Fiberglass Reinforced Plastic is a composite reinforced with very thin strands of glass fibers woven or matted and then saturated with a polymer matrix, typically epoxy resins, which hardens around the fibers. The natural analogy is bone, a mix of hard fibers and binding. If the process is layered into a mold with an initial thin coating of a pigmented hard epoxy called gel-coat, a beautifully smooth pre-colored surface results, which can also be painted. The end result is a solid material that is heavier than water, strong, attractive and very water resistant. Many recreational boats are FG but few light airplanes are due to the weight- compared to aluminum or fabric. In road vehicles, fiberglass is the light weight material- compared to sheet steel or metal castings. Efforts to reduce the weight and retain the other favorable qualities of fiberglass have spawned materials like carbon fiber composite, extensively used in aircraft and high end sporting gear. This material is frequently left unfinished to show off the brown/gray weave look in high tech material. Fiberglass will often be called plastic because of the epoxy resin content that binds the glass fibers. More fiberglass technical info is from the Composites Technology Magazine website, top page at www.compositestech.com.

The glass fibers in fiberglass is mostly silicon (Si) most often seen as sand. The Si is blended and melted with lime and it flows out or adopts a mold shape nicely when heated. This is the same substance used as the substrate for semiconductor electronics when allowed to grow in a crystalline form, then sliced and polished. Factoid: Glass even when cold and brittle is actually still a liquid with flow rates that may take eons for a Coke bottle to become a puddle. It can be argued that cold glass is a solid but the primary physical characteristic is that there is no energy storage or release due to phase change between the liquid and solid conditions.

Plastic is one word that refers to a lot of different organic or inorganic polymeric materials that have one thing in common - giant molecules which can be shaped by flow. The term usually refers to the final product, with fillers, plasticizers, pigments and stabilizers included, versus resin- the homogeneous polymeric starting material. Linear or branched molecules are thermoplastic which soften when heated for the chance to cast, mold, extrude or spin into a shape, then freeze in place. Thermoplastic remains somewhat flexible and it can possibly be heated and reshaped again. Cross-linked molecules make thermoset plastic that permanently hardens into shape after heating, making for harder, more stable materials. Thermoset will char when heated enough- without melting. (Source: SAE) Historically plastic was sought after as a replacement for ivory in billiard balls cir. 1860. Celluloid was first, followed by Bakelite in 1906, seen in old radio boxes. Cellulose acetate, PVC and more came out of rapid development during the 1920's spurred on by chemist Hermann Staudinger. More progress continued prior to WWII with Plexiglas, urea formaldehyde resins, (tableware) and materials for radio frequency insulators used in early radar systems. Warring nations created demand for more and better materials with the reduced supply of natural raw materials. Nylon and neoprene latex, a synthetic rubber were suddenly produced. The postwar era gave us much more such as epoxies, polypropylene, linear polyethylene, polyesters and more "engineered materials" intended to replace metals. All of this can be categorized in several ways based on the quality of interest. Now plastic is everywhere - even though what we candidly call "plastic" is often referred to as "space age", "molded", "polymer", "composite" or "rustproof" to embellish its identity. Our Alamance County NC is a hub for synthetic textiles, making the world class "Sunbrella" outdoor fabric at Glen Raven Mills, as well as many brands of stockings. Kettler fabrics are solution dyed acrylic synthetic textiles. We now have numbered codes in a triangle symbol to identify the numerous codes of materials for recycling the various plastics. Kettler resins are special formulated blends of polypropylene and materials designed to resist various weather conditions. The North American automakers use over 2 million tons of plastic each year and have led the world in the plans to identify and reuse plastic materials in large quantities.

Plastics are shaped by flow and may continue to change shape later when under stress. The effect is called "cold flow" when plastic gradually relaxes in the direction of reducing the stress. If you lean a plastic wagon rack against a wall for 4 months, it will be curved. Turn it over and lean it again or just lay it flat and it will straighten itself out. Plastic wagons beds and racks can warp over many months or years if continuously bearing a large static load. Wagons from L&L and Valley Road that have sheet plastic could warp although they each have a steel backbone frame, end cross members and a perimeter berm so warpage has not been a serious issue. Speedway has plastic bottom sheet only with a hardwood perimeter over a steel frame and thus has no cold flow issues. Berlin Wood has discontinued their plastic version of the Loadmaster wagon. Plastic wagons are preferred for weather and cleanup water resistance and for uses where wood could support growth. An example on our Plastic Wagons page shows a pony not chewing on what is not wood. Learn more from the American Plastic Council's plastics primer page.

Paints--liquids that solidify as a surface covering--have been around for millennia in one form or another with a variety of common ingredients. There are four basic parts which make up paint, the solvent, binder or vehicle, filler and pigment. The solvent is also called thinner and the binder is also known as drying oil. Varnish is resin, drying oil and thinner. Enamel is paint that uses varnish instead of drying oil. These types dry by chemical reaction with oxygen along with a drier to shorten the time. Lacquer usually means cellulose nitrate or acetate that dries rapidly by evaporation of a volatile thinner. Water-based paints may have glue, casein, methyl cellulose, etc. with emulsions of synthetic latex or other materials and possibly Portland cement.

In summary, paint is largely characterized by the solvent and vehicle combination. In order of increasingly "hard" solvents, there is water (latex paint), enamel then lacquer. The result of different levels of solvent may prevent, for example, putting lacquer over enamel. The exceptions are there, due to additives, etc such as hardener. The solvent has the job of allowing the rest of the paint to be a liquid long enough to spread it and to have it "float" to a glossy finish, then disappear into the atmosphere. The binder is the glue that holds it together, and it may be a two part epoxy plastic or solids dissolved in the solvent. The filler adds bulk, to thicken the mix for structure when cured or for facilitating application. The pigment is varied in its chemical source. Lead was once used to make vivid reds and yellows, now something else has come around. Black is carbon, like charcoal dust. White and other colors are from oxides, chromates, sulfides and sulfates of many elements. Paint technology is driven in large part by the American automakers, in the variety of colors, metal flake content, and clear coat over the color. To avoid the environmental effects of the evaporating solvent, many cars are painted with a water- based paint or they have solid-emulsion paint "powder coating", keeping many tons of hydrocarbons (VOCs) out of the air. Paint has numerous variations in both materials and processes for different applications, such as to make it flat or glossy, or hard or even pearlescent. Some paint is meant to connect compatibility with a surface, or to have a smoothly sandable bulk, or to thwart rust; that is a primer. Some paints are designed to be soft and carry a bio- active metal such as copper in boat bottom paint. There is even an additive called "fish eye remover", to change the surface tension to span small areas of bad surface compatibility.

Powder coating is an advanced method of applying a decorative and protective finish to a wide range of materials and products that are used by both industries and consumers. How does it work? Powder coating is a dry finishing process. Finely ground particles of pigment and resin are electrostatically charged and sprayed onto the products to be coated. The parts to be coated are electrically grounded, so that the charged particles adhere to them until melted and fused into a solid coating in a curing oven. The result is an attractive, durable, high-quality finish. The powder coating process itself offers another advantage -- it is environmentally friendly, virtually pollution-free. Unlike liquid paint, no solvents are used, so only negligible amounts of VOCs are released into the air. In addition, unused or oversprayed powder can be recovered, so any waste is minimal and can be disposed of easily and safely. Look for products with the powder coated tough logo on our pages and learn more from the Powder Coating Institute.

Aluminum (Al) is an element, in fact the most plentiful metallic element in the earth's crust. Oxygen is the most plentiful element overall with much of it bonded to aluminum to form the oxide alumina. Aluminum is characterized mostly by its light weight- one third the density of steel and also by its high corrosion resistance. Until the 20th century, reasonably pure aluminum was costly to extract from naturally found ore and thus rare- making it a novel metal worn as jewelry by the wealthy. The Hall-Héroult Process uses direct current electricity to extract the metal from naturally found alumina. This very low cost technique, not superseded in a century, has changed the basic uses and even the perceived image of the lightweight metal. Aluminum is highly conductive of heat and electricity so it is used in electrical wiring, integrated circuits and heat sinking forms. It can be left unpainted because it immediately skins over with a thin clear coating of oxide, stopping further corrosion. Aluminum can be polished to a mirror finish with Mother's Aluminum Polish or sputtered on glass to make a mirror. Structurally, aluminum can be cast, forged, arc welded or extruded into complex shapes, often with no further finishing steps. Aluminum wheels on vehicles are stylish while self protecting, strong, low inertially and dissipative of brake system heat. In fact, modern painted plastic wheel covers are almost all styled to look just like aluminum wheels- such as on the new Kettrike Splash.

There are many other ways to form aluminum, with some methods actually creating a functional grain structure within the metal, further increasing its useful specialization. A wide variety of alloys mixed in vary the desirable characteristics of the metal for many uses; it is hardly ever used in pure elemental form. Decorative and protective coatings are many; paint, powder coating, plastic dipping, electro-plating. Further classes of finishes add nothing but contact, such as shot peening, sandblasting and solvent etching to give any desired look. Aluminum is popular in boats and aircraft where its two primary traits in combination plus a non-magnetic nature (compass use) are ideal. Powdered Aluminum is used as pigment in what we call "silver" paint. Aluminum has more oddities such as use as a low neutron absorber in nuclear reactors, in cryogenic vessels and in addition to more common packaging or architectural uses. Automobiles use increasing proportions of aluminum in body panels, engine blocks and cylinder heads, heat exchangers and suspensions. Aluminum is highly recyclable, from making the low end "pot metal" which contains the alloy soup of the day to highly pure metal for the same uses as newly refined material. We know from drink cans that it is generally too valuable to throw away.

Iron (Fe) is an element- a single atom weighing only 9.28 x 10 -23 grams is still iron. Iron is very plentiful in the earth's molten core and its rotation-induced flow is believed to be the source of the magnetic poles. Pure iron has limited uses such as in the making of electromagnets and galvanized sheet. Generally, iron is used in processed form such as wrought iron, cast iron or steel. Wrought iron is hammered into shape when hot by blacksmiths; it is naturally more rust resistant compared to steel. Cast iron is poured as a hot liquid into a mold where it hardens upon cooling. Steel is an alloy primarily of elemental iron and 0.04% to 4.4% carbon (C) and possibly more elements alloyed to create a stronger, harder metal. Steel has many possible solid phases that vary by temperature and alloy to set the molecules into different patterns. The greatest part of the effort in isolating iron and making steel goes into a series of chemical reactions to burn out the excess carbon and other impurities from the iron. A clever arrangement of air or oxygen, carbon for fuel, lime and other materials are arranged and introduced in a vertical vessel in the blast furnace method. The temperature layers' convective draft, pumps and gravity move the intermediate forms on their way up or down reacting out the desired liquid metal from everything else. Temperatures of 2500° F (1370° C) are needed to purify the alloy using one of several processes, open-hearth, basic oxygen or electric furnace. Even the leftover materials are useful as lawn fertilizer or black slag "cinders" for traction on snowy northern roads. Learn the technical details of blast furnace steelmaking from The American Iron and Steel Institute.

Steel is highly elastic, meaning it can make springs which absorb little energy internally when flexed. For example, a steel ball bounced on a steel surface will bounce very high and steel wheels on rails offer low energy loss. Yet steel can also be malleable enough to absorb energy to allow shaping into complex curves which require a thickness variation to avoid wrinkles. Steel is finished by forming it while still hot to both shape the mass of metal as well as cause the internal crystal structure to freeze into the correct molecular form- making for desired characteristics. Steel can be heat treated or cold treated to reshuffle the tiny amounts of alloying elements within molecules of mostly iron resulting in dramatic effects on the material's overall strength. In continuous mills the metal enters rollers as an ingot of 13' long by 35" wide and 4.5" inches thick. After successive pairs of closer and faster moving rollers a sheet emerges with the same width but it may be 1210 feet long and 0.05" thick. Tool steels have tungsten, molybdenum and other alloying elements to make very hard cutting tools. Stainless steels contain chromium, nickel and other alloying elements that keep them bright and rust resistant. Stainless is both decorative and useful for tough environments such as marine, space and food and chemical handling. You see stainless in mixing bowls, milk shake makers and in automotive exhaust pipes. It is inert to living tissue making it useful for joint repair parts and skin contact jewelry. What is chrome plated steel? Electro plating is like recharging a battery. Dissimilar metals are connected through immersion in a liquid electrolyte allowing for the movement of the ionic forms. Direct current electricity is forced across the two "electrodes" (opposite of the accidental battery) then the more noble metal will swim across and stick to the less noble metal. Done right, this is a three layer process. Copper then nickel then chrome is the order of the plating on steel to achieve the required durability with correct compatibility. The result is very corrosion resistant with the classic mirror finish of real car bumpers. Electro plating is similarly done with lots of other metals.

Welding - method of joining metals without fasteners. Fusion welding is the process of melting two or more pieces of like metal together, often with more filler metal, to form one piece. Welding is distinct from the brazing process technically known as non-fusion welding. In the (fusion) welding process a metal work piece and possibly identical or very similar filler metal all melt together to solidify into literally one piece of metal. Non-fusion brazing and its subclass soldering work by melting and wetting a lower melting temperature metal over the unmelted work pieces, then the filler freezes solid. Several methods of (fusion) welding exist from earliest known form: blacksmiths pounding hot metal with a hammer- forge welding. A later method is cast welding where molten metal is poured into a mold around the joint area. Carbon-arc street lighting was noticed to make useful amounts of excess heat, enough to locally melt metal together.

By 1948 arc welding grew out and diversified from the carbon arc heat source into three common and mature welding techniques. The first is known as Shielded Metal Arc Welding or commonly as simply arc welding or stick welding. A welder (machine) is a power supply as simple as a transformer stepping down its supply voltage into a lower voltage with current capability from 30 Amp up to 230 Amp or more. Since the physics of the molten metal within an arc establishes a relatively low and stable voltage, the power for heating is set by controlling the current flow. An arc welding rod is a stick of metal between about 1/16" and 1/4" thick by 14" coated in "flux", material that makes inert smoke over the weld site promoting arc stability and oxidation prevention. The rod is held by a bare end in a spring clamp with an insulated grip electrically connected with a heavy wire to the welder. The other side of the electrical circuit is the work piece with typically a spring clamp and another thick wire back to the welder. The welder (person) slides the rod or "stinger" over the work area like a match and pulls back as the initial arc immediately expands into a stream of molten metal and plasma from the heat and effects of the flux. The rod consumes over a few minutes by depositing metal in a pattern using a hand motion like a series of cursive "e" or "&" strokes. The welder also moves the grip closer to maintain about a 1/4" long arc as the rod shortens. The welder’s advancing technique produces a repeating process of lapping new and existing liquid metal while the molten pool cools behind at a constant distance behind the arc. The results have to be cleaned of hardened flux deposits to reveal the "bead" of shiny metal and some hardened splattered metal.

As you might expect, looking at a 6000 Watt arc with brightly glowing liquid metal at arms length from a font of molten droplets requires some protective gear. A full face shield with very dark movable glass covers the whole front of the head. Leather gloves and jacket are generally worn to protect the arms and chest, even when the weather may be already hot. Sweating inside a heavy jacket is more pleasant than sunburn or splatter burns that could ignite clothing. Some newer face shields have a lens of liquid crystal display (LCD) to darken on signal at the first 0.001 second of arc, this helps to locate the original point of contact using an unattenuated view. This is the same system used to darken many automobile rear-view mirrors from glare. The typical uses of a basic system are for welding steel in thickness ranging from 0.10" to 0.25" with current settings between 90 A and 140 A AC (alternating current). This is often referred to as "farm welding" where strength is vital but appearance is unimportant at a reasonably low skill level. A step up is DC (direct current) arc welding which opens up the possibility of welding aluminum and increases the options and variable characteristics of steel welding. The DC flow can be either direction for more penetration or cutting- or it can be the opposite way for more build up of the filler metal both with less unsightly splatter around the weld. A variation is "spot welding", where a big pulse of current is forced through the two sides of an electrified clamp squeezing a small area. The resistance to a large burst of current makes a hot spot fusing a 1/4" or so dot of weld on a larger area while the clamp ends are not melted. No protective flux (or inert gas) may be needed for such a short duration, but molten droplets fling outward.

The better form of arc welding is known as Metal Inert Gas or MIG welding. MIG does not need the flux material coating as on a straight 14" rod, so the consumable filler and arc source together is bare metal wire fed from a spool, a.k.a. wire feed. The lack of flux also means that there is no flux residue to cause porosity or contamination of the weld area; important for strength and for food, medical or chemical contact. A tank of Argon, Helium or other inert gas protects the weld area by excluding the oxygen in the atmosphere to prevent oxidation. MIG is usually DC with fine control over the arc and new material feed rate thus it makes for both strong and better looking welds almost devoid of splatter; this is important for smooth fluid or aggregate flow and even wear within welded pipes. Using inert gas instead of flux smoke makes it easier to see and thus gain better control of the heat and metal feed rates, often with a foot pedal. A distinct variation of MIG is "heli-arc" or Tungsten Inert Gas (TIG) welding. TIG has separate heat source and filler metal feed, with a pair of non-consuming tungsten electrodes supporting the arc to generate heat. Tungsten has a much higher melting point than the weld metals, so it stays relatively intact as it does in a light bulb filament. Filler metal is in the form of bare rods are fed in by hand, and again inert gas is supplied to keep the area bathed in clear gas that does not allow oxidation. Collectively, MIG and TIG are referred to as simply inert gas welding.

Gas torch welding uses a flame torch fueled by a hydrocarbon fuel known as acetylene made ultra hot by metering in pure oxygen. Gas welding, or oxy/acetylene welding, is much like TIG except for the heat source. Two pressure tanks with a long double hose terminate in a highly adjustable mixing torch head. After lighting, the torch head is adjusted manually with valve knobs for correct flame shape, color and sound. Gas welding is especially good for thin metals where difficult arc stability or melt-through would be a problem, i.e. applications such as automotive exhaust pipes. The torch head usually has provision for a temporary boost in the oxygen flow to make it better at cutting metal, since the oxidation helps consume metal to be removed.

Electric welding is understood well enough to have observed master welders and programmed welding robots. Typical robotic welding is by MIG or spot welding used for mass production consumer product or automobile manufacturing. Welding can even be done underwater or in space with the correct skill, materials and equipment. There are also many more technical solutions to specific welding challenges addressing costs, conditions or materials not covered here.

Wood...What is wood? Duh ha!? We all thought that we knew more than enough about the hard, tough material that forms in the trunks of trees! Useful as both a construction material and fuel, wood has been used for tens of thousands of years. The technical term "wood" even includes the "veins" in leaves, but for this discussion only the materials that have commercial importance are mentioned. The structure of wood visible in the grain is primarily vertical fine cellular ducts which carry water and dissolates from root to leaves. The grain results from seasonal variation in growth rate and thus the new wood layer's density- darker is more dense. Classification of wood as hardwood or softwood depends on the type of tree from which it came. Hardwoods come from broad- leaved trees and wood from coniferous trees are called softwoods, regardless of the actual hardness. In softwood, life fluids are transported cell to cell and there may be resin ducts but hardwood has long continuous ducts parallel to the grain. Wood's physical properties vary over a wide range, and if it is not attacked by living organisms, wood lasts for centuries. One preservative is zinc chloride used in pressure treating wood for ground contact. Surface protection against weathering for wood is effective unless there is underlying deterioration caused by insect, fungi or borers. Factoids: Some fresh water wooden boats actually have salt placed in the bilge as a preservative. Spruce is the only material with the right resonance properties for piano sounding boards. Most US lumber is softwood with hardwood reserved for flooring, funiture and of course durable wood toys.