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Quality Control

Conducting the entire list of tests is the daily work for Döcke Home Systems quality control specialists. Professionalism, strict adherence to technology and formulas – are the key to high quality and long lifespan of Döcke roofing materials.
RAW MATERIALS CONTROL
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Bitumen viscosity properties

Determination of the bitumen softening temperature by the “ring and ball” method (GOST 11506-73). Samples of material are poured into two rings on the upper plate of the device holder, and steel balls are placed on each of the rings. The device then is placed into the tank filled with glycerin, which than gradually warms up. The device records at what temperature the bitumen extruded by the ball touches the lower plate.
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The second method used is called “The penetration depth of the needle” (GOST 11501-78). This test is performed on a special device called Penetrometer. The essence of the method is to measure the penetration depth of a standardized needle when 100g weight applied to it for 5 seconds at a temperature of +25° C. Penetration is an indirect indicator that characterizes bitumen hardness degree. This important parameter allows creating a bitumen mixture that can sustain high temperatures.
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Base material strength
Fiberglass and polyester fabric are used as the basis material for products like bitumen shingles, underlayment, and valley membranes. Testing these materials, parameters like mass per unit of surface and tensile strength are controlled. The tensile strength in longitudinal and transverse directions are the main parameters confirming the quality of fiberglass or polyester fabric. The quality and strength of the base material has a direct influence on the quality and longevity of the final product. We test such indicator on a professional Instron tensile testing machine.
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Granulometric composition
Granulometric composition is tested using a sieve system and a vibrating table. Granulate samples are poured into the upper sieve, and, due to vibration, gradually separates through the other sieves with different diameters from larger to smaller. By weighing the results from the sifting of the samples, the percentage ratio of different fractions is determined.
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Granulate color stability
This test involves boiling the sample granulate in water for a given time. The color stability determined by the absence of stain in water in which the sample are evaluated.
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Granulate humidity
This parameter is also important in the final product quality. Humidity is determined using high-precision scales with a heating element. This parameter is determined by weighing the difference before and after drying samples by the heating element of the machine.
PRODUCTION PROCESS CONTROL
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Bitumen-polymer compound viscosity control
Bitumen-polymer compound viscosity at various temperatures is an important parameter for optimizing the operation of the production line. This indicator is determined using a Brookfield rotational viscometer.
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Compliance with the reference
color mix

The recipes of colored granules proportions are the manufacturer commercial secret. The color mix preparation for various collections can take months of work and tests. After designers and engineers achieve the desired combination, a reference color mix is created. It is stored in the laboratory as physical sample, when the mix data is stored on a computer that controls mixing equipment. Despite the fact that all operations on the Döcke manufacturing facility are automated, laboratory specialists regularly check the granules consistency and color compliance. That is why there are no color deviations from the reference mix in different batches of the product or they are minimal.
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Filler content determination
This test used to determine the actual amount of filler in the finished bitumen-polymer compound. A compound sample taken from the line is placed in a heat-resistant cuvette and then placed in a muffle furnace. At a certain temperature, bitumen and polymer modifiers burn out, leaving only dolomite flour, which is not subject to burnout and can be measured.
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