d1337r
28.04.2021 7:02:54
Re: how many fiberglass layers?
See full version: How many fiberglass layers
Re: how many fiberglass layers?
With polyester you need to use mat as the first layer and in between each layer of cloth or roving. So unless you already have the 9oz cloth the better bet would be to use one layer of mat and one layer of 24oz roving. A biax product like 1708 or something similar will also work, but will be a little tougher to find and cost more. more
Re: how many fiberglass layers?
APPLICATION SEQUENCE
The application consists of four coats of resin. the FIRST coat is the SEAL COAT, and seals the wood surface prior to applying the cloth. The SECOND coat is the BOND COAT, and is used to wet out and bond the cloth to the surface. The THIRD coat is the FILL COAT and fills the weave of the cloth. The FOURTH coat is the FINISH COAT and provides enough resin build-up for final sanding and finishing. Throughout ALL coats, do NOT apply any more resin than is necessary to accomplish the purpose of each coat. A typical problem with beginners is that they use too much resin. This is a waste of resin, makes finish work difficult, and increases weight and cost. Do NOT attempt to spray any of the coats of resin. more
ABOUT THE RESIN
The Poxy-Shield epoxy resin consists of 2 PARTS. These are to be mixed according to the ratios given on the containers; 5 parts A (resin) to 1 part B (hardener). DO NOT VARY THE RATIOS. Do not add solvents or thinners. Sanding between coats of resin is not absolutely necessary to achieve a bond (although some sanding may be required as will be explained later). Note: Resin without hardener is NEVER used. Always add hardener in the 5 to 1 ratio.
TOOLS REQUIRED
Resin is applied using disposable brushes and foam rollers. You will also need a squeege for working out excess resin when applying the bond quote. Power sanders will save work during finishing and other sanding operations. The reciprocal/orbital types are safe and easy to use, but are slow and remove only small amounts of material. The disc and belt types are fast, but require some practice for proper control. A foam pad backing disc should be used to minimize gouges. A sanding block can be used in areas where power tools can’t be used. Scissors and a utility knife are used to trim the fiberglass material. Cleaning materials should be ready to use at the work site. These would include a bucket of hot soapy water or a waterless resin cleaner, safe for skin contact; and suitable solvents, such as denatured alcohol, acetone, or lacquer thinner, for keeping tools clean.
INTRODUCTION
If you have not worked with GLEN-L Poxy-Shield epoxy resins, or you have applied fiberglass before using polyester resins, make sure you read and understand all of the following information before starting any aspect of the job or handling any materials. Epoxy resin works and handles differently from polyester. SAFETY PRECAUTIONS ARE IMPORTANT!
Gelcoat has other benefits - it's often more durable and a convenient way of adding a coloured layer. Gelcoat can be applied directly to the mold to form a convenient and better bonded composite, but can also be applied later.
In production (after initial curing), loose strands will often have to be sanded down and additional resin applied to ensure a compete seal. If, through faulty manufacture or damage, glass is exposed to water (especially salt-water) this will cause to composite to break apart/de-laminate. [links]
What if any damage might soaking fiberglass in water do to the fiberglass? more
Often when we say "Fibreglass" we're actually referring to a composite of both fibreglass and resin (usually polyester for glass, epoxy for carbon/kevlar - sometimes glass). This is important, that resin is a distinct component was missing from the question. more
The composite is formed when glass fabric is shaped in/on a mold and saturated with resin. The resin then cures, forming a rigid structure. more
So why gelcoat? To protect the glass/resin composite, primarily from UV. Exposing resin to UV will cause it to degrade and crack over time, eventually exposing the fibres to the elements. [links]
Hammers can be made of bronze, steel, plastic or any hard material. As long as an audible report is made when the device taps the component being inspected. The difference in the sound made is what the surveyor is listening for. I have found metallic hammers give the most discernible reports, but I primarily use plastic hammers above the waterline. If an audible difference is determined I will also tap in the area a second time using a small metal hammer.
The tapping can be done with virtually anything. Depending on the material and thickness of the component which is being tapped variances can be found using a finger nail, edge of a coin, butt of a screw driver or of course the preferred tool, a hammer. [links]
Its primary use in a boat yard is determining the condition of fiberglass laminates. It is also useful with wood and other construction materials. In fiberglass or composite boats, tapping allows detection of delamination. Fiberglass boats and their component parts, are made of several layers of lamination. Gelcoat, coring and fiberglass material with resin are among the most common types of laminates. A separation or “disbond” can occur at any level. Percussion testing allows detection of separation between the gelcoat and the first fiberglass laminate (skin coat). It can also detect delamination within any of the layers of the fiberglass, including delamination caused by osmosis (blisters) and disbanding of the layers adjacent to the core. more
The vast majority of boats are manufactured with a cored deck. Hulls, stringers and other parts may also be cored. Coring is usually balsa, foam or plywood, sandwiched between layers of fiberglass. The fiberglass encasement on either side of the deck coring can delaminate. Thus, percussion testing both the top and bottom of the deck, where accessible, is a useful inspection technique. Fiberglass bulkheads are usually tabbed (fiberglass taped) to the hull sides. Tapping the fiberglass tabbing can determine if the tabbing is properly attached. Occasionally the tabbing does not bond (usually to the plywood bulkheads and I have seen vessels in which the fiberglass tabbing attachments (secondary bonds) were never well made. On a few occasions, this has left virtually all of the bulkheads “adrift” and grossly weakened the hull structure. Properly made tabbing can become detached due to an external force from impact, heavy weather operation or even over tensioning a sailboat’s rigging (usually a backstay). more
In vessels that use organic coring material, and there are many, the most type is balsa or plywood. This wooden coring can deteriorate (fungus deterioration or dry/wet rot) and the deteriorated coring can often be detected by tapping. A properly made deck cored with balsa sounds solid and sharp when tapped; if the balsa is deteriorated the same deck sounds soft or dull. Deteriorated coring can also be detected by tapping stringers and transoms, particularly on smaller boats. more
Tapping wood boats or wooden components also allow detection of deterioration. Bulkheads are often constructed of plywood which is covered with fiberglass, upholstery or carpet; tapping can reveal secrets that even the owner was unaware of. Occasionally when tapping deteriorated wood, this inspection technique becomes destructive.
Many of the things detected by tapping are minimal including “voids”. Voids are air bubbles trapped just below the gelcoat or skin coat. Tapping a void is distinguishable by the higher pitch. The area around the void will have a lower report than the thin skinned void. The voids are cosmetic and a nuisance occasionally but are rarely ever significant structurally. [links]