This article published with the permission of Dave Yost, Board and Sail Magazine.
Volume 3, Issue 4, Number 10 (1982)


Glass That Board!  Con Colburn Shows You How

The difficulty in writing a "how-to" article is trying to figure out what the reader already knows. If you've had some experience with glassing  this information might seem elementary. On the other hand if terms like tape-off, hot coat,  and glossing arouse confusion you need all the help you can get. Talks to a few people who know something about it before you actually try anything.
     I have to assume that most of you know pretty much what to do but that you've never actually done it. It that is the case, I urge you to familiarize yourself with the materials and techniques by experimenting on foam and fiberglass scraps. Once the glassing process  begins, you're committed. Testing your expertise on a board could be an expensive lesson.

Glassing involves three basic steps:
1. Laminating.
2. Sanding.
3. Glossing.
     Color, depending on what you want, can be added during the laminating and/or glossing steps Any color used on the board must first be determined to be compatible with polyester resin. Test it on scraps first.
     Fin boxes, some mast steps and centerboard wells are installed prior to sanding. Other mast steps and centerboard wells are installed after glossing! Dry deck (non-skid surface of fiberglass cloth squeegeed almost dry of resin) is applied prior to or after glossing.
     Allow several days to do the job. It may not lock like that much work but you can only do one side of your board

(deck or bottom) at a time and each coat of resin has to cure several hours per coat before you proceed. In other words, plan to spend as much time waiting as you do working.
The tools and materials (listed below) should be available at your local hardware and marine supply stores, Even it they don't have everything they should be able to direct you to other sources. A walk through a custom sailboard or surfboard factory, if you can arrange it, will give you some good ideas for setting up your work area. The most important thing is that it is well-ventilated and totally shaded


  • Tools and Supplies Needed:
  • 1" wide masking tape.
  • Masking paper.
  • Scissors.
  • Single edged razor blades.
  • Sureform file.
  • Tape measure.
  • Drop cloth.
  • Respirator mask for protection from fumes & dust.
  • Particle mask* (optional)
  • Rubber gloves.
  • Disposable unwaxed containers (1 and 2 quart).
  • 4" Natural bristle brush (for laminating & hot coat).
  • 3" Natural bristle brush (for glossing).
  • Rubber squeegee.
  • Polyester laminating resin.**
  • Polyester hot coat or sanding resin.**
  • Polyester gloss or finish resin.**
  • Acetone (for cleanup).
  • Sandpaper - 60 & 120 grit.
  • Wet and dry sandpaper - 320 & 600 grit (optional).
  • Rub out compound.

Article by Con Colburn
Demonstrations by Nestor Otazu
Illustrations by Stephanie Akers
Photography by Chan Bush

*  A particle mask will not protect you from fumes, but it is much more comfortable than a respirator mask and you might prefer to use it while sanding.
** Follow the manufacturer's instructions regarding the amount of catalyst to add to all resins. Be sure to test all the proportions before mixing a full batch


Cleaning your board is something you'll have to do before each step. Because I don't want to bore you (or me), I'll explain it just once. To remove dust particles and foam debris use a clean bristle brush or air hose. To remove fingerprints or grease, use 120 grit sandpaper. Do not use paper towels or rags. They will leave lint particles that can only be removed by sanding. Believe me, you'll be doing plenty of that as it is.


Large or complex color areas like fading tones, illustrations, geometrics, etc can be applied to the foam blank before laminating. After cleaning the blank cover the areas to remain unpainted with paper, defining the edge and securing the paper with masking tape. You can use water soluble acrylics with an airbrush or small spray gun. This takes some skill. If you're not an artist you might want to consider finding one. Allow 24 hours after the color has been applied before continuing on to the next step.



Preparation for laminating. Your shaped foam blank, painted or not, requires a thorough cleaning just prior to lamination. Any extraneous material (you can't always see it) will hinder the resin penetration and weaken the fiberglass adhesion.
     As I mentioned before' glassing is done one side at a time (deck or bottom). To protect the side of the board you are not working on from drippy excess resin, you'll have to do what's called taping-off.
     Attach strips of paper about 4" wide around the perimeter of the board with masking tape, 2" to 3" in from the rail on the side opposite the one you are going to laminate. Follow the contour of the board as closely as possible with the tape because later this will be your guide for trimming the excess fiberglass.

     The next step involves working with fiberglass. If you ve never worked with the stuff before, let me warn you, it's pretty nasty. Fiberglass is just that, glass fibers. If these fibers get into your skin (which they do if you're not careful) you'll burn and itch and be miserable for hours.
     The best precaution is to expose as little of your skin as possible. Wear long pants and a long-sleeved high neck shirt. Handle the fiberglass only as necessary.

Laying out the cloth. Lay a piece of the cloth over the entire length of the board. The piece should be more than large enough to cover the entire board surface plus wrap around the rails and overlap the tape on all sides. If it isn't, you have three choices: Get a larger piece of cloth, move the tape out closer to the rails, or settle for a less than satisfactory job.


     After you've determined that the cloth is the correct size, smooth out all the creases and wrinkles until it drapes smoothly off the edges.

     Finally, trim it to the contour of the board, leaving just enough to still overlap the tape. Too much excess cloth could cause drooping problems later.


Nose and Tail. In tightly contoured areas of the board, such as the nose or tail (depending on the shape of your board), you'll have to cut wedge shaped pieces out of the cloth to get it to hang straight and wrap around to the underside without wrinkling or puckering. It's okay that the edges overlap as long as the fit is smooth and flush to the board and there are no wrinkles, pleats or folds.


     You cannot be too meticulous about this because any wrinkles that appear in the cloth now will be laminated in forever. It not only looks messy, but these laminated wrinkles become air bubbles that will be ruptured during sanding, weakening the board.



Laminating. This is the messy part. Use a drop cloth under your board and wear the oldest, grungiest clothes and shoes you own, because you'll never be able to wear them for anything else again. Rubber gloves and a respirator mask are also important.
     If you want solid color covering the entire side of the board, mix pigment right into your laminating resin (go easy, a little at a time, testing it on scraps along the way). Otherwise the resin is clear.
     Pour the resin on your board in small amounts, spreading it evenly over the entire surface of the board with a brush or squeegee. Work from the center to the edge, stroking evenly back and forth, to keep the cloth in position.


When the cloth is thoroughly wetted, remove the excess resin with a squeegee. Work from the center of the board out to an edge until you've finished that half. Then do the other half, again from the center to the edge. See the diagram on the next page to get a better idea of how you do the squeegeeing



     As you're working out from the center, also work nose-to-tail. Then alternate, tail-to-nose. keep a constant eye for wrinkles, air bubbles, creases, or slippage in the cloth. If you see it, correct it immediately.

     As you reach the rails, tilt the squeegee to direct the excess resin off the edge and hopefully onto the drop cloth. When the board surface looks less shiny and the texture of the fiberglass becomes visible, the resin content is just about right. Too dry can cause air voids which will weaken the fiberglass adhesion.


     Laminate the perimeter last, wrapping the cloth smoothly around the rails so it lays flat and snug over the tape.
     After this is finished, let the board sit undisturbed until the resin has reached the gel stage (sticky to the touch but hard enough so it doesn't move). The time will vary according manufacturer and age of resin, amount of catalyst used, and temperature and humidity in your work area. You'll just have to keep checking because it might take ten minutes, or two hours. However long it takes, when the resin has gelled, carefully turn the board over so the taped side is up.


     Use a single edged razor blade or matt knife and carefully slice the fiberglass where it meets the tape. In the areas where the board is flat, you'll be cutting down on the foam. Be careful to apply only enough pressure to cut the fiberglass.

     Remove the tape and with it comes the paper, the excess glass, and resin drips. This is where your taping makes a difference. If your fiberglass edge is a clean line that parallels the contour of the board, give yourself a pat on the back. You've done a good job. If the edge is a bit jagged and the line wobbly, better luck next time ...it's too late to correct it now.


After the tape is removed, turn the board back over. When the resin cures (totally hard and dry), use a Sureform blade or metal file to smooth the fiberglass edge Look for burrs or sharp fibers popping up. Remove the shavings with a brush or air hose.


Laminating the bottom.
To make life simple, I'm going to assume that you've laminated the top, or deck side, first. Now you'll have to do the same thing on the bottom, following the same procedure; clean, tape-off (see the diagram above), fit and trim the glass cloth, laminate, etc.
     You'll notice that there is a double layer of fiberglass on the rails. This will provide additional strength on the most vulnerable part of the board.
     Some of you might want multiple layers of fiberglass on the entire board surface. The procedure is the same for additional layers as it is for the first layer, except that you cut, fit and laminate multiple layers all at the same time. i.e. you don't re-tape, and you do all the layers on one side before you turn the board over and do the other side. Of course, each layer must cure before the next layer is put on.

Before you get too carried away with multiple layers, remember that each layer adds strength and weight.


Sanding . . . then the "hot-coat."

In order to protect the fiberglass from sanding, it's necessary to add another coat of resin called the sanding or hot-coat. Tape off the board just like you did in the laminating step, except this time apply the tape along the center of the edge. Refer to the "Hot Coat" diagram above.


Distribute the resin evenly over the board with a brush. Pay particular attention to concave or flat areas in the board where the resin tends to build up. The object is to have a smooth, even coating over the entire board surface. After you have done this, smooth the application with nose-to-tail strokes for the full length of the board, starting in the center, working toward the edge, one-half of the board at a time.

Overlap  strokes slightly and  alternating direction, nose-to-tail, then tail-to-nose. Do not lift the brush mid-stroke. Begin the stroke at the nose or tail edge and end it by going off the opposite edge, tail or nose. Stopping and starting could cause globbing. This procedure may have to be repeated more than once


Taping-off for the bottom hot coat. Again, just like in the laminating step, the tape is removed when the resin has gelled. The bottom coat is applied after the deck coat has cured. When you're taping off for the bottom coat, tape on and flush to the edge of the cured deck coat so that when the bottom coat is applied, it will butt up to the edge of the deck coat

After the sanding coat has cured on both sides and prior to sanding is when you install fin boxes, tie-down deck inserts, slot-type mast steps, and molded fiberglass centerboard wells. Round mast steps and the two-piece plastic centerboard wells are installed after the board is finished as are foot strap inserts. You can also use a fin as a centerboard.


Fin Boxes. To install fin boxes, measure and mark the positions on the board. Remove sections approximately  1/16" larger than  the overall dimensions of the fin boxes.


For each box you're installing, you'll need a patch of fiberglass cloth large enough to line the channel with excess sticking out on all sides. Test the fit of the box in the lined channel before you mix your resin.


This will be a lot easier and more precise if you can get your hands on a router. Remove the loosened foam particles.


Masking the board. Cover the board with paper leaving only the channels exposed. Tape down flush to the edge of the channel. Also, tape the open side of the fin box.


Mix your resin and fill each channel about half way.


Cover the channel with the glass patch and push it down into the channel with the fin box (tape side up) allowing the resin to gush up all around.

Continue pushing the box in until it sticks up about 1/16" from the deck, using a rocking motion. Just like the other steps, the tape comes off when the resin has gel led. Don't worry if it still looks messy. It will all come off when you sand.

The procedure for the deck insert and slot-type mast step is similar. Use the mast step foot ("T") or a wooden plug cut to the shape to mold the fiberglass. Coat with a release agent such as paraffin or car wax, or cover with a polyethylene bag. You'll have to devise a way to grip the plug or mast step foot so you can remove it when the resin cures.


     The molded fiberglass centerboard well is an ambitious project if you really think you want it. The fin box version is much easier though and with the proper fin, should, in most cases, provide the stability you need. Besides, most custom sailboards don't need centerboards unless they're used for serious racing. You can always install a centerboard after the board is finished. If you do install one and decide later than you don't need it, you can plug with wood to stop water from rushing up.

Sanding can be done manually with a block or mechanically with a rotating disc-type power sander. Make sure it's the kind with a full sanding surface; no nuts in the center of the sanding pad.

con26The power sander makes life a lot easier, but if you've  never used one, watch out ...it's like the first time you drive a car with power brakes and steering. You've really got to lighten your touch. It's also important to keep the pad at the proper angle. One slip of the wrist and you've got a nasty gouge  in  the board.

     The object of sanding is to remove the lumps, bumps, seams, and edges until you have a smooth finish. You are primarily sanding the hot coat. If you sand beyond that you will rupture the fiberglass and weaken the whole structure of the board.
     The only exception is on the rails where the fiberglass layers overlap. Here you want to taper the top layer just enough to blend the edge into the second layer.
     Sand the board first with 60 grit sandpaper. Clean off the dust and sand the entire board again with 120 grit sandpaper. The board should appear satin -smooth after the dust is removed. There shouldn't be any shiny spots.

Before Glossing
If you're interested in applying intricate designs, pinstripes, curlicues, lettering, or any kind of fine, detailed brushwork, do it now. Let this work dry before continuing.
     Dry deck can be applied before glossing if you want a non-slip deck surface. You can also do it later, if you want.
     The procedure is similar to laminating except you are covering a smaller area and you'll be squeegeeing out more of the resin. Tape off the area where you want the dry deck, covering the remaining area with paper. The inner edge of the tape will be your trim guide and represents the eventual edge of the dry deck

   Smooth the fiberglass over the exposed deck area, trimming it so it just overlaps the tape. Apply the laminating resin with a squeegee using short, even, back-and-forth strokes to keep the cloth in position. Continue until the resin content is minimal. When the resin gels, trim the cloth at the tape, remove the tape and paper, and allow the resin to totally cure.

     Tape off the board the same way you did for the hot coat. If you have a dry deck patch, cover it, taping the paper down around the edge of the patch.


.  Apply the finish or glass resin using the same technique you used in the hot coat step. For best results, use a new brush.
     Tape off and repeat for the bottom, just like you did for the hot-coat.

Final Sanding and Polishing
After the gloss coat has cured on both sides, polish or rub out the board by hand or with a buffing machine. Your taste will determine how much effort


you exert in this step. If you want a showroom shine, start with 320 grit wet-and-dry sandpaper with water over the entire board. Follow with 600 grit wet-and-dry sandpaper with water.

 Finish it off by buffing with a rubout compound (the grade will depend upon whether or not you're doing it by hand or machine). You can use the  same stuff you'd use for an automotive paint job.


Con Colburn is truly one of the "old timers" of board-sailing; he built the first windsurfers for Jim Drake and Hoyle Schweitzer. With 25 years of experience with fiberglass surfboards and sailboards, Con is our resident expert on custom sailboard construction.

Appearing in the photos is Con's head glasser and factory supervisor Nestor Otazu. Nestor has been with Con for almost eighteen years.

     Your board will reflect the time, attention, and care you put in this job. A beautiful board is admired by all but glassing is more than a matter of aesthetics. The job you do will affect your board's performance in terms of strength, weight, and balance.
     As long as you are going to take the time to do the job at all, you might as well take the extra time to do it right.

Author's Postscript
     I've been doing fiberglass lamination for twenty-five years, so there are a lot of things about the process that I do without thinking about them. The steps have been simplified and you may find yourself with questions that I haven't answered. This is why it is so important for you to experiment with scraps. When you learn through your own experience about the characteristics of the materials, you'll have better judgment when decisions are called for.
     Some of you might be wondering why I haven't mentioned some of the more sophisticated board materials such as Kevlar, graphite (carbon fiber cloth), and epoxy and isothalic resins. Although these materials are often superior (they usually last longer and are stronger with less weight), they are also more expensive, more hazardous (toxic and flammable), and difficult to work with. If you're beginning, stick with the polyester/fiberglass. If you're ready for the more advanced materials, hang in there; I'll be covering them in future articles in
Board & Sail.-Con Colburn


This article is Copyrighted to Board and Sail Magazine (1982) and printed here with the permission of Dave Yost.