How to avoid prickly heat pinholes in painting

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How to avoid "prickles" and "pinholes" in painting

how to avoid "prickles" and "pinholes" in painting

June 9, 2020

in summer painting construction, we often encounter "prickles" and "pinholes" and other painting defects, which not only affect the effect of paint film, but also damage the beauty of painting, For the samples of tensile reduction and zigzag test, two steel bars can be selected from each batch of materials to cut the appearance value of low furniture. How can we avoid this kind of problem

pay more attention to contact with foreign countries 01

prickly heat

bubbles of different sizes appear on the surface of the coating, which are as dense and convex as prickly heat



very small pinhole like coating appears on the surface of the coating

in fact, prickly heat and pinhole phenomenon are a kind of paint film defect caused by the solvent not volatilizing after paint film construction and the bubbles not being eliminated in time! They show different phenomena, but the reasons have many similarities

01 cause analysis of prickly heat:

01 the construction environment or the temperature of the coating is too high (closed air in the workplace is not circulating)

02 the coating mixing proportion is inaccurate, the viscosity is too high, or the one-time spraying is too thick

03 the wood conduit is too deep, Filling is difficult or the material sanding is poor

04 the volatilization speed of diluent is too fast

05 film bottom and reasonable and correct operation method continuous spraying before the layer is fully dry

06 the product film surface with excessive air pressure of spray gun or fan blowing is not dry

07 the paint film is not fully dry and goes into the drying room for baking

08 there is complex internal interaction between wood matrix and fiber, the moisture content is too high or the reworked product is not fully dry

Coping strategies:

1. Adjust the temperature and humidity of the workplace and maintain air circulation

2. Mix the paint according to the mixing proportion, properly adjust the viscosity of the paint, and do not apply thick paint at one time

3. The sanding of the substrate should be good before painting. The deep pipe wood can be made into a wood filler or a sealing primer

4. Select diluent suitable for seasonal temperature or add slow dry water appropriately

5. When the primer and finish paint are sprayed for many times, the intermediate drying time shall be extended, and the sanding shall be good when recoating

6. Adjust the air pressure of the spray gun, and do not blow with a fan when the surface of the product coating is not dry

7. The natural drying time should be enough before heating and drying. The recoating interval shall be sufficient

8. The drying and testing of wood before painting must be strictly controlled, especially for products stored in the open air or reworked

9. Products with prickly heat should be ground and repaired before painting

02 cause analysis of pinhole:

01 poor material surface treatment, material surface fuzzing, catheter too deep; Difficult to fill

02 the viscosity of the coating is too high or the one-time spraying is too thick, so that the air in the material duct and the solvent in the coating cannot volatilize

03 the temperature difference between the coating and the coating is too large

04 the previous coating is not completely dried before spraying again, and the upper coating is dried too fast

05 the construction environment temperature is too high, and the drying time of the coating surface is too short, resulting in the surface drying and the interior drying, The solvent is sealed in the wood and does not volatilize sufficiently

06 use too fast drying or bad diluent

07 reactive coatings add too much hardener, or misuse hardener

coping strategies:

1. The material should be sanded well, and fillers and primer should be done well

2. Adjust the viscosity of the coating, the spraying thickness should be appropriate, and the interval time should be enough when spraying multiple times

3. Do not store the product in the open air, and the temperature difference between the coating, environment and coating should be small

4. Each film shall be dried thoroughly before the next spraying

5. Improve the coating environment, control the temperature and humidity, reduce the temperature or increase the humidity. Delay the rapid drying of the surface

6. Use the correct diluent. Add slow drying solvent appropriately

7. Paint blending proportion should be correct and accurate

8. Products with pinholes must be thoroughly ground before recoating

in coating production, "prevention is better than treatment", how to avoid "paint film defects" and achieve "cool summer"? The above painting experience is shared with you, and I hope it will be helpful to you

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