Special Finishes

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Autofix Fibreglass Filler

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Fibreglass Filled Polyester Resin Strong Flexible Waterproof Filler

Another Unique Time Saving Product

  • Fix rust, dents, holes on steel or fibreglass permanently
  • Drill it / hammer it / abuse it still holds on
  • Used to repair all types of fibreglass boats, cars trucks buses steel and automotive panels
  • Leaks in roofs, on galvanised iron, wood, timber wherever you need a strong waterproof repair.

Specification Data / Instructions for Use


Autofix is a unique pure resin polyester filler, blended with chopped-strand fibreglass that provides exceptional performance properties.  Its the strongest flexible filling compound available, designed to repair and fill all rusty panels with permanent results, and is used to repair fibreglass cars, boats, truck bodies, all types of automotive panels, direct on to steel or fibreglass, used on cars, vans, trucks, buses, boats etc.  It can also be used to repair galvanised iron roofs, wood weatherboards and all types of timber surfaces.

  • Permanently fixes rust / dents / holes
  • Strongest flexible filler available
  • Waterproof filler
  • Screw it - drill it - fix to it - hammer it - abuse it - it still holds on
  • Summer and winter grades available

Operating Tips:

To achieve the best performance from repairing rust on automotive vehicles grind back all paint, rust etc, larger than then the area to be fixed, then use a pointed hammer and hammer down metal around the repair, considerably lower than normal to allow a thick film thickness of AUTOFIX to provide sufficient strength for a strong waterproof repair.

Mix AUTOFIX thoroughly with 3% Benzoyl perxoide until a complete colour change  is achieved, then apply to the repair.  Cellophane plastic film (Glad wrap type) can be used to support large fills and will assist in smoothing out along with supporting the filler and will also prevent a tacky surface.  Masking tape used on the cellophane will hold it to the panel.  You may need to block the rusty hole on the inside of the panel to prevent the Autofix falling out inside, use a piece of clean steel, or masking tape / packaging tape etc.

Once cured approximately 10 minutes, remove the cellophane and machine grind smooth if required or apply Lightning / Autopatch / Superlite or Duraglass conventional fillers to achieve a smooth finish, then apply primer and Lacquercoat top coat as required.

To ensure the best performance from polyester fillers and to assist with the use of Autofix we highly recommend the following:

  1. Ensure a minimum of 3% Benzoyl Peroxide is always used with Autofix, amounts less will cause bleed through, as there will be insufficient catalyst to thoroughly cure the polyester, this leaves free amine to bleed out through the paint.
  2. Thorough mixing to achieve complete colour change is essential this improves adhesion / stops pin holing / also prevents bleed through.  Mix with a folding and flop action and always spread a layer out on mixing board to press and extrude all the air entrapped, then retrieve small quantities and use.  Build up in thin layers, extruding the air each time.  Always build higher than the repair to allow for sanding.
  3. Do not use Winter grades in the summer, as it is not possible to include sufficient Benzoyl Peroxide!
  4. Always immediately apply a waterproof Primer to the filler after all repairs have been completed, even if the vehicle is to stay inside the workshop, and especially if it is stored, or is used outside, as all fillers are extremely porous and any water or even atmospheric moisture will penetrate the filler down to the metal and immediately cause rusting, that will result in failure with loss of adhesion.
  5. Do not use DURAGLASS or any other conventional filler directly over rusty repairs always use a water-proof filler such as AUTOFIX first, then use conventional filler to finish, as failure will arise due to continued rusting causing loss of adhesion.  To further assist with rust prevention apply Autobody-Seal Underseal or Autoguard Rustproofing to the inside panels after the repairs have been completed, this prevents moisture ingress and then will prevent rusting.
  6. Always sand the surface of all fillers before priming or painting, Even Autofix, any unsanded filler will cause loss of adhesion and blistering.  Even sand filler used on small pin holes or spot repairs as these will also definitely fail.
  7. Ensure the lid is kept securely closed on all fillers to prevent evaporation of the styrene monomer (solvent), as this will dry out filler and moisture or water may enter.  This will cause massive pin holing, along with future rusting.

Directions for Use:

For best results and improved adhesion it is important that ALL paint, rust, etc, be completely removed.  Sand back (or machine grind) to a good clean bare metal surface, always larger than the area to be filled, to allow for feathering.

Autofix requires addition of 3% hardener.  Cut off nozzle leaving ΒΌ" outlet, press out a 1" strip of hardener to add to half a cup of filler.  Sufficient hardener has been added when a medium even colour change is seen, it is important to thoroughly mix hardener and filler together with a scoop, flop and drag action until colour completely changes evenly throughout.  This mixing action forces out entrapped air and helps eliminate pinholing, never mix with stirring action.  Always spread out on mixing board to remove air then use.

Apply to surface with suitable spreader, using reasonable pressure, build up with thin layers (this eliminates pinholing), and leave dents slightly over-filled to allow for smothing down.  It is easier to remove excess filler before a fully cured condition is reached using a surform or dreadnought file, 40 grit sandpaper can be used when fully cured, then use 100 grit paper for final finish.  Always coat repair with suitable primer, fillers should never get wet as this results in metal rusting and then loss of adhesion.

Store in a cool dark place.  Keep well sealed down.  Do not use mixing tool for taking additional Duraglass from tin.


Contains Styrene Monomer.  Causes eye irritation.  Vapour Irritation - Combustible. Hardener contains Benzoyl Peroxide.

Health & Safety:

Avoid contact with eyes.  Avoid breathing vapour.  Avoid prolonged or repeated contact with skin.  Keep away from heat and open flame.  Use adequate ventilation.  Keep container closed.  Wash thoroughly after handling.

First Aid:

In case of contact, immediately flush eyes with plenty of water for at least 15 minutes.  Call a physician.

Warranty / Liability

Special Finishes (NZ) Ltd provides all the enclosed information in good faith but without warrantee and is to assist your application. However the use of this product being used is beyond their control. The manufacturers can accept no responsibility whatsoever for any damage or failure arising from its application or use. It is totally the responsibility of the user to insure that the product is suitable for its intended use.