Building surfboards isn’t exactly a walk in the park, especially if you’re doing it for the first time. Whether you’re an amateur or an expert builder, you can expect the entire process to take at least a week to complete.
Fortunately, attempting this DIY project is pretty manageable if you proceed with proper preparation, trusty supplies, uncompromising meticulosity, and of course, godly patience.
In this post, we’ll talk about one of the most crucial steps involved in surfboard building: the glassing process.
Glassing refers to the process of waterproofing and finishing a surfboard. This is accomplished by laminating layers of fiberglass cloth onto the board and then seal coating it with resin.
To better understand how this all comes together, it’s important to plan about some factors before you gather your tools and supplies. These are the glass schedules that you’ll use, the resin, and the board’s tint.
Surfboard Glass Schedules
The amount of fiberglass cloth that you’re going to laminate onto your board is known as the glass schedule. This will determine your board’s final weight and strength. Simply put, more fiberglass translates to heavier weight, but also sturdier build.
Fiberglass cloth is typically measured in ounces per square yard. This denotes how much resin it takes to completely saturate the cloth. The most commonly used fiberglass for surfboards are 4 oz. and 6 oz.
Most surfboards have two layers of fiberglass on the deck for durability purposes. This is where most of the action happens, after all. Hence, it needs to be able to withstand strong impacts.
4 oz. and 6 oz. are generally used together for strength and safety reasons. A sample glass schedule with both weights is 6+4 x 4, which means that there’s a 6 oz. and a 4 oz. layer on the deck, and a 4 oz. layer at the bottom.
There are also two common types of fiberglass cloths for surfboards: the E-glass and the S-glass (also called S-2 glass). E-glass refers to “electrical grade” as it was initially made for electrical purposes. This is the most common cloth for glassing a surfboard.
S-glass, meanwhile, was made for military purposes. Between the two, the S-glass is the stiffer and stronger cloth, and it’s also the more expensive one. It’s often used on decks since its main purpose is to prevent dents and dings as much as possible.
The two less common fiberglass cloths are the WARP glass, which is also an E-glass, and the Volan. The WARP glass has more fibers up the weave’s length, which adds vertical strength to your board. Oftentimes, the WARP is overlain with a standard E-glass for added stability.
The Volan, on the other hand, is a heavier cloth that generally comes in 8 oz. and 10 oz. sizes. It was originally used in the boat and tools industry. It was also what surfboard makers used back in the 1950s to 1960s. Since Volan is a heavy cloth, it is typically used for longboards where weight is considered a plus.
Common Glass Schedules
- Lightweight: 4+4 x 4 (common in competitions)
- Lightweight Plus: 4+4 x 6 (lightweight with extra sturdiness at the bottom)
- Standard: 6+4 x 6 (strong and durable; good for egg and fish boards)
- Heavy-duty: 6+6 x 6 (minimum requirement for a longboard)
These are just some of the common glass schedule combinations for surfboards. Of course, you’re not limited to these. After all, the schedules you’ll choose will depend on the board type you’re glassing and its purpose.
Polyester Resin vs. Epoxy Resin
Surfboards can be glassed with two types of resin: polyester and epoxy. If you need help with choosing, we’ve previously reviewed 5 products that have been proven to work well with surfboards here.
Listed below are some of their pros and cons:
Polyester Resin Pros & Cons
- Gives the board a lively and bouncy feel, especially when new
- Affordable and easy to get
- Polyester resin tends to degrade faster
- Smelly and not the best option health-wise
Epoxy Resin Pros & Cons
- Tougher and stronger; can handle harder impacts
- More health and environment-friendly
- More expensive
- Yellows faster than polyester resin
Sometimes, people also use these terms to refer to the board’s core (e.g., fiberglass boards and epoxy boards). This is an important consideration, since the board’s material and the resin you must use go hand in hand. Here’s the general rule to remember:
- For polyurethane boards (fiberglass), you can use either polyester or epoxy resin.
- For expanded polystyrene (EPS, Styrofoam, or epoxy boards), you must only use epoxy resin. This is because the polyester resin can melt away the epoxy board’s core.
Thus, before you buy your resin, make sure that you’re getting the right one for your board.
Freelap vs. Cutlap
The last piece of the puzzle before starting the glassing process is choosing whether you’re doing a clear glass job or a tinted one. That’s because this will eventually lead to choosing between freelap or cutlap technique.
For clear glass jobs, you can do freelap. If you wish to design or paint your surfboard, do it before you start glassing your board.
This technique involves saturating the fiberglass’ overlaps with resin and simply sticking it onto the other side of your board. Once the resin cures, you’ll have to sand down the overlaps until it’s flush to the board.
Be careful during the sanding process as you don’t want to hit the foam while doing so. This is done to prevent air bubbles once it’s time to glass the other side.
Cutlap, meanwhile, is the technique to use when you’re using tinted or pigmented resin. This involves taping off the other side of the board’s outline with a masking tape.
The tape is usually 1.5 inches thick from the edge of the rail. Sometimes, a masking paper is also used to ensure that no color makes it to the middle of the board.
Doing this marks the lap line and prevents the tinted fiberglass from sticking to the other side. Instead, it sticks to the masking tape.
Once the resin “kicks”, you’ll need to cut the glass along your tape line, making it easy to peel the excess glass together with the tape. Then, lightly sand the overlap to smoothen the lap line.
You then repeat the process with the other side.
It is often recommended for first timers to just go with a clear glass job because the freelap is so much simpler. Of course, if you really want to go for tinted glass, we won’t stop you either. At least you’ll know what to expect with both scenarios!
Supplies You’ll Need for Glassing Your Surfboard
Now that we have a pretty good picture of how this project is supposed to go, it’s time to gather the necessary supplies. Here’s what you’ll need:
- Fiberglass cloth
- Sharp scissors
- 1-quart mixing buckets with volume markings
- Mixing sticks
- Resin hardener
- Rubber or plastic squeegee
- Sandpaper or abrasives (60-80 grit)
- Masking tape (go for high-quality ones to ensure it sticks)
- 4-inch paint brushes
- Digital scale (optional; for accurate resin measurements)
Optional tools for cutlaps
- Masking paper
- Razor blade
- Respirator mask (especially important if you’re using polyester resin!)
- Gloves (you can go with latex or nitrile)
How to Glass Your Surfboard (7 Steps!)
We finally get to the exciting part! Now that you’ve set up your workshop, tools, supplies, and gears, it’s time to put together everything you’ve just learned about glassing.
Step 1: Lay and cut the glass on the bottom
Whenever you glass a surfboard, you should always start at the bottom. If you’re going to do a cutlap, tape off the deck first. Otherwise, you can skip this step.
Lay your board with the bottom up on the glass stands. Roll out the glass from nose to tail, ensuring that it’s relatively centered. If you’re doing only one layer, trim the glass approximately 2 inches below the rail so it can stick to the underside.
If you’re doing multiple layers, trim the first layer about 1 inch away from the nose and tail. Then, lay out the top layer and trim it with longer laps (e.g., 2 inches, like described above). Also, the heaviest cloth must always be the one closest to the board.
Finally, to prevent creases and wrinkles on the laps, make relief cuts along the rounded and cornered parts of the board (nose and tail). Usually, this is done with a V notch, but you can develop your own technique as well.
Step 2: Mix the surfboard resin
Resin has two parts: the resin itself and the hardener. The ratio of resin to hardener is 2:1 by volume. If you plan to measure by weight, a 2.2:1 ratio must be achieved. Between the two methods, weight measurements are generally more accurate.
Hardeners usually come in two speeds: fast and slow. The cure time of fast hardener is around 2.5 hours, while the slow hardener is around 4 hours. Warmer air temperatures will lead to fasting curing times for both.
Mix the resin and the hardener thoroughly for at least two minutes. Make sure that you scrape all material on the bottom and sides of the bucket to ensure that your resin is well-blended.
It’s worth noting, though, that fast hardeners can get hot during the curing process. This can melt the EPS board, or worse, cause the board to catch fire.
Just like epoxy resin, polyester resin also has a hardener, which is called a catalyst. This catalyst instigates a chemical reaction that changes the resin’s state from liquid to solid. The polyester resin’s hardener is methyl ethyl ketone peroxide (MEKP).
The standard ratio of catalyst to polyester resin is 1-2% of catalyst to the total volume of resin. Once you’ve mixed the resin, the mixture will be usable for the next 15 to 20 minutes before it starts to harden. Also, polyester resin is a highly flammable substance, so be careful with heat.
No matter which type of resin you’ll use, the general rule is to mix at least 3 oz. per foot of the board’s length, and then add 3 oz. more. So, if you’re working with a 6-foot board, you should have at least 21 oz. of resin mixture.
You’ll also want to add tints or color pigments once you’ve mixed the resin and the hardener. Of course, don’t forget to wear your protective gears for safety!
Step 3: Laminate the bottom
Pour the resin on the center of the board and spread it evenly across the board’s length from nose to tail. Once the board is saturated, pour some resin near the rails, then spread it lengthwise to create a “resin waterfall” on the overlap.
When the overlaps are fully saturated, tuck them to the deck, starting from one side towards the nose, and then on the other side towards the tail.
For Tinted Glass Jobs (Cutlap)
You must turn the board around and cut along the tape lines before the resin fully cures. If you wait too long, it’s going to be hard to cut the overlaps, and you’re going to end up with jagged cuts.
Step 4: Sand flush the laps on the deck
Using your sanding tools, sand flush the wrinkles and bumps that you see along the lap line. Keep a light pressure as you do this because you don’t want to hit the foam as you do so.
Make the laps as flat as possible to prevent air bubbles when you laminate the deck. You can also use popsicle sticks or wallpaper rollers to flatten the lap line onto the foam.
Step 5: Repeat steps 1 to 3 for the deck
Glassing the deck involves the same steps as glassing the bottom. Thus, you simply have to follow Steps 1-3 again for this portion.
Step 6: Sand flush the laps on the bottom
Just like in Step 4, you’ll also need to sand the laps flush on the bottom of the board.
If you did a tinted glass job, make sure that you avoid sanding too aggressively, as doing so may cause the color to fade. The purpose of this step is to just smoothen any bumps along the lap line.
Step 7: Sealcoat your surfboard
Now that your board is looking good, it’s time to apply the second layer of resin which is called the sealcoat (or hotcoat, if you’re using polyester resin).
This step aims to fill in the remaining gaps of the fiberglass weave and smoothen out the bumps. This seals the board and makes it waterproof.
For sealcoating, we’ll be working on the deck first. To start, make sure the board is clean and free from any dust, debris, fingerprints, etc. Then, tape off the rails, following the outline of the board. Let the bottom edge of the tape hang so it leads the excess resin to the ground.
Before you mix the resin, get your brush ready by mashing it on the sticky side of a masking tape. This removes loose bristles, which is something you don’t want on your board as you work on the sealcoat.
The recommended amount of sealcoat is 3 oz. of mixture per foot of the board’s length. So, a 6-foot board would require 18 oz. of sealcoat. Prepare your mixture like you did during the lamination process.
Pour half of your mixture down the board lengthwise, where the stringer line is supposed to be. As for the other half, split them a few inches away from the rails.
With your brush, “paint” the resin down using moderate pressure. This should leave a thin coat of resin in your brush’s wake. Continue “painting” the resin from nose to tail until you reach both tape lines. Switch to a lighter pressure and keep on spreading the resin lengthwise.
This whole process shouldn’t take more than 10 minutes. The final product looks like a shiny, wet surface. After this, walk away and let it cure.
If you happen to see bubbles or anything like that while it is curing, don’t attempt to “fix” it. Resist the temptation as you will only have more issues to fix later on if you mess with it.
Depending on the hardener you used and the temperature, you can expect the board to be ready in 2-8 hours. Remove the tape from the rails before the resin completely cures. Once the sealcoat is fully cured, you can now flip the board and repeat the same process.
Additional Tips for Surfboard Glassing
Glassing Wooden Surfboards
We’ve extensively discussed glassing polyurethane and epoxy surfboards, but what about wooden surfboards? If that’s what you’re working on, you may wonder if you still need to go through the processes above or if you can simply varnish it.
If you’re planning to use the board for actual surfing, then yes, you should glass it the same way that you would a foam board. This will keep the water out of your board and give it the durability that it needs to withstand powerful waves.
Meanwhile, if your wooden board is just for decorative purposes, then varnishing it is enough.
Working with Tints & Pigments
For those who want to do a colored glass job, make sure that you only pour a small amount of tint or pigment into your resin mixture. No need to use up all the colors for a vibrant hue. If you use too much pigment, chances are, the resin will never harden like it should.
The entire glassing process is a job for dedicated souls who have become experts at delayed gratification. This is simply not a project for those who love shortcuts.
If you go about the job haphazardly — not sanding enough, not being accurate with your mixtures, etc. — the results will quickly make you see that patience is a must-have virtue. Yes, you may still end up with a functional board, but it may not look as awesome as you planned!
Frequently Asked Questions
How long does the whole glassing process take?
Let’s use the maximum curing durations to compute the total time.
It can take a maximum of 4 hours to laminate one side of the board. We’re already including all the preparation time here.
For sealcoating, it can take one side a maximum of 8 hours to cure. Overall, the glassing process can take a total of 24 hours at most. Of course, in reality, it can be a lot faster than that if you chance upon good temperature conditions.
Which glass schedule should I pick?
There’s really no one correct answer to this. Ultimately, it will depend on the type of board that you have, your priorities, and your preferences.
It’s worth noting, however, that using S-glass may be the better option if you like to travel with your surfboard a lot. The S-glass board is more capable of handling impacts from being bounced around in transit. Thus, it usually has far less travel dings than an E-glass board.