Green Sand Metalcasting Foundry News

"L" - Glossary of Foundry Additives (including Lignin "Goulac" core binder)

Posted by Hill and Griffith Company on Apr 24, 2018 11:41:09 PM

L - Foundry Additives Glossary

LAC (See: RESIN-SHELLAC)

LAKE SAND (See: SAND, LAKE)
Sand occurring in, or near, lake areas which may contain some impurities is called "Lake Sand." It is used in many Midwestern foun­dry core and molding compositions. It is an economical foundry base sand.

LAMPBLACK (See: CARBON -CARBON BLACK
Lampblack is actually soot formed by the smudge process of burning oils, resins, tars, or other carbonaceous material where there is an insufficient supply of air. The soot is allowed to settle on the metallic, cooler walls or areas before it is collected. Lampblack is practically pure carbon. It is used in the foundry as a coloring agent and in a few commercial facing mixtures. Chemically it resembles carbon black which is made by burning gas. Lampblack is very fine and colloidal in form. One pound may occupy over 200 cubic inches in volume.

LARD Oil (See: LIQUID PARTINGS-OILS-PARTINGS)
Lard oil is a fluid oil which contains oleic, stearic and palmatic acids. It is widely used in foundry lubricating oils, but it is also used in many liquid partings of the foundry. It is usually blended with kerosene and other compatible liquids. It has a specific gravity of 0.92. Lard has been used in the past as an additive for certain core oils, as a pattern or core box release.

Foundry-Additives-Glossary-A-1.jpg

LATEX (See: RUBBER BINDER)

LEONARDrTE (See: LIGNITE)

LIGNIN (See: SULFITE [SULPHITE] LIQUOR)

LIGNIN BINDER (See: BINDERS-BONDS-CALCIUM LIGNIN-GLUTRIN-GOULAC-LIGNIN SULFONATE-LIQUID ORGANIC BINDER-LIGNONE)
It is a brown, crystalline-like product, recovered from paper­pulp sulfite liquor and is used in the foundry as an auxiliary binder. The melting point of lignin is 482°F. to 527°F. (250°C. to 275°C.). It is a complex product having a composition of (C41H3.0J. There are many forms of lignin and many chemicals react with it to form numerous binders.

LIGNIN LIQUOR (See: LIGNIN BINDER-LIGNIN [SULFONATE] SULPHONATE)

LIGNIN SULFONATE (See: BONDS-GOULAC-GLUTRIN-LIG­NIN BINDER)
Also known as Lignin Liquor, Sulfite Liquor, Sodium or Calcium or Magnesium or Ammonium Lignosulfonate. It is the water soluble dried by-products of the Sulfite process in paper mills. Cellulose in wood is bonded together by lignin. Suifite paper-making dissolved the lignin in a solution of sulfur dioxide gas in an alkali. This dissolved lignin, freed of excess sugars, is concentrated first to a syrup (lignin liquor, sulfite liquor) then spray-dried. Lignin sulfonate's use began in the 1900's as an organic core binder and as a binding agent to increase the surface hardness and the dry compression strength of molding sands.

LIGNIN SULPHATE (See: LIGNIN SULFONATE)

LIGNITE (See: BITUMINOUS COAL-CARBON-COAL-COAL DUST-SEACOAL)
Lignite is a "low ranked coal." It is harder than peat, but softer than bituminous coal. A highly oxidized form of lignite is "Leonardite," which when converted to a water soluble compound with an alkali is used to reduce the thickness (viscosity) of bentonite slurries in the slurry system for rebonding molding sands. Lignite contains 50% to 75% carbon, and is used as a partial replacement for seacoal in some foundries. Lignite shows promise for increased usage. Caus­ticized lignite is used in foundry molding sands to replace seacoal. It offers improved flowability to molding sand mixtures.

LIGNOSULFONATE (See: LIGNIN SULFONATE)

LIME (See: CALCITE)
Is a calcium oxide having the chemical composition (CaO). It is one of the more abundant minerals found in nature. It may be found in limestone, chalk, coral, marble, shells, various marine deposits and others. Seldom is it recommended for addition to foundry mold­ing sands or cores, but it is found in many cements, fluxes, mortars and other commercial items used in the foundry. When treated with wax and ground, it makes a good dry parting. Its specific gravity is 3.08 to 3.25 and its chemical composition varies with the percentage of impurities contained in it. Silica is an impurity in lime. Clay, iron oxide and various minerals are also contaminants to limestone. Some lime is especially prepared after being ground as a powder, mixed with water, and used as a coating on certain permanent molds where hot metal comes in contact with the metal molds. Usually, foundries are reluctant to use lime bearing aggregates or minerals containing lime in core and molding sand formulations. However, years ago some foundrymen added 1 % to 2 % ground lime to their naturally bonded sands, as they claimed this lowered the fusion point and prevented rat-tails on thin, flat castings. Even today, some of the smaller foun­dries still practice the addition of small amounts of lime or limestone to naturally bonded sands.

LIMESTONE (CaCOs) (See: CALCITE-LIME)

LINSEED OIL (See: BINDERS-CORE OIL-OILS)
In addition to the fibers, flax plants also yield a valuable oil called "linseed oil." The seeds contain about 40% oil. In extracting the oil, the seeds are crushed by machinery, heated to 165°F. (74°C.) and treated with naphtha, which extracts the oil, or the oil is removed in a continuous screw pressing operation. This oil is a drying oil and is used in many cores and core compounds in foundry operations. It is also used widely in the manufacture of commercial paints. The cake left after the oil is pressed from the seeds is generally used as a cattle food, or it is ground into an oily meal and sold to the foundry industry as a cellulose material. Linseed oil contains about 48% of linoleic and 34% linolenic acids. Its specific gravity is 0.93 to 0.935. It is a heavy, viscous liquid, soluble in turpentine, benzene, and ether. An iodine test determines the grade of linseed oil quite well and is recommended for determining its quality in the foundry. For foundry core oil, linseed oil is most often blended with rosin oil and kerosene. Many of the early core oils contained 60% linseed oil as the base, 20% resin and 20% kerosene. Linseed oil can be bleached by heating and by forcing oxygen through it, or it is prepared as "boiled linseed oil" by boiling the linseed oil in a kettle. It may also be produced by heating it with oxidizing driers such as manganese salts or lead salts.
When it is prepared with such driers, it is often termed "bung oil." The foundry uses linseed oil in many applications of the core room. It is used in certain molding sands to give high, dry skin strength and it is added to various sprays, blackings, and coatings for similar reasons.

LINSEED OIL-ALKYD RESIN BINDER (See: ALKYD RESINS)
Is used for air-set molding methods as a binder. These are claimed by the foundry to be chemical setting binders and a number of accel­erators are used with the mixtures.

LIQUID ORGANIC BINDER
There are many liquid organic binders. Glutrin, a commercial lignin binder is one popular binder. Various glucose and dextrin type binders are of this type. Vegetable oils are another type. Polymers are faster baking types, whether vegetable or mineral. A few asphaltums are called "Liquid Organic Binders."

LIQUID PARTING (See: KEROSENE-LARD OIL-PARTINGS)
Usually it is composed of quick drying solvents in which waxes have been dissolved. Many foundries have used kerosene and lard oil as a parting compound while others use stearic acid dissolved in a kerosene base. A safe liquid parting is usually one which has a high flash point, so as to eliminate hazards in storage and while in use.

LIQUID RESIN (See: NOVALAK)

LIQUID UREA BINDER (See: RESINS-UREA FORMALDEHYDE RESIN)
They are made by condensing urea or thiourea with formalde­hyde. They belong to a group known as amino-aldehyde resins made by the interaction of an amino and an aldehyde. They are the initial condensation products obtained which are soluble in water, and used as coatings for sands. These sand coatings are then made into cores or molds by several processes in the foundry.

LITHARGE (See: GLYCERIN)

LUMNITE CEMENT (See: CEMENT-PORTLAND CEMENT)
This is a trade name for a quick setting Portland Cement used to develop strength in a very short period. Lumnite Cement is made with bauxite as the base raw material. Its chemical composition is 40% alumina (Al2O3), 40% lime (CaO), 15% iron oxides (Fe2O3), 5% silica-magnesia (SiO2 • MgO), with some impurities. It dehydrates rapidly in a short period of time. Lumnite Cement is used in refractory mixtures, molds, cores and other operations. Lumnite cement is a commercial product of the Atlas Lumnite Cement Company.

LYCOPODIUM PARTING (See: DRY PARTINGS-PARTINGS)
This is a natural vegetable dust obtained from the steppes of Russia and harvested in Gnydia. It is a light, fluffy and bright yellow dust. It is used as a dry parting compound for making castings such as ornamental name plates, memorial plaques, or castings which require great detail. Lycopodium is an extremely good parting, but is generally too expensive, and other lesser cost dry partings have been substituted. 

Review of "Glossary of Foundry Additives" by Clyde A. Sanders, American Colloid Company


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