Glassing the surfboard is one of the most exciting parts of this project. It can be a little daunting if you have little experience with glassing. It helps to practice on a miniature surfboard to get used to working the resin on the cloth.
It also signifies that you are almost there. The hardest yards (shaping and designing) are now behind you. There are a couple things that you need to consider when you are glassing:
- Environment and ambient temperature.
In my case, the foam core consists of polystyrene. Polyester resin would react with the foam and eat it up. Therefore, we need to glass with epoxy resin which is inert and easier to deal with. I purchased some 2 to 1 UV stabilised epoxy resin from a fiberglassing supplies store.
We need to consider the strength of the glassing, and decide on a glassing scheme. For performance surfboards one might glass it really lightly, with 4 oz glass for the top and bottom. However, I wanted this board to be a little more durable, so I decided to glass it with 6 oz cloth on the bottom, and a total of 10 oz on the top (6 oz + 4 oz).
In case of any spills, etc, make sure you have a bunch of acetone and old rags for cleaning up.
You will need:
- A plastic scraper to spread the resin across the fiberglass cloth.
- A means of accurately mixing the correct volume of resin. I use a sensitive digital scale for complete accuracy.
- A circular bucket that lets you mix the resin and hardener to get a homogeneous mixture.
- A mixing stick.
- Scissors to cut the fiberglass cloth to shape.
- A heat gun (optional for pros only).
- Gloves (so you don’t get epoxy all over yourself).
- Razor blade to cut off the laps.
Glassing can get quite messy. You want to make sure that there is plenty of ventilation where you are working. And you want to prepare the space so that any drips or spills will not permanently damage your house/garage/shed. I lined my work-space with plastic sheets to prevent any epoxy getting onto the table or floor. You also want to ensure that you can walk around the surfboard relatively easily to spread the epoxy. Finally, you want to do this as the temperature is dropping (e.g. in the evening), as the foam will release gasses as it gets warmer and ruin your glassing job.
Method and Technique
First, I laid the glass cloth on the foam and used the scissors to cut around the surfboard, leaving approximately 5 inches to wrap around the rail. I kept the leftover glass since it would be useful for ding repairs in the future. At this stage it is important to decide on a free lap or a cut lap. A cut lap requires you to mask the other side and cut the cloth once it is wrapped, giving you a very clean professional line. If you do it free lap, no masking is required and you simply wrap the rails. I decided to go with the free lap for the bottom.
I estimated the amount of resin I would require for the job. I guessed around 150g. I poured 100g of resin into the bucket and mixed this with 50g of hardener with the bucket sitting on the digital scale. Carefully, I stirred the epoxy hardener mix trying not to introduce bubbles. Once mixed there is maximum of 15 minutes of working time before the mixture starts to gel. One way of increasing the working time is to cool the mixture by pouring it all onto the surfboard.
I poured the epoxy across the surfboard trying to spread it evenly in the middle, and left the bucket upside down on the surfboard to let all the resin out. Using the plastic scraper I spread the epoxy and let the resin saturate the cloth. You want to spread it to the rails as soon as possible to saturate the cloth at the rails so that you can wrap it around. Around this stage you will know if you have prepared enough epoxy. If required, mix more and quick add. Spread the epoxy at thinly as possible once it has saturated the cloth and then using the scraper, wrap the cloth around the rails. You should notice the epoxy start to get quite sticky (the beginnings of gelling), this is the perfect time to ensure that you have wrapped your rails. Wrapping the rails too early might result in the cloth falling off the rails due to a lack of stickiness and gravity.
Once I wrapped the rails, I left the board and waited until it was semi-hard. Using a razor blade, I removed any unwanted cloth. If you do not wait long enough, you can cause damage to the glassing job if you touch the wet cloth. If you wait too long, it will require much more effort to cut the cloth. I waited another 12 hours before proceeding to the next step.