Boat Painting DIY Series: How to Apply Antifouling Paint

Applying Antifouling

Colin Anderson, Specialist in Antifoulings Development at Interlux

Antifouling can be applied using a brush or roller. Using a small roller is less work on the arm but takes longer to cover the surface area. If a brush is preferred, choose a large width brush; the finish will not be as smooth as a topside paint so the type of brush used is not critical.

1. Health and Safety

Before commencing preparatory work, ensure the area you are working in is adequately ventilated. Ensure you are wearing the correct
PPE; we recommend safety glasses, goggles or visors, nitrile rubber gloves, overalls (ensuring skin is not exposed) and a solvent mask.

Previously Painted Surfaces:

2. Inspection

Check for areas of damage, separation or peeling, or any other indications that the existing coating is not firmly adhered to the substrate.

3. Preparation - In Good Condition

Clean using high pressure fresh water wash. Remove any contamination by wiping down with Special Thinner 216. Sand any bare areas
and remove sanding residue.

Preparation - In Poor Condition

Completely remove all antifouling paint with Interlux Interstrip 299E for fiberglass or wood and by
sandblasting steel surfaces to a near white metal.

4. Masking

Before priming or applying antifouling, mask off the area to be painted.

5. Repair/Priming

Repair damaged areas with Watertite Epoxy Filler where necessary. Do not apply Watertite over antifouling paint. Inspect gelcoat for damage and signs of osmosis and treat accordingly.

Seal incompatible or unknown antifoulings with Primocon. Bare substrates should be primed, according to substrate. Product
recommendations are provided on labels and data sheets. Remember to pay particular attention to drying times and overcoating
intervals.

6. Application

Mix paint thoroughly with a stirring stick, ensuring that any settlement is mixed in. Apply according to label recommendations,
using a brush or roller.

Apply the antifouling at the correct thickness; this may mean an extra coat is needed, depending on application methods and conditions.

Apply an extra coat to leading and trailing edges; e.g. waterline, trim tabs, outdrives keels and rudders. These areas experience
more water turbulence and so more wear on the paint surface.

Follow overcoating times and immersiontimes carefully. Failure to do this couldresult in detachment, blistering or cracking
of the antifouling. The marine environment is harsh for paint so it must be allowed todry thoroughly before immersion.