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The most comprehensive analysis of marble fissure lines, fissure line ≠ defective product!

It is said that having fissure lines on the surface of marble is not good, so why do some artificial stone like products have to be labeled with fissure line texture labels? Moreover, they are often artificial stone like products with high prices, which look more realistic.

The beauty of fissure lines in marble

Most natural marble fissure lines are widely regarded as beautiful textures and are highly sought after by people. Don't doubt them, such as Hermes Grey marble, Tundra Grey marble, Castle Grey marble, and so on.

The color and texture of these natural marbles are determined by their composition. It is different from artificially made materials such as ceramic tiles and artificial stone, and its natural characteristics are beyond human control, which is precisely what attracts people to marble.

Marble stone is a widely used material in various buildings, but many people have questions about the texture of marble, that is, if there are fissure lines on the marble, can it not be used? Is the presence of fissure lines in marble a quality issue with the stone material? What exactly is the situation?

PART 01. What is fissure line?

Fissure line refers to the small cracks that exist in rocks, most of which are natural and commonly present in marble. With the increasingly mature processing technology, the quality and beauty of natural stone are not affected by the presence of small fissure lines. The National Building Materials Administration has also issued industry standards for natural marble and granite.

PART 02. Difference between fissure line and crack

The fissure line of marble is naturally present, and the national industry standard stipulates that the fissure line refers to a length that does not exceed 1/10 of the total length extending from both ends to the edge of the slab, and a length less than 20mm is not counted. So as long as the fissure line is within this standard, it doesn't matter, is it also a kind of defect beauty?

Of course, with current technology, this kind of fissure line can be solved, but there are also some defects in marble called cracks. What is the difference between the two?

1. Different reasons for cracking

It is normal for marble to have fissure line, but the absence of fissure line may indicate that this is not natural marble. The main reason why marble has fissure lines is that it is composed of various natural minerals, and the arrangement of these minerals is usually not very precise, which naturally leads to fissure lines.

Marble cracks are usually caused by internal cracking of the marble. Different from natural fissure lines. If this kind of crack is not treated, it may lead to the fracture of marble in the future, so many manufacturers will stick a layer of resin fiber mesh on the back of marble.

2. Different touch feel and appearance

Fissure lines mostly do not affect the normal use of marble, while cracks can affect the normal use of marble. If you touch it with your hands, you will clearly feel that the fissure line is smooth and flat, while the crack is rough and uneven. And many cracks in marble are caused by quality and handling issues, so the crack locations have not undergone special repair treatment and can be seen with the naked eye.

3. Different color differences

There is usually a color difference between the fissure line of marble and the surrounding marble, and it is obvious that there is a fissure line. However, the crack of marble does not have a color difference with the surrounding marble, and fragments may appear. Therefore, if the manufacturer uses glue to repair the crack position, it can be directly identified by the naked eye.

4. Different permeability

If soy sauce or other stains are leaked, the fissure line usually does not penetrate, but if the crack, it will penetrate, and the pollution in this internal gap is difficult to clean thoroughly.

PART 03. Quality standards for measuring stone materials

The evaluation of the quality of stone mainly depends on its appearance quality, processing quality, and mirror glossiness. There are also physical indicators such as volume density, water absorption, compressive strength, and flexural strength.

Definition of commonly used indicators for measuring the physical properties of stone

1) Volume density

The ratio of quality to volume of stone. A high density indicates the specific gravity and volume of the rock, and it has high stability during processes such as sawing, grinding, polishing, and cutting.

2) Water absorption rate

Refers to the water absorption capacity of stone, reflecting the number, size, distribution, and connectivity of pores inside the stone. The water absorption rate of rocks is generally less than 1.5%. If it is less than 0.5%, it can be considered to have good weathering resistance and frost resistance, and frost resistance tests are not required.

3) Compressive strength

The ability of rocks to resist damage under unidirectional compression. The magnitude of compressive strength indicates the hardness of the rock. The compressive strength is expressed in MPa, with 1MPa=10.2kg/cmr (kilograms per square centimeter).

4) Flexural strength

The ability of a certain specification of decorative panel to resist fracture at two support points. After testing, the flexural strength of stone is about 1/14 to 1/8 of its compressive strength. The flexural strength of stone can be roughly inferred from its compressive strength. The greater the flexural strength, the less likely the board is to break.

The physical performance indicators that qualified marble should meet

 Volume density ≥ 2.6g/cm ²

 Water absorption rate ≤ 0.5%

 The compressive strength is ≥ 50MPa (according to the "JC79-92 Natural Marble Building Board" standard, the compressive strength of marble is not less than 20MPa; the compressive strength of marble is generally between 70-110MPa)

 The flexural strength shall be ≥ 7MPa (according to the "JC79-92 Natural Marble Building Board" standard, the flexural strength shall not be less than 7MPa)

The physical performance indicators that qualified granite should meet

 Volume density ≥ 2.56g/cm ²

 Water absorption rate ≤ 0.6%

 Dry compressive strength (compressive strength) ≥ 100MPa (according to the "JC205-92 Natural Granite Building Board" standard);

 The compressive strength shall not be less than 60MPa; The compressive strength of granite is generally between 110 and 245 MPa

 Bending strength (flexural strength) ≥ 8MPa (according to the "JC205-92 Natural Granite Building Board" standard, the flexural strength shall not be less than 8MPa)

The beauty of natural marble lies in its unpredictable natural texture, so for natural marble, having fissure lines or flaws is not necessarily a defective product. It is precisely because of the existence of these natural textures that natural marble stands out, and these textures are the charm of marble.