The part of the setting that holds the center stone or solitaire in place.Moh's scale of hardness is useful for comparing the relative hardness of different gem materials. The values are as follows: 10 – Diamond (hardest) 9 – Corundum 8 – Topaz 7 – Quartz 6 – Feldspar 5 – Apatite 4 – Fluorite 3 – Calcite 2 – Gypsum 1 – Talc (softest)
A material's ability to resist a distorting force. Measured by the relative resistance of the material to an indentor point. See durometer.
The degree of resistance of a given mineral to scratching, indicating the strength of the bonds that hold the mineral's atoms together. The hardness of a mineral is measured by rubbing it with substances of known hardness.
In gemology, the resistance of a substance to surface scratching. It does not relate in any respect to ability to escape other kinds of injury such as crushing or breaking. Diamond is the hardest mineral substance, with a rating of 10 on the Mohs scale; talc is the softest, with a rating of 1 on the Mohs scale. Diamonds can be scratched only by other diamonds. They can, however, be cut and cleaved apart with conventional tools.
1. mineralogy. The measure of the resistance of a mineral to scratching or abrasion. 2. water. A property of water resulting from the presence of calcium carbonate and magnesium carbonate in solution.
A measure of the calcium and magnesium salts present in water. Hardness is measured in milligrams per liter and expressed as calcium carbonate (CaCO3).
A measure of the amount of calcium and magnesium salts in water. Usually expressed as grains per gallon or ppm as CaCO or °dH.
A property of wood that enables it to resist indentation. It is measure in kN and is often determined by the Janka hardness test.
A gem's ability to resist scratching.
The hardness of a water is a measure of the concentration of the multivalent cations (positively charged particles) in the water, but primarily it is equivalent to the calcium and magnesium concentration of the water. Hardness is typically reported as mg /L as CaCO3 (calcium carbonate), but it may also be reported as grains per gallon (1 gpg (US) = 17.12 mg CaCO3/L ). Hardness Classification: Soft: 0 to 17 mg CaCO3/L; Slightly Hard: 17 to 60 mg/L; Moderately Hard 60 to 120 mg/L; Hard 120 to 180 mg/L; and Very Hard 180 mg/L. For more information visit the Hardness Website.
The hardness of a material is measured by pressing a pointed diamond or hardened steel ball into its surface. The hardness is defined as the indenter force divided by the projected area of the indent.
It is the ability of a gem to resist scratching.
Hardness is the resistance of a material to deformation, indentation, or scratching. Hardness is measured on various scales, such as Mohs, Brinell, Knoop, Rockwell, and Vickers.
Hardness is the intrinsic property of a wood that enables it to resist indentation. It is measured in the pounds per square inch of pressure that is required to sink a .444 inch steel ball one half its diameter into the surface of the wood dried to a 12% moisture content. This method is called the Janka test. Harder woods have higher numbers.
A stone's resistance to wear and scratching measured on Mohs hardness scale. Diamond is hardness 10 which is the hardest on the scale.
a measure of the hardness of a metal or mineral. Hardness is a property easy to appreciate but difficult to quantify and measure. The Mohs hardness scale is used in geology to give a rough estimate of hardness by testing which minerals are able to scratch the sample. In metallurgy, samples are tested for hardness by machines which indent the surface under a controlled pressure; the resulting measurement is often computed as the force applied divided by the surface area of the indentation. The Brinell, Vickers, Rockwell, and Knoop tests are among the techniques used. Plastics, rubber, and similar materials are tested with instruments called durometers and the resulting readings are often designated duro.
The resistance of a material to surface damage, such as indentation, scratching, abrasion, or crushing. The hardness test used most commonly for archaeological pottery is the Moh's Scale.
The concentration of calcium and magnesium ions in water; frequently expressed as mg/L (milligrams per liter) calcium carbonate equivalent.
A characteristic of water caused by mineral salts of magnesium and calcium.
Hardness is the total amount of calcium and magnesium ions found in water. Hard water affects detergents (by limiting suds formation). Scale formation in pipes is accelerated with hard water. Some scale formation is desirable to protect pipes from corrosion. Excessive scaling clogs pipes and can shorten the life of home appliances. There is no drinking water standard for hardness, and it is usually reported in mg/L of calcite.
In materials science, hardness is the characteristic of a solid material expressing its resistance to permament deformation.
The resistance of the wood against indentation and abrasion. Values are given in Newtons (N) and are a measure of the load required to embed a 11.3mm ball to one half its diameter in the wood.
the relative ability of a mineral to scratch or be scratched by another mineral or object
A measure of the ease with which the surface of a mineral can be scratched.
Opal registers between 5.5 - 6.5 on Moh's Scale of Hardness (Similar to glass)
Natural waters contain various amounts of dissolved impurities. Some of these impurities affect the lathering of soap with the main offenders being the soluble salts of magnesium and calcium. The hardness of water is defined as its difficulty in raising lather, and is measured in terms of the equivalent amount of calcium carbonate in a solution, which would cause equal difficulty in lathering. It is expressed in milligrams per litre (mg/L). The hardness is generally determined by finding the quantity of a specially prepared soap solution that is necessary to add to a known quantity of water in order to establish a permanent lather, however, it can also be determined using general chemical analysis techniques. A general classification of waters would be as follows; Type Hardness Soft 0-49mg/L
(r) a material's ability to resist a distorting force (indentor point).
Measure of a materialâ€(tm)s resistance to localised plastic deformation. Most hardness tests involve indentation, but hardness may be reported as resistance to scratching (file test), or rebound of a projectile bounced off the material (scleroscope hardness). Some common measures of indentation hardness are Brinell Hardness Number (HBN) and Rockwell Hardness Number (HRC).
A measure of the resistance of a metal to indentation by a loaded indenter. The common tests used to determine hardness are the Vickers, Brinell or Rockwell tests.
A property of water that causes the formation of an insoluble residue when the water is used with soap and a scale in vessels in which water has been allowed to evaporate. It is due primarily to the presence of ions of calcium and magnesium. Generally expressed as milligrams per liter as calcium carbonate (CaCO3). A general hardness scale is: Description Milligrams per liter as CaCO3 Soft 0 - 60 Moderately hard 61-120 Hard 121-180 Very hard More than 180
Ability of a species of wood to resist denting. Determined by gauging the amount of pressure needed to sink a 1/4" steel ball ½ its diameter into the wood.
Hardness is the resistance of a material to deformation of an indenter of specific size and shape under known load. This definition applies to all types of hardness scales except Mohs scale, which is a based on the concept of scratch hardness and is used chiefly for minerals. The most generally used hardness scales are Brinell (for cast iron), Rockwell (for sheet metal and heat-treated steel), Knoop (for metals).
The total concentration of the calcium and magnesium ions in water expressed as calcium carbonate (mg/ CaCO3 /litre). Hard waters from both underground and surface water supplies are most common in areas having extensive geological formations of limestone.
An expression of the concentration of inorganic salts in water which prevents effective cleaning and germicidal action. Hardness is measured in ppm (parts per million) calculated as calcium carbonate' (CaCO.).Also (a) Knoop Hardness value relating resistance to indentation by a weighted wedge shaped diamond. (b) Pencil Hardness a measure related to the hardness of various grades of graphite. Pencil Hardness is related to a polishes' resistance to both indentation and tearing, Very soft 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H Very Hard.
The resistance to surface indentation usually measured by the depth of penetration of a blunt point under a given load using a particular instrument according to a prescribed procedure.
Concentration of calcium and magnesium salts in water. Hardness originally referred to the soap-consuming power of water; as such it is sometimes also taken to include iron and manganese. "Permanent hardness" also known as "noncarbonated hardness " is the excess of hardness over alkalinity. "Temporary hardness" also known as "carbonated hardness" is equal or less than the alkalinity. Permanent hardness can cause boiler or pipe scale and failure of reverse osmosis membranes.
See Mohs’ hardness scale.
property of a material: A hard material is difficult to scratch or indent
The end result of a number of properties such as modulus, state of cure, and cross-link density. It should never be used, as it often is, as a sole specification. "Hardness" as applied to elastomers, is defined as the relative resistance to indentation (not puncture) of a probe of specified dimensions under specified spring load, read on a scale of 0-100. The instrument used is called a durometer. Shore and Rex are names of manufacturers of ASTM recognized durometers. There are two generally used scales: "A" and "D". They overlap as shown in the diagram on page 8. By convention, we allow tolerance in reading of +/- 5 points on the durometer "A" up to 90, and +/- 3 points from 90 to 96 durometer A. The "A" scale is not reliable above 96A, so we use the durometer "D" scale for harder materials and a tolerance of +/- 5 points. See ASTM D-314, ASTM D-2240.
The quality of metal that describes resistance to denting, scratching, or bending.
A characteristic of water representing the total concentration of calcium and magnesium ions.
The capacity of a substance to be scratched or penetrated by another.
The sum of the divalent cation concentrations expressed as meq/L or mg calcium carbonate per liter [mg CaCO3/L]. It is important because hard waters require increased amounts of soap for bathing or washing clothes and because of scale formation on piping, cooking vessels, water heaters, boilers, heat exchangers, etc.
Resistance of material to permanent deformation.
The resistance of the film to cutting, indentation, or penetration by a hard object.
In reference to gems and minerals, the resistance offered to abrasion or scratching. Minerals are measured and numbered on a relative hardness scale, where the intervals between the numbers are very different (e.g. a diamond, the hardest, is far harder than the next mineral down the list).
A measure of the amount of dissolved minerals found in water, specifically calcium and magnesium.
The amount of calcium, magnesium, iron, carbonates, sulfates, chlorides, nitrates, phosphates, and silicates dissolved in the water. Scale deposits are formed when there are high levels of hardness in pool water.
A general term that correlates with strength, rigidity, and resistance to abrasion or penetration. Measured on Shore or Rockwell scales.
the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
The amount of calcium or magnesium dissolved in the water. High levels contribute to scale deposits.
The levels of hardness in terms of parts per million of dissolved calcium carbonate are: 0-75 ppm Soft 75-150 ppm Moderately hard 150 - 300 ppm Hard 300 + ppm Very hard
Calcium and magnesium are the main hardness minerals. Although hardness is not a health threat, excessive levels may be harmful to plumbing fixtures and pipes. White deposits around faucets and on dishware are often caused by excessive hardness.
The ability to resist being scratched.
The hardness specifies the material ability to resist a hard object that is pressed into the material. An example of a method of measurement for hardness is Brinell.
Hardness of tubular products is measured by a destructive test performed on a standard Rockwell Penetrator and recorded on the Rockwell "B" scale. Hardness is inversely proportional to the temperature and duration of the annealing process. In general, as the hardness number increases, both tensile and yield strengths increase while elongation (ductility) decreases.
The ability of a surface to resist penetration or scratching.
See Mohs Scale of Hardness
that characteristic of water caused by calcium and magnesium that causes scaling, spots on glassware and other aesthetic concerns. Colorado River water in Lake Mead is considered to be very hard, having a calcium carbonate value of about 300 milligrams per liter.
The property of metals and their alloys relating to strength, elasticity, and toughness and defined as the measurement of its resistance to indentation. Through-hardened parts are typically measured by the Rb, Rc or Brinell scales. Case-hardened parts usually have a hardness specified to a specific depth.
Ability of a dry paint film to withstand indentation.
Resistance to a distorting force measured by the relative resistance of the material to an indented point of a standard hardness testing instrument.
approximates to the concentration of calcium and magnesium salts in water. Total hardness is the sum of carbonates and non-carbonate hardness. It may be expressed as degrees of hardness, millimoles per litre (expressed as calcium Equivalent), or as parts per million of CaCO3 equivalent.
The measure of a material's resistance to indentation, normally expressed in Brinell (Bhn) or Rockwell "C" scale (Rc) units.
The resistance of a material to compression, indentation and scratching. There are several scales, and the data in the book gives both the scale used and the value on it.
A measure of a panel's resistance to surface indentation, or impact resistance, which is stated in pounds, and is related to panel density.
The ability of a metal to resist penetration, defined in terms of the measurement (Brinell, Rockwell, etc.)
Resistance of metal to penetration of the surface.
The amount of scratch resistance on a mineral's surface
Mineral's resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it.
The resistance of a metal to plastic deformation by indentation. Common methods of measurement are Rockwell, Brinell, Scleroscope and Vickers.
The amount of dissolved minerals in water measured in grains per gallon (GPG). The most common minerals are calcium and magnesium
Degree of hardness using the Shore standard for compressable rollers and Rockwell standard for steel rolls.
The measure of a material's strength, rigidity, and resistance to abrasion or penetration.
A measure of a mineral's resistance to scratching. The hardness of a mineral is measured by scratching it against another substance of known hardness.
the tendency of a water to form scale or soap scum due to the presence of dissolved minerals, primarily calcium and magnesium.
The resistance of surface indentation usually measured by a prescribed hardness tester.
that property of a material concerned with how difficult it is to scratch. A hard material is difficult to scratch; a soft material is easy to scratch
A water quality index that describes the concentration of alkaline salts in water, mainly calcium and magnesium. If water is "hard" then more soap, detergent or shampoo is necessary to make bubbles for effective washing/ cleaning. Hardness is measured in milligrams per liter (mg/l) but may also be reported in the archaic form of grains per gallon. [One grain of hardness equals 17.1mgl] Typical water hardness classifications are: Soft water less than 17mg/l Slightly hard 17 - 60 mg/l Moderately hard 60-120 mg/l Hard 120-180 mg/l Very hard 180 + mg/l
The degree of pressure a material will withstand without becoming deformed or scratched.
A measure of how easily a substance is scratched or dented.
in minerals, resistance to scratching. Usually listed as a number on a scale of 1 through 10 (Moh's Scale of Hardness).
Measure of the amount of calcium and magnesium dissolved in the water, normal range 200-400 ppm.
The amount of calcium and magnesium dissolved in water; measured by a test kit and expressed as parts per million (ppm).
That property of the wood species or dried film of finishing material that causes it to withstand denting or being marked when pressure is exerted on its surface by an outside object or force.
A measure of the resistance of a material to indent when an indentor of known geometry is impressed against a surface under a given load.
Resistance to deformation, indentation, abrasion, cutting, etc.
The relative resistance of rubber to the penetration (without puncturing) of a blunt point impressed on its surface.
A measure of resistance of balls to penetration.
A characteristic of tubular products that is measured on samples of tubing using a standard Rockwell Penetrator and recording the results on the Rockwell "B" scale. Hardness is the direct result of annealing temperatures and material properties; in general, as the hardness number increases, both tensile and yield strengths increase along with a corresponding decrease in elongation (ductility).
A measure of the calcium and magnesium ion content in water. Carbonate or alkaline hardness is due to bicarbonates, carbonates and hydroxides of these elements.
A characteristic of water caused by the presence of various salts, calcium, magnesium, and iron. Water is soft if the content of these materials is low, hard if the content is high.
a characteristic of water determined by the levels of calcium and magnesium
A hard material is one that resists indentation, which means it resists scratching, wear and abrasion and is difficult to machine. Ceramics are one of the hardest types of materials.
The resistance of a metal or alloy to the penetration of another substance, or to abrasion i.e., wearing or machining. The hardness (or temper) of a metal determines its ability to be worked. Hardness is measured by a scale known as VPN (Vickers Pyramid Number). Certain manufacturing processes in the jewellery industry require material at a given hardness e.g., pins for earwires and material may be ordered as hard, half hard, quarter hard or by a specific VPN number.
Resistance to plastic deformation, usually by indentation. The term may also refer to stiffness or temper, or to resistance to scratching, abrasion or cutting.
The combined measured total of calcium and magnesium in water (measured in mg/l) as calcium carbonate.
An assessment of water quality based on the content of calcium and magnesium. Different scales are used in England, France. Germany and the United States. In the Atlas, hardness is expressed as an equivalent to 1 rag/L CaCO3 following a practice developed by early water supply engineers who wanted to standardize hardness and alkalinity to the same units.
Hardness is probably the most widely used and recognized property of elastomers. Most people can discern differences in hardness between two similar parts simply by their feel. This elastomeric quality is analogous to Rockwell Hardness in steel. Elastomer hardness is measured using an instrument called a durometer. The durometer is a device with a spring loaded indentor. The indentor is pushed against the elastomeric sample. Depth of penetration of the indentor into the sample indicates the hardness. The farther the indentor penetrates, the lower the durometer or the softer the sample. In general, hardness will range from approximately 15 to 100 on the A scale. Material with a 15 durometer will be very soft like sponge and material with a harness of 100 will be extremely hard just like a rigid plastic. Not all types of elastomers can be compounded to the extremes listed above. Many cannot be compounded below approximately 40 or above approximately 90.
The concentration of calcium and magnesium salts in water. Gives rise to scale formation and reacts with soap.
the measure of steel's resistance to permanent deformation by a penetrator
the resistance to indentation. Usually measured with a durometer. (See ASTM D 2240.)
Refers to the amount of calcium present in the water.
A term typically used to describe a gem's ability to survive a scratch. Usually rated on a Mohs' scale.
The measure of a materialâ€(tm)s ability to resist indentation.
Condition of water, caused mostly by naturally occurring mineral impurities, that prevents suds formation by soap.
Hardness measures the ease with which soap can be lathered. It is easier to produce a lather using soft water. Water hardness is generally divided into the following categories. Soft Moderately Hard Hard Very Hard 0 to 75 parts per million 75 to 150 parts per million 150 to 300 parts per million more than 300 parts per million To convert hardness levels in parts per million to hardness in grains per gallon, divide by 17.1.
Hardness is essentially a measure of the calcium and magnesium in water. Hard water is not a health risk; however, it keeps soap from lathering, decreases cleaning action of soaps and detergents, leaves soap "scum" on plumbing fixtures, and leaves scale deposits on water pipes and hot water heaters, possibly shortening the life of the heater. Softening treatment is recommended for very hard water (above 180 mg/l). Water with hardness of about 80 mg/l or less does not need softening. Water hardness may also be reported in units of grains per gallon, or gpg (1 gpg = 17.1 mg/l hardness).
The resistance of a material to deformations by indentation. For electroless nickel plating, common hardness values range from 44 HRC to 59 HRC.
Resistance a material offers to scratching or abrasion. Generally measured using the MOHS scale.
a characteristic of water caused by various salts, calcium, magnesium and iron (e.g. bicarbonates, sulfates, chlorides and nitrates).
The ability of a material to resist penetration.
The resistance of a mineral to scratching and abrasion (see Mohs scale).
Hardness as a property of rubber stocks is difficult to define except according to the methods used to determine it, These methods measure the resistance of the stock to indentation by the blunt point of a metal rod, bail or needle. Thus the hardness of rubber can best be described as the resistance to identation. Various instruments measure indentation. The most common instrument used on rubber is the Durometer. Several scales are used depending on the hardness range (00, 0, A, B, C, 0), but the A scale, ASTM 02240, is used for most compounds. Readings on each scale are from 0 is 100. Durometer hardness is a convenient nondestructive method of testing which can also be correlated to other properties such as tensile strength, tensile modulus, plasticity, and resilience. Since indentation hardness is dependent upon elastic modulus and viscoelastic behavior of the compound, rubber compounds which are not completely elastic will “creep” during the test. This creep should be noted an the difference between the initial hardness rending and the reading after 15 Seconds of engagement with the specimen. A properly noted reading: Durometer A 61, creep 4 at 15 seconds. 73°F.
The amount of calcium and magnesium dissolved in the water. "Water" or "total" hardness refers to the total of the magnesium and calcium dissolved in the water. Calcium hardness refers to just the calcium. Measured by a test kit and expressed as ppm. Proper range is 200 - 400 ppm.
Resistance of a stone to force, scratching etc. Determined by the Mohs Scale of hardness (a relative scale of hardness where the lowest is talc at a hardness of 1 and the highest is diamond, at 10).
A material’s resistance to indentation, scratching or cutting.
The degree to which a material will withstand pressure without deformation or scratching.
The amount of calcium and magnesium in the water in grains per gallon, (expressed as calcium carbonate). This level is important to control during distillation or reverse osmosis processes to prevent scaling. Each grain is equal to 17.1 ppm of calcium and magnesium (expressed as calcium carbonate). What constitutes truly "hard" water is subject to much debate and controversy. Proponents of water softening systems tend to call water "hard" which contains between 3 and 10 grains of hardness. This definition is supported by the American Society of Agricultural Engineers and the Water Quality Association, major supporters of the water softening industry. Water with 10 grains of hardness, is regularly used by consumers, with little or no adverse affect on plumbing or other household functions. Water, which approaches 15 to 20 grains is more in line with situations which require water softening or conditioning. Water with 3 grains of hardness and is termed "moderately hard" by these organizations is typically found in surface and spring water sources, far removed from what one would consider hard water sources.
Generally defined as resistance to indentation using a modified Janka hardness test, measured by the load required to embed a 11.28 mm (0.444 in.) ball to one-half its diameter. Values presented are the average of radial and tangential penetrations.
Resistance to scratching. The higher the number, the more resistant.
A good indicator of steel's ability to hold an edge. A blade's hardness is measured on the Rockwell "C" scale, a testing process described in Making a Knife.
The amount of minerals present in a water supply, usually measured in grains. The hardness of your water is used to calculate the capacity of the Water Conditioner you will need.
The resistance of a plastic material to compression and indentation. Among the most important methods of testing this property are Brinell hardness, Rockwell hardness and Shore hardness.
The measure of a materials resistance to deformation by surface indentation or by abrasion.
Hardness is measured using the Mohs Scale of Hardness. A substance's hardness value indicates the materials resistance to scratching and grades minerals on a comparative scale from 1 (very soft) to 10 (very hard).. In the Mohs scale, a mineral of a given hardness rating will scratch other minerals of the same rating, as well as any minerals of a lower rating. For example, sapphires and rubies have a Mohs rating of 9 and will scratch each other, as well as any mineral with a rating lower than 9. However, they will not scratch diamonds, which are rated 10. The Mohs scale of mineral hardness was devised by the German mineralogist Frederich Mohs (1773-1839) in 1812. Substance Hardness Talc 1 Amber, Fingernail, Ivory, Shell, Jet 2.5 Gold 2-3 Bronze, Coral, Pearl 3 Iron 4 Glass 5 Opal 5.5-6.5 Amethyst, Chalcedony, Quartz, Steel (pocket knife) 7 Spinel, Topaz 8 Ruby, Sapphire 9 Diamond 10
In mineralogy, the ability of one mineral to scratch another. This can be measured by the Mohs scale.
There are numerical measures of hardness, but for our purposes, I rank the woods we use by this subjective scale, garnered by experience: moderately hard, hard, very hard. The harder the wood, the more resistant to denting, wear, and abrasion.
The resistance of a gem mineral to scratching and abrading. There are several hardness scales with the one devised by Mohs being best known. See also Toughness.
Quality of the paint film that gives it resistance to surface damage.
A term used to describe the ability of a paint film to resist impact damage, scratching or abrasion.
A formal test of resistance to penetration by a pointed or rounded indentor under a given load. There are many useful hardness tests where the depth or width of the penetration is measured. Often this relates to other material properties such as strength.
Resistance of a paint film to surface damage measured as in pencil hardness.
The hardness of steel is generally determined by testing its resistance to deformation. A number of methods are employed including Brinell, Vickers and Rockwell. The steel to be tested is indented by a hardened steel ball or diamond under a given load and the size of the impression is then measured. For steel there is an empirical relationship between hardness and tensile strength and the hardness number is often used as a guide to the tensile strength, e.g. 229 Brinell = 772N/mm2 (50 tons/sq.in).
A comparative measurement of impact stress required to produce a level of surface deformation on a metal product. Some of the popular testing scales are Brinell and Rockwell hardness tests.
Coatings should not scratch or mark easily. The most extreme example is paints for the bows of icebreakers, which use extremely hard pigments to enable them to stand up to months of cutting through pack ice. Another form of marking can occur when coatings rub together, particularly in printing and packaging applications. Rub resistance may be improved by using small amounts of waxes as additives.
A measurement of the calcium and magnesium in water.
a water-quality indication of the concentration of alkaline salts in water, mainly calcium and magnesium. If the water you use is "hard" then more soap, detergent or shampoo is necessary to raise a lather.
Also called calcium hardness. The amount of dissolved minerals (mostly calcium and magnesium) in a body of water. In unbalanced water, high levels cause scale and low levels corrode surfaces and equipment.
The scale-forming and lather-inhibiting qualities which some water supplies possess, caused by high concentrations of calcium and magnesium. Temporary hardness, caused by the presence of magnesium or calcium bicarbonate, is so called because it may be removed by boiling the water to convert the bicarbonates to the insoluble carbonates. Calcium and magnesium sulfates and chlorides cause permanent hardness.
A measure of the resistance of a material to surface indentation or abrasion; a function of the stress required to produce some specified type of surface deformation.
A characteristic of natural water due to the presence of dissolved calcium and magnesium. Water hardness is responsible for most scale formation in pipes and water heaters and forms insoluble "curd" when it reacts with soap. Hardness is usually expressed in grains per gallon (gpg).
A measure of the hardness of a metal, as determined by pressing a hard steel ball or diamond penetrator into a smooth surface under standard conditions. Results are often expressed in terms of Rockwell Hardness Number (HRB or HRC) or Brinell Hardness Number (BHN).
Undesirable scale-forming salts, principally calcium and magnesium.
The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specified indenting shape as determined by specified methods.
A measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness; therefore, to express hardness quantitatively, each type of test has its own scale of arbitrarily defined hardness. Indentation hardness can be measured by Brinell, Rockwell, Vickers, Knoop, and Scleroscope hardness scales.
The hardness of water is equal to the concentration of dissolved calcium and magnesium ions. Usually expressed as ppm of (CaCO3).
The quantity of multivalent cations (cations with more than one +), primarily calcium (Ca++) and magnesium (Mg++) in the water expressed as milligrams per liter of CaCO3. Amount of hardness relates to the presence of soluble minerals, especially limestone, in the lake watershed.
The resistance to indentation, as measured under specific conditions.
Hardness of a mineral is a measure of its resistance to being scratched. It can be given a number by reference to Moh's scale
the resistance of a substance to surface abrasion.
After volumetric weight (density), hardness is the most important characteristic of a foam. Matresses and furniture, for example, demand complete body support from their foam elements. A material which is too soft offers insufficient support in extreme cases, while too hard a material lacks comfort. In this context thickness also plays a role. The synergy between foam quality, foam thickness and the nature of the substructure is decisive. Hardness is labotratory tested by compressing a foam sample of given dimensions to 65%, 40% and 25% of its original thickness, while measuring the force nedded to achieve this. In order to ensure the highest degree of comfort, different degrees of hardness are available, depending on the relevant sector and the intended application of the foam.
The ability of a paint film to resist denting, scratching, or marring.
A measure of the minerals, predominantly calcium and magnesium, dissolved in water that affect its soap neutralizing characteristics and the formation of scale on pipes and in boilers.
The wood's resistance to impact. Hardness depends on the density of the fibers and is measured in terms of the pressure required for a steel ball to mark the wood to a certain depth. The harder the wood, the higher the pressure required.
the amount of dissolved calcium and magnesium in a water sample, typically measured in grains per gallon (gpg)
This is a property of wood that enables it to resist indentation.
Many State Department of Environmental Services recommend treatment at 125-150mg/L. Hardness is the result of segregation of minerals such as calcium, magnesium and silica. Excessive hardness can cause scale formation in heating systems and combined with soap may leave insoluble particles.
(1) Water-quality parameter that indicates the level of alkaline salts, principally calcium and magnesium, and expressed as equivalent calcium carbonate (CaCO3). Hard water is commonly recognized by the increased quantities of soap, detergent, or shampoo necessary to lather. (2) In mineralogy, the degree of hardness of a mineral is an aid in identification. Geologists have assigned numbers to the hardness of several minerals; in this hardness scale, softer minerals are assigned a low mineral and the harder minerals a higher number.
Resistance of rubber to forced distortion measured by the standard hardness testing instruments.
Hardness is defined as a stone's ability to resist scratching, surface inclusions, abrasions or cracking.
The state or quality of being hard. Able to resist wear and abrasion. The ability to resist penetration and scratching.
A common quality of water which contains dissolved compounds of calcium and magnesium and, sometimes, other divalent and trivalent metallic elements. The term hardness was originally applied to waters that were hard to wash in, referring to the soap wasting properties of hard water. Hardness prevents soap from lathering by causing the development of an insoluble curdy precipitate in the water; hardness typically causes the buildup of hardness scale (such as seen in cooking pans). Dissolved calcium and magnesium salts are primarily responsible for most scaling in pipes and water heaters and cause numerous problems in laundry, kitchen, and bath. Hardness is usually expressed in grains per gallon (or ppm) as calcium carbonate equivalent.
The quantity of calcium and magnesium dissolved in water. High levels contribute to cloudy water and scale formation, while low levels cause water to "attack" pool components. Calcium hardness is used for water balance.
Resistance of a material to indentation as measured by such methods as Brinell, Rockwell, and Vickers. The term hardness also refers to stiffness of a material, or its resistance to scratching, abrasion, or cutting. See BHN, Brinell Hardness, Vickers Diamond.
The measure of a stone's ability to resist scratching, surface inclusions, abrasions or cracking. See Mohs scale.
A property of wood that enables it to resist indentation. Hardwoods. Generally one of the botanical groups of trees that have broad leaves in contrast to the conifers or softwoods. The term has no reference to the actual hardness of the wood. - Category: Equipment and Gear
Degree of hardness. Shore and Rockwell being two (2) scales used to measure and compare hardness. Usually ‘Shore’ is used to describe the hardness factor of rubber rollers.
the relative resistance of a material to indentation.
A measure of the amount of calcium and magnesium salts in boiler water . Usually expressed as grains per gallon or parts per million as CaCO2
Resistance of a mineral to abrasion or scratching.
Resistance of a body to indentation by another body; hardness is either intrinsic or is achieved by heat treatment processes (steel) and/or thermochemical diffusion; for rolling bearings, hardness is measured in Rockwell (HRC) or Vickers (HV).
A substance's hardness is how resistant it is to being scratched. Hardness is measured using the Mohs Scale of Hardness. In the Mohs scale, one substance is harder than another if it can scratch it. For example, a diamond will scratch garnet, but not the other way around, so a diamond in harder than garnet.
The compactness of the steel molecules determine the hardness of the steel. Harder steel tends to hold an edge longer, while softer steel is easier to sharpen. A blades hardness is measured by the Rockwell test which is understood and accepted worldwide. A Rockwell hardness above 60 will be difficult to sharpen, but a hardness below 56 will not hold an edge very well.
Resistance of a material to deformation by indentation. See Shore Hardness.
Resistance of material to plastic deformation, usually by indentation.
The ability of an ink film, as distinct from its substrate, to resist indentation or penetration of a hard object.
1. When used in reference to water hardness is the total parts per million (ppm) of calcium an CaCO3 plus the magnesium expressed as equivalent CaCO3 [ppm hardness (as CaCO3) = (ppm Ca x 2.497 + ppm Mg x 4.116)]. 2. Used in reference to pulp to denote the degree of delignification.
1. A property of a material that resists indentation. 2. Of water, the quantity of dissolved minerals, such as calcium and magnesium compounds.
The degree to which a metal will resist cutting, abrasion, penetration, bending and stretching. The indicated hardness of metals will differ somewhat with the specific apparatus measuring hardness. (See Brinnell Hardness, Rockwell Hardness, Vickers Hardness, Scleroscope Hardness). Tensile strength also is an indication of hardness.
Measure of a materials resistance to dents or scratches.
When referring to graphite or charcoal, the degree of softness or hardness of the lead. Hard leads (labeled with H) tend to be lighter in value, while softer leads are darker (labeled with B). Hard leads include 9H (lightest) to 2H (darkest of the hard leads). Softest leads start at 9B (darkest) and vary to 2B (lightest of the soft leads). In between the two scales are H, HB, B and F.