Repair Dents, Shape Panels & Prepare for Paint

Soudal Metal Plastic gives panel repairers, mechanics, fabricators & maintenance crews two-component polyester body fillers for repairing suitable dents, scratches, tears & surface imperfections before sanding & refinishing. The range covers both general profile correction & the finer finishing work needed as a repair approaches the paint-preparation stage.

The key is to match the filler to the damage, substrate & stage of repair. A panel that still needs straightening shouldn't simply receive more filler, while pinholes in an otherwise finished repair don't need the same treatment as the original dent.

For the wider vehicle-repair job, browse Car Repair & Maintenance. For grinding, shaping & preparing damaged metal before filling, explore Metal Cutting & Grinding Tools.

What Is Soudal Metal Plastic?

Soudal Metal Plastic is a range of two-component polyester body fillers designed to restore & refine suitable rigid surfaces before subsequent sanding, painting or refinishing.

The two main formulations perform different jobs:

► Metal Plastic Soft – a fast-curing, easy-to-sand polyester putty suited to general filling & repair work
► Metal Plastic Extra Fine – a finer polyester putty for small imperfections, finishing layers & refinement of suitable previous polyester filler repairs

Soudal lists applications across metal plate, automotive body repairs, polyester & suitable rigid timber. Metal Plastic Extra Fine is also specified for appropriate zinc-coated & galvanised metal surfaces.

The practical distinction is straightforward:

Metal Plastic Soft restores the profile. Metal Plastic Extra Fine refines it.

Why Choose Soudal Metal Plastic?

Body filler works best when it has one clearly defined job: correcting the remaining surface profile after the underlying damage has been properly assessed.

A typical repair progresses through several stages:

► Assess the panel & determine whether straightening or structural work is required
► Prepare the substrate by removing corrosion, contamination & unsuitable material
► Fill the remaining lows & surface damage
► Shape the repair through controlled sanding
► Refine pinholes, scratches & smaller imperfections
► Finish the surface for the coating or paint system that follows

Problems usually appear when those stages are compressed into one.

Excess filler creates unnecessary sanding. Filler over active rust conceals rather than repairs deterioration. A general filler used for every tiny finishing defect can make final refinement harder.

Using the appropriate product at the appropriate stage keeps the repair controlled.

Common Applications

Automotive Panel Dents

Start with the panel—not the filler tin.

Check whether the dent can be brought closer to its original profile through appropriate panel correction before filling. Polyester filler can then restore suitable remaining low areas rather than becoming a substitute for straightening.

After curing, controlled sanding blends the repair into the surrounding panel.

For examining vehicle damage & difficult-to-see areas during workshop work, browse Vehicle Inspection.

Scratches, Tears & Surface Damage

Surface damage can range from a shallow scratch to an irregular area requiring more substantial correction.

Before filling, inspect the surrounding material for corrosion, loose coatings, previous repairs & deformation.

The visible defect isn't always the full extent of the problem.

Galvanised & Zinc-Coated Metal

Coated metals need to be identified before repair.

Soudal Metal Plastic Extra Fine is specified for suitable repairs on metal plate including zinc-coated & galvanised surfaces.

The substrate still needs correct preparation. It should be rigid, dry, clean & free from grease, dust & unresolved corrosion before filling.

Pinholes & Fine Imperfections

A repair can appear smooth during initial shaping yet reveal smaller defects as preparation progresses.

Pinholes, slight roughness, shallow scratches & small low spots are where Metal Plastic Extra Fine becomes particularly useful.

Instead of rebuilding a largely completed repair, the finer putty can address suitable remaining imperfections before final preparation.

Previously Filled Repairs

Don't automatically spread another heavy layer over an existing repair.

First check whether the previous filler is sound, well bonded & free from cracking.

Where the underlying repair is stable & only minor surface defects remain, Extra Fine can be used as a finishing layer.

Loose, cracked or questionable filler should be investigated rather than buried.

Fabricated Metal Components

Grinding marks, minor dents & cosmetic irregularities can remain after fabrication work is structurally complete.

Polyester filler can help correct suitable surface imperfections before coating or painting, but it shouldn't be used to hide poor welding or structural defects.

Complete the fabrication first.

For related metal repair & fabrication equipment, browse Welding Equipment.

Suitable Rigid Timber Repairs

Soudal also lists rigid timber among the suitable substrates for Metal Plastic Soft & Extra Fine.

This can provide a hard, sandable repair where the application is appropriate.

Consider movement before using a rigid polyester filler on timber. Joints or cracks expected to move require a product designed to accommodate that movement rather than a rigid body filler.

Product Selection Guide

Match the Product to the Repair Stage

How Much Panel Correction Is Still Required?

If the filler needs to compensate for substantial distortion, reassess the panel first.

The closer the underlying metal is to its intended profile, the more controlled the filling & sanding stages can be.

At the other end of the process, don't rebuild an entire area because you've found a handful of pinholes. Match the scale of the correction to the defect that remains.

Is the Substrate Ready?

Soudal specifies suitable substrates as rigid, clean, dry & free from dust & grease.

Before mixing, inspect for:

► Rust or corrosion
► Oil & grease
► Sanding dust
► Loose paint or coatings
► Moisture
► Weak previous filler
► Surface contamination
► Excessively smooth bond areas
► Damage requiring further panel correction

Rust should be removed before filling. Soudal also notes that rough grinding smooth surfaces can improve adhesion.

Soft or Extra Fine?

A useful decision is to ask what you're trying to achieve right now.

Still rebuilding the shape?
Metal Plastic Soft is the stronger starting point.

Shape is established but small defects remain?
Metal Plastic Extra Fine becomes the more logical choice.

Changing filler as the repair progresses can reduce unnecessary material build & sanding.

How Much Should You Mix?

Metal Plastic is a two-component system.

Soudal specifies mixing 2% B-component with the A-component until the mixture is homogeneous.

Don't prepare a large batch simply because the repair area is large. Mix an amount you can apply properly within the available working period.

At the published test conditions, the working time is approximately 5–8 minutes.

Can You Apply More Than One Layer?

Yes, where required for the appropriate repair.

Soudal's application guidance allows the putty to be applied in several layers.

The objective isn't maximum thickness in one pass. It's controlled profile restoration that can be shaped accurately afterwards.

When Can You Start Sanding?

Soudal's technical information lists relatively fast sanding times for the Metal Plastic range.

Metal Plastic Soft is listed as sandable after approximately 20 minutes under the stated technical conditions. Metal Plastic Extra Fine is also fast curing, with application guidance indicating approximately 20–30 minutes depending on ambient temperature.

Treat those figures as product guidance rather than a reason to sand material that hasn't cured sufficiently under actual workshop conditions.

Expert Tips

Straighten before filling. Correct as much of the underlying panel profile as practical before relying on polyester filler.

Remove corrosion rather than covering it. Filler over rust can make a repair look complete while deterioration continues underneath.

Check old repairs carefully. Cracked or poorly bonded filler deserves removal & investigation rather than another layer.

Degrease appropriately before final preparation. Avoid working contamination deeper into the repair surface.

Give smooth substrates the preparation they require. Appropriate mechanical preparation can improve adhesion on suitable rigid surfaces.

Keep broad repairs controlled. Concentrated sanding pressure can create new lows instead of restoring the intended panel shape.

Use reflections to read the panel. Changing the viewing angle or lighting can expose waves, highs & lows that aren't obvious head-on.

Don't keep reaching for general filler. When the repair reaches pinholes & fine imperfections, change to the product designed for refinement.

Respect panel edges & body lines. Excess material around sharp features creates unnecessary shaping work.

Mix thoroughly but efficiently. Once the hardener is incorporated, the working period has started.

Control the batch size. Smaller manageable mixes are easier to apply properly than oversized batches racing against cure.

Manage sanding dust. Body-filler preparation can generate airborne dust, so select task-appropriate PPE & workplace controls. Browse Respiratory Protection & Accessories.

Protect your hands during preparation & chemical handling. Select gloves appropriate to the products & task being performed from Chemical-Resistant Gloves.

For a workshop perspective on automotive repair work, read A Day With An Automotive Mechanic Peninsula.

For metal preparation & abrasive selection, see Complete Guide Abrasive Cutting Grinding Discs.

For handling information supplied with fillers & workshop chemicals, read How to Read a Safety Data Sheet - A Quick Guide for Workshop Operators.