• Waterborne paint testing and standards
    Waterborne paint testing and standards

    2019-12-02

    Waterborne paint testing and standards:hardness Hardness is one of the most important physical properties of a coating. Coating hardness reflects the coating's ability to resist constant dents, scratches, scribes, and penetrations caused by a hard object. Testing the hardness of materials with different methods will give different results because the testing methods are for different amounts of materials, and each method has its own scale to determine the hardness characteristics of the material. Due to different emphasis, there is no absolute scale that can unify the hardness measured by different methods, but the results obtained by one method are comparable. The commonly used hardness test method for wood coatings is the pencil hardness method. The hardness side measured by pencil hardness test focuses on the coating's resistance to dents, scratches, and scratches. Although some people think that the technical content of pencil hardness is very low, but because it is simple and practical and can be directly measured on wood, the pencil hardness method is still widely used in the coating industry. Before the preparation of the sample, the wood should be polished, smoothed and cleaned. The dry thickness of the coating should be between 25 and 40 μm. It should be dried for 7 days after painting. The film thickness and long drying time affect the hardness test results. The set of pencils used for the test consisted of the hardest 9H to the softest 6B. Commonly used are 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, and 6B. F is the intermediate hardness, etc., "H," means "Hardness", "B" stands for "Blackness" The hardness of a pencil is determined by the ratio of graphite and clay used in the manufacture of lead cores. The darker, the softer; the more clay, the harder the lead core made. The hardness number of the pencil is used to indicate the hardness of the paint film. Test the pencil first to remove the wooden rod to expose a lead of about 3mm in length. The pencil should be ground vertically on the sandpaper to make a flat surface, and the edges should be sharp. Hold the pencil so that it is 45 degrees from the paint surface to be tested. Corner, apply pressure, and continuously draw the pencil lead on the paint surface. Each hardness pencil is measured 5 times on the sample, each time with a new sharp-lead lead, find the pencil number that scratched or scratched the paint at least 2 out of 5 times, and then use a soft The number one pencil test, if you get no more than one sting or scratch, the latter number is set as the hardness of the coating. In order to eliminate the deviation caused by uneven force and angle of holding the pencil, various pencil hardness testers have been put on the market. The range of pencil hardness grades has a wide range, which cannot reflect the small hardness difference between paint lacquers, that is, the actual soft hardness of paint films with the same pencil hardness may be significantly different. However, the pe...

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  • Water - based paint spraying - water - based wood paint coating process 3
    Water - based paint spraying - water - based wood paint coating process 3

    2019-09-05

    Spraying construction paint film than brush paint film more flat. Spray with water-based wood paint should be added on the basis of the original paint 5% ~ 30% of the tap water dilute after use, for the viscosity of the paint water should also increase, the diluted paint after its coating a 4 cup viscosity should be around 18 ~ 20s. Dilute mix well should be static at least 20 minutes, until the bubbles into the basic disappearance of coating. Before spraying the paint must be more than 200 mesh filter, so as not to bring impurities, affecting the quality of paint film. Water - based paint can be used ordinary spray machine or high - pressure airless spray machine construction. Pay attention to not too fine atomization, but also to prevent bad atomization. The amount of paint should not be too large, not spray too thick, wet film thickness around 50um is good, or easy to produce flow hang, orange peel and other ills. Water-based paint spraying common mistake is a construction too thick, if you want to increase the film thickness, it is appropriate to use multiple spraying method. When spraying on the vertical surface, the spray gun should be slightly at an Angle to the construction surface. Avoid excessive spraying on the vertical surface to avoid sagging. The two paints must be sanded with more than 400# sandpaper. The compressed air is blown off and cleaned with a damp cloth, which increases the adhesion between the two paint films.

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  • 3.Process variations of different paint types-Waterborne wood paint application process 2
    3.Process variations of different paint types-Waterborne wood paint application process 2

    2019-09-03

    3.Process variations of different paint types Applying a matt lacquer to the varnish can change the coating to a matte finish, while applying a varnish to a matt lacquer reduces the brightness of the film and does not achieve maximum brightness and transparency. The color paint of waterborne wood lacquer can be divided into two types: coloured coating and transparent color paint. The coloured coating is made of red, yellow, blue, white and black pigment paste and varnish. It has sufficient hiding power and can be made into matt type. The construction method is the same as varnish. Generally, 2 to 3 passes can achieve satisfactory results. Transparent paint can be done in two ways. One is to use a transparent pigment (or dye) to make a transparent paint and then apply; Another way is to use the base coloring method,First use water - based or oil - based paste to brush wood, then varnished after polishing.After repeated treatments, the coloring and fullness are satisfactory.For open painting, because the micropores on the surface of the wood are to be revealed, the solid color paint with strong hiding power is not easy to use, and the effect can be achieved by coating with a transparent color paint. Of course, the number of paintings is not excessive.

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  • Tools needed for the paint process of putty water-based paint
    Tools needed for the paint process of putty water-based paint

    2019-08-30

    1.The tool Before using the soft brush, thoroughly soak it in clean water, remove excess water, and do not drip. The enamel paint should only reach half the length of the bristles.Brush as fast as possible, gently and smoothly brush the wood grain, do not apply it back and forth repeatedly, because the water-based paint is fast drying and the opening time is short, so it should be completed as soon as possible. 2.Process Generally, a water-based primer is applied before the coating of water-based putty to improve the infiltration of wood and increase adhesion. In addition, multiple primers can be used to increase the thickness and fullness of paint film on the putty after grinding.For occasions where the requirements are not high, the primer can also be used as a topcoat, the so-called bottom-type water-based wood lacquer. The primary role of the first primer is the back cover. When painting, the paint liquid should be thin. It can be added with 5%~30% water and diluted to make the paint liquid easily penetrate into the pores of the wood, which is beneficial to increase the adhesion of the paint film.After the first paint is dried (depending on temperature and humidity, it takes about 2~8h), use 400#~600# sandpaper to remove the burrs from the surface of the wood, so that the surface is basically smooth and ready to be putty.After the surface of the putty is sealed, the surface of the wood can be re-primed after being polished and cleaned. After 2 hours, it can be lightly ground and then coated. If it is to be ground, the time should be longer (more than 4 hours). Repeat this process, re-grind and re-coat until you are satisfied. Generally, the primer is applied 2 to 5 times. The more the coating is applied, the better the fullness. After the multi-primer finish is applied, if the surface condition and fullness of the paint film are basically satisfactory, the coating can be finished. However, when there is a higher requirement for the coating effect, the varnish or the matt lacquer having a certain degree of glaze may be applied 1 to 4 times on the basis of the primer, usually not less than 2 times.The primer should be dried for at least one day before applying the topcoat. Before applying each finish, it is necessary to polish the previous finish with 800# sandpaper to increase the adhesion between the coatings. This is especially important for waterborne polyurethane topcoats. As the last top coat, it is best to add 5% to 10% of water to dilute the original paint before use. Various topcoats not only have great differences in gloss, but also have great differences in feel, hardness and solvent resistance, especially for more intuitive handfeel performance. Personal preferences are different and can be used with hobbies.

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