Which diamond blade for porcelain tiles?

A blade for porcelain is chosen for three things: the material, the machine and the cutting method – dry or wet. Price and a “premium” label come last.

How a diamond blade cuts

The work is done by diamond: its grains grind the material, and a metal bond holds them in the rim. The bond slowly wears and exposes new, sharp grains. Choosing a blade means matching this wear rate to the material – which is why a blade that cuts porcelain smoothly wears out quickly on brick, and a concrete blade on porcelain soon starts to glaze and stops cutting.

1. Material: hard or abrasive

The key rule: hard material needs a soft bond, abrasive material needs a hard bond. These are two different properties and must not be confused.

• Porcelain stoneware and sintered stone are hard and dense but not very abrasive. They need a blade with a soft, self-sharpening bond; a bond that is too hard does not wear, the diamond goes blunt and the blade glazes. See diamond blades for porcelain.
• Wall tiles and ceramics are softer than porcelain. A porcelain blade cuts them easily, and a thin continuous rim gives the cleanest edge on the glaze.
• Brick, blocks, fresh concrete and asphalt are abrasive and strip the bond – a porcelain blade loses its rim after a few cuts. Use a blade made for these materials.
• Sintered stone is cut like porcelain, but more carefully: it is hard and brittle, so a thin continuous rim with a soft bond works best – ideally wet and without pressure.

2. Machine: diameter, bore, speed

• 125 mm angle grinder – 125 × 22.23 mm blade, the most common choice for cutting porcelain on site.
• 115 mm angle grinder – 115 × 22.23 mm blade; check the guard before buying.
• Speed – the maximum speed printed on the blade must not be lower than the machine's speed; for 125 mm blades it is typically about 12,200 rpm. A machine that is too fast risks the blade breaking, not just wearing faster.
• Direction – the arrow on the blade must match the spindle rotation.

Bevelling tile edges at 45° is a separate job: it needs 45° blades, not an ordinary cutting blade.

3. Dry or wet

• Wet: water cools the blade, flushes out the slurry and binds the dust. The blade lasts longer and the edge is cleaner.
• Dry: use only blades the manufacturer marks for dry cutting. Turbo and segmented rims shed heat better, but there are also continuous rim blades approved for dry cutting.
• Cut in sections: lift the blade out of the cut regularly and let it spin in the air – that cools it fastest. Never put a hot blade into water, the core can crack.
• Dust: dry cutting porcelain produces silica dust. Work with extraction and a dust mask, preferably FFP3.

Signs of overheating: discoloration on the core, a burning smell, a constant shower of sparks, dark burn marks on the tile edge. The answer is less pressure and a break – not pushing harder.

How to tell the blade is wrong

• The blade shines, sparks and cuts more and more slowly – the bond is too hard for the material and the diamond has glazed. A few cuts in an abrasive material such as brick strip the top layer of bond; in the long run you need a softer bond.
• The rim wears away quickly – the bond is too soft, typically a porcelain blade used on concrete or blocks.
• Chipped glaze – feeding too fast, a blade that is too aggressive (turbo, segmented) or a worn rim.
• The tile breaks at the end of the cut – the off-cut is not supported or the feed is too fast. Take the last centimetres slowly.
• The blade wobbles – an overheated or deformed core, a wrong bore or flange. Stop using such a blade.

Frequently asked questions