When restoring your car’s bodywork, the right filler can be the difference between a seamless result and a frustrating repair. Rustbuster supplies a wide range of high-quality fillers, each tailored to different repair needs — from light dents to structural and deep metal repairs.

Here’s a guide to help you choose the best Rustbuster filler for your project.

Rustbuster Body Fillers Comparison

• PROXL Ultrafill Deep – Best for deep dents and large repairs. High-build, excellent adhesion, and easy to sand. (3L – £24.99 ex. VAT)

• PROXL Ultrafill Glass Fibre – Ideal for structural repairs needing reinforcement. Contains glass fibre strands for added strength. (1.85L – £21.99)

• PROXL Ultrafill Gold – Designed for premium finishes. Smooth application, superior sanding, and perfect for show-quality results. (3L – £23.99)

• PROXL Ultrafill Lite – Suited to minor repairs. Lightweight, easy to apply, and simple to sand. (3L – £23.50)

• PROXL Ultrafill Metal Filler – Specially formulated for metal surface repairs with strong adhesion. (Various sizes £5.50 – £12.20)

• Dinitrol Alusoft Metal Filler – Best for corroded or rusted metal. High aluminium content provides galvanic protection and a rust-free finish. (Various sizes approx. £33.50)

Which Body Filler Should You Use?

• Small to Medium Repairs: PROXL Ultrafill Lite is lightweight and perfect for minor dents.

• Deep or Large Dents: PROXL Ultrafill Deep fills larger imperfections with ease and sands to a smooth finish.

• Structural Repairs: PROXL Ultrafill Glass Fibre reinforces repairs thanks to added glass fibre strands.

• Premium Finishes: PROXL Ultrafill Gold delivers the smoothest results, ideal before painting.

• Metal-Specific Repairs: PROXL Ultrafill Metal Filler is made for bonding directly to metal panels.

• Rust and Corrosion: Dinitrol Alusoft Metal Filler provides galvanic protection to help stop rust spreading.

FAQs About Rustbuster Body Fillers
Can I use these fillers on plastic? These fillers are designed mainly for metal or painted surfaces. For plastics, use a specialist plastic filler.
How long before sanding? Typically 20–30 minutes, though this varies with temperature and filler thickness. Always check the product label.
What preparation is required? Surfaces must be clean, dry, and free from loose rust or filler. Treat rust with a converter or primer before applying filler.
Can I paint directly over filler? No, you should always prime first for best adhesion and finish.
Are they suitable for professional use? Yes, Rustbuster fillers meet professional standards for adhesion, sanding, and finish.
What’s best for classic cars? PROXL Ultrafill Gold is ideal, offering an ultra-smooth, fine finish to preserve detail and achieve a show-standard look. For deeper repairs, combine with PROXL Ultrafill Deep or Glass Fibre.
Can I apply filler over rust? No — rust will spread beneath and cause the filler to fail. Always treat rust first.

Final Thoughts
Choosing the right body filler sets the foundation for long-lasting, professional results. Whether you’re handling light cosmetic work or repairing corroded panels, Rustbuster’s range provides reliable solutions for every stage of the job.