See full version: Epoxy Versus Polyester Resin for Fiberglass Boat Repair Projects
In our initial point-load testing of a wide range of FRP sandwich samples, we found that by increasing the laminate skin thickness, we lessened the damage caused by the controlled drop test. Going from one to two layers of 10-ounce cloth on each side of the core was enough to show a significant decrease in the damage caused by the controlled impact. [links]
This symbiotic partnership between reinforcement fibers and resin matrix is just the opposite of what was found in the bad old days of ferro-cement boat building. In ferro-cement boats, the composite structure is based on a matrix (concrete) that will fail before the reinforcement can be fully engaged. Epoxy’s elasticity can be fine-tuned to the fibers it locks in place. Pros often post-cure epoxy composite hulls to stiffen panels and increase hardness. more
There’s something to be said for destructive testing—a tried and proven approach to engineering that still has its place even in an era of finite element analysis. Our point-load drop testing delivered some dramatic results and equally important lessons. here
If you’re contemplating some major build or repair projects involving fiberglass this summer, then you are probably trying to decide whether it is worth the added expense of using epoxy instead of polyester resin. Most do-it-yourselfers understand that epoxy’s adhesive bond is much stronger than polyester, but two additional characteristics might also tilt the scales in favor of epoxy, especially for structural repairs.
First of all, panel stiffness can be achieved through the use of core materials and fewer units of FRP reinforcement. But when it comes to keeping a floating log, bow of another boat or the ramrod at the end of our jig from penetrating a structure, there is no replacement for skin thickness. here
During our test of flexibility, we discovered another of epoxy’s inherent attributes—its double-edged ability to retain excellent adhesive quality and elongation characteristics. On its own, this is not an overly valuable quality, as we found the dollop chips of resin to be neither much harder nor much stronger than their polyester cousins, but if you add fiber reinforcement, the whole deal changes. What happens is the flexibility of the highly adhesive resin adds enough stretch to keep the resin matrix intact as the fiber bundles comprising the laminate take up the load. more
Prepreg is fabric that has been pre-impregnated with resin (typically epoxy). The resin is cured to stage B, creating a gel that is neither liquid nor solid. Prepreg materials need to be kept frozen to prevent it from being fully cured. The prepreg is cut into shapes and applied to the mold in layers. A vacuum bag is then placed over the material and a vacuum pump draws all of the air out and compresses the layers together and consolidating the materials. The loaded mold is then put into an oven liquefying the resin so it will wet out the fibers. As the temperature increases, the resin will polymerizes and become hardens. The advantages of prepreg are very tight control of fibers ratio, low voids and precise location of the fabric and thickness uniformity. Prepreg materials are typically used for aerospace products and high-performance light weight parts.
Mechanics and analysis of composite materials more
The purpose of this design guide is to provide some general information on fiberglass and composite materials and to explain how to design products with these materials. If you have specific questions, please contact our engineers at Performance Composites and they will gladly assist you.
Composite materials are very versatile and are utilized in a variety of applications. Composite parts provide superior strength, stiffness and light weight, and can be formed into any shape. An ideal applications are large complex-shaped structures such as fiberglass covers. Composite products are ideal in applications where high-performance is required such as aerospace, race cars, boating, sporting goods, and industrial applications. The most widely used composite material is fiberglass in polyester resin, which is commonly referred to as fiberglass. Fiberglass is lightweight, corrosion resistant, economical, easily processed, has good mechanical properties, and has over 50 years of history. It is the dominant material in industries such as boat building and corrosion equipment, and it plays a major role in industries such as architecture, automotive, medical, recreational and industrial equipment. here
Composites materials are replacing metals and plastics in many industries and composites are the material of choice for many new applications. Please see table 1 for a comparison of cost and properties of commercial grade composite materials to aluminum, steel and wood. here
Next week, we will show you more car maintenance tips like How to replace Windshield or Easy ways to unlock your car, thus, don’t forget to follow CAR FROM JAPAN to read more useful car information. more
Cut several pieces of fiberglass cloth to one-inch larger than the cracked or holed area. Then mix the resin with the hardener in the mixing tray. Blend in small amounts and remember that the working life of the mixture will be nearly 8 to 12 minutes at 75°F. You have to use ten drops of hardener for one ounce of resin.
To know its use, you first have to about the materials come with a standard kit and the additional items you may need for repairing the crack or hole. more
Let the area dry properly. The curing will be better if the temperature of the place remains at 75°F. After that, sand the area with Sandpaper 80 grit. You can use a body filler at this stage to smoothen the small curves.
Use the paintbrush to apply a coat of mixed resin on the damaged area. The resin should cover the area that extends 2 to 3 inches beyond repair. Then, place a piece of fiberglass cloth onto the damaged spot and saturate it with the mixed resin. Keep applying layers of cloth pieces and resin until the area is repaired completely. Follow the same procedure for the both sides. [links]
Use the Sandpaper 80 grit to sand the damaged area. It will remove all the rust, paint, primer, and gel-coat. Sand the other side of the damaged spot too because repairing both sides will strengthen the surface. Clean the area again with acetone or soapy water. more
What resin R U using? Poly or Epoxy? If poly then You need both CSM and 1708 Biaxial. CSM on both top and bottom and then 12" 1708 biaxial tape to tab it to the hull sides. Epoxy. 8.5 oz cloth for the total deck topside, no cloth needed on the bottom side, but I'd use 17 oz biaxial cloth 12" tape to tab the deck to the hull. Epoxy does not use mat. the 1708 has mat sewn to the backside of it so you use it for poly only. more
Re: Type fiberglass cloth for floor rebuild?
Thanks woodonglass, I will be using epoxy, is one layer 8.5oz enough on top or do I need 2 and lay them differing directions, I probably will use a light weight cloth on bottom(3-4oz) just to fell good. plan on using 17oz biaxial on tabbing floor to hull, 4" then 8" then 12" where needed. Ordering supplies Monday am, hopefully they will be here when our rain stops later in the week, then I will start foaming the stringers and then do floor and then foam under the floor..using 4 lb foam for stringers..2lb for under floor.. more
Grind the area of the metal that will be getting fiberglass applied to it using an air grinder. Scuff the entire area, removing any loose or damaged metal down to solid metal.
Lay the fiberglass mat on a hard surface and cut it to size using a razor knife. The size and number of layers will be determined by the specific job you are doing. here
Wet the surface of the ground metal with the resin mixture using a 4-inch felt roller. Apply the first layer of mat to the surface and saturate it with resin using the felt roller. Remove any air bubbles and flatten the mat with an air roller. Add the remaining layers of mat following the same process for each layer. Let the fiberglass harden.