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Melt and Pour soap crafting is a process often used by soapmakers, [1] both for large scale (commercial) and small scale (domestic, artisanal) manufacture. Small scale artisan soap makers find "melt and pour" production useful when trying out new product lines. The process differs from the cold process or hot process in utilising a pre-manufactured solid soap base which has already undergone saponification, so the soap maker does not need to handle caustic alkali, i.e. lye.
A commercially acquired "melt and pour" soap base is melted in a pan or commercial melting vessel, using direct heat, or in a water jacket melting pot, (large double boiler or "bain marie"), and re-solidifies as it cools. Domestically, a microwave oven can be used for melting small quantities of the base. Additions can be added at the still-hot liquid stage, such as fragrance, fragrant essential oils, moisturizing agents, colorants, or exfoliating agents, e.g. poppy seeds, coffee grounds or pumice, along with coloured micas, metallic glitter, honey and flower heads. The liquified concoction can be poured into individual molds, tray molds, or blocks. Molds are made of metal or, more commonly, from plastic or reinforced silicone rubber, allowing artisans to make their own molds using a two-part mold kit. Upon cooling, the soap can be removed from the molds as individual soaps, or as blocks for slicing into bars. Layers of different colors, or transparent layers, can be built up, or pre-cast embeddable soap shapes, called embeds, can be set into the soap during moulding to produce novel patterns. Melt and pour bases can be transparent or opaque, and are sometimes enriched with products like goat's milk or shea butter to add value. The small-scale process lends itself to bespoke manufacture; a single soap bar can be individually manufactured if desired.
Some soapmakers prefer "melt and pour" because the process is simple and safe, allowing the soapmaker to concentrate more on the aesthetic aspects of soap making. Because it avoids the need to handle lye, a hazardous and very caustic chemical, it is a hobby even children can enjoy under adult supervision. Unlike cold-processed soap, which requires a period of "curing" to allow saponification to complete and excess water to evaporate, the "melt and pour" process is completed once the base has cooled and hardened. The meltable base is usually naturally rich in glycerine, a by-product of saponification that has humectant and emollient properties, whereas commercial soap bars have often had this component removed.
As with the rebatching method, it can be considered a misnomer to refer to the melt and pour process as soap making. The process has much in common with candle making using meltable wax which, using a similar process, can be scented, dyed, and shaped on a small or large scale of production.
Other processes used by soapers are cold process, hot process and rebatching.
Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts.
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−.
A lye is an alkali metal hydroxide traditionally obtained by leaching wood ashes (potassium), or a strong alkali which is highly soluble in water producing caustic basic solutions. "Lye" most commonly refers to sodium hydroxide (NaOH), but historically has been used for potassium hydroxide (KOH).
Saponification is a process of converting esters into soaps and alcohols by the action of aqueous alkali. Soaps are salts of fatty acids, which in turn are carboxylic acids with long carbon chains. Sodium stearate is a typical soap.
An ingot is a piece of relatively pure material, usually metal, that is cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products. Ingots usually require a second procedure of shaping, such as cold/hot working, cutting, or milling to produce a useful final product. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, particularly when cast by mold based methods. Precious metal ingots can be used as currency, or as a currency reserve, as with gold bars.
Stearic acid is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula CH3(CH2)16CO2H. The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid is a prevalent FA in nature, found in many animal and vegetable fats, but is usually higher in animal fat than vegetable fat. It has a melting point of 69.4 °C and a pKa of 4.50.
Saponification value or saponification number represents the number of milligrams of potassium hydroxide (KOH) or sodium hydroxide (NaOH) required to saponify one gram of fat under the conditions specified. It is a measure of the average molecular weight of all the fatty acids present in the sample in form of triglycerides. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice versa. Practically, fats or oils with high saponification value are more suitable for soap making.
An electric arc furnace (EAF) is a furnace that heats material by means of an electric arc.
Rotational molding involves a heated mold which is filled with a charge or shot weight of the material. It is then slowly rotated, causing the softened material to disperse and stick to the walls of the mold forming a hollow part. In order to form an even thickness throughout the part, the mold rotates at all times during the heating phase, and then continues to rotate during the cooling phase to avoid sagging or deformation. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.
Glycerin soaps are soaps that contain glycerol, a component of fat or oil. They are recognizably different from other soaps because they are translucent. The clarity is due to the alignment of the soap molecules, which can be induced through the addition of alcohol and sugar. This is usually done for homemade glycerin soaps that are not remeltable.
A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals processed are aluminum and cast iron. However, other metals, such as bronze, brass, steel, magnesium, and zinc, are also used to produce castings in foundries. In this process, parts of desired shapes and sizes can be formed.
Continuous casting, also called strand casting, is the process whereby molten metal is solidified into a "semifinished" billet, bloom, or slab for subsequent rolling in the finishing mills. Prior to the introduction of continuous casting in the 1950s, steel was poured into stationary molds to form ingots. Since then, "continuous casting" has evolved to achieve improved yield, quality, productivity and cost efficiency. It allows lower-cost production of metal sections with better quality, due to the inherently lower costs of continuous, standardised production of a product, as well as providing increased control over the process through automation. This process is used most frequently to cast steel. Aluminium and copper are also continuously cast.
Rebatching, or hand milling, is a soapmaking technique used by hobbyists and artisan soapmakers. The commercial equivalent is French milling.
Spray forming, also known as spray casting, spray deposition and in-situ compaction, is a method of casting near net shape metal components with homogeneous microstructures via the deposition of semi-solid sprayed droplets onto a shaped substrate. In spray forming an alloy is melted, normally in an induction furnace, then the molten metal is slowly poured through a conical tundish into a small-bore ceramic nozzle. The molten metal exits the furnace as a thin free-falling stream and is broken up into droplets by an annular array of gas jets, and these droplets then proceed downwards, accelerated by the gas jets to impact onto a substrate. The process is arranged such that the droplets strike the substrate whilst in the semi-solid condition, this provides sufficient liquid fraction to 'stick' the solid fraction together. Deposition continues, gradually building up a spray formed billet of metal on the substrate.
Marseille soap or Savon de Marseille is a traditional hard soap made from vegetable oils that has been produced around Marseille, France, for about 600 years. The first documented soapmaker was recorded from the city in about 1370. By 1688, Louis XIV introduced regulations in the Edict of Colbert limiting the use of the name Savon de Marseille to olive oil based soaps. The law has since been amended to allow other vegetable oils to be used.
Permanent mold casting is a metal casting process that employs reusable molds, usually made from metal. The most common process uses gravity to fill the mold, however gas pressure or a vacuum are also used. A variation on the typical gravity casting process, called slush casting, produces hollow castings. Common casting metals are aluminium, magnesium, and copper alloys. Other materials include tin, zinc, and lead alloys and iron and steel are also cast in graphite molds.
Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass.
A cupola or cupola furnace is a melting device used in foundries that can be used to melt cast iron, Ni-resist iron and some bronzes. The cupola can be made almost any practical size. The size of a cupola is expressed in diameters and can range from 1.5 to 13 feet. The overall shape is cylindrical and the equipment is arranged vertically, usually supported by four legs. The overall look is similar to a large smokestack.
Aleppo soap is a handmade, hard bar soap associated with the city of Aleppo, Syria. Aleppo soap is classified as a Castile soap as it is a hard soap made from olive oil and lye, from which it is distinguished by the inclusion of laurel oil.
Uddeholms AB is a multinational producer of high alloyed tool steel with production in Hagfors, Sweden. Since 1991, the company is part of the Austrian Böhler-Uddeholm group which in turn is part of the voestalpine AG group since 2007. Uddeholms AB has 800 Swedish and 3,000 total employees.