Tools

Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes.

The shank is the part of the drill bit grasped by the chuck of a drill. The cutting edges of the drill bit are at one end, and the shank is at the other.

Drill bits can be made in any size to order, but standards organizations have defined sets of sizes that are produced routinely by drill bit manufacturers and stocked by distributors. A comprehensive drill and tap size chart lists metric and imperial sized drills alongside the required screw tap sizes.

A hole saw (also styled holesaw), also known as a hole cutter, is a circular saw designed to cut through relatively thin workpieces. It is used in a drill.

A power tool is a tool powered by an electric motor, an internal combustion engine, a steam engine, compressed air, direct burning of fuels and propellants, or even natural power sources like wind or moving water. Power tools are classified as either stationary or portable, where portable means handheld. They are used in industry, in construction, and around the house for driving, drilling, cutting, shaping, sanding, grinding, polishing, painting, and heating. Stationary power tools for metalworking are usually called machine tools. The term machine tool is not usually applied to stationary power tools for woodworking, although such usage is occasionally heard, and in some cases, such as drill presses and bench grinders, exactly the same tool is used for both woodworking and metalworking.

Stationary power tools are prized not only for their speed, but for their accuracy. A table saw not only cuts faster than a hand saw, but the cuts are smoother, straighter and more square than even the most skilled man can do with a hand saw. Lathes produce truly round objects that cannot be made in any other way.
Common power tools include the drill, various types of saws, the router, the electric sander, and the lathe.

The term power tool is also used in a more general sense, meaning a technique for greatly simplifying a complex or difficult task.

A chainsaw (or chain saw) is a portable mechanical saw, powered by electricity, compressed air, hydraulic power, or most commonly a two-stroke engine. It is used in activities such as tree felling, limbing, bucking, pruning, by tree surgeons to fell trees and remove branches and foliage, to fell snags and assist in cutting firebreaks in wildland fire suppression, and to harvest firewood. Chainsaws with specially designed bar and chain combinations have been developed as tools for use in chainsaw art. Specialist chainsaws are used for cutting concrete.

The circular saw is a metal disc or blade sometimes with saw teeth on the edge as well as the machine that causes the disk to spin. It is a tool for cutting wood or other materials and may be hand-held or table-mounted. It can also be used to make narrow slots (dados). Most of these saws are designed with a blade to cut wood but may also be equipped with a blade designed to cut masonry, plastic, or metal. There are also purpose-made circular saws specially designed for particular materials. While today circular saws are almost exclusively powered by electricity, larger ones, such as those in “saw mills”, were traditionally powered by water turning a large wheel.

A miter saw (also spelled mitre) is a saw used to make accurate crosscuts and miters in a workpiece. A power miter saw, also known as a chop saw or drop saw, is a power tool used to make a quick, accurate crosscut in a workpiece. Common uses include framing operations and the cutting of molding. Most miter saws are relatively small and portable, with common blade sizes ranging from eight to 12 inches.

The miter saw makes cuts by pulling a spinning circular saw blade down onto a workpiece in a short, controlled motion. The workpiece is typically held against a fence, which provides a precise cutting angle between the blade and the longest workpiece edge. In standard position, this angle is fixed at 90°.

A primary distinguishing feature of the miter saw is the miter index that allows the angle of the blade to be changed relative to the fence. While most miter saws enable precise one-degree incremental changes to the miter index, many also provide “stops” that allow the miter index to be quickly set to common angles (such as 15°, 30°, 45°, or 75°).

There are several types of power miter saws:

• A standard miter saw has a fixed vertical pivot with rotating cutting table allowing horizontally angled cuts while the blade always remains vertical.
• A compound miter saw has a rotating vertical pivot allowing the cutter head & blade to be tilted sideways in addition to the horizontally rotating table. This allows vertical & horizontal angled cuts as well as cuts angled in both planes.
• A sliding compound miter saw is a compound miter saw with horizontal sliding arms for the cutter head allowing much wider cuts.
• A dual compound miter saw is like a sliding compound miter saw, but its blade and motor can tilt both left and right. This provides more flexibility for cutting complicated angles such as required for crown molding.

A table saw or sawbench is a woodworking tool consisting of a circular saw blade, mounted on an arbor, that is driven by an electric motor (either directly, by belt, or by gears). The blade protrudes through the surface of a table, which provides support for the material, usually wood, being cut.

In a modern table saw, the depth of the cut is varied by moving the blade up and down: the higher the blade protrudes above the table, the deeper the cut that is made in the material. In some early table saws, the blade and arbor were fixed, and the table was moved up and down to expose more or less of the blade. The angle of cut is controlled by adjusting the angle of blade. Some earlier saws angled the table to control the cut angle.

A bandsaw is a power tool which uses a blade consisting of a continuous band of metal with teeth along one edge to cut various workpieces. The band usually rides on two wheels rotating in the same plane, although some small bandsaws have three wheels. The saw may be powered by wind, water, steam, gas engine, electrical motor or animal power. Bandsawing produces uniform cutting action as a result of an evenly distributed tooth load. Bandsaws are used for woodworking, metalworking, or for cutting a variety of other materials, and are particularly useful for cutting irregular or curved shapes, but can also be used to produce straight cuts. The radius of a curve that can be cut on a particular saw is determined by the width of the band and its lateral flexibility.

A reciprocating saw is a type of saw in which the cutting action is achieved through a push and pull reciprocating motion of the blade.

The term reciprocating saw is commonly assigned to a type of saw used in construction and demolition work. This type of saw, also known as a recipro saw, Sabre Saw, or Sawzall (a trademark of the Milwaukee Electric Tool Company) has a large blade resembling that of a Jigsaw and a handle oriented to allow the saw to be used comfortably on vertical surfaces. The typical style of this saw has a foot at the base of the blade, also similar to a jigsaw. The user rests this foot against the surface being cut so that the tendency of the blade to push away from or pull towards the cut as the blade travels through its cycle can be countered.

Designs range widely in power, speed, and features, from less powerful portable, handheld models that are usually shaped like a cordless drill, to high-power, high-speed, corded models. Modern reciprocating saws almost all have variable speed, either through trigger sensitivity or through a dial. Another feature that has become important to the way these saws are used is the inclusion of an orbital action. The action consists of oscillating the traversed reciprocation in up and down fashion (perpendicular to the motion of cut) causing the tip of the blade to move in an oval pattern, up and down as well as back and forth. This feature is primarily for wood, allowing quick cuts.

The reciprocating saw is a popular tool used by many window fitters and construction workers. Reciprocating saws have many uses; here it is cutting through hard-to-remove nails in a staircase.

The term reciprocating saw (or oscillating saw) is also applied generically to any saw which cuts with a back and forth motion. These include:

• Jigsaw
• Scrollsaw
• Sabre Saw
• Rotary Reciprocating Saw

 

Powered Reciprocating tools are also found in surgery and dental surgery, where they are used in operations that require cutting or grinding of bone.

A backsaw is any hand saw which has a stiffening rib on the edge opposite the cutting edge, allowing for better control and more precise cutting than with other types of saws. Backsaws are normally used in woodworking for precise work, such as cutting dovetails, mitres, or tenons in cabinetry and joinery. Because of the stiffening rib, the backsaws are limited in the depth to which they can cut. Backsaws usually have relatively closely-spaced teeth, often with little or no set.

Different types of backsaw include:

• Mitre saw — often referred to a large backsaw (20-30 inches or 60-90 cm) used either in a wooden mitre box or in a metal frame which allowed cutting mitres of any specified angle. Note that not all mitre saws are backsaws, and the electric mitre saw (or chop saw) has taken its place today.
• Tenon saw, or often just backsaw — a midsized backsaw used to cut tenons or in a mitre box. The saw derives its name from its use in the cutting of tenons for mortise and tenon joinery. Tenon saws are commonly available with rip-filed teeth for rip cutting and cross-cut for cutting across the grain. Teeth are relatively fine, with 13 teeth per inch being a common size for the saw.
• Sash saw — name that seems to have been used in the 18th and 19th century for a smaller tenon saw, used in fabricating window sashes. The term is also used currently to refer to a thin, flexible saw used to free sashes that have been painted shut.
• Dovetail saw — a small backsaw used to cut dovetails. Although most dovetail saw teeth are set for cross-cutting, a rip saw tooth pattern is more efficient. These saws will usually have a higher number of teeth per inch (around 15 T.P.I.) with teeth sharpened to favor ripping operations and set to leave a narrow kerf.
• Gent’s saw or Gentleman’s saw (rare) — a small dovetail saw with a straight turned handle, rather than an open one typical of most saws. The name seems to have arisen from its use by the nineteenth century dilettante who would now be called a hobbyist but it is hard to find a nineteenth century reference to it. For example, in the section on tools in Every Man his own Mechanic (1881) (816pp), tenon, dovetail and sash saws are listed as a group but there is no mention of a gent’s saw. It is adapted for use in making joints in very small woodwork such as that in some musical instruments, dolls’ furniture or other model-making. Its distinguishing features are its small size and turned handle.
• Razor saw — A very small backsaw having very finely-pitched crosscut teeth, often with no set. The Razor saw is used by hobbyists, notably Model aircraft, Model boat, and Model railroad enthusiasts. Razor saws typically use disposable blades (or are occasionally designed to be completely disposable), since their teeth are so small as to be impractical to re-sharpen. Unlike most other types of backsaws, razor saws are also frequently used to cut plastics and soft metals.
• Dōzuki — a Japanese backsaw, used for centuries by carpenters and cabinetmakers in Japan. Although this saw does not share an ancestry with the other backsaws in this group, the concept is the same. Like most Japanese saws, the dōzuki cuts on the pull stroke, allowing for much straighter and narrower cuts than those achieved with push-stroke saws. This is due to tension on the blade during the cut (versus compression for a western saw), so less thickness is required to keep the saw blade straight.

An abrasive saw, also known as a cut-off saw or metal chop saw, is a power tool which is typically used to cut hard materials, such as metals. The cutting action is performed by an abrasive disc, similar to a thin grinding wheel. The saw generally has a built-in vise or other clamping arrangement, and has the cutting wheel and motor mounted on a pivoting arm attached to a fixed base plate.

They typically use composite friction disk blades to abrasively cut through the steel. The disks are consumable items as they wear throughout the cut. The abrasive disks for these saws are typically 14 in (360 mm) in diameter and 7⁄64 in (2.8 mm) thick. Larger saws use 410 mm (16 in) diameter blades. Disks are available for steel and stainless steel.

A drill or drill motor is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for drilling holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of the drill and rotated while pressed against the target material. The tip, and sometimes edges, of the cutting tool does the work of cutting into the target material. This may be slicing off thin shavings (twist drills or auger bits), grinding off small particles (oil drilling), crushing and removing pieces of the workpiece (SDS masonry drill), countersinking, counterboring, or other operations.

Drills are commonly used in woodworking, metalworking, construction and do-it-yourself projects. Specially designed drills are also used in medicine, space missions and other applications.

There are many types of drills; some are powered manually, others use electricity (electric drill) or compressed air (pneumatic drill) as the motive power, and a minority are driven by an internal combustion engine (for example, earth drilling augers). Here are a few:

• Pistol-grip (corded) drill
• Hammer drill
• Rotary hammer drill
• Cordless drills
• Drill press
• Geared head drill press

An angle grinder, also known as a side or disc grinder, is a handheld power tool used for cutting, grinding and polishing.

Angle grinders can be powered by an electric motor, petrol engine or compressed air. The motor drives a geared head at a right-angle on which is mounted an abrasive disc or a thinner cut-off disc, either of which can be replaced when worn. Angle grinders typically have an adjustable guard and a side-handle for two-handed operation. Certain angle grinders, depending on their speed range, can be used as a sander, employing a sanding disc with a backing pad or disc. The backing system is typically made of hard plastic, phenolic resin, or medium-hard rubber depending on the amount of flexibility desired.

A bench grinder is a type of benchtop grinding machine used to drive abrasive wheels. A pedestal grinder is a larger version of a bench grinder that is mounted on a pedestal, which is bolted to the floor. These types of grinders are commonly used to hand grind cutting tools and perform other rough grinding.

Depending on the grade of the grinding wheel it may be used for sharpening cutting tools such as lathe tools or drill bits. Alternatively it may be used to roughly shape metal prior to welding or fitting.

A wire brush wheel or buffing wheels can be interchanged with the grinding wheels in order to clean or polish work-pieces.

Grinding wheels designed for steel should not be used for grinding softer metals, like aluminum. The soft metal gets lodged in the pores of the wheel and expand with the heat of grinding. This can dislodge pieces of the grinding wheel.

A belt sander is a machine used to sand down wood and other materials for finishing purposes. It consists of an electrical motor that turns a pair of drums on which a seamless loop of sandpaper is mounted. Belt sanders can be either hand-held, where the sander is moved over the material, or stationary (fixed), where the material is moved to the sanding belt. Stationary belt sanders are sometimes mounted on a work bench, in which case they are called bench sanders. Stationary belt sanders are often combined with a disc sander.

Belt sanders can have a very aggressive action on wood and are normally used only for the beginning stages of the sanding process, or used to rapidly remove material. Sometimes they are also used for removing paints or finishes from wood. Fitted with fine grit sand paper, a belt sander can be used to assure a completely smooth surface.

Stationary belt sanders are used for removing non-ferrous metals, such as aluminum. Non-ferrous metals tend to clog grinding wheels, quickly making them useless for grinding soft metals, while belt sanders continue to grind without clogging. This is because the small grooves in the sand paper are opened up as they go around the arc of the drive wheel.

Belt sanders can vary in size from the small hand-held unit shown in the illustration to units wide enough to sand a full 4-by-8 foot sheet of plywood in a manufacturing plant. Some belt sanders can be as tall as 1.2 metres and 70 centimetres long.

Sanding wood produces a large amount of sawdust. Therefore, belt sanders employed in woodworking are usually equipped with some type of dust collection system. It may be as simple as a cloth filter bag attached to a portable sander or a large vacuum system to suck dust particles away into a central collector.

Slack belt sanding is commonly used in the manufacturing process of guitars and other medium-sized wooden objects. It is a long sanding belt which runs slackly over the object. The machinist then exerts pressure to it to sand down specific areas. It is a very precise process which takes great skill and accuracy.

Gas Metal Arc Welding (GMAW), sometimes referred to by its subtypes Metal Inert Gas (MIG) welding or Metal Active Gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used. There are four primary methods of metal transfer in GMAW, called globular, short-circuiting, spray, and pulsed-spray, each of which has distinct properties and corresponding advantages and limitations.

Originally developed for welding aluminum and other non-ferrous materials in the 1940s, GMAW was soon applied to steels because it allowed for lower welding time compared to other welding processes. The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common. Further developments during the 1950s and 1960s gave the process more versatility and as a result, it became a highly used industrial process. Today, GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation. The automobile industry in particular uses GMAW welding almost exclusively. Unlike welding processes that do not employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors or in other areas of air volatility. A related process, flux cored arc welding, often does not utilize a shielding gas, instead employing a hollow electrode wire that is filled with flux on the inside.

Gas Tungsten Arc Welding (GTAW), also known as Tungsten Inert Gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by a shielding gas (usually an inert gas such as argon), and a filler metal is normally used, though some welds, known as autogenous welds, do not require it. A constant-current welding power supply produces energy which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma.

GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing for stronger, higher quality welds. However, GTAW is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result is often automated.

The final step in the process usually involves grinding, sanding, or machining the component in order to achieve the desired dimensional accuracies, physical shape and surface finish using a finish tool.

Wood finishing refers to the process of embellishing and/or protecting the surface of a wooden material. The process starts with surface preparation, either by sanding by hand (typically using a sanding block or power sander), scraping, or planing. Imperfections or nail holes on the surface may be filled using wood putty or pores may be filled using wood filler. Often, the wood’s color is changed by staining, bleaching, ammonia fuming and a number of other techniques. Some woods such as pine or cherry do not take stain evenly, resulting in “blotching”. To avoid blotching, a barrier coat such as shellac or “wood conditioner” is applied before the stain. Gel stains are also used to avoid blotching.

Once the wood surface is prepared and stained, a number of coats of finish may be applied, often sanding between coats. Commonly used wood finishes include wax, shellac, drying oils (such as linseed oil or tung oil), lacquer, varnish, or paint. Other finishes called “oil finish” or “Danish oil” are actually thin varnishes with a relatively large amount of oil and solvent. Water-based finishes can cause what is called “raising the grain” where surface fuzz emerges and requires sanding down.

Finally the surface may be polished or buffed using steel wool, pumice, rotten stone and other polishing or rubbing compounds depending on the shine desired. Often, a final coat of wax can be applied over the finish to add a slight amount of protection.

French polishing is not polishing as such, but a method of applying many thin coats of shellac using a rubbing pad, yielding a very fine glossy finish.

Special tools used to apply wood finishes include rags, rubbing pads, brushes, and spray guns. The processes involved and the terminology for the materials used are quite different in Britain than the processes and terms used in the USA. For instance, the process of replicating the look and feel of traditional French polished wood is more commonly done in the UK by “pulling over” precatalysed lacquer, within 24 hours of spraying, whereas in the U.S. a “rubbed” finish is more common.

Spray painting is a painting technique where a device sprays a coating (paint, ink, varnish, etc.) through the air onto a surface. The most common types employ compressed gas—usually air—to atomize and direct the paint particles. Spray guns evolved from airbrushes, and the two are usually distinguished by their size and the size of the spray pattern they produce. Airbrushes are hand-held and used instead of a brush for detailed work such as photo retouching, painting nails or fine art. Air gun spraying uses equipment that is generally larger. It is typically used for covering large surfaces with an even coating of liquid. Spray guns can be either automated or hand-held and have interchangeable heads to allow for different spray patterns.

An air compressor is a device that converts power (usually from an electric or diesel or gasoline engine) into kinetic energy by pressurizing and compressing air, which is then released in quick bursts. There are numerous methods of air compression, divided into either positive-displacement or negative-displacement types.

Positive-displacement air compressors work by forcing air into a chamber whose volume is reduced to effect the compression. Piston-type air compressors use this principle by pumping air into an air chamber through the use of the constant motion of pistons. They use unidirectional valves to guide air into a chamber, where the air is compressed. Rotary screw compressors also use positive-displacement compression by matching two helical screws that, when turned, guide air into a chamber, the volume of which is reduced as the screws turn. Vane compressors use a slotted rotor with varied blade placement to guide air into a chamber and compress the volume.

Negative-displacement air compressors include centrifugal compressors. These devices use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air, which pressurizes it.

The air compressors seen by the public are used in 5 main applications:

• To supply a high-pressure clean air to fill gas cylinders
• To supply a moderate-pressure clean air to supply air to a submerged surface supplied diver
• To supply a large amount of moderate-pressure air to power pneumatic tools
• For filling tires
• To produce large volumes of moderate-pressure air for macroscopic industrial processes (such as oxidation for petroleum coking or cement plant bag house purge systems).

 

Most air compressors are either reciprocating piston type or rotary vane or rotary screw. Centrifugal compressors are common in very large applications. There are two main types of air compressor’s pumps: Oil lubed and oil-less. The oil-less system has more technical development, but they are more expensive, louder and last for less time than the oiled lube pumps. However, the air delivered has better quality.

A plane is a tool for shaping wood. Planes are used to flatten, reduce the thickness of, and impart a smooth surface to a rough piece of lumber or timber. Planing is used to produce horizontal, vertical, or inclined flat surfaces on workpieces usually too large for shaping. Special types of planes are designed to cut joints or decorative moldings.

Hand planes are generally the combination of a cutting edge, such as a sharpened metal plate, attached to a firm body, that when moved over a wood surface, take up relatively uniform shavings, by nature of the body riding on the ‘high spots’ in the wood, and also by providing a relatively constant angle to the cutting edge, render the planed surface very smooth. A cutter which extends below the bottom surface, or sole, of the plane slices off shavings of wood. A large, flat sole on a plane guides the cutter to remove only the highest parts of an imperfect surface, until, after several passes, the surface is flat and smooth.

Though most planes are pushed across a piece of wood, holding it with one or both hands, Japanese planes are pulled toward the body, not pushed away.
Woodworking machinery that perform the same function as hand planes include the jointer and the thickness planer, also called a thicknesser.

Wood putty, also called plastic wood, is a substance used to fill imperfections, such as nail holes, in wood prior to finishing. It is often composed of wood dust combined with a binder that dries and a diluent (thinner), and, sometimes, pigment. Pore fillers used for large flat surfaces such as floors or table tops generally contain silica instead of or in addition to wood dust. Pores can also be filled using multiple coats of the final finish rather than a pore filler.

The main problem in using putty is matching the colour of the putty to that of the wood. Putties are usually sanded after they dry before applying the finish.
Many different brands, types and colours are commercially available. Binders include lacquer, water-base, and linseed oil. Some woodworkers make their own putty using fine sanding dust (not sawdust which is too coarse) with wood glue or a wood finish such as shellac.

A grain filler or paste wood filler is a woodworking product that is used to achieve a smooth-textured wood finish by filling pores in the wood grain. It is used particularly on open grained woods such as oak, mahogany and walnut where building up multiple layers of standard wood finish is ineffective or impractical.

Shellac is a resin secreted by the female lac bug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes (pictured at right), which are dissolved in ethyl alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. Shellac functions as a tough all-natural primer, sanding sealant, tannin-blocker, odor-blocker, stain, and high-gloss varnish. Shellac was once used in electrical applications as it possesses good insulation qualities and it seals out moisture.

A wood stain consists of a colorant suspended or dissolved in a ‘vehicle’ or solvent. The suspension agent can be water, alcohol, petroleum distillate, or the actual finishing agent (shellac, lacquer, varnish, polyurethane, etc.). Colored or ‘stained’ finishes, like polyurethane, do not penetrate the pores of the wood to any significant degree and will disappear when the finish itself deteriorates or is removed intentionally.

Two types of colourants are used, pigments and dyes. The difference is in the size of the particles. Dyes are microscopic crystals that dissolve in the vehicle and pigments are suspended in the vehicle and are much larger. Dyes will color very fine grained wood, like cherry or maple, which pigments will not. Those fine-grained woods have pores too small for pigments to attach themselves to. Pigments contain a binder to help attach themselves to the wood.

The type of stain will either accentuate or obscure the wood grain and neither is superior to the other. Most commercial stains contain both dye and pigment and the degree to which they stain the appropriate wood is mostly dependent on the length of time they are left on the wood. Pigments, regardless of the suspension agent, will not give much color to very dense woods but will deeply color woods with large pores (e.g. pine). Dyes are translucent and pigments are opaque.

Gel stains are more akin to paint and have little penetrating ability.

Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss sheens by the addition of “flatting” agents. Varnish has little or no color, is transparent, and has no added pigment, as opposed to paints or wood stains, which contain pigment and generally range from opaque to translucent. Varnishes are also applied over wood stains as a final step to achieve a film for gloss and protection. Some products are marketed as a combined stain and varnish.

After being applied, the film-forming substances in varnishes either harden directly, as soon as the solvent has fully evaporated, or harden after evaporation of the solvent through certain curing processes, primarily chemical reaction between oils and oxygen from the air (autoxidation) and chemical reactions between components of the varnish.

Resin varnishes “dry” by evaporation of the solvent and harden almost immediately upon drying. Acrylic and waterborne varnishes “dry” upon evaporation of the water but experience an extended curing period. Oil, polyurethane, and epoxy varnishes remain liquid even after evaporation of the solvent but quickly begin to cure, undergoing successive stages from liquid or syrupy, to tacky or sticky, to dry gummy, to “dry to the touch”, to hard.

Environmental factors such as heat and humidity play a very large role in the drying and curing times of varnishes. In classic varnish the cure rate depends on the type of oil used and, to some extent, on the ratio of oil to resin. The drying and curing time of all varnishes may be sped up by exposure to an energy source such as sunlight, ultraviolet light, or heat.

Many varnishes rely on organic solvents, or on organic oils or resins for their binder; these are highly flammable in their liquid state. All drying oils, certain alkyds, and many single-component polyurethanes produce heat during the curing process. Therefore, oil-soaked rags and paper can smolder or ignite hours after application if they are bunched or piled together, or, for example, placed in a container where the heat cannot dissipate.

A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The oil hardens through a chemical reaction in which the components crosslink by the action of oxygen (not through the evaporation of water or other solvents). Drying oils are a key component of oil paint and some varnishes. Some commonly used drying oils include linseed (flax seed) oil, tung oil, poppy seed oil, perilla oil, and walnut oil. Their use has declined over the past several decades as they are replaced by alkyd resins and other binders. Oils that are susceptible to drying are also susceptible to becoming rancid autoxidation, the process by which fatty foods develop off-flavors.

In a general sense, lacquer is a clear or colored varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required.

The term lacquer originates from the Portuguese word for lac, a type of resin excreted from certain insects. Regardless, in modern usage, lac-based varnishes are referred to as shellac, while lacquer refers to other polymers dissolved in volatile organic compounds (VOCs), such as nitrocellulose, and later acrylic compounds dissolved in lacquer thinner, a mixture of several solvents typically containing butyl acetate and xylene or toluene.

While both lacquer and shellac are traditional finishes, lacquer is more durable than shellac.

Steel wool, also known as wire wool, is a bundle of strands of very fine soft steel filaments, used in finishing and repairing work to polish wood or metal objects, and for cleaning household cookware.

Steel wool is made from low-carbon steel (low enough to be close to plain iron). It is not made by drawing “steel wool wire” through a tapered die, but rather by a process more like broaching where a heavy steel wire is pulled through a toothed die that removes a thin wire shaving.

A brush is a tool with bristles, wire or other filaments, used for cleaning, grooming hair, make up, painting, surface finishing and for many other purposes. It generally consists of a handle or block to which the filaments are affixed, either parallel of perpendicular depending on the way the brush is to be gripped during use. The material of both the block and bristles, filaments, is also chosen to withstand hazards of its application, such as corrosive chemicals, heat or abrasion, this gives rise to a range of possible choices including plastic, metal, wood or even animal hair.

Rotten stone, sometimes spelled as one word, and also known as tripoli, is fine powdered rock used as a polishing abrasive in woodworking. It is usually weathered limestone mixed with diatomaceous, amorphous, or crystalline silica. It has similar applications to pumice, but it is generally sold as a finer powder and used for a more glossy polish after an initial treatment with coarser pumice powder.

It is usually mixed with oil, sometimes water, and rubbed on the surface of varnished or lacquered wood with a felt pad or cloth. Rotten stone is sometimes used to buff stains out of wood. Some polishing waxes contain powdered rotten stone in a paste substrate. For larger polishing jobs, rotten stone mixed with a binder is applied to polishing wheels.

It has also been used to polish brass, such as that found on military uniforms, as well as steel and other metals. Plates used in daguerreotypes were polished using rotten stone, the finest abrasive available at the time.

French polishing is a wood finishing technique that results in a very high gloss surface, with a deep color and chatoyancy. Shellac is the purified secretion of the lac beetle, a sap-sucking insect from India and Thailand. It can be bought ready mixed, or in flakes or “buttons” and may be clear or tinted red (ruby) golden, (blonde) or other colors. French polishing consists of applying many thin coats of shellac dissolved in alcohol using a rubbing pad. The rubbing pad is made up of absorbent cotton or wool cloth wadding inside a square piece of fabric (usually soft cotton cloth) and is commonly referred to as a fad, (also called a tampon or muneca, Spanish for “rag doll”).

The pad is first used to put a thinned coat of shellac on, then thicker coats with small amounts of superfine pumice, a crushed volcanic glass. The pumice acts both as a fine abrasive and to fill the pores of open-grain woods. Each coat must be fully dry before the next application, to avoid lifting out the softened finish.

The finish is considered to be one of the most beautiful ways to finish highly figured wood, but it is also recognized to be fragile. It is softer than modern varnishes and lacquers and is particularly sensitive to spills of water or alcohol, which often produce white cloudy marks. However it is also simpler to repair than a damaged varnish finish, as patch repairs to French polish may be easily blended into an existing finish.

“French polish” is a process, not a material. The main material is shellac, although there are several other shellac-based finishes, not all of which class as French polishing.
The process is lengthy and very repetitive. The finish is obtained through a specific combination of different rubbing motions (generally circles and figure-eights), waiting for considerable time, building up layers of polish and then spiriting off any streaks left in the surface.

The ‘fad’ is commonly lubricated with an oil that is integrated into the overall finish. This helps to prevent the ‘fad’ from lifting previously applied layers of shellac. Typically, “softer” oils, such as mineral oil, will produce a glossier and less durable finish whereas “harder” oils, such as walnut oil and olive oil, will produce a more durable finish.
Additives to the shellac mixture include sandarac (sap of an African cedar) and copal, sap of a South American tree. These and other additives combined with heat and light can make the finish tougher, by cross-linking the polymers and oils in the shellac.

The piece is usually finished off after leveling (1500 grit oil sanding), then light buffing with carnauba paste wax. Too much heat or pressure from buffing will melt off the shellac and result in a bare spot that must be refinished.

French polishing became prominent in the 18th century. In the Victorian era, French polishing was commonly used on mahogany and other expensive woods, and was considered the best possible finish for fine furniture and string instruments such as pianos, lutes and guitars. The process was very labour intensive, however, and many major manufacturers abandoned the technique around 1930, preferring the cheaper and quicker techniques of spray finishing nitrocellulose lacquer and abrasive buffing. In Britain, instead of abrasive buffing, a fad of “pullover” is used in much the same way as traditional French polishing. This slightly melts the sprayed surface and has the effect of filling the grain and burnishing at the same time to leave a “French polished” look.

Another reason shellac fell from favor is its tendency to melt under low heat; for example, hot cups can leave marks on it. However, French polish is far more forgiving than any other finish in the sense that unlike lacquers, it can be easily repaired.