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Technical Support / Technical articles

The Routine Performance Test Methods for Paint Laboratory
  • 1. Pencil Hardness (MITSU-BISHI'UNT')

    a. To cut the front end of the special pencil (MITSU - BISHI 'UNT')  which is used to test hardness into rectangles, flat head, With sandpaper friction flat when necessary;

    b. When testing, hold the pencil keep a 45° with the test board, launched forward at a evenly speed of 3 mm/S line length is about 1 cm. repeat it for 5 times to get five lines and then to erasure these lines, when 4 lines no scratches in 5 lines, that is the hardness of the coating;

    Attn: When testing, all the hardness value of the pencil from low to high until to the largest, then can be determine the hardness of the coating. 

    2. Adhesive Force (Frame method)

    a. Using special strokes, or pen knife row 11 crossing lines to form s ten boxes with a 1mm gap on the specimen (cut the coating to have a crack)

    b. With special adhesive tape (Model: CTZ-405),  Stick on the grids and ensure that no gap then to hardly tearing the adhesive type on a 45°;

    c. No loss, such as squares can be sure about the adhesion is 100/100; loss 1 grip, it means adhesive is 99/100, follow as the same method.


    3. Impact/ Shock Resistance ( Dupont impact machine)

    a. Put the test plate under the impact head of the impact machine and fixed.

    b. Drop the heavy hammer at a height of 50cm (impact head size: 1/2", weight of the hammer: 500g)

    c. Observe the impact effect on the convex surface, it’s qualified if no crack and no exfoliation.


    4. Waterproof/ Water Resistance

    a. Folding the edge of the sample plate (Usually cover the electro phoresis)

    b. Sometimes may required to test light loss rate and adhesion evaluation before and after the water resistance (edge 1 cm can be ignore)


    5. Moisture-proof/ Wet Resistance

    To put the sample plate into the constant temperature humidity environmental test chamber ( Usually required 40×RH59%×500hr , place corner: 15-30° but in fact the corner isn’t be consideration when testing ). After testing, the coating is qualified when it no light loss, blistering or exfoliation.


    6. Salt Spray Resistance Test

    a. Use the scotch tape to cover the edge of the sample plate, with a width over 5mm; and scratch crossing lines on a 75°, the scratch need deep into the inner of the plate.

    b. To put the sample plate into the salt spray test chamber; placing corner: 70±5° with horizontal;

    c. After testing and take out the sample plate, clean it in water and wipe away the rust softly, place for 2 hours;

    d. Use the adhesive type hardly pulling the crack on a 45°, use the ruler to measure the width from crack to the largest exfoliation as a result of the test.


    7. Cupping Test/ Erichsen Test

    a. Cup drawing instrument first back to zero and put the sample plate into the instrument, clamp tightly.

    b. Rotate the screw to the required depth ( usually 6mm is required).

    c.  Observe whether the concave coating is fall off, craze, etc or not.

    8. Acid Resistance Test

    a. Prepare a mass fraction of 5% or 10% of the sulfuric acid solution, installed in a container.

    b. Put the 1/2 to 3/3 of the test board area immersed into the solution, soaked to the required time; (average: 5%, 48 hr, 10%, 24 hr)

    c. Remove and observe whether the coating is loss of light, sparkling, fall off, become yellow or not when the time is up.

    9. Alkali Resistance Test

    a. Prepare a 10% mass fraction of sodium hydroxide solution, installed in a container.

    b. Put the 1/2 to 2/3 area of the test board immersed into the solution, soaked to the required time ( generally for 48 hr)

    c. Remove and observe whether the coating is loss of light, sparkling, fall off, become yellow or not when the time is up.

    10. Petrol-resistance Test

    a. Put the 1/2 to 2/3 test board area soaking into the sold 97 # gasoline, under 25 for 7 hours, take out after 2 hr, observe the coating surface.

    11. MIBK Resistance Test ( Only for reference, the Pencil hardness is given priority )

    a. Using white soft cloth dipped with a little MIBK solution, with about 10N of force to wipe 20 times back and forth on the coating.

    b. Using white soft cloth dipped with a little MIBK solution, with about 10N of force to wipe 20 times back and forth on the coating.

    c. To observe the impact effect on the convex surface, no crack, fall off as a qualified.

Main Products : Environmental Chamber, Climatic Chamber, Thermal Shock Test Chamber, Walk in Test Chamber, Altitude Chamber, Battery safety testing equipments ,Tensile Testing Machine  etc. 

Tel:0086-769-23280910 Fax: 0086-769-22673576 Email : sales@bellgroup.cc Skype: bell.sales1&a