Which material is less likely to seal the surface when used as a bull float?

Which material is less likely to seal the surface when used as a bull float?

• A. Wood
• B. Magnesium
• C. Aluminum
• D. Steel

Answer: (A)

The surface sealing you want comes from pushing and smoothing the cement paste with a hard, stable surface. A bull float made from a hard metal will compress the cream and bring the surface to a denser, more sealed finish. Wood is much softer and porous, so it doesn’t compress the paste as effectively and tends to leave drag marks or a rougher texture. That’s why wood is less likely to seal the surface compared with magnesium, aluminum, or steel, which all provide a firmer contact and a smoother, more sealed top layer. Wood is usually used earlier in finishing for rough leveling, not for final sealing.

The surface sealing you want comes from pushing and smoothing the cement paste with a hard, stable surface. A bull float made from a hard metal will compress the cream and bring the surface to a denser, more sealed finish. Wood is much softer and porous, so it doesn’t compress the paste as effectively and tends to leave drag marks or a rougher texture. That’s why wood is less likely to seal the surface compared with magnesium, aluminum, or steel, which all provide a firmer contact and a smoother, more sealed top layer. Wood is usually used earlier in finishing for rough leveling, not for final sealing.