We at Melker love stylish kayaks and always strive to produce the most beautiful kayaks on the market.
But kayaks must also be used, and that means they will get scratched eventually. The question we all naturally ask ourselves when we've used the kayak for a while and that first scratch has turned into a new work of art with lines along the keel line is, do I need to do anything about this?
To fix or not to fix Gelcoat?
Repairing the gelcoat on your kayak by adding new layers is more of a project than polishing a scratch or two and is not something we recommend in the first place. The risk of starting to sand and adding new layers is that you end up with a dull, uneven hull with color shifts that are uglier than the scratches were to begin with.
Before starting such a project, we therefore recommend trying to polish the kayak with a abrasive rubbing and then boat wax, it's relatively easy and can't really make things worse than they are.
The next step would be to see if it is possible to gently sand down the scratches, if they are not that deep it may be enough to just sand them and not put anything on to make it look nice. The gelcoat will slowly but surely get thinner that way, eventually it will run out and you will come down to the laminate, then new layers of gelcoat are needed.
If the gelcoat is so damaged or worn that the laminate is exposed, we always want to do something about it.
Tips and tricks, working with thermosetting plastic and fixing scratches in gelcoat.
Work Environment & Safety
- Always work in a well-ventilated area and avoid inhaling fumes and dust.
- Avoid getting gelcoat on the skin and use safety glasses.
- Cured gelgoat will only come off with mechanical abrasion so be sure to wipe off spills immediately and use clothing that you don't care about.
- Unhardened gelcoat can be washed off with acetone.
- Use the correct amount of hardener, during curing heat is created and if too much hardener has been mixed in, the chemical reaction can greatly accelerate and the gelcoat can start to boil or ignite.
Work with gelcoat
Gelcoat is a thermosetting plastic that needs to be mixed with hardener to solidify into a hard plastic. When you have mixed the gelcoat and hardener, it is liquid for about 10-15 min, so it is important to prepare everything else beforehand and not mix too much paint at a time.
Gelcoat hardens best if it is not in contact with air during the process. It can therefore be smart to cover small repairs with overhead film, plastic film or masking tape immediately after you have applied the new gel coat.
Overhead gives a glossier surface immediately, but can be difficult to get there without pushing air bubbles into the gelcoat, especially on larger surfaces or sharp radius and double curvatures.
If the area cannot be covered, the gelcoat will not harden on the surface, it will then have a small sticky layer that is most easily wiped off with acetone, t-red also works. Make sure the gelcoat has had enough time to cure before applying any chemicals to it.
An alternative to covering the gelcoat with plastic or tape is to work with topcoat, which is gelcoat mixed with a wax solution where the wax prevents air from coming into contact with the gelcoat.
If you choose to work with topcoat and want to apply several layers, only the last layer should be topcoat.
Several layers can be painted as soon as the previous layer has hardened, in our opinion it is the easiest way to get as smooth a surface as possible before sanding. For scratches below and along the keel line, we usually apply two thin layers of gelcoat and finish with a layer of topcoat if the surface is too large/difficult to cover with plastic.
It is also worth noting that gelcoat hardens more slowly if it is cold where you work and hardly at all if it is below 12°c, it is optimal to work in a well-ventilated space that maintains a temperature above 18°, without direct sunlight.
Order to fix scratches in
- Wash the entire boat with, for example, green soap.
- Sand the surface where you want to apply new gelcoat with a sandpaper, 240-400 wet sandpaper is usually enough.
- Carefully wipe off all dust.
- Wipe the surface with acetone or t-red and be careful not to touch it afterwards so as not to add new grease.
- Make sure you have brushes, gloves and all you need picked out and tape off surfaces that are not to be painted with masking tape.
Remove any masking tape before the gelcoat hardens so that the next project won't be trying to remove tape under cured gelcoat.
- Make sure you have something to cover the gelcoat with after you paint it on. Some use plastic wrapping but we find it difficult to get a good look and prefer tape or overhead film for small damages & work with topcoat for larger surfaces.
- Mix the gelcoat and hardener and work with a small area at a time to avoid the gelcoat hardening before you finish. If you want to apply several layers, mix a new gelcoat when the first layer has "gelled", usually 15-30 minutes after the first layer. When all layers are painted, allow to cure for at least 24 hours before the next step.
- Remove what you covered the gelcoat with, wipe off the sticky surface or wipe off any wax solution from topcoat.
- Sand with wet sandpaper, start with 240 to smooth out roughness and work your way up to at least 1000 for smoothness. Be careful with the rougher papers so you don't sand through the new gelcoat, it's so sad to have to start over. For proper shine, even finer paper is required, we use up to 4000 when it needs to be really fine.
- Wash the boat again to get rid of sanding dust and polish the surface with polish to give a hopefully shiny finish and finish with a coat of boat wax to protect it.