Stripping Bottom Paint – How to Remove Antifouling Paint

Remove antifouling paint from your boat by scraping, stripping, or blasting.

Remove antifouling paint safely and cleanly

The seasons are changing and you are looking forward to getting back on the water. But when you pull your boat out of the water to find the antifouling looking scabrous with excessive layer buildup, cratering, peeling, flaking, or blisters appearing across the hull, there is no getting round it; you need to remove and reapply your antifouling. Whether you hire a professional or choose the DIY route for stripping antifouling paint, it is important to be aware of the steps involved and the regulations and best practice guidelines of your state or territory. Different antifouling paints require different care, and it also affects how often you need to remove antifouling or even whether you do at all.

In this article we look at the steps you need to take to remove antifouling from your vessel, as well as the various laws and regulations that affect US waters.

First things first – Antifouling health and safety

Before you even think about stripping antifouling paint, there are some health and safety factors you need to be aware of. Each of the processes involved in stripping bottom paint has the potential to introduce pollutants into the environment. The paint itself contains copper and other toxic substances that are best kept out of the water. The stripping chemicals, dust from sanding or blasting, and fumes from paint reapplication are all a health hazard. In Maryland, the ‘Clean Marina Initiative’ releases a guidebook to best practices of clean boating which you can find here.

The 3 essential steps for antifouling removal

Stripping antifouling back will ultimately give your vessel better protection and will let you see the condition of your hull that the old antifouling may have been hiding before you apply new paint. Though it seems big and mucky, removing antifouling can be broken down into three simple steps: Preparation, Removal, and Clean Up.

Not all antifouling paints are compatible, and whether the antifouling is hard or eroding will affect how often you need to clean it back. If in doubt, start from scratch.

Step 1: Preparation

Like anything to do with the coating universe, preparation is a key aspect of the job. To adequately set-up for removing old antifouling you must:

  • Wear PPE (Personal Protection Equipment) such as goggles, masks, gloves, and overalls to cover bare skin.
  • Ensure the area in which you are working is properly ventilated.
  • Do not remove antifouling on windy days as the material that is removed from the hull needs to be collected and contained in order to avoid contaminating and polluting the environment.
  • Lay out drop cloths and tarpaulins or bunds to catch liquid and solid wastes.

Step 2: Removal

This part is where the the hard work really starts. There are three main DIY antifouling removal methods, each with different strengths and weaknesses.

  1. Dry scraping/Sanding – This method is fairly self-explanatory. Using a coarse sandpaper (80 grit) or a scraper (flat-bladed, triangular, electrical or other), you manually remove the antifouling. When using sandpaper it is advised to wet sand the coating – this keeps the aerial distribution of dust to a minimum. For scrapers, always have spare blades and, to avoid scratching the underlying substrate, round down the corners. This is the cheapest removal option, but also the most labor intensive.
  2. Chemical stripping – Using a chemical stripper on the antifouling takes some of the grunt out of the work, but it also increases the amount of toxic waste material. And not all chemical strippers are suitable for the purpose – always check the instructions and, if still uncertain, consult with a specialist.
  3. Soda blasting – This involves blasting the hull with soda, which explodes when it hits the surface and takes the paint with it. This is the method with the least effort but it is slower, and does create a lot of clean up – you can only use blasting methods if the appropriate screening and containment is available.

Step 3: Clean Up

The relevant authorities in any state or territory will have outlined specific rules for the collection and disposal of all residues, solid coatings, liquid or any other form of waste (including any biofouling you may have removed). Antifouling coatings should not be incinerated. If you have taken care with the preparation stage, the clean up stage should be much easier. Essentially all contaminants and pollutants need to be contained and kept away from:

  • Any body of water
  • Stormwater
  • Land below the high-water mark
  • Any tidal body of water

There are a number of guidelines and regulations which apply when it comes to removing antifouling, and you need to be aware of the laws in your region.

Some final points about stripping antifouling paint

Though it is definitely the most expensive option, having a trained professional remove antifouling from your vessel is still the best way to go in terms of the quality and assurance of the final job. It is also the best way to ensure that local regulations regarding clean up and disposal are properly adhered to. If you do choose to remove antifouling yourself, check with the local Port Authority or Fisheries Department for guidelines and advice.

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