Surfboard Glassing & Sanding

glass and sand
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When you think of building a surfboard, many people just think about the shaping of it – planers, rasps, and sanding blocks mowing foam.

But, one of the most important parts of the build process is often overlooked – glassing & sanding.

You can shape a perfect surfboard from a foam blank, but without a proper glassing and sanding, it’ll be no good.

This is also where you’ll need to determine your final step and whether you’ll stop with a sanded finish or a gloss finish.

Glassing a Surfboard

Glassing a surfboard is the step that waterproofs and finishes the board. Fiberglass, resin, and any tints, color, and art are added to provide the board with strength, rigidity, and its overall style.

The glassing step influences a board’s final weight as well as resistance to dings and abuse.

For many surfboards – its overall production is handled by a number of people. Someone shapes the blanks and then it goes to the glasser for glassing and sanding. But, if you’re making your own boards, you can glass and sand the surfboard yourself.

Basic materials needed for glassing and sanding a surfboard:

  • Fiberglass Cloth
  • Resin
  • Mixing Cups
  • Mixing sticks
  • Scissors
  • Squeegee/Resin Spreader
  • Masking Tape
  • Chip Brushes
  • Power sander
  • Hard, Medium, and Fine Grit Sanding Pads

Glassing Schedules

The first step in glassing your surfboard is to determine the glassing schedule.

A glass schedule refers to how many layers and what weights of fiberglass cloth will be used on the top and bottom of your surfboard.

Fiberglass rolls for surfboards is typically available in 4oz and 6oz. Some common glassing schedules include:

  • 2 layers of 4oz on the top, 1 layer of 4oz on the bottom
  • 2 layers of 4 oz on the top, 1 layer of 6oz on the bottom
  • 1 layer of 4 oz and 1 layer of 6 oz on top, 1 layer 6 oz on bottom
  • 2 layers of 6 oz on top, 1 layer of 6oz on bottom

Lighter glass schedules are typically used on shortboards, while heavier glass schedules are used for heavier board (longboards, retro shapes, etc.).

The more glass on a board, the heavier and the stronger it will be.

You may also see glassing schedules that use partial layers on the top or bottom. These are extra layers of glass used in areas that have to stand up to the most abuse – fin box, tail area, etc.

How to Glass a Surfboard

Glassing a surfboard is not necessarily difficult, but it is certainly a step that’s prone to errors if you’re not careful in your preparation.

The best way to do a good job on your first few times is to make sure you’ve got all the tools and materials you need, mix enough resin, and move smoothly and cleanly.

How to glass your surfboard:

  • Start with the bottom, and roll out the fiberglass cloth.
  • Cut evenly around the glass so it can wrap the rails.
  • Cut a notch near the nose and tail or any other hard corners where the cloth will need to wrap – this prevents wrinkles.
  • Mix your resin – adding any tints or color pigments you plan to use.
  • Start by pouring resin around the center of the board and following it around the board towards the rails with your spreader.
  • At the rails, saturate the overhanging cloth and wrap it around. You can spread any pooled resin from the center of the board if necessary.
  • Finish tucking the rails all the way around and try to clean up any stray threads or wrinkles.
  • Check the board for any air bubbles or wrinkles – fix if necessary.
    • With Epoxy, you’ll have more time to fix mistakes, once polyester resin kicks, you won’t really be able to fix anything.
  • Allow the bottom to cure.
  • Once the glass is hard, you can flip the board, clean up the laps with a medium grit sanding pad – being careful not to sand into any foam.
  • Repeat the process on the top.
  • Start with the heavier weight cloth first.
  • Mix a little more resin than you did for the bottom since you’ll be using more glass.
  • Allow the top to cure.
  • Clean up any laps, bumbs, and imperfections.
  • Remove dust and debris with air, denatured alcohol, and a clean rag.
  • Glass on fins and leash loop at this stage.
  • Get ready for the hot coat.

Surfboard Hot Coat

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The hot coat proceeds pretty similarly to the laminating layers, but should be a bit easier.

The purpose of the hot coat is to fill in any remaining gaps and bumps in the fiberglass weave. This prevents any water from seeping into the cloth overtime and gives you a nice smooth finish.

To hot coat your surfboard:

  • Start with the top and use masking tape to tape around the rails – starting about midway on the rail.
  • Mix your resin.
  • Start by pouring the resin down the middle of the board and pushing it with your chip brush.
  • Continue towards the rails.
  • Follow the rails at the tape line with your brush.
  • The key is to work quickly so that there’s an even layer of resin that can level itself out over the board.
  • Remove the tape before the resin cures completely.
  • Allow the top hot coat to fully cure.
  • Flip the board, tape the rails, and repeat for the bottom.

Sanding a Surfboard

Sanding is another important step in making your surfboard. Don’t get lazy here!

Sanding your hot coat is done by starting with a medium grit sandpaper and moving up to finer grits.

You can use a power sander or hand sanding here or a combination of the two. A power sanding will be faster and more consistent, but you may want to use your hands for more sensitive or tight areas of the board.

The goal of sanding is to smooth out the hot coat to get flat, even surfaces throughout the board. Try to keep the sander level and moving to avoid creating any gouges. Go slow and apply light pressure.

After moving around the board and up through grits, inspect the top and bottom for any burn throughs.

Burn throughs are areas where the fiberglass weave has been exposed. You’ll need to apply a little resin to these areas. If you have a lot of them, you may want to apply a second hot coat.

Once burn throughs are dealt with, move up to your finish grits.

From here, you can add any painted art or pinlines your were planning on and apply a gloss and poish coat.

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