Marine Filler and Marine Sealant

In this article, we will be talking about the use of marine filler and marine sealant. The aim is to give you an easy to understand step by step guide on using these products correctly. Nothing is more disappointing then going through the time and effort of a boat repair job, just to have things come apart again soon after.

If you have any questions or would like to book the Floating Boatyard team for a job, then don’t hesitate to call us on 07886 388 689. You can also message us through the contact section of this website, or via our Facebook page.

Using Marine Filler and Marine Sealant

There are many applications of marine fillers and marine sealants for canal boat owners. We will talking about these from a boat painting point of view. The principle should be the same for any other repairs you want to carry out. Make sure that the products you use to work on your boat are marine grade. Standard building materials will not last in a marine environment.

Marine filler and marine sealant are very useful products, but they must be used in the right way. We always take special care not to drop any of the filler or sealant in the water. These products are toxic to aquatic life. Always get permission from your local waterway authority, before carrying out any works on your boat while it is in the water.

Where To Use Sealant Or Filler

We often use fillers and sealant in our daily business of fixing boats on canal and rivers in the London, Essex and Hertfordshire area. Marine sealant can be used to reseal windows and other overlapping edges of materials where rain water ingress is to be stopped. We also use sealants as adhesives and in places where a flexible or vibration resistant filler is needed.

Marine Filler and Marine Sealant - Before - Rust Pitting Needs Filling

Pitted steel in need of Marine Filler on one of our Narrowboat painting projects.

Our boat painters mostly use marine filler to skim over rust pitting and minor holes in the steel work. Marine filler can be used to flatten any dents in the steel work. It is also an excellent material for seamlessly filling over welds. We use liquid metal filler when carrying out long term repairs to the steel work of the boat. This is suitable in areas above the waterline where welding isn’t possible to or too complex. Marine filler should only be used for this purpose where the structural strength of the boat isn’t affected.

Before Use

All surfaces and areas where marine fillers and marine sealants are used must be prepared correctly. Surfaces must be dry and clean. If we were to apply the filler or sealant to dirty or wet surfaces, it would not hold and bring problems down the line. It takes less time to prepare the surface correctly, than carrying out repairs later. We do not want to have just finished a paint job and discover that the filler or sealant isn’t holding.

Some marine sealants and marine fillers are designed for extreme circumstances. These products may be applied to dirty or wet areas. Some are even suitable for under water use and hull repairs. Always read the manufacturers data sheet before using the product.

How To Apply Marine Sealants

Marine sealant are usually sold in cartridges. We always use a good quality cartridge gun. Cheap cartridge guns tend to break and malfunction. This could potentially leave a mess with marine sealant getting into places where we don’t want it. We always have plenty of disposable rags or paper towels at hand and wear gloves.

We squeeze a small amount of sealant in to the gap or area we are working on. It is important not to apply to much at this stage. We can always add more later and cleaning up surplus marine sealant is tricky and often creates a mess. We can then wrap a rag or paper towel over our index finger and smooth the sealant. The sealant will be pushed into the gap while we are taking off excess material as we move along.

How To Apply Marine Filler

Most marine fillers come as a two component pack. It is better to use a little less hardener hot temperatures. This will extend the time to work the marine filler before it gets too hard and starts to set. The opposite effect can be achieved by using a little more hardener in very cold temperatures.

Marine Filler and Marine Sealant - Filler Applied Ready For Sanding

The damage to the steel has been filled in. This will now need sanding.

We always wear gloves and a fume filter mask when working with marine filler. A flexible scraper or putty knife is used to apply the filler. We make sure not to apply too much and remove any surplus as we go along. Marine filler sets very hard and applying too much of it means more work down the line.

After Aplication

It is important to be patient when waiting for marine filler or marine sealant to set. The material may seem dry and hardened out on the surface, but could still be soft on the inside. All the work will be undone if the sealant or filler is worked on before it is properly dried out. We always wait longer than the recommended drying time. The ambient temperature, relative humidity and temperature of the steel all play a role.

Marine Filler and Marine Sealant - After - Ready for Painting The Boat

This filler has been sanded and is now ready for painting.

Marine filler can be sanded smooth once it is dry. We use quality sandpaper with cloth back or latex paper back. Two component fillers dry very hard and cheap sandpapers will tear and become blunt very fast. Always apply marine primer and undercoat before painting over fillers and sealants.

For bookings, call us on 07886 388 689 or message us through the contact section  or via our Facebook page.

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