How grit size affects surface finishing quality
Grit size is one of the key factors that determines the result of grinding and polishing.
Choosing the right grit ensures the optimal balance between material removal and surface finish.
What is grit size?
Grit size refers to the size of abrasive particles in a grinding tool.
It’s indicated by a number: the higher the number, the finer the grit.
For example, P36 is coarse, while P400 is fine for final finishing.
How does grit size affect the result?
Coarse grits (P24–P60) are used for:
- removing rust or old coatings;
- shaping rough surfaces;
- heavy-duty work on metal, stone, or concrete.
Medium grits (P80–P150) are ideal for:
- surface prep before painting;
- sanding wood, plywood;
- smoothing light imperfections.
Fine grits (P180 and above) are used for:
- final finishing and polishing;
- stainless steel processing;
- creating smooth, uniform textures.
Incorrect grit selection may lead to:
- visible scratches;
- wasted material or time;
- poor adhesion during further coating.
How to choose the right grit?
Selection depends on:
- material type (metal, wood, plastic);
- stage of work (roughing or finishing);
- desired outcome (smoothness, gloss, detail).
It’s recommended to test different grits on a sample surface before starting the main task.
Solutions from Stark Abrasive
Stark Abrasive offers a wide range of abrasives from P24 to P800, suitable for all stages of grinding.
Our tools guarantee precision, consistency, and efficiency in both rough and fine surface treatment.
Stark experts are ready to help you choose the best grit for your specific task.
3M™ Flap Disc 769F – is our durable, high-performance abrasive flap disc with precision-shaped grains from 3M™ Precision-Shaped Grain and durable polyester base.
3M™ Flap Disc 769F – convenient, strong, efficient and universal petal disc. Our discs are coated with 3M™ Precision-Shaped and proven to be more effective than traditional zirconium corundum petal discs. This abrasive is constantly breaking down to form sharp particles that cleanly cut metal, unlike traditional abrasives that tend to plow through the substrate. This breaking down into particles, together with the destruction of individual petals to release fresh layers of mineral, ensures a high grinding speed that is stable throughout the life of the disc. Polyester base additionally extends durability. Together with the high adhesion, this makes the discs an ideal choice for high-pressure jobs such as beveling, grinding welds and deburring edges. In addition, they create clean surfaces, which makes them indispensable for smoothing and surface preparation. In many cases, 3M™ Flap Disc 769F provides sanding and finishing without changing the abrasive tool. This is possible because under normal conditions the 769F disc finish is one step thinner than a fiber disc of the same grade. Although the fiber disc grinds faster, this petal disc simplifies the process flow, eliminating the need to change tools, which saves time and increases productivity. An ideal choice for processing carbon steel, stainless steel and other alloys sensitive to high temperatures.
The belt grinding machine is equipped with a module for sampling the radius of all types of pipes (round, square, monolithic) with diameters from 17 to 70 mm. The Scantool 75RB grinder is designed for contact grinding/polishing and radius sampling of metal workpieces manually. It is a simple and reliable machine that is easy to use and practical to operate, with a well-designed system for quick change of the abrasive belt and type of grinding.
Designed for finishing the surface of the pipes and rods on round grinding machines. CK918X is a balanced combination of long service life, uniformity of surface roughness and a high level of shine.
Petals End Conical Disc 3M ™ 577F with P40 grain and 125mm diameter consists of aluminum zirconate in a dense polyester base. It is used for hard metals, stainless steel.
