What is a Plaster Knife?
A plastering knife (also known as a plaster knife or plasterers’ knife) is a flat, handheld tool used in plastering and drywall finishing to apply, spread and smooth plaster and render materials. Generally, they’re made with a flexible stainless steel blade that allows for controlled application and a smooth, even finish across walls and ceilings.
Unlike standard scrapers, plastering knives are built specifically for finishing work, helping professionals achieve a clean surface with minimal sanding required.
We supply high-quality plastering tools and equipment for construction professionals, combining trade expertise with carefully sourced materials. With extensive experience in plastering, we understand the importance of durable, reliable plastering tools that deliver consistent results on site. Our range is designed to offer professional-grade performance at competitive prices, ensuring you get the best value without compromising on quality.
We only supply equipment we would use ourselves, so you can trust our handpicked range.
What are Plastering Knives Used For?
Plastering knives are designed for a range of finishing and preparation tasks in plastering and drywall work. Whilst it depends on the type of plasterer’s knife you have, this can include:
- Applying plaster or joint filler to walls and ceilings
- Spreading and smoothing finishing coats of plaster
- Filling cracks, dents and surface imperfections
- Taping and finishing plasterboard joints
- Feathering edges to create a smooth wall transition
- Repairing damaged plaster surfaces during refurbishment work
- Levelling compound over larger areas for a smooth finish
- Smoothing filler before sanding and decorating
Why Add a Plastering Knife to Your Toolbox?
A plastering knife is a core tool to have in your kit, with a direct impact on the quality and speed of your work. Choosing between different types, such as a putty knife or a taping and jointing knife, helps improve accuracy and finish quality, depending on the task.
- Better Control
A flat, flexible blade will respond directly to pressure, giving you full control and better handling over how much material is applied and how it’s spread.
- Smooth Finishes
Create smoother surfaces by evenly distributing render or plaster, reducing ridges and marks that would otherwise require extra sanding.
- Less Sanding
With a blade that flattens and feathers the material as you apply it, the finished surface is cleaner and needs less corrective sanding afterwards.
- Access Tight Areas
Smaller blade sizes let you work accurately in corners, around fittings and in confined spaces where larger tools can’t reach effectively.
What are the Different Types of Plastering Knives?
Plastering knives come in a few key types, each designed for specific stages of the job. Choosing the right one will help improve control and the finish quality on the job.
Jointing Knives
A joint knife is designed specifically for drywall and plasterboard work. They’re used to apply and smooth joint compound over seams in between boards and create a smooth finish before decorating.
Taping Knives
These are wider blades, used to embed joint tape and spread compound over the plasterboard joints. Their size helps feather out the material smoothly so joints blend into the surrounding wall.
Putty Knives
These are smaller tools used for filling cracks, holes and minor surface imperfections with filler or putty. They’re best suited for detailed repair and preparation work before finishing.
What’s the Difference Between a Jointing, Putty and Tape Knife?
The main difference between jointing, putty and taping knives is their size, flexibility and intended use, with each designed for a specific stage of surface preparation and finishing work.
This comparison shows the differences between joint knives, taping knives and putty knives to help you choose the right tool for your job.
| Knife Type | What it’s used for | Key differences |
| Jointing knife | Used for applying and smoothing joint compound over plasterboard seams and larger filled areas | Medium-sized and versatile, designed for general drywall finishing work |
| Putty knife | Used for filling smaller cracks, holes and surface imperfections with filler or putty | Small, rigid blade designed for precise repair and detail work |
| Taping knife | Used for embedding joint tape and spreading compound over drywall joints | Wider blade designed to cover larger areas and feather joints smoothly for a seamless finish |
Frequently Asked Questions
Find answers to all your plastering knife queries. Got a question we’ve not covered? Give our team a call today.
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What is a joint knife?
A joint knife is a flat, flexible hand tool used in plastering and drywall work to apply and smooth joint compound over seams between plasterboards. It helps create a smooth finish before decorating.
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What size joint knife is needed for drywall?
For drywall work, joint knives typically range from 100mm to 250mm. Smaller sizes, like the 100mm (4 inch), are used for applying compound and detail work, while larger sizes, like the 250mm (10 inch), are better for feathering and smoothing wide areas for a flat finish.
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How do you clean a putty knife?
Clean the putty knife immediately after use with warm water to remove any filler or plaster before it hardens. Then dry it thoroughly with a cloth to prevent rust and keep the blade in good condition.
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What is a taping knife used for?
A taping knife is used to apply joint compound over drywall tape and smooth it into seams between plasterboard sheets. It helps create a strong bond that hides joins and prepares walls for finishing.
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What size plasterer’s knife do I need?
The size depends on the task. Smaller plasterer knives (around 100-150mm) are ideal for filling and detail work, while larger knives (200-300mm) are better for smoothing and finishing larger wall areas.
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Which plastering knife is best for beginners?
A smaller plastering knife or putty knife is often recommended for beginners as it offers better control and easier handling. NELA’s putty knife is one of the easiest to use. It offers good control for applying filler and smoothing surfaces without being too large or difficult to handle.
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What are plastering knives made from?
Plastering knives are typically made with stainless steel blades, chosen for durability and flexibility. This option also has an ergonomic comfort grip handle for ease of use.
