Polysiloxane Topcoat

Common issues

• Premature gloss loss and chalking under UV/heat exposure when dry film thickness is below the specified range
• Poor adhesion or delamination when applied over insufficiently prepared or contaminated substrate (salts, oil, mill scale)
• Orange peel or sagging from incorrect thinning or spray technique
• Pinholing or holidays in high-build applications, especially at edges, welds and corners
• Intercoat adhesion failure when the recoat interval between primer and topcoat is exceeded
• Blistering from moisture entrapment when applied over a damp substrate or in high humidity
• Color/gloss mismatch between touch-up areas and the original application due to batch variation

Inspection checklist

• Visual check for gloss retention, chalking and color fading on topside surfaces
• Check for blistering, particularly near the waterline, scuppers and deck fittings
• Holiday (pinhole) detection with a wet-sponge or high-voltage spark tester on critical areas
• Dry film thickness spot checks with a calibrated gauge, compared against the specified range
• Inspect edges, welds and corners for adequate film build (edge retention)
• Check for mechanical damage - scratches or gouges exposing primer or bare steel
• Inspect any touch-up areas for adhesion and color match
• Review the application inspection report (surface prep grade, ambient conditions, recorded DFT)

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Compatible primer/tie-coat from the same system (per Jotun data sheet)
• Thinner/solvent as specified for the applied product
• Touch-up material, ideally from a matching batch
• Surface preparation abrasives per the specified prep grade
• Wet-film and dry-film thickness gauges for application/inspection control

Safety

• Solvent vapors are flammable and can accumulate in enclosed or poorly ventilated spaces during application
• Forced ventilation and gas-free certification required before hot work near coated compartments during application or curing
• Skin and eye irritation from uncured coating and solvents - PPE required
• Spray application generates fine airborne mist - respiratory protection required
• Confined space entry procedures apply when coating enclosed tanks or voids

Class survey

Coating condition is assessed as part of hull/topside surveys rather than under Continuous Survey Machinery. Classification societies note coating breakdown (blistering, corrosion breakthrough, film loss) as a factor in special/renewal survey scope, particularly where the IMO PSPC applies to ballast tanks. For topside/superstructure coatings there is no fixed statutory renewal interval, but surveyors generally expect maintenance records showing breakdown is repaired before it progresses to structural corrosion.