Filling Knives & Fillers

About Filling Knives & Fillers

Filling knives and fillers are fundamental tools for achieving professional surface finishes across plastering, decorating, and general building work. This category encompasses the application tools – including flexible putty knives, taping knives, and spatulas in various widths – alongside the filling materials themselves, from ready-mixed compounds to powder fillers and specialist formulations for exterior use or rapid repairs. Whether repairing damaged walls, preparing surfaces for painting, or creating smooth plaster finishes, MyToolShed.co.uk supplies the essential tools and materials for seamless results.

Quality filling knives feature well-balanced handles for comfortable extended use, with blades constructed from flexible yet durable stainless steel or carbon steel. Modern filler products have evolved significantly, with innovations including quick-drying formulations, low-shrinkage compounds requiring fewer coats, and specialist fillers designed for specific substrates such as wood, plaster, or masonry. Matching the correct knife width and flexibility to the specific filler type ensures professional finishes that stand the test of time.

Applications

Filling knives and fillers are indispensable across numerous trades and applications:

• Plasterers – finishing coats, repairing damaged plasterwork, and filling minor imperfections before decoration
• Painters and Decorators – surface preparation, filling nail holes, cracks, and minor damage prior to painting
• Carpenters and Joiners – filling nail holes, gaps in timber work, and concealing fixings in wood
• General Builders – repair work, making good after first fix trades, and general filling applications
• Maintenance Teams – ongoing property maintenance and quick repairs in commercial and residential settings
• DIY Enthusiasts – home improvement projects, decoration preparation, and general household repairs
• Shopfitters – creating pristine finishes in retail environments where appearance is critical

Choosing The Right Filling Knives & Fillers

Blade Width: Narrow knives (25-50mm) suit detailed work and tight spaces. Medium knives (75-100mm) offer versatility for general tasks. Wide taping knives (150-300mm) excel at covering large areas and achieving flat finishes across broader surfaces.

Blade Flexibility: Stiff blades provide control for thicker fillers and scraping. Flexible blades are superior for feathering edges and working around contours. Many professionals maintain several knives with varying flexibility levels.

Filler Type: Interior fillers suit dry conditions. Flexible fillers accommodate movement in joints around door frames and skirting boards. Exterior-grade fillers withstand moisture and temperature fluctuations. Rapid-setting formulations save time when decoration schedules are tight.

Substrate Compatibility: Plaster-based fillers bond well to masonry and plasterboard. Wood fillers contain fibres suited to timber. Multi-purpose fillers offer versatility but may not match specialist products for specific applications.

Frequently Asked Questions

What's the difference between interior and exterior filler?

Interior fillers are formulated for dry, protected environments. Exterior fillers contain weather-resistant additives preventing cracking or deterioration when exposed to rain, temperature fluctuations, and UV light. Always use exterior-grade products for outdoor repairs or moisture-prone areas.

How long should I wait before sanding filler?

Drying times vary depending on filler type, depth, temperature, and humidity. Rapid-setting fillers may be ready in 30-60 minutes. Standard interior fillers typically require 2-4 hours for shallow fills. Deeper applications may need overnight drying. The surface should feel completely dry before sanding to avoid clogging abrasive paper.

What width filling knife is most versatile?

A 75-100mm filling knife represents the ideal versatility for general use at MyToolShed.co.uk, handling everything from small holes to moderate areas. Many tradespeople pair this with a narrower 25-40mm knife for detailed work and a wider 150mm taping knife for broad surfaces.