Natural stone is beautiful and generous, with various colors. It is a good material for home decoration. The quality standards of natural marble mainly include appearance quality, processing quality, and mirror gloss.
- Observe the appearance quality at three distances.
The appearance quality also includes appearance defects, such as missing edges, missing corners, cracks, color spots, color lines, pits, and pits. Marble plates also have warpage, depression, stains, and other appearance defects. In the standard for natural granite and marble building boards, the appearance quality index stipulates that the color and pattern of the same batch of boards should be basically harmonious, and no apparent defects are allowed in the superior products. The defect detection method is as follows: place the tested plate flat on the ground, and the obvious defects at 1.5m away from the plate are considered as defects; Defects that are not obvious at 1.5m away from the plate, but are visible at 1m, are considered as no obvious defects; Defects that cannot be seen 1 m away from the plate are considered as no defects.
- Three proportions measure the processing quality
The processing quality of stone directly affects the decorative effect of stone facing, which is also the main basis for stone grading. The technical indicators are respectively specification and dimension deviation (length deviation, width deviation, thickness deviation), flatness tolerance, and angle tolerance. According to the deviation and limit tolerance of these technical indicators, the plates are divided into superior products, first-class products, and qualified products. Consumers shall specify the grade to be reached in the purchase contract, and avoid using products with general words such as “meeting national standards”. In each batch of products, no more than 5% of the first-class products are allowed to exist if they are superior products, no more than 10% of the qualified products are allowed to exist if they are first-class products, and no more than 10% of the unqualified products are allowed to exist if they are qualified products
- The three gloss units are graded.
In the stone standard, the glossiness is called specular glossiness. The current standard for natural granite plates stipulates that the front of the mirror plate should have a mirror luster, which can clearly reflect the scenery. The specular gloss value of the specular plate shall not be less than 75 gloss units. Most granite plates have good specular luster only when the glossiness value is 80 to 90 gloss units. According to their different requirements, consumers should indicate the value that the glossiness should reach in the purchase contract, or take the glossiness value of the agreement board as the standard. The current standard for natural marble plates has classified the glossiness value. The minimum glossiness value of superior products is divided into three categories according to different chemical principal components, namely 90, 80, and 60 gloss units.
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