What is a bolster chisel?
A bolster chisel is a long, wide chisel of hardened steel that is ground on one side. Bricklayers use it to split bricks and concrete blocks at exactly the right point. You place the bolster on the brick with the flat side facing the part you want to keep and strike it with a brick hammer or club hammer. It is also known as a bolster or brick set; in Dutch it is called a sabel.
How to split a brick
- Mark the break line in pencil all the way round the brick.
- Lay the brick on a slightly yielding surface, such as a sand bed or a stack of bags. On a hard surface the brick is more likely to break in the wrong place.
- Place the bolster on the line, with the bevelled side towards the waste piece. That way the break runs straight along the side you are going to use.
- Give light taps all round to score the brick, then strike one firm blow on the line.
- Trim the broken edge with the brick hammer if necessary.
Uses
- Making closers and three-quarter bats for the brick bond.
- Cutting bricks to length at corners, reveals and junctions.
- Splitting tiles and clay pavers for paving, although a block splitter or a saw is used more often there.
For facing work where a clean edge is needed, or for hard engineering-type bricks, a masonry saw with a diamond blade is often better. The bolster is quicker and dust-free, but gives a rougher break.
Safety and maintenance
- Always wear safety glasses. Sharp splinters fly off, including from the chisel itself.
- Wear work gloves, and consider a bolster with a hand guard (a rubber cap around the shaft).
- Grind down a mushroomed head. Striking creates a mushroom-shaped burr at the top; pieces of it can fly off. Grind it away regularly.
- Do not use an ordinary wood chisel. It is not hardened for striking stone and can break.
Related terms
- Chisel in construction
- Cold chisel
- Brick hammer
- Sledgehammer
- Masonry unit
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.