How the Structure of Gray Velvet Polishing Cloth Improves Surface Flatness

Gray velvet polishing cloth is a metallographic consumable made for final-stage precision polishing. Its working surface uses high-quality short fibers—dense, uniform, and with just the right amount of flexibility and absorbency. This product is suitable for the final polishing of high-precision samples—such as hard metals, cemented carbides, and carbon-based materials—and is capable of removing fine scratches while simultaneously reducing the risk of inclusion pull-out.

What Polishing Cloth Does and Why It Matters for Flatness

In mechanical polishing, the cloth does three things: it holds abrasive particles so they can cut, it retains lubricant to keep things from overheating, and the fibers themselves create a wet friction that helps smooth out the surface. How well these actually work comes down to fiber length, density, and softness.

Short Pile Means Stable Support

Gray velvet is a short-pile cloth—fibers typically run 0.2 to 0.8 millimeters long, tightly packed with fine, even gaps between them. The big advantage here is mechanical stability.

Under high pressure or improper processing conditions, long fibers are more prone to bending and collapsing.That can mean uneven force on the sample—edges get overloaded and round off, soft phases sink because the fibers give way too much. Short fibers don't compress as much. They hold up, Helps produce a more consistent grinding trajectory.

Capillary Action Keeps Fluid in Check

With short, dense fibers, the gaps between them form a fine capillary network. Instead of storing polishing fluid deep down, this structure pulls it up and holds it near the surface. As the polishing pad rotates, the polishing fluid adsorbed onto the surface fibers is continuously and steadily released, helping to maintain the abrasive concentration within a stable range. This slow-release characteristic prevents the polishing fluid from splashing away or being lost, while also guarding against surface burn damage caused by dry friction, thereby ensuring a uniform and controllable polishing process.

How the Fibers Contact the Surface

Short-pile fibers are short and upright; their contact with the specimen is predominantly multi-point in nature, resulting in moderate friction. This ensures sufficient abrasive action without causing surface damage due to excessive friction. Long-pile fibers, conversely, establish a larger contact area with the specimen and generate stronger friction. While this can yield a highly polished surface, it may adversely affect the examination of non-metallic inclusions in steel and graphite in cast iron—specifically, excessive friction can easily cause inclusions or graphite particles to dislodge, thereby preventing an accurate reflection of the material's internal microstructure.

Where It's Used and How to Get the Most Out of It

Given its short-pile structure, gray velvet cloth is a solid fit for final polishing of hard metals, steels, cemented carbides, ceramics, and carbon-based materials.

Before first use, give it a quick prep: wet it with water, spin it slow to spread the moisture, then add polishing fluid so abrasives seat into the fibers. Run a dummy sample or two to settle things in. During polishing, adjust pressure and speed to the material—harder stuff can take more force, softer or coated materials need a lighter touch. And clean it right after use, before the fluid dries and fibers stiffen up.

Shenyang Kejing Gray Velvet Polishing Cloth

Shenyang Kejing's gray velvet Polishing cloth uses quality short-pile fibers—uniform, stable, and good at holding fluid. The backing is pressure-sensitive adhesive that stands up to water, oil, and alcohol, so it stays put on UNIPOL series polishers and other standard platens. Available in 230mm and 300mm diameters, it fits common metallographic prep gear. It's already in use at labs in Shandong University, University of Electronic Science and Technology of China, and other research institutions.