• Intermittent spray

    Possible Causes – Remedies:

    Worn gaskets and seals – Replace.

    Gelcoat starting to gel – Flush gun immediately with acetone.

    Partially blocked jet – Strip gun and clean.

    Low pot pressure – Increase pressure to obtain good fan at 50cm distance.

  • Difficult to spray

    Possible Causes – Remedies:

    Delivery lines too small – Increase Diameter of lines.

    Gelcoat too cold or too thick – Warm to 15°C minimum or dilute with maximum *2% styrene.

    Hard gelcoat in gun – Soak gun in methylene choride or acetone, then blow it dry.

  • Poor leveling

    Possible Causes – Remedies:

    Gelcoat viscosity is too high –

    Warm Gelcoat to 15°C minimum. Dilute with maximum *2% styrene.

  • Orange Peel

    Possible Causes – Remedies:

    Atomisation too low – Increase pressure to obtain good fan at 50 cm from mould.

    Gun held too close – Hold Gun 50cm from mould.

    Gelcoat temperature too low – Warm to 15°C minimum.

  • Porosity

    Possible Causes – Remedies:

    Poor atomisation – Pressure too high gives fine porosity.Or Pressure too low gives coarse porosity.

    Gelcoat too cold or too thick – Warm Gelcoat and mould to minimum 15°C. Thin with maximum *2% Styrene.

    Excess or wrong catalyst – Maximum 2% catalyst. Check with supplier.

    Covering too heavily or too rapidly – Lower gun pressure. Hold gun 50cm from mould. Wet thickness .018 – .023 apply in 3 passes.

    Water or solvent – Check the product for contamination.

    Gun held too close – Hold gun 0.6-1.0m from mould surface and as perpendicular as possible.

    Uneven Catalysation – Service and calibrate equipment.

    Wrong or worn tips – Replace tips.

    Catalyst fizz – Use correct catalyst.

    Use of solvents to thin gelcoat – Do not thin gelcoat.

    Pump cavitation – Check equipment for air leaks.

  • Sags and Runs

    Possible Causes – Remedies:

    Applied too thick – Wet thickness 15-20 thou.

    Pressure too high – Reduce pressure or move gun 50cm from mould.

    Gelcoat too thin – Lower gun pressures, rotate old stock, check with supplier.

    Gun too close to mould – Keep gun 50cm from mould.

  • Colour separation

    Possible Causes – Remedies:

    Settling of Colours – Stir before use.

    Excessive thinning of Gelcoat – Do not add more than *2% styrene monomer.

    Sagging of Gelcoat – Refer to (Sags and Runs).

    Overspray – Keep to minimum.

    Non-uniform catalysation – Mix thoroughly.

  • Resin Tearing

    Possible Causes – Remedies:

    Gun pressure too high – Lower pressure.

    Gelcoat too cold or too thick – Warm gelcoat and mould to 15°C minimum. Dilute with max *2% styrene.

    Gelcoat tip worn – Replace tip.

    Excessive over spray – Keep to minimum.

  • Soft Dull Gelcoat Wrinkling Sticking to Mould

    Possible Causes – Remedies:

    Insufficient coverage – Apply a total of 18-23 thou. Wet film in 3 passes.

    Slow Gel or Cure

    Increase Catalyst to maximum 2%.

    Low temperature

    Gelcoat and mould must be min. 15°C.

    Trapped Styrene

    Hold Gun at least 50cm away from mould. Adequately ventilate, or tilt mould to expel styrene vapor.

    Styrene evaporation

    Do not use over 30°C.

    Uneven Gelcoat

    Apply at uniform distance from mould.

    Wet P.V.A. Release agent – Dry thoroughly.

    Water/Oil in air lines – Flush out and drain traps.

    Laminate applied too soon – Do not laminate for at least 2 hours.

    Uneven Catalysation – Service and calibrate equipment.

    Surge in catalyst delivery – Ditto.

    Pre-Release – Refer Pre-Release.

    Laminate too slow – Increase catalyst in laminate if temperature low.

  • Fibre-Pattern & Print Through

    Possible Causes – Remedies:

    Insufficient cure

    – Correct catalyst level in gelcoat and/or laminate.

    Wait longer before pulling. part from mould.

    Do not laminate in low temperature.

    Check for contamination by water, oil or solvent.

    Wait longer before demoulding.

    Transferred from mould –

    Resurface the mould.

    Woven roving / Too close to the gel coat –

    Should have 3 layers of 1.5 oz. mat or equivalent chop between gelcoat and woven roving.

    Gelcoat too thin

    Use .018 – .023 wet film thickness.

    High exotherm of laminate – Cure laminate slower. Laminate in layers.

    Use lower exotherm laminating resin.

  • Dull part when pulled

    Possible Causes – Remedies:

    Wax build up on mould

    Polish mould.

    Polystyrene build up on mould –

    Scrub with stiff brush or stainless steel wool and strong solvent, rebuff and re-polish.

    Dust on mould –

    Keep mould covered when not in use.

    Rough or wet P.V.A. – Apply smoothly and allow to dry.

    Releasing part too soon – Allow more time before releasing part from mould, particularly at low temperature.

    Raw Catalyst – Start catalyst flow away from mould.

  • Pre-Release

    Possible Causes – Remedies:

    Allowing gelcoat to cure too long –

    Gelcoat must be laminated same day.

    Use of waxed gelcoat –

    Do not use waxed gelcoats on mould.

    Excessive or soft wax on mould – Polish mould before use.

    Excessive styrene added –

    Add maximum *2% styrene.

    Over-catalysation at high temp.

    Reduce catalyst to 1% minimum.

    Uneven cure due to uneven thickness –

    Apply gelcoat to uniform 18-23 thou wet film thickness. Avoid heating or fan blowing before gelation.

    Uneven cure due to styrene vapor in low spots –

    Ventilate mould properly.

    Gelcoat applied too thick – Apply gelcoat at 18-23 thou wet film thickness.

    Trapped solvant or water – Check for contamination.

    Moving or Bumping mould – Take care until laminate applied.

  • Fish Eyes/Pin Holes

    Possible Causes – Remedies:

    Silicone in wax or polishing cloth – Eliminates silicones in contact with mould.

    Contaminating on mould –

    Keep mould covered when not in use.

    Excessive thinning of gelcoat – Thin maximum *2% styrene.

    Thin gelcoat –

    Rotate stock, Contact supplier.

    Gun pressure too low – Increase pressure to obtain good fan.

  • Crazing

    Possible Causes – Remedies:

    Too much catalyst in hot weather –

    Drop catalyst to minimum 1%.

    Applied too thick –

    18-23 Thou. Wet thickness.

    Bad handling when demoulding – Demould carefully.

    Applied unevenly – Keep consistent distance from mould when spraying.

    Thinning with acetone or other solvent –

    Thin only with styrene monomer.

  • Blisters, Bubbles

    Possible Causes – Remedies:

    Air trapped between gelcoat and laminate – Remove with roller.

    Over catalysation – Use maximum 2% catalyst.

    Catalyst Drops

    Service and calibrate equipment.

    Poor catalyst dispersion in gelcoat or laminate –

    Mix thoroughly.

  • Scratched Gelcoat

    Possible Causes – Remedies:

    Removal of finished article from mould –

    Sand back, buff and polish.

  • Fading Or Bleaching

    Possible Causes – Remedies:

    Poorly cured gelcoat

    Refer to remedies.

    “Soft dull Gelcoat”

    Under cure

    Allow longer to cure.

    Ensure correct catalyst –

    Create air flow to remove access styrene from deep areas.

    Water exposure (before full cure)

    Do not allow water contact untill gelcoat is cured.

    Inappropriate use of shrink wrap

    Use only white pollyethylene film.

    Exposure to harsh chemicals – Clean only with mild detergent solution. Do not use solvents strong alkalies or acidic cleaners

    Refer to supplier.

  • Spider cracks & Stress Cracks

    Possible Causes – Remedies:

    Impact damage – Take care hammering moulded parts.

    Stress due to flexing – Take care demoulding parts.

    Allow product to cure.

    Gelcoat too thick – Use a wet film gauge.

    Mould mark –

    Resurface mould.

    Laminate too thin –

    Increase thickness.

  • Yellowing

    Possible Causes – Remedies:

    Polystyrene / wax build up transferred to part during lay-up – Clean mould regularly.

    Poor cure of gelcoat –

    Apply gelcoat at correct thickness, catalyst level, and temp.

    Avoid contamination by oil, water, or solvent.

    Do not add solvents.

    Inhibition of cure by styrene vapour.

    Thick or uneven gelcoat – Apply at .018 – .023 wet.

    Strong Alkaline Cleaners –

    Avoid cleaners with Ammonia or high pH levels.

  • Flaking Gelcoat

    Possible Causes – Remedies:

    Faulty adhesion between gelcoat and lay-up –

    Avoid use of soft mould waxes, which can penetrate gelcoat and adversely affect adhesion.

    Gelcoat left too long before laminate applied.

    Pre-Release –

    Refer to Pre-Release section

    Innappropriate use of shrink wrap

    Use only white polyethylene film.

    Contamination –

    Ensure no solvent, moisture, catalyst, dust, or overspray is deposited on gelcoat before laminating.

  • Pull Marks

    Possible Causes – Remedies:

    Resin Drainage from laminate –

    Avoid resin rich areas.

    Uneven laminate cure –

    Avoid abrubt changes in laminate thickness

    Under cure – Use Correct cat level. Create airflow over mould to remove styrene from deep areas.

    Gelcoat too thick – Apply at .023-.025 in 3 passes wet on wet.

    Incorrect insertion of cores and stringers – Use compressing material between the item and laminate.