HOW TO GLASS A SURFBOARD
"Glassing" is a term used for the entire process of fiberglassing and sealing the board. Laminating the fiberglass to the foam is step one, seal coating with resin is step 2.
Like shaping, glassing your surfboard becomes much less intimidating once you break it down into clear steps, use the right tools, and do some simple preparation prior to each step. At Greenlight, we like to focus on the more environmentally friendly methods of construction, which is one reason why we prefer glassing with Epoxy resin. Epoxy is much less toxic to work with, but just as importantly, we feel it makes a stronger, longer-lasting, better flexing surfboard. Epoxy resin must be used with EPS foam cores but can also be used on Polyurethane foam cores with great success as well.
This guide will cover glassing your surfboard with traditional fiberglass hand layup method, both “freelap” and “cutlap” techniques, using state-of-the-art Greenlight Marine Grade Epoxy resin and Silmar 249B Polyester resin. Don’t expect your first glass job to go perfectly. Like anything, it takes some practice to perfect the art of glassing. Nonetheless, we are confident you’ll get a good result if you prepare and follow these directions.
CHOOSING A GLASS SCHEDULE
The first step in glassing is to determine how much fiberglass cloth you are going to put on your board. This is called the “glass schedule” and it dictates the final strength and weight of your board. The more glass you use, the heavier, but stronger your board will be. Surfboard and SUP fiberglass comes in rolls which are 30” to 42” wide and meant to be cut to the correct length and width once the glass is rolled out over your blank. Fiberglass is measured by weight per square yard. The most common weights for surfboards are 4 oz and 6 oz per square yard.
There are a few more types of fiberglass cloth used in surfboard building and you can tailor the strength-to-weight-ratio by incorporating different fiberglass in your surfboard lamination. Read more about the different types of fiberglass cloth
The lightest glass schedule that you would want to use is one layer of 4 oz on the bottom and two layers of 4 oz on the top. The extra glass on the top gives you some protection from pressure dings from your feet and other bodily contact. For this super-light glass schedule, you may also want to add a small patch of 4 oz glass under the main layer in the fin box area. This gives you additional strength in the fin area without adding too much weight. If you want to increase the strength/weight of your shortboard, you can simply go up from there. The next step might be two layers of 4 oz on the bottom and a layer of 6/4 on the top. Another way to add additional strength is a “deck patch” under the main layers to reinforce the area you stand on, which takes a lot of abuse from your feet.
When you are layering 4 oz and 6 oz together, it is best to put the heavier cloth on first, and the lighter cloth on the outer layer. This setup will use less resin in the seal coat stage of glassing and keep the board lighter. For most shortboards, it is not recommended to have much more than 10-12 oz total on the bottom and 12 oz of glass on the top, it'll make the board heavier and not worth the extra strength.
Most longboards typically have at least a single 6 oz bottom and double 6 oz top glass schedule. This would be for a pretty light longboard. Go up from there if you want to increase the durability (and weight) of your longboard. The max glass schedule you would want on a longboard is about 16 oz on the bottom and 18 oz on the top.
FREE LAP VS. CUT LAP IN SURFBOARD GLASSING
A final decision you need to make before you begin glassing is whether you are going to use the “freelap” technique or the “cutlap” technique. This is a pretty cut-and-dried decision (no pun intended). If you are going to do a clear glass-job with no tint or pigments in the resin, then you can just do the simpler freelap. You can skip to the Cutting and Laying Down Fiberglass section if you are doing a freelap. If you plan to tint or pigment the resin, then you should go with the cutlap.
The cutlap requires s few more tools/materials and a bit more preparation. While we wouldn’t recommend doing this on your first glass job, we wouldn’t talk you out of it either. You can do a pretty good cutlap on your first try if you have good tape and good technique. More details on cutlap techniques are presented in the Cutlap Preparation section.
If you choose to do a cutlap, you need to tape off and mask the top of the blank before you lay your fiberglass down on the bottom of the blank. You always laminate the bottom of the blank first. To prepare your board for cutlapping, you need good masking tape (we recommend the industry standard ¾” high-temp masking tape). The tape provides a clean line to act as a border for your lamination and guide to cut the cured fiberglass.
Start by laying your blank top-up on your glassing stands. Using ¾” high-temp masking tape, run the tape around the perimeter of the deck, about 1 1/2"- 2 inches from the outline of the board. You can taper this distance from the outline near the nose and tail down to 1 ½ inches or so if you like. Make sure the tape matches up cleanly at the nose and tail where both sides meet. This border you created with the tape will be where the fiberglass wraps around from the bottom and will eventually be cut with a razor blade. Once the glass is cut on the tape line, you are left with a straight, clean lap-line.
Once you have laid down this initial “border” of tape, do another round of wider masking tape just inside the first one (toward the middle of the board). The second round of tape should slightly overlap the first one, making sure there is no exposed foam between the two strips of tape. Repeat as many layers of tape as you feel you need to ensure no resin will get onto the deck when you push the fiberglass around the rail to the deck. If you're using tints or pigments it is very important to keep the deck foam clean and free from color. Use a few rows of tape or include masking paper or newspaper to cover the entire deck area.
CUTTING/LAYING DOWN GLASS
Most glassers begin the process by laminating the bottom of the board. Lay your blank bottom up on your glassing stands, double checking that the board is level on the racks from rail to rail. If you are going to laminate the bottom with more than one layer of fiberglass, roll out the first layer of fiberglass along the bottom of the board from nose to tail (or tail to nose, doesn’t matter) and cut the fiberglass with sharp scissors about an inch past the the nose and tail area. Make sure the fiberglass is relatively centered from rail to rail as you roll it out.
Once the fiberglass is laying flat on your board, the first layer needs to be trimmed so the glass is hanging down about halfway down the rail around the entire board. If you are doing three layers of fiberglass, the second layer is put on and trimmed the same way as the first, with perhaps a slightly longer overlap around the rail area. Your top layer of fiberglass must have longer “laps” which will be wrapped around the underside of the board when you spread the epoxy on the fiberglass. When cutting the top layer of fiberglass, make sure you cut the glass about 2 inches below the bottom of the rail. The glass needs to wrap completely around the rail to the deck-side. The wet resin will hold it in place as it cures. If you have a tape-border on the deck for a cutlap, make sure your laps are cut low enough to extend beyond that tape border.
Once you have cut the top layer of fiberglass, try to trim away any hanging threads of fiberglass or uneven sections. You want the edge of the glass to be as clean as possible, as loose-hanging threads become a nuisance while laminating. A final step you need to take is to cut a “v” notch in the top layer of fiberglass in the nose area of the board and the tail of the board. If you have a swallow tail, you should also cut a v-notch at the “points” of each swallow. This will allow you to fold the laps under the board without forming wrinkles or overlaps in the glass. Cured wrinkles/overlaps require you to do additional sanding which is nice to avoid. A nice trick we do at Greenlight is to fold the fiberglass around the nose and let it fold naturally around the curves or point of the nose. This will show you where the fiberglass will lap over itself. You can push on the glass to crease it along the overlapping lines to mark the triangular Vee to be cut away. This trick helps get the notches right and eliminates extra sanding.
If you have printed out any logos or artwork that you’d like to place under the fiberglass, this should be done right before you are ready to laminate. To do this, carefully roll up all of your fiberglass layers to a point just beyond where you want to place your artwork. Try not to shift the placement of the fiberglass as you roll it up, as you will eventually be rolling it back down, and you want it in the same place. If the artwork is closer to the tail, roll up the glass from the tail. Vice-versa if the artwork is closer to the nose. You will be basting the logo to the foam with a thin layer of resin once your resin is mixed and ready to be spread on the fiberglass.
HOW TO MIX SURFBOARD RESIN
We are assuming you are using the Greenlight Marine Grade Epoxy Resin System, which is the best surfboard laminating and seal coating epoxy available at this time. Epoxy resin is considered to be more durable, more flexible, and even a bit lighter than polyester resin, which was the standard in surfboard construction for nearly 70 years. Epoxy is a bit more expensive than polyester, but typically you need to use less epoxy when glassing a surfboard than polyester, so the cost nearly evens itself out, while the benefits of epoxy are substantial. Another big benefit to epoxy is its low toxicity and lack of bad smell. This allows you to glass your board safely indoors.
You don’t really need to use a respirator with epoxy, but it's always a good idea to wear a mask when using any chemical as a good habit. You should use disposable vinyl or rubber gloves at all times when handling epoxy. Another precaution you should take is to put a plastic sheet or tarp down below your glassing stands to catch the resin that will drip on the floor. When the epoxy cures on the plastic, it will flake right off.
Greenlight Marine Grade Epoxy System comes in two components: resin and hardener. There are two primary hardener speeds: FAST and SLOW. Epoxy mixed with fast hardener gives you a cure time in 2 1/2 hours (the warmer the air temp, the faster the cure), epoxy mixed with slow hardener gives you a cure time in about 4 hours. Beginner glassers shouldn’t have a problem using the fast hardener but it's recommending to start with Epoxy with Slow hardener to make sure you have all the time in the world to get the best results your first time. You should, however, consider using slow hardener or Quik Kick when you are installing fin boxes or leash plugs. The fast hardener can get pretty hot (exotherm) while it is curing, and it has been known to melt EPS foam, even with Engineered 2lb foam, in fin installs. Resin Research recently released an even faster curing resin, called Quik Kick, which promises cure times in less than an hour in warm temps, and about 1.5 hours at 70 degrees F. Another nice thing about Quik Kick is it doesn’t exotherm (produce heat) as much as fast hardener, so it can safely be used for fin-installs and leash plugs. Quik Kick is OK for beginners, as long as you aren’t going to be glassing in very warm temps (over 80F) which will reduce your working time with the Quik Kick resin to about 15 minutes and could start to cure before you've fully wet out the fiberglass.
Regardless of which Epoxy Resin System you choose, the resin/hardener need to be mixed in a 2:1 ratio by volume. There are 3 methods of measuring epoxy ratios. We highly recommend using a digital scale for the most accurate measurements and 100% cure strengths. You can also use metered resin pumps or transparent/marked measuring buckets.
As a rule of thumb, for the laminating stage, you want to use at least 3 oz of mixed resin per foot of surfboard length plus 3 more ounces. So for a 6-foot surfboard, you should use AT LEAST 21 oz of mixed epoxy/hardener, or 14 oz of epoxy mixed with 7 oz of hardener. Beginners should plan to use a little more, like 16 oz of epoxy with 8 oz of hardener, or 24 oz total mixed material for a six-foot board. Having a little resin left over is better than stressing to mix additional material if you come up short...
Check out our Resin Amount Chart per Board Length and Epoxy Mixing Ratios
You should mix your epoxy and hardener thoroughly for at least two minutes to make sure it is completely blended. Use clean, strong mixing sticks and make sure you scrape the bottom and sides of the mixing bucket to get all of the material blended.
Quick Cheat Sheet on Using Epoxy Resin:
- Measure accurately - Greenlight Marine Grade Epoxy Resin is mixed 2 parts Resin : 1 Part Hardener. Extra resin or hardener in the mix will cause soft or uncured spots in your project.
- Mix thoroughly - mix epoxy resin slowly for about 2 minutes making sure to scrape the sides and bottom of the mixing bucket to get all the resin molecules cross linking perfectly. Again, under mixing the epoxy will lead to soft or uncured areas.
- DO NOT LET THE EPOXY EXOTHERM! Exotherm is a chemical reaction that creates heat (and keeps creating more and more heat) when the mixed resin is left to sit in the mixing bucket. Exotherming epoxy will cure in the bucket and prematurely on the board. Avoid exotherm by mixing the resin thoroughly and pour at least 1/2 the mixture on the board to give you essentially twice as much time to glass. Slow hardener has very low exotherm so it's a good choice for beginners.
- Epoxy resin is temperature sensitive. It is designed for use in average room temperature (~77 degrees F). Colder will slow the resin cure time, hotter will increase the resin cure time. A rule of thumb with epoxy resin cure time is an 18 degree F increase in temperature from 77 degrees (let's say ~95 F) will cause the resin to cure 2X faster. Conversely, resin at 59 degrees F will take twice as long to cure.
- Epoxy in cold temperatures (less than 55 degrees F) will start to crystalize or "freeze". This crystalization may occur during transit in the winter time or if the epoxy is left in a cold garage or floor. If your epoxy resin is thick or frozen, simply place the resin bottles in a hot water bath or near a heat source to re-liquify it. You can also microwave the resin (a Greenlight favorite trick) for about 3 seconds per ounce of resin. Never more than 1 minute though.. don't melt the bottle!
Silmar 249B Polyester resin is the standard resin for Polyurethane Foam (PU) surfboards [US Blanks and Millennium Foam]. Polyester resins differ from epoxy as they are hardened by adding a small amount of catalyst (MEKP catalyst) to the resin and mixing it in thoroughly. The amount of MEKP catalyst added to the polyester resin will affect the gel time (working time) and cure time. We recommend using just a small amount of catalyst as you begin glassing surfboards so you have plenty of time to fully saturate the fiberglass cloth and eliminate air bubbles.
Here is a chart for MEKP Catalyst amounts for polyester resin quantities. Please note temperature and humidity will affect the amount of Catalyst you put into the resin.
TINTS AND PIGMENTS
If you plan on using any tint or pigment in your resin, you should mix it in before you put in your Hardener [Epoxy] or MEKP Catalyst [Polyester]. Tints give your glass-job a translucent color, while pigments give an opaque color. You will be surprised that a very small amount of pigment or tint (less than a teaspoon) will give you a very rich color. Be careful, though, because the color will look darker in the mixing bucket than it will look on your board. If you want to make sure you have the right color, spread a little bit of the mixed material on a piece of scrap white surfboard foam (from your off-cuts) and adjust accordingly. When you achieve the desired color you can add in the Hardener or Catalyst and mix it all up.
HOW TO LAMINATE THE BOTTOM OF A SURFBOARD
SATURATING AND WRAPPING THE LAPS
As you work your way with the spreader toward the rails, your next step is to saturate the laps (the fiberglass that is hanging over the rails) and wrap then around the underside of the board. To saturate the laps, use your spreader to “waterfall” the epoxy over the side of the rails. Try to catch the resin in your bucket so you can re-use it to complete the rail-saturation. Hopefully you are wearing your latex gloves, because this is where things start to get messy. You need to saturate all of the glass on the laps, so use your hand on the underside of the glass as support, and use the spreader to spread and saturate the resin on the lap glass. If you find yourself running short on resin, use your spreader to work from the stringer (but no further than the stringer) toward the rail with harder pressure and a vertical angle with the resin spreader. There will probably be excess resin pooling in the center of the board that you can plow over toward the rails to help saturate the laps. This resin will collect on your spreader, and you can just rub it off your spreader on to the dry areas of the laps.
Once the laps are substantially saturated, it’s time to tuck them under the board so they adhere to the deck-side rail. Always start in the middle of the board when you are tucking laps. Work your way toward the nose and when you finish, go back to the middle and work your way toward the tail, being careful not to create wrinkles as you are tucking the laps under. If you cut your v-notches in the nose and tail, you shouldn’t have a problem with wrinkles.
Another thing to watch for while tucking the laps is hanging “strings” of saturated fiberglass. If there are any hanging strings, take your resin spreader and gently pull them off the foam and let them hang. Be careful not to pull the strings too hard and pull a section of glass off the board. If this happens just squeegee it back down. When the resin cures you can snap the strings right off. Small strings can be pushed sideways in line with the lap line to make sanding the lap easier and less change of hitting the foam chasing a single string laying on the deck.
If you did a good job saturating the laps, they should stick well to the deck-side rail. Get down low and double check that the adhesion is good, and that there are no unsaturated areas of glass. You should spend 10 minutes or so making sure the laps are well saturated, adhered to the foam, and free of wrinkles. You also need to try to eliminate any air bubbles that may form in the lap area. This is prone to happen along the sharp edge along the tail, so take extra care to squeeze out these bubbles with your spreader.
Finally, take a good look at the entire lamination and check for any pooling of resin on the flats and air bubbles on the flats and especially the rails and nose/tail areas. The nice thing about epoxy is that it hardens gradually and can be moved around even as it cures. Polyester resin will “kick” and then be very difficult/impossible to move around. (unless it's UV cure polyester resin)
Once you are satisfied with the lamination, leave the board alone, and do some clean up. While it is still wet, Epoxy can be cleaned off of most things (skin, mixing sticks, spreaders, and scissors) with citrus-based soap (Gojo) and water. Polyester resin is cleaned up with Acetone Solvent.
It takes 1-2 hours for the fast-cure epoxy to be ready to flip. Epoxy really likes to cure without a large fluctuation in temperature, so if you are glassing in a garage, it’s a good idea to time your lamination for a period where the outside temperatures won’t change much during the 1-2 hour cure period. If this isn’t possible, you can carefully carry your board inside and allow it to cure in a controlled environment, or just leave it overnight and glass the deck the next day...
CLEANING UP THE LAPS
Your board is ready to flip over once the bottom lamination is no longer sticky to the touch. If you are using Quik Kick epoxy, this could be as quick as a half-hour if you are working in warm (95F) temps. If you are using regular fast hardener, this could be as long as 3-4 hours if you are working in cooler temperatures (50-60F). Once the bottom is no longer tacky, you will need to clean up and flatten the cured laps before you begin laminating the top of the board.
If you are doing a cut-lap, you first need to cut your lap with a razor blade along the tape line and remove all of the masking tape from the deck. This is done by carefully holding a sharp razor blade and cutting right along the tape line on the deck. Try to hold the razor blade as vertically as possible as you cut to avoid making a gouge in the foam. If you hold it vertical while you cut, the cut will be much cleaner. It is best if you can do this “cut lap” before the epoxy fully hardens. It should be cured enough that it is not tacky or gummy, but not so hard that it becomes difficult to cut with the razor blade. Make sure you remove all of the tape while you are cutting with the razor blade, or else it will show up under the top lamination.
Once you are done cutting the lap, you should be left with a nice, clean lap-line along the deck rail. Don’t worry if you aren’t perfect the first time. Like many techniques in surfboard building, cut laps require repetition and practice to perfect.
FLATTENING THE LAPS
One of the keys to a good glass-job is making sure your laps are as clean and flat as possible. To do this, you need to carefully sand away any bumps or wrinkles along the lap line using a hard sanding block or hard FlexPad with medium grit sandpaper (60-80 grit). Try to feather the edge of the lap as flush to the foam as possible, being careful not to sand into the exposed foam. Now is the time to sand away any of those hanging-strands of fiberglass, wrinkles, or bubbles that may have formed during your lamination. The flatter you can make the laps, the better your chance of minimizing “burn throughs” when you are doing your final sanding of the hot coat.
Another technique to flatten the laps is using a hard roller (drywall seam roller or wallpaper roller) or popsicle stick to carefully “mush” the laps into the foam along the lap line. This forms that nice flush seam between lap and foam. This is best done right after you cut the laps while the epoxy is dry, but still pliable. Just make sure you don’t press so hard that you deform the foam along the seam and change the intended shape of the board.
HOW TO LAMINATE THE DECK OF A SURFBOARD
Laminating the deck of the board is essentially the same as laminating the bottom. It is standard to use 2 layers of fiberglass cloth on the deck to strengthen the board from your feet and knees constantly pounding on the deck while surfing. For high performance shortboards it is typical to use 2 layers of 4 oz. E-cloth to save weight. Fish, eggs, and hybrid boards usually get 1 layer 6 oz E-cloth and 1 layer 4 oz. E-cloth on the deck. Longboards normally use 2 layers 6 oz. E-cloth or 7.5 oz. Volan cloth... Extra deck patches can be added to prevent pressure dings for heavier footed surfers.
The first layer of fiberglass layed on the foam is trimmed to the outline shape of the surfboard along the mid-point of the rail line. It does not need to lap around to the bottom, only the 2nd layer needs to have laps extending at least 2 inches below the rail line. Also don’t forget to cut your v-notches at the nose and tail areas. We recommend if using a 6 oz. / 4 oz. glass schedule on the deck to lay the 6 oz. down first and the 4 oz. on top. It is easier to lap the 4 oz. around the rails and uses a bit less resin to fill the weave when hotcoating, making the board just a little lighter...
If you are doing a cutlap, you now need to lay your tape perimeter and mask over the bottom of the board, leaving a similar 1.5-2 inch lap area around the perimeter of the bottom of the board. You are now placing the tape over a cured lamination, which is a bit bumpy, so make sure you push the tape down well to avoid bleeding of resin under the tapeline. This is one reason why it is critical to use high-quality masking tape for your cutlaps. You want to use ¾” wide tape or less, as it conforms to curves better than wider tape. Don’t take a shortcut with cheap masking tape on your lap-line tape, it’s not worth it. You can use cheaper masking tape and masking paper to cover the area inside the lapline.
Once your bottom lap-line is taped and masked off, you follow the exact same procedure for laminating the deck as you did for laminating the bottom.
Since your top lamination has more fiberglass you need to make sure to mix a little bit extra resin for the top, as the thicker layers of fiberglass will absorb more resin. Use 2-4 ounces (depending on how much glass, long or shortboard) more than what you used on the bottom lamination.
FLATTENING BOTTOM LAPS
Once your deck lamination has cured enough to flip, you’ll want to clean up the lap left on the bottom of the board. The key here is to try to smooth out this seam as much as possible using a hard sanding block or sanding disc with medium (60-80) grit sandpaper. If you have a tinted/pigmented cutlap, you need to be careful not to sand too aggressively as you will be sanding away at the color. Really just try to stay on the high-side of the lap and smooth away any big bumps or dried strings of fiberglass that are out of place.
Once you have sufficiently flattened the bottom laps, you will want to wipe down the entire board with some denatured alcohol and a clean rag. This cleans up and prepares the surface of the board for the hot-coat stage.
HOW TO SEAL COAT (HOTCOAT) A SURFBOARD
Sealcoating, or Hot-coating, is the second layer of resin applied to the board which fills in and smooths out all of the bumps from the saturated weave of the fiberglass and seals the board from water getting in.
Sealcoating is the term for coating the board with epoxy resin. Hotcoating is an old term for Polyester resin where glassers add more catalyst to the resin to make it cure faster, which creates heat coming off the board, thus named a "hot coat" (by the way, accelerating the cure of polyester resin makes the resin brittle and weak - but mass produced surfboard brands can be made faster and break easier so you buy more boards!)
Epoxy Sealcoats are done with the same exact epoxy resin you laminated with. Greenlight Marine Grade Epoxy Resin System was designed for high gloss, flat, and bubble free sealcoats that do not require sanding or polishing if done correctly.
Resin Research Quik Kick epoxy resin requires Additive F for the seal coat.
A good sealcoat is really all about good preparation, clean/warm working conditions, and using the right tools and resin for the job. Typically you will seal coat the deck of the board first.
The first thing you need to do, if you haven’t already, is try to make sure the board and air are completely free of dust, debris, fingerprints, and any other potential contaminants. Wiping down the board with a lint free cloth and denatured alcohol followed by a quick wipe with an epoxy sealcoat prep cloth to remove any remaining particles will do a good job of prepping the deck prior to the sealcoat. As far as the air, you want to apply and cure the sealcoat in a controlled space without wind or bugs. You don’t want dust or bugs landing on your resin as it cures (but bugs in the board does give it DIY character!). You also want to have decent lighting for your sealcoat, so you are able to see any dry spots or areas of uneven coverage while you apply the resin.
We start by Sealcoating the deck first...
TAPING THE RAILS
Once the board is cleaned off, you need to tape off the rails with high quality masking tape, preferably 1 ½ inches wide or more, leaving the bottom edge of the tape hanging vertically to guide any excess resin toward the floor. The top edge of the tape should be stuck to the mid-point of the rail around the nose and middle of the rail, and then as it heads toward the tail, the tape should taper down toward the very bottom of the rail. You want to get your sealcoat to cover the entire tail-rail on this deck-side sealcoat, because you will be covering up this area completely when sealcoating the bottom of the board in order to create sharp tail-rails.
Once the board is dust free and taped, it’s time to get everything prepared for your seal coat. Most people sealcoat with a disposable 4” chip brush. Before you mix your resin, you should take some cheap masking tape, sticky side up, and mash your chip brush into the tape. This pulls out any loose bristles in the brush. When you are sealcoating, you want to avoid getting loose bristles (or any other junk) floating around in the resin as you brush it on.
MIXING THE RESIN
Once your board is clean and taped and your brush is plucked, it’s time to mix your seal coat with epoxy. First step is to put on a clean pair of latex gloves. Since you are not putting any more fiberglass on the board, and the goal is to apply a thin, flat coat of resin to encapsulate the board. The rule of thumb for seal coat resin quantity is 3 oz. of mixed material per foot of board length. So for a six foot board, mix 12 oz. epoxy with 6 oz. of hardener, for a total of 18 oz. of mixed material. Seal coats are usually clear resin but you can add pigments or tints in the seal coat mix if you wish but be careful when sanding not to burn through as the color will get uneven by exposing the color underneath. As always, mix the resin slowly but thoroughly for 2 minutes with a clean mixing stick before applying it to the board, taking care to scrape the bottom and sides of the mixing bucket. Make sure to mix slow and do not whip air bubbles into the resin as they may make the seal coat look a little cloudy on painted or pigmented boards.
BRUSHING ON THE SEAL COAT
The key to a good seal coat is to do it QUICKLY and then LEAVE IT ALONE. You have a relatively short window for the epoxy to flow freely and self-level on the board. If you push the epoxy around for too long, it will cure with brush strokes and other uneven bumps. If you lay down a good seal coat with the Greenlight Marine Grade Epoxy Resin System it will be dead flat and glossy with no need to sand it if you don't want to!
To get started pour about half of your seal coat mix down the stringer line of the board, and split the other half a few inches in from the perimeter of the rails. Immediately take your 4” chip brush and “plow” the resin down the stringer line with medium pressure, leaving a thin coat of resin in its wake. Work your way nose-to tail on either side of the stringer with this snowplow method. You are pushing a pile of resin in front of the brush, and leaving a thin, smooth layer behind the brush. Keep working nose to tail outward, until you reach the tape-line on the rails.
Without delay, your next step is to "walk out" or "tip out" the resin from nose to tail with just the weight of the brush dangling between your finger tips, starting at the center and working your way toward the rails. When this is done, double-check all around the deck and rails to make sure you didn’t miss any spots. The sealcoated area should have a shiny, wet, flat surface. Check for any brush bristles, body hair, dirt, or other contaminants and pull them off with tweezers, or the edge of your wet brush now (or never). Lightly brush over the area that you removed contaminants to smooth it out.
Note: You may see or read other instruction which includes "cross stroking" the seal coat from rail to rail before "tipping out". DO NOT DO CROSS STROKE if you want a problem-free seal coat! It is not necessary and only reduces the surface tension of epoxy resin - which causes fish eyes and pin holes.
If you have any areas on the board where the epoxy doesn’t want to stick, this usually means you have oil residue from your hands there. Rub that area with your gloved finger to dissipate the oil, and then lightly brush the area with your brush to smooth it out.
A final area to double check is the rails. Make sure there are no drips forming that will become a nuisance to sand when they harden. Work the rails lightly with your brush to remove any thick or drip areas that form on the rails.
Finally, try to do all of the double-checking/fixing QUICKLY. The entire hot-coat process should take 10 minutes or less. Once you are done put the brush on top of the mixing bucket (you may need it later) and just WALK AWAY. Resist the temptation to play with the resin. Come back in 10 minutes and check for any separations or pinholes that may have appeared when the resin is settling. If you see anything just lightly brush over and walk away... Wash or toss out your gloves and go have a beer. With fast hardener, your board will be ready to flip in 2-3 hours, with Quick Kick, it should be ready to flip in between 45-90 minutes, depending on the temperature.
SEAL COATING THE BOTTOM
Before you seal coat the bottom, you need to pull the tape off the rail from your deck seal coat. Peel it off and make sure you remove any remaining tape pieces carefully with a razor blade. It is easier to do this before the seal coat becomes completely hard, but make sure it isn’t tacky or gummy when you pull the tape. This is also a good time to use a razor blade to scrape off any lumps/drips on the top seal coat that you didn’t catch earlier. When this area is cleaned up, do a final pass with a clean cloth and denatured alcohol to clean off any dust/debris/oil that may have collected on the area you are about to seal coat.
TAPING RAIL AND TAIL DAM
Preparing for your bottom seal coat requires a new tape barrier along the perimeter of the rail to protect the deck from getting unwanted drips. This tape step also gives you the ability to make a “dam” in the tail area to collect resin and help you form the sharp edges that most boards have. Start in the nose area and lay down your tape on the rail just below the old seal coat line. You want to make sure you don’t leave any spots on the rail untouched by a seal coat. If you did your taping correctly on the previous step, your rail along the tail area should already be completely seal coated, so taper your tape up toward the tail, and actually have the top of the tape a few millimeters above the level of the tail area. This will act as the dam to catch and collect resin in this critical area. Finally, make sure your board is as level as possible to promote an evenly distributed flow of the resin when it settles on your board.
LAYING DOWN THE SEAL COAT
Once the rail is taped and board prepped, the process to seal coat the bottom is identical to the top. All of the same rules and techniques apply. Pull off loose bristles on the 4” chip brush, put on clean vinyl gloves, and mix approximately the same amount of resin and hardener as you did for the top. If you find that you made too much, or too little resin on the top hot-coat, adjust your quantities accordingly.
The only difference when seal coating the bottom of the board is you have the dam in the tail that is catching, collecting resin as you seal coat. You want to make sure that there is an even bead of resin settled in around the entire elevated tape area, but not so much resin collecting in this area that it is pooling or overflowing the dam.
Just as in seal coating the deck, double check all of your work for a smooth even coat, brush away any drips, pull out any bristles/hairs, cover any dry spots, and rub-out and refill any separations. Remember to perform this clean-up work quickly and once again, WALK AWAY. Let the resin settle, flatten, and cure on its own.
HOW TO INSTALL FIN PLUGS AND LEASH PLUG AFTER GLASSING A SURFBOARD
FIN BOX INSTALLATION
Some fin systems, such as FCS X2 and single-fin boxes, are installed after your hot-coat has cured. There are also a few quality fin systems, such as FCS Fusion, FCS II, and Futures Style, which are installed directly into the foam prior to the lamination step. We are not going to go into specifics of the installation for each of these systems. Greenlight provides an installation video and complete installation instructions of each of these fin-system on our website .
Regardless of which system you use, you will need some specific jigs and tools for the installation. Greenlight sells the installation kits for all the fin systems.
If installing FACTORY fin plugs or FCS X-2 fin plugs we recommend using Slow Hardener or Resin Research Quick Kick to avoid exotherm when installing fin boxes in warmer temperatures. The heat from fast-curing epoxy has been known to melt EPS foam in fin plug installs because there's about 1/2 of resin per plug curing in a tight space. If using Fast Hardener with FACTORY or X-2 fin plugs we recommend installing the plugs in 2 steps to avoid exotherm. First fill the drilled plug hole about 1/3rd deep with resin, set the plugs in, and wait about 1 hour for the resin to harden. Then mix another batch of resin to "top off" the perimeter of the plug hole.
FCS II, FCS Fusion, and Future Style fin boxes can be installed in EPS foam with any speed hardener as very little resin is required an no threat of exotherm.
If using UV cure polyester resin, you must add catalyst to the resin for finbox and leash plug installs because the sun will not penetrate the fin boxes to cure the resin.
LEASH PLUG INSTALLATION
Installing leash plugs is a fairly simple affair, but you can screw it up if you are not careful. Most leash plugs are installed after the sealcoat has cured. For EPS cores, Greenlight has invented the Vented Leash Plug, which helps to equalize pressure inside/outside the surfboard core due to hot temperatures or pressure changes (airplane holds). If you are making an EPS/Epoxy Board, we highly recommend you install a vented leash plug. It costs a few bucks more than a regular leash plug, but you get some peace of mind that you won’t have overheating/delaminating issues caused by big swings in temperature or pressure.
The Vented Leash Plugs need to be installed with a fairly specific (but still simple) process, so if you go this route, follow the instructional video on the Vented Leash Plug product page. For any leash-plug installation, there are a few tools you need to do the job right:
- Power drill
- Forstner Bit or Holesaw Bit
*Vented leash plugs and FCS leash plugs require a 1 1/8" diameter bit
You can make a drill jig by using your bit to drill through a thin scrap piece of masonite or plywood. Then tape the jig to the board to ensure the bit does not run across the hotcoat before penetrating the lamination and foam.
DRILLING THE HOLE
Put tape around the bit as a visual depth guide so that the bit cuts about 1/16” shallower than your leash plug depth. This will give you something to sand off into a flush, leak-free edge. Tape the drill jig to the board with masking tape at the desired location. You can pulse the trigger of the drill to slowly bore through the fiberglass, making sure to keep it at a 90 degree angle so you don’t distort the hole. Keep a light touch on the drill, because once you get through the fiberglass, the bit is going to cut much faster in the soft foam. Drill with light pressure until the tape depth guide gets near the drill jig. Check the depth with the plug and drill a bit more if needed. Blow any excess junk out of the drilled hole, and now you should have a nice clean hole for the plug install.
INSTALLING THE PLUG
The first thing you should do before mixing your resin for the leash plug is to tape off a little area around the hole on the deck of the board using high-temp masking tape. This masks the board from drips and overflow, so you don’t have to sand them off later. Also, put a strip of high-temp masking tape over the top surface of the leash plug itself. Trim the tape around the circumference of the top of the leash plug, and make sure you have a good seal between the tape and plug to prevent resin from dripping down into the plug.
You only need about an ounce of mixed epoxy for a leash plug install, so we recommend mixing it in very small graduated mixing cups that have small enough increments to make sure you can accurately gauge your 2:1 resin/hardener ratio. After you’ve added the hardener to the resin, a nice touch (but not totally necessary) is to add some opaque pigment to the mix, along with a teaspoon of thickening agent which helps reduce air bubbles. Additive F is not needed for your leash-plug install.
Make sure everything is mixed in thoroughly, then pour the mixed blend into the hole you drilled in the board. Pour enough resin in to fill about 1/3rd of the depth of the hole. Then take your leash plug and carefully press it into the hole. The resin should rise up around the sides of the hole. You want the resin to rise just above the surface of the board, so pour some extra resin in around the sides of the plug until it reaches that level. There may be some settling of the resin, so double check after a few minutes and top off the fill to make sure the resin cures slightly above the surface. You will sand everything flush and remove the tape once you do your final sanding of the glass job.