Gelcoats & Flowcoats During Application

OBSERVATION	POSSIBLE CAUSES	REMEDIES
Intermittent Spray	Worn gaskets and seals Gelcoat starting to gel Partially blocked jet Low pot pressure	Replace. Flush gun immediately with acetone. Strip gun and clean. Increase pressure to obtain good fan at 50 cm distance.
Difficulty to Spray	Delivery lines too small Gelcoat too cold or too thick Hard gelcoat in gun	Increase diameter of lines. Warm to 15°C minimum or dilute with maximum 2% styrene. Soak gun in acetone, then blow it dry.
Poor Leveling	Gelcoat viscosity too high Atomisation too low Gun held too close Gelcoat temperature too low	Dilute with maximum 2% styrene. Increase pressure to obtain good fan 50 cm from mould. Hold gun 50 cm from mould. Warm to 15°C minimum.
Porosity	Poor atomisation Gelcoat too cold or too thick Excess, or wrong catalyst Covering too heaviily or too rapidly	Pressure too high gives fine porosity. Pressure too low gives coarse porosity. Warm gelcoat and mould to minimum 15°C. Thin with maximum 2% styrene. Maximum 2% catalyst. Check with supplier. Reduce gun pressure. Hold gun 50 cm from mould. Maximum wet thickness 0.7 mm.
Sags & Runs	Applied too thick Pressure too high Gelcoat too thin Gun too close to mould	Maximum wet thickness 0.7 mm. Reduce pressure or move gun 50 cm from mould. Reduce gun pressure, rotate old stock, check with supplier. Keep gun 50 cm from mould.
Colour Separation	Settling of colours Excessive thinning of gelcoat Sagging of gelcoat Overspray Non-uniform catalysation	Stir before use. Do not add more that 2% styrene monomer. Refer to “Sags and Runs” Keep to minimum. Mix thoroughly.
Resin Tearing	Gun pressure too high Gelcoat too cold or too thick Gelcoat tip worn Excessive overspray	Reduce pressure. Warm gelcoat and mould to 15°C minimum. Dilute with max 2% styrene. Replace tip. Keep to minimum, thickness.