of the pattern depends on the viscosity of the melt.
Cracked coatings have a purely decorative purpose. Sometimes they are used to finish dashboards, cladding slabs and panels indoors.
Textured coatings (Fig. 11.6) create the effect of a surface with a large “shagreen”, similar to coatings made from paints and varnishes with poor spreading. The most widely used coatings are textured coatings based on thermosetting powder paints. Regulation of film texture is achieved purely by prescription - by introducing additives that change
Rice. 11.7. Antique colored coatings:
A- with aluminum powder; B- with bronze; IN- with zinc powder
Viscosity of melts (aerosil, thermoplastic polymers, etc.). Coatings can be different color, containing reflective pigments and not containing them. An example of compositions of this type are epoxy-polyester paints P-EP-259-T-1 and P-EP - 259-T-2, produced by OJSC NPF "Pigment". The macrorelief of the coatings formed from them makes it possible to hide defects in the surface of metals - casting, stamping, small irregularities with a film thickness of 80-100 microns.
"Antiques" (Fig. 11.7). The term “antique” appeared in coating technology with the development of a large number of powder paints containing flaked reflective pigments and fillers - powders made of aluminum, bronze, copper, zinc and other metals, as well as mica, pearlescent pigments, etc. Possibility of varying the decorative effect of such coatings practically unlimited. They are determined not only by the type of reflective component, but also by its dispersion, the method of introduction into the composition, the nature and amount of color pigments, and the presence or absence of structuring agents.
There are basically two methods of introducing flake pigments into powder compositions: before extrusion and after extrusion. In the first case, powder particles are chaotically distributed in the melt of the film former and, due to its high viscosity, lose the ability to float when producing coatings. A high reflective effect is achieved only in the second case, when the powder composition, after extrusion and grinding, is mechanically mixed with powder. Particularly attractive for obtaining compositions is the bonding process (mixing under moderate heat), in which powder particles are firmly attached to film-forming particles. This eliminates the separation of powder compositions when applied in an electric field. Any thermosetting film formers are suitable for producing antique-type coatings. The powder paint manufacturer Ekolon (St. Petersburg) has achieved particularly great success in developing formulations for such compositions.
Among other decorative coatings special attention deserve paint coatings called "chameleon". Their main feature is the change in color when viewed from different angles. Powder varnishes for chameleon-type coatings are produced on the basis of light-resistant polyester film formers using special pigments, which are SiO2 compounds WITH microlayers TiO2, Fe2O3 and 2Yu2. Such pigments are offered by the company "Megsk".
In a more understandable everyday way, a moiré pattern can be achieved by superimposing two or more layers of tulle curtain on top of each other. A similar illustration of the moire effect would be scanning an image that was originally printed. During the scanning process, patterns overlap, and as a result, some parts of the image are painted over into a wavy, uneven pattern when reprinted.
Moiré fabric
Despite this, in some areas “moire” creates unwanted patterns, while in others it pleases the eye. Moire ribbons adorn the costumes of famous generals and emperors in paintings. This proves the popularity of the moire pattern back in medieval times. The fabric of the same name, moiré, is produced by creating a rep weave.
Externally, moiré fabric is quite beautiful; it shimmers in the light, creating a play of colors with so-called “stains”. Moiré fabric resembles a surface of water disturbed by raindrops. Currently, there are many ways to create a moire pattern. One of them is to pass the fabric between hot engraving rollers, which helps change the direction of the thread.
Highlight effect
Clothing designers still use the moire effect to highlight the details of a suit. With the help of moire you can draw attention to the finish, it is very easy to add shine and play of color.
But moire has gained its most notable popularity in the field of interior design. The external beauty of the fabric has opened up great possibilities for using it in decoration. Today you can buy moire curtains with different types pattern: moire-antique or gromoire. Such curtains will decorate the bedroom and will look advantageous in both natural and artificial light.
You may have already seen moire in images - it's a strange wave-like pattern that doesn't appear on the subject.
This effect occurs when an image of an object with many details, such as lines, is superimposed on the pattern of pixels on the matrix.
As a result, it is most often seen in detailed, high-contrast images of patterns. It usually appears when photographing fabric, hair, or scenes that contain repeating details, such as pronounced vertical lines in architecture.
As you can see in the picture, when two patterns are superimposed on each other, moiré is formed.
What is color distortion?
This term is used to refer to those colors in a digital image that differ from the actual colors of the object. The light coming from an object is not detected by all RGB color sensors, which causes the stored colors to change. In digital images, moire and color distortion usually appear together.
In the image above, the U-shaped pattern on the slate wall is the result of moire. In addition, there are areas of red color in the image, which are the result of color distortion.
Many digital cameras use an optical low-pass filter to reduce aliasing and color distortion.
By understanding the nature of these effects and why they occur, these problems can be minimized during shooting or editing.
1. Change the shooting angle and the distance between the camera and the subject.
Since the effects of distortion are affected by the angle at which you shoot and the distance between the camera and your subject, small changes can eliminate or reduce these imperfections. Move the camera left or right, up or down, or move a little closer or further away.
2. Change the focus point.
The reasons for the occurrence of moire and color distortion are very sharp focusing and high detail of the patterns. By manually adjusting the lens and setting the focus slightly in front of or behind the focus point, you can avoid such effects.
3. Change the focal length using a different lens.
4. Decrease the lens aperture.
MTF chart with resolution values for lenses with different meanings diaphragm.
The optimal resolution for each lens is achieved at a certain aperture value (in the graph this is f/8). Optimal resolution is usually achieved by setting the aperture value 2-3 stops below the maximum.
Closing the aperture too much (beyond optimal resolution) will cause diffraction. In this case, the resolution will decrease slightly, but at the same time the distortion effects will also decrease.
To check whether there are such phenomena in the picture, it is best to view the images on a computer screen in full size(100 %). When pictures are reduced in size, false moire and color distortion may occur due to the pattern on the monitor tube (or panel).
These effects can appear in images from all digital cameras and scanners, but are more likely to occur in images from digital SLR cameras because of the lens, sensor, and software designed to provide the sharpest, most accurate images possible.
The distortion may not be eliminated, but it can be reduced if you know under what circumstances the problem occurs and how to fix it.
How to remove moire from a photo? Complete removal of moire takes place in two stages. Let's remove the colored moire first, and then the patterned one.
Open our image in Photoshop:
1. Removing colored moire.
Make a duplicate of the main layer ( Ctrl+J). Change the blending mode to Color(Color).
Choosing a tool Brush Tool (Brush), preferably with soft edges. To do this, change the brush settings Hardness(hardness) by 0% . Click Alt and hold it, the mouse cursor will turn into a pipette. We click on the photo in the place where we do not have moire and there is a primary color corresponding to the one on which we will remove moire.
Letting go Alt, and move on to removing moire: carefully paint over all the places where there is moire; periodically the brush color will need to be changed to a more suitable one. If suddenly the wrong area of the photo is affected, we use Eraser tool (Lastic) or a mask.
Comparison of the initial image with the image after processing (clickable):
The colored moire was successfully removed, but in the photo there was a patterned moire all over the fabric. Therefore, below we will consider a method that will help us remove it.
2. Removing patterned moire.
Merge all layers ( Ctrl+E), and again create a duplicate ( Ctrl+J).
Let's go to the menu Filter->Blur->Gaussian Blur(Filter->Blur-> Gaussian blur), and increase the radius value until the moire stripes completely disappear. Let's see what value the parameter took Radius(Radius). In our example 10,5% . We remember it, but don’t apply the filter!
Let's go to the menu Filter->Other->High Pass (Filter->Others->Colorcontrast). For this filter, we set the radius value that we obtained earlier - 10,5%. Select blending mode Linear Light(Linear light) And Opacity(Opacity) — 50%.
Now let's invert the layer Image->Adjustment->Invert (Image->Edit-> Invert) or simplyCtrl+I. This is necessary so that the filter works to suppress, and not enhance, moire .
Now apply to this layer filter Filter->Blur->Gaussian Blur(Filter->Blur-> Gaussian blur). Slowly increase the blur radius from zero until the texture is preserved and moire does not appear and press OK.
Now you can experiment with Opacity(N opacity), in order to get a more suitable effect. It's okay if the image looks a little wrong. Assign a mask to our layer and fill it with black. Take the tool Brush Tool (Brush) we ask her White color and carefully use the mask to go through the places where there is moire.
A moire color or pattern creates a visual sequence with the obligatory overlay of similar patterns relative to each other. For example, when two identical (usually transparent) patterns on a flat or curved surface are superimposed at an offset relative to each other.
These can be straight lines that take the form of grids or points that overlap each other with rotation or displacement.
How would you say it in French?
The term comes from the French word moiré - moire, also called moira. It means a ripple or wave, a striping pattern that appears when an object is examined under different angles falling light. Moiré is also a type of fabric.
Traditionally, the moire color, or more correctly, the pattern, was associated with the type of fabric, usually silk High Quality. Ripples or waves can now be seen on cotton and synthetic fiber fabrics.
The picture shows the moire effect; it doesn’t matter what color it might be.
Structure formation or fine design
In addition to developing on fabrics, moire patterns are often an undesirable artifact of digital imaging and computer graphics images. For example, a similar visual effect occurs when scanning a fuzzy image through a transparent checkered pattern.
The photo above shows a moire pattern. The lines can represent the fibers in the silk as ripples or waves, and they can be drawn on paper or appear on a computer screen. To the question of why this happens:
- The nonlinear interaction of systems of multidirectional lines creates a real and visible moire color or pattern of approximately parallel dark and light stripes superimposed on each other in an offset manner.
In the photo below shining example wave visualization.
- If the lines are curved or not exactly parallel, more complex linear moirae are created, as in the photo of the parrot's wing.
- Patterns that reveal complex shapes or sequences of symbols embedded in one of the layers (in the form of periodically repeating compressed figures) usually give very interesting images that are specially created using groups of moiras.
- One of the most important properties All types of moire is their ability to magnify or stretch tiny forms of lines, stripes, dots along one or both stretch axes, creating stunning 2D effects.
A general 2D example of magnification and distortion of the underlying pattern can be seen by viewing a chain link through another chain link of identical design. The subtle design of shimmering ripples is clearly visible even from a distance.
What color is moiré? A photo of a garage door shows a pattern - the effect of the design lines shifting relative to each other. The gate is a structure of two planes with metal strips connected with an offset.
Flaw or Feature: Moire Color in Fine Art
Simulate colored moira using modern technologies in order to still achieve a high-quality image, it is quite difficult.
The best color scheme provide images of fabrics or finely constructed enclosures.
Black and white moire is more amenable to experimentation. For example, the Italian designer Andrea Minini began an experiment in designing images of animals with a graphical offset effect.
- In order to achieve complex shapes and depth, he begins drawing the object with a small number of basic lines.
- Using Adobe Illustrator, Minini deepens the design in different directions, creating wonderfully textured moire patterns.
- Each illustration is unique and interesting with its intense expressiveness.
Moire color and shape, photo by Andrea Minini.
Waves on posters
But usually moira is considered a defect or artifact, especially, for example, in printing full-color images that involve the overlay of halftone screens.
These are rectangular dot patterns, four of them to be exact, printed in cyan, yellow, magenta and black. You can’t completely get rid of stains and spots, but when favorable conditions the overall image is quite “dense”, and the spatial frequency of moire is so high that it is not noticeable.
In fact, in fine arts the term refers to an overly noticeable distortion pattern, that is, the deliberate use of waves and lines. True, the visibility of moire is not always predictable. Everything is done by trial and error, so sometimes you get amazing images with unusual results, like in a painting by Brian Thomas. Moire with discoloration is shown in the photo below.
Now he's on TV
Moire patterns have been used in the textile industry for a long time. At the royal courts, ribbons made of fabric with shimmer served as a badge of honor.
Studying microscopic changes in fabric tension, deformation of the main weaving lattice in relation to, for example, the weaving lattice on the right, always gives new and new moiré colors and patterns.
No matter how we feel about moire, we cannot but agree that it is an interesting and mysterious visual effect that makes us rethink it, study it and find application in everyday reality.