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Strings Centerboard Adjustment

By Greg Bull

Strings, as unique as the man who designed it, continues to be a work in progress for us at GBI. In Jan Gougeon’s first year of sailing Strings, he noticed the boat felt sticky at times. He thought it might be the centerboards jibing too much and the solution might be locking them straight. The center boards work as jibing boards by having two high spots on each side of a centerboard head creating the pivot point to get the boards to change angle, or jibe. The actual pressure from the boat going through the water and wanting to slide sideways gets the boards to jibe. Continue reading

The decorative plaque than hangs on Julie's office wall, after repairs.

When the Cat’s Away

By Julie Van Mullekom

Like a lot of people, when I’m at work I like to keep busy. It makes me feel good about myself and the bonus is that the day just flies on by. Having said that, it’s also nice to escape from the walls of my office now and then and head out into the shop to see what the guys are working on. For some reason this gravitational pull I feel from the shop occurs more when my boss is away. We can just call it an unexplained phenomenon and leave it at that. During some of my excursions to the shop rather than just observing they let me help them with the projects they’re working on, which I Continue reading

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Light as a Feather

By Tom Pawlak

Last Father’s Day I received a new light and sleek bicycle from my family. It is by far the nicest bike I’ve ever owned. I enjoy riding it to work in the spring, summer and fall. Because it is so nice, I decided I didn’t want to bolt on the aluminum bracket used previously over the back wheel on my old bike. The bracket had served multiple purposes. It supported my travel bag and it acted as a fender to keep road water off my back while riding. I decided I would ride with a backpack instead to reduce bulkiness and thought it would be nice to make a lightweight fender that I could snap on for those rainy days. That would allow me to remove it for longer trips and on nice weather days. Continue reading

Close up of the gas-powered vehicle.

588 Miles Per Gallon

By The Students of Goshen High School’s Engineering Design & Development Class

We are a group of students from Goshen High School in northern Indiana and for the past six years we’ve had the opportunity to design, build and test high mileage prototype vehicles in a class called Engineering Design and Development. Year to year this program serves about 30 students aged 15 to 18. We begin with little to no background in an automotive or engineering technology background, and through the course of this program learn many new skills. Continue reading

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Drumming In Circles

By Tom Pawlak

In 1991, during testimony before the United States Senate Special Committee on Aging, Grateful Dead drummer Mickey Hart stated:

”Typically, people gather to drum in drum ‘circles’ with others from the surrounding community. The drum circle offers equality because there is no head or tail. It includes people of all ages. The main objective is to share rhythm and get in tune with each other and themselves. To form a group consciousness. To entrain and resonate. By entrainment, I mean that a new voice, a collective voice, emerges from the group as they drum together.”

I recently joined a group of mostly old guys who meet a couple of weekends a year to experience nature and the great outdoors. We all come from a diverse cut in society yet we all get along so well. One reason is we Continue reading

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Controlling Exotherm

By Mike Barnard

 

When mixing larger batches of resin and hardener, pot life— or the amount of time that elapses before the epoxy hardens in the container—is very important. You need to estimate how much mixed epoxy you will use in a certain amount of time. Variables that affect this calculation include temperature, volume, surface area, hardener speed, the insulating quality of the substrate the epoxy is exposed to, and any fillers used.

Generally, for every 18°F increase in temperature, pot life is cut in half (see Hardener Selection Guide). This is useful for a approximation. However, the data we provide pot life is based on 100 grams or four pump strokes each of resin and hardener using our 300 Mini Pumps. If you are using a larger amount of resin, or simply a different size cup, the length of pot life can vary. To increase the pot life of a cup of mixed epoxy, spread it over a larger surface area, work in a cooler environment, or mix multiple, smaller batches as you go.

The chemical reaction between resin and hardener as epoxy cures will generate heat. When this heat cannot escape, it builds up, causing the epoxy to cure faster because epoxy cures faster at higher temperatures. Curing faster because of the heat, the epoxy generates even more heat, even faster. This snowball effect is why a gallon of epoxy mixed all at once will turn solid in about 5 minutes. The resulting massive build up of heat can cause the cured epoxy to crack because of the temperature differential between the top and bottom of the container.

This uncontrolled heat build-up is called uncontrolled exotherm. Epoxy heating out of control can foam, smoke, give off dangerous vapors and generate enough heat to melt its container or cause nearby items to catch fire. It’s crucial to understand epoxy’s exothermic curing reaction and follow the instructions in this article very closely if you are planning to fill a large area with thick casting of epoxy.

The mechanism that causes heat buildup when epoxy is contained in a thick mass is also why epoxy takes longer to cure when it is applied in a thin film. The film does not build heat, so the temperature through the thickness of the epoxy film is pretty close to the ambient temperature.

Occasionally customers are interested in filling a void by pouring a pouring large mass of epoxy all at once. This can be very dangerous because it will generate a lot of heat, and can lead to poor results because of the snowball effect mentioned earlier. Some faster epoxy systems, blended in a mass large enough, can reach temperatures over 400°F: hot enough to melt or at least soften plastic. This level of heat could also damage whatever the epoxy is poured into. High temperature can also result in severe cracking throughout the thickness of cured epoxy; so much so that if the epoxy were not supported, it could fall away. Shrinkage can introduce significant stresses into the structure the epoxy is attached to. Customers casting large epoxy sections into boat bilges have reported hearing loud snapping or cracking sounds after the epoxy cured.

Pouring a large mass of epoxy is a very difficult to do safely and effectively. Temperature, volume of epoxy, depth of the epoxy, and amount of heat sink in contact with the epoxy are all major variables in this application.

 


 

Proven methods for controlling exotherm:

If you do want to pour or cast a large volume of epoxy, here are several proven methods for minimizing heat buildup which we’ve developed over the years.

Pour the epoxy in timed, multiple batches.

Timing is important when doing multiple pours. Ideally, you want to wait for mild exotherm to peak and begin falling before mixing a new batch and pouring. Waiting too long could cause an insufficient bond between the two pours. Not waiting long enough can cause too much heat to build and cracks to propagate.

Choose 209 Extra Slow Hardener or G/flex

Slower cure allows a deeper pour before too much heat buildup occurs. For this reason, we recommend to use our slowest systems when casting larger amounts of epoxy: 105 Resin with 209 Extra Slow Hardener, or G/flex.

Work at cooler temperatures.

Cooler shop temperatures and cooling the epoxy itself will both work to your advantage in slowing cure and controlling epoxy’s exothermic reaction. A deeper pour can be accomplished with less heat buildup by starting with cooled epoxy and a cool substrate until the epoxy initially cures to a soft solid. Then you could expose it to room temp or higher to complete the cure.

Use heat sinks.

A heat sink is any object that can absorb lot of heat. If you are applying the epoxy into or over a heavy metal object, it will absorb much more heat than a lower-density object.

High-density fillers can also act as a heat sink, reducing exotherm by absorbing more heat than a low-density filler, and taking up more volume. This leaves less room for mixed resin and hardener, reducing the resulting heat reaction.

If the wrong epoxy/filler combination is used for a certain cure temperature, the epoxy may generate enough heat to smolder and burn. Adding more low-density filler will certainly reduce the amount of epoxy in a given volume, but the filler will act as an insulator instead of a heat sink. This effect is shown in the testing that we did.

Graph 1

Graph 1 shows the temperature of about 4 fluid ounces (4 pump strokes with 300 Mini Pumps) of epoxy over time. The epoxy is contained in a small cup with a plastic top covering so little heat can escape. As is typical, the slower epoxy systems release less heat and take longer to reach that temperature. Keep in mind that the epoxy is not necessarily fully cured when the line ends. Sure, this is nearly the highest temperature it will reach, and it has started to cool, but as the next graph demonstrates, it may not be hot enough to fully cure the epoxy that quickly.

Graph 2

Graph 2 shows how different additives will affect the peak temperature and the time it takes to get to the peak temperature. For this testing we used the 105 Resin/209 Extra Slow Hardener because it is more readily available at retail stores in larger quantities than G/flex. The various fillers produce effect similar to what in the graph when used with G/flex, the lowest exotherming product from WEST SYSTEM.

 

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Flying Dutchman Restoration

By Douglas Heckrotte

Surcease is a late ’50s International Flying Dutchman Class sailboat. The Mahogany hull was cold-molded in Holland and imported by Paul Rimoldi of Miami Florida. Mr Rimoldi made everything else, including many pieces of hardware. He raced the boat on Biscayne Bay into the ’60s and sailed it for many years. He rebuilt the boat in the late ’80s but died before he finished. We bought the boat in August 1992 from his widow and sailed it for almost a season before we discovered that the hull was in very poor condition; the Urea-resin glue between the veneers had begun to turn to dust. We stored the boat and bought another Flying Dutchman.

I began restoring the boat in 2001, working summer evenings when it was not too beastly hot. I built a rollover cradle which would carry the hull at any angle for ease of working. I stripped off the outer layer of veneer. I removed all of the screws, most of which had corroded to dust, and replaced them with mahogany dowels set in WEST SYSTEM epoxy. I cut out all delaminated areas in as many as three of the remaining four thicknesses of veneer and epoxied in new mahogany veneer. I steam-bent and installed a new White Oak stem. I re-veneered the hull with 1/16” flat-cut mahogany and coated it in epoxy.

Next, I rolled the boat right-side up and stripped the deck, all later repairs to the hull, and the finish. I added new mahogany stringers matching the originals. I laminated new frames in place. I also laminated and installed a new thwart and any small pieces of plywood required for the boat. I also replaced the centerboard trunk cap, all the deck supports, and repaired the original deck frame.

After varnishing the entire interior I installed a new deck of 1/4″ Khaya marine plywood. I reinstalled the original spray shield and coamings, and made new rubrails of wood from a 1963 Hinckley B40 mast.

After varnishing the topsides, I reinstalled most of the original hardware and made new stainless steel hardware in ’50s style where I felt it appropriate. I rolled the boat upside down and made new rubbing strips from fiberglass rod; the Flying Dutchman class requires the shape of the old-style bronze strips on the hull but I did not want screw holes. The new strips are painted gold and were varnished along with the rest of the hull. I made three new kick-up rudders and centerboards using some old parts, but laminated new mahogany plywood cheeks and made new stainless steel hardware. I replaced the running rigging.

We sailed Surcease for the first time in 19 years in August 2012.

We showed and sailed the boat at the Chesapeake Bay Maritime Museum’s annual Mid-Atlantic Small Boat Festival in October of 2013. They awarded her a First Place ribbon in her class for the race. Of about 70 boats, only a wooden Thistle was really in her class; we were first by a very large margin. They also awarded Surcease a First Place ribbon for her restoration.

There are several of us Flying Dutchman sailors in the mid-Atlantic area who refer to ourselves as “Gouge Brothers” (as contrasted with the Blues Brothers)

I have coated several wooden countertops and one antique heart pine bathroom floor in WEST SYSTEM Epoxy and urethane. The shower door and frame are made of cedar coated in epoxy and painted.

We also own a 1970 LeComte North East 38 and much of the work I have done to her over the last decade involves WEST SYSTEM Epoxy as well.

 

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Vacuum Bagging a Skim Board at MITES Competition

By: Ben Gougeon and Don Gutzmer

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For the past couple of years Gougeon Brothers Inc. has been involved with the Michigan Industrial and Technology Education Society (MITES). This non-profit organization consists of over 600 members involving both high school teachers and students who believe in the power of hands-on learning. The students build a project throughout the year and compete in the MITES annual regional, state and national competition.

Ben Gougeon and I were invited to participate at this year’s MITES state competition held at Saginaw Valley State University. We demonstrated one of the processes in manufacturing composites, vacuum bagging. We were excited to participate and decided it would be fun to show the students how to build a carbon fiber skim board with WEST SYSTEM Epoxy 105 Resin and 207 Special Clear Hardener by vacuum bagging a sandwich composite.

Here are the steps we used to build the carbon fiber skim board:

First we needed a mold surface to lay the board on. We used ¼” plywood and glued on a sheet of 1/16” thick G-10.

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Next, we used another piece of ¼” plywood with weights to evenly distribute enough pressure to make good contact between the G-10 and plywood.

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Skim boards have a little rocker to make them perform better, so in order to get this we glued a 1” strip of wood on the bottom center of the mold to make it easy to clamp it on a work bench. The ends were propped with 2” angle iron to get the desired 1” rocker into the board.

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5 coats of Partall Paste Wax #2 were applied to the mold surface to provide an adequate release agent. Before applying epoxy we put the 883 Vacuum Bag Sealant around the perimeter of the mold to be sure it would stick well and not risk applying it later when surfaces may be contaminated with epoxy.

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Our core was ½” balsa that was 56” long by 20” wide, and we used a batten to draw a fair curve. We cut the first side and used the excess pattern to make it symmetrical.

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We used one layer of 5.8 oz. 0-90 plain weave carbon fiber cloth on each side of the balsa core. Before applying epoxy we laid the dry fabric down on the mold surface to straighten the fiber bundles. An 808 Plastic Spreader was used at a low angle to apply the epoxy. We decided it would be nice to finish off the edge of the board with a pre-made strip of G/flex-650 and 30% finely ground rubber (¼” wide X ½” thick). We wanted to take advantage of the toughened chemistry of G/flex to have an edge that would hold up. The G/flex strips were glued on during the bagging process.

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One layer of 879 Release Fabric was applied over the wet epoxy. The release fabric is a finely woven nylon fabric treated with a release agent. This fabric peels away easily and leaves a smooth textured surface that is ready for bonding. After the release fabric, a perforated film was used to control the amount of epoxy in the laminate. Excess epoxy bleeds through the release fabric and gets absorbed in the 2 layers of 881 Breather Fabric (polyester blanket)we’d also applied. The Breather Fabric provides air passage within the bag while absorbing excess epoxy. Removing excess epoxy improves the strength-to-weight ratio of the finished cored composite. We then applied our 882 Vacuum Bag Film to complete the bagging process.

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The bag was pulled down to 25 inches of mercury (12.3 psi) until the epoxy gelled.

To provide a smooth waterproof coating we applied multiple thin coats of 105/207. For the finishing touch, the traction pad was attached. The board turned out pretty nice and is ready for the beach.

 

 

502 Black Pigment

On January 1st, 2015 we will begin selling a new WEST SYSTEM Epoxy pigment. We already have the 501 White Pigment and the 503 Gray Pigment, so it seems right to introduce our new 502 Black Pigment. Just like the 501 and the 503, it alters the color of the epoxy mixture without affecting the cured physical properties. Similarly, the maximum acceptable loading is 3%. This is great for hiding a surface with a single coat of black epoxy. Adding more pigment will increase the opacity, but can skew the mix ratio because there is epoxy resin in the pigment.

Here are a couple projects that can be completed with 502 Black Pigment:

A great application for this pigment is to fill imperfections in wood. Rather than try to hide the imperfections, this would accentuate them and draw the eye to them. It makes for a really nice rustic accent. A great example of this is found in the last Epoxyworks issue where Tom Pawlak filled a crack in a goblet with black pigmented G/flex.

Another example of this is when there are knotholes in wood that need to be filled. This is probably most common in wood flooring applications. Customers have done this with our 423 Graphite Powder, and the result with our 502 Black Pigment would be similar.

Another great project for the 502 Black Pigment is to create a border for a table. I used this method on my coffee table at home. I wanted a nice sharp line of black tinted epoxy around the edge of the table, so I put masking tape directly on the wood and applied the pigmented epoxy half over the taped line so it would be a sharp line. When I did this, the epoxy penetrated into the wood a little ways and was soaked up by the wood under the tape. This created a very uneven, jagged line that was unsightly. A beginner’s mistake.

To solve this, I coated the entire table top with 105/207, let it cure, sanded, re-taped over the cured epoxy, and applied another batch of the black pigmented epoxy around the edges. This same process could be used when filling knotholes or drilled holes with black epoxy to prevent the black color from seeping into the surrounding wood grain. Recycled barn lumber is often used in this manner to give it an earthier look. As you can see, the end result turned out great and I learned a valuable lesson.

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Smiles All Around

By Mike Barnard

The keel to hull joint on sailboats with lead keels undergo some very high loads, but the outer skin of the keel doesn’t. Instead, whenever the sailboat tacks, the fiberglass skin experiences more movement than anything. This causes a crack along the leading edge of the keel that is so common on Catalina sailboats that owners of these boats refer this damage as the “Catalina Smile.: Of course this problem is found on other brands of sailboats too.

Many try to fix this crack by fiberglassing over it, and it seems to work well… for about a year. Over a fairly short amount of time, the crack comes back because there is so much flexing that the repair laminate cracks and breaks. Instead, this repair should be done with a structural, yet flexible, epoxy: G/flex 655.

In the years since G/flex was introduced, we have had many customers (and employees) inquire about using it in this application. Year after year we recommend it, and year after year more sailboats are repaired like this. Several customers have our method and been happy with the results. None of these repairs have had to be been redone.

Here is how we recommend fixing the Catalina Smile:

Open up the joint ½” wide and ¼” deep with a Dremel tool. Once the crack is cleaned and widened, dispense G/flex 655 Resin and Hardener in equal lines on a plastic sheet (or 1.2:1 by weight) and mix by folding it over itself. Then begin applying it into the crack. The pot life of G/flex is 45 minutes, so unless a huge batch is mixed, there should be enough time to dispense it, although mixing multiple batches would give even more time. This combination has 32% elongation before breaking which helps to prevent cracks from reappearing on the joint. It can then be wet-sanded, dried and painted for a lasting repair.