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Filler · ZN-120

Fibreglass Filler

High-strength, glass-fibre-reinforced 2K structural filler. Ideal for deep dents, tears, small holes and repairs to GRP/fibreglass parts.

  • 2K · Two-component
  • Steel panel
  • Aluminium
  • GRP / Fibreglass
  • Existing paintwork
Request TDS / SDS
FIBREGLASSPOLYESTER FILLER2KZN-1201 kg

Packaging

1 kg · 2 kg

Overview

What is Fibreglass Filler?

ZN-120 Fibreglass Filler is a two-component structural filler reinforced with glass fibres dispersed in polyester resin. The fibre reinforcement provides significantly higher mechanical strength and flexibility than standard fillers. This makes it a reliable choice for deep dents, torn panels and bridging small holes – demanding repairs in which the filler itself has to form a solid body of fill.

The fibrous structure minimises the tendency to crack and sink, even in thick applications. Thanks to its high filling capacity, it builds a solid base of fill in a single application on heavily damaged areas, reducing the number of steps. It works well with GRP and fibreglass parts and retains its integrity even in areas exposed to vibration and slight flexing. Its typical green colour makes the treated area easy to distinguish from the substrate.

Because the fibres leave a rough texture on the surface after sanding, ZN-120 is usually used as an intermediate filling coat. After rough shaping, the surface is covered with a thin coat of ZN-110 Universal Polyester Filler or ZN-130 Soft Finishing Filler. Where a smoother fibre-reinforced intermediate coat is required, ZN-125 Micro Fibreglass Filler can be used. Finally, the surface is primed with ZN-210 4+1 Acrylic Primer Filler.

Key features

  • High mechanical strength from glass-fibre reinforcement
  • Bridges and closes small holes and tears
  • Low tendency to crack or sink in thick coats
  • Flexible structure, compatible with GRP and fibreglass parts
  • A solid base of fill in a single application on heavy damage
Technical specifications

Technical data

Values are typical at 20 °C and 65% relative humidity. Please review the product's current Technical Data Sheet (TDS) before application.

Fibreglass Filler technical data
Components2K – glass-fibre-reinforced polyester filler + BPO hardener paste
Mixing ratio100 : 2–3 (by weight); BPO hardener paste included in the pack
Pot life (20 °C)4–6 min
Ready to sand (20 °C)25–35 min
Ready to sand (short-wave IR)4–6 min
Recommended coat thicknessMax. 5 mm per coat
Recommended abrasivesP60–P80 for rough shaping, P120 to finish (dry)
ColourGreen
DensityApprox. 1.5–1.7 g/cm³
Application toolRigid metal spreader

Pack sizes

  • 1 kg
  • 2 kg

Colour

Green

Technical documents

Our technical team will send the Technical Data Sheet (TDS) and Safety Data Sheet (SDS) you request by email.

Request TDSRequest SDS

Drying times vary with temperature, humidity, film thickness and air circulation. Consult our technical team about special conditions.

Application

Step-by-step application

The recommended application sequence for a professional result.

  1. 01

    Surface preparation

    Remove loose paint, rust and broken fibre ends. Sand metal surfaces with P80, and GRP and fibreglass surfaces with P80–P120 until all gloss has gone. Then clean with ZN-530 Surface Cleaning Thinner and allow the surface to dry completely.

  2. 02

    Mixing

    Mix the filler with 2–3% BPO hardener by weight on a clean mixing board, folding and pressing. Work the mixture thoroughly so that the fibres are evenly distributed, taking care not to trap air.

  3. 03

    Application

    Press the first coat firmly onto the substrate. On small holes, draw the filler from the edges towards the centre to form a bridge; if necessary, support the back with tape. Do not exceed 5 mm per coat, and leave the final surface slightly low to allow for finishing filler.

  4. 04

    Drying

    Ready to sand after 25–35 min at 20 °C. With short-wave IR this drops to 4–6 min; avoid overheating the surface on GRP parts.

  5. 05

    Sanding

    Rough-shape with P60–P80 and complete with P120. As the surface will be covered with finishing filler, fine sanding is not needed at this stage; do not wet sand.

  6. 06

    Finishing and priming

    Cover the surface with a thin coat of ZN-110 Universal Polyester Filler or ZN-130 Soft Finishing Filler; after sanding, apply ZN-210 4+1 Acrylic Primer Filler.

Storage and safety

  • Store in the closed original packaging at 5–25 °C in a dry, well-ventilated place.
  • Shelf life in unopened packaging is typically 12 months; close opened tins tightly after use.
  • Keep away from direct sunlight, heat and naked flames. The BPO hardener paste contains organic peroxide: protect it from heat and never dip a spreader contaminated with hardener into the filler tin.
  • Sanding dust from fibre-reinforced filler can irritate the skin and respiratory tract; wear gloves, safety goggles and at least an FFP2 dust mask. Always consult the product's Safety Data Sheet (SDS).
System compatibility

Products used together

Zenova products tested in the same system as this product, which give the best results together with it.

  • 2K
    FillerZN-110

    Universal Polyester Filler

    Multi-purpose 2K polyester filler for dents and surface defects on steel, aluminium, galvanised steel and fibreglass; non-sagging, fast-drying and easy to sand.

    View product
  • 2K
    FillerZN-130

    Soft Finishing Filler

    Ultra-flexible, creamy 2K finishing filler for large surfaces and thin fills. Sands very easily without clogging the paper, leaving a flawless base for primer.

    View product
  • 2K
    FillerZN-125

    Micro Fibreglass Filler

    2K filler reinforced with micro glass fibres, combining the strength of a fibreglass filler with a smooth, pore-free surface and much easier sanding.

    View product
  • New2K
    FillerZN-150

    3-in-1 Filler

    2K filler combining strong filling, fine finishing and glass-fibre bridging in one hybrid formula. Enables fast repairs without a separate soft filler.

    View product

Application systems that include this product

Frequently asked

Questions about Fibreglass Filler

Does fibreglass filler need a separate finishing filler on top?

Yes. After sanding, the fibres leave a rough and partly porous texture on the surface. The fill built up with ZN-120 should therefore be covered with a thin coat of ZN-110 Universal Polyester Filler or ZN-130 Soft Finishing Filler. For jobs that call for fewer steps, ZN-125 Micro Fibreglass Filler can be considered as an alternative.

How large a hole can I close?

ZN-120 is suitable for bridging and closing small holes and tears in sheet metal. For larger openings or in areas that carry structural loads, a welded metal patch or a glass-fibre mat laminate must be applied first; the filler is then used only for filling over that repair.

How should I prepare a GRP (fibreglass) part?

First wash the part with soapy water and dry it, then remove grease and release-agent residues with ZN-530 Surface Cleaning Thinner. Abrade the gelcoat with P80–P120 until all gloss has gone, remove broken fibre ends and apply the filler once the dust has been removed.

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