Tools, Equipment, and Materials
This domain tests whether you can select, set up, maintain, and use the tools and materials for boarding, taping, plastering and stucco, and explain why one choice beats another on a real job.
Hand tools and their jobs
- Knives: 100-125 mm for taping and small patches, 150-200 mm for the fill coat, 250-300 mm for the finish coat. A knife that is too narrow on a finish coat leaves ridges you will sand away at the cost of the paper face.
- Hawk and trowel for plaster; mud pan and hawk for compound; corner tools, snips, rasps, drywall saws, rotary cutters, T-square, chalk line and laser.
- Screw guns need an adjustable depth nose so screws dimple without breaking the paper; collated guns keep depth consistent on ceilings.
- Automatic tools (banjo, bazooka, box tools) require looser compound than hand taping, so mud consistency changes with the tool.
Materials
- Drying-type compound (all-purpose, lightweight, topping) sets by evaporation, shrinks, and re-wets.
- Setting-type compound (20, 45, 90, 210 minutes) sets chemically; harder, less shrink, preferred for prefill, deep gaps and cold conditions. Once it stiffens, water will not revive it.
- Taping compound carries more binder for the first coat; topping is softer for final coats; all-purpose does both.
- Paper tape is stronger and is required in many fire-rated designs; mesh is self-adhesive and convenient for small repairs but has lower tensile strength.
- Fasteners: Type S fine thread for steel studs, Type W coarse thread for wood; length must penetrate framing at least 10 mm (3/8 in.).
Worked example
A wall has 15.9 mm Type X board on 25-gauge steel studs, and the specification demands 10 mm of penetration.
Reasoning: 15.9 + 10 = 25.9 mm, so a 25 mm screw fails. Use a 32 mm (1-1/4 in.) Type S screw, the standard length for single-layer 5/8 in. on steel, then check the rated design, which often calls for longer fasteners than the minimum. Fine thread gives better holding in thin-gauge steel than coarse thread.
Traps
Taping with topping compound; adding water to setting compound after it stiffens; coarse-thread screws in steel studs; over-thinning with a high-speed mixer, which whips air into the mud and causes pinholes.