Preparation and properties of commonly used dyes
Dye, substance used to impart colour to textiles, paper, leather, and other materials such that the colouring is not readily altered by washing, heat, Light, or other factors to which the material is likely to be exposed. Dyes differ from pigments, which are finely ground solids dispersed in a liquid, such as paint or ink, or blended with other materials. Most dyes are organic compounds (i.e., they contain carbon), whereas pigments may be inorganic compounds (i.e., they do not contain carbon) or organic compounds. Pigments generally give brighter colours and may be dyes that are insoluble in the medium employed.
Preparation of dyes
In 1856 the first commercially successful synthetic dye, mauve, was serendipitously discovered by British chemist William H. Perkin, who recognized and quickly exploited its commercial significance. The introduction of mauve in 1857 triggered the decline in the dominance of natural dyes in world markets. Mauve had a short commercial lifetime (lasting about seven years), but its success catalyzed activities that quickly led to the discovery of better dyes. Today only one natural dye, logwood, is used commercially, to a small degree, to dye silk, leather, and nylon black.
Recognition of the tetravalency of carbon and the nature of the benzene ring were key factors required to deduce the molecular structures of the well-known natural dyes (e.g., indigo and alizarin) and the new synthetics (e.g., mauve, magenta, and the azo dyes). These structural questions were resolved, and industrial processes based on chemical principles were developed by the beginning of the 20th century. For example, Badische Anilin- & Soda-Fabrik (BASF) of Germany placed synthetic indigo on the market in 1897; development of the synthetic process of this compound was financed by profits from synthetic alizarin, first marketed in 1869.
There was also interest in the effects of dyes on living tissue. In 1884 the Danish microbiologist Hans Christian Gram discovered that crystal violet irreversibly stains certain bacteria but can be washed from others. The dye has been widely used ever since for the Gram stain technique, which identifies bacteria as gram-positive (the stain is retained) or gram-negative (the stain is washed away). The German medical scientist Paul Ehrlich found that methylene blue stains living nerve cells but not adjacent tissue. He proposed that compounds may exist that kill specific disease organisms by bonding to them without damaging the host cells and suggested the name chemotherapy.
Properties of commonly used dyes
- The outstanding characteristics of the basic are brilliance and intensity of their colors.
- The bright colors achieved from basic dyes do not usually occur with other dye classes.
- Many of the basic dyes are sparingly soluble in water.
- The addition of glacial acetic acid helps to dissolve the basic dye quickly in water.
- Basic dyes are readily soluble in alcohol or mentholated spirit.
- The basic dyes are poor fastness to light and vary with regard to washing fastness from poor to moderate.
- An important property of basic dyes is that they will combine with tannic acid to form an insoluble compound provided mineral acid is absent.
- The wet fastness of the basic dyes on protein fibres can also be improved by back tanning. This consists of after treating the dyed material with tannic acid in order to form the insoluble complex thereby reducing the tendency to migrate.
- The basic dyestuff will combine with direct or sulphur or some acid dyestuffs. So they cannot be used together in the same bath. But basic dyestuffs are used in after treating Cotton or other materials dyed with direct colors. Here the direct dyestuff acts as mordant.
Preparation of detergents
Although there are three ways of manufacturing dry laundry detergent, only two are commonly used today. In the blender process favored by smaller companies, the ingredients are mixed in large vats before being packaged. The machines used are very large: a common blender holds 4,000 pounds (1,816 kilograms) of mixed material, but the blenders can accommodate loads ranging from 500 to 10,000 pounds (227 to 4,540 kilograms). By Industry standards, these are small batches for which the blender process is ideal. While some settling may occur, the resulting detergent is of high quality and can compete with detergents made by other processes. The second commonly used method of production is called the agglomeration process. Unlike the blender process, it is continuous, which makes it the choice of very large detergent manufacturers. The agglomeration process can produce between 15,000 and 50,000 pounds (6,800 and 22,700 kilograms) of detergent per hour. In the third method, dry ingredients are blended in water before being dried with hot air. Although the resulting product is of high quality, the fuel costs and engineering problems associated with venting, reheating, and reusing the air have led to this method being largely replaced by agglomeration.
The blender process
- First, ingredients are loaded into one of two machines: a tumbling blender or a ribbon blender. The tumbling blender, shaped like a rectangular box, is turned and shaken from outside by a machine, while the ribbon blender is a cylinder fitted with blades to scrape and mix the ingredients. After the ingredients inside the blender have been mixed, a doorway at the bottom of the bowl is opened. With the blender still agitating the ingredients, the mix is allowed to run out onto a conveyor belt or other channeling device. The belt then moves the detergent to another area of the factory where it can be dropped into boxes or cartons for delivery to wholesalers or distributors.
The agglomeration process
- In this method, dry ingredients for a detergent are first fed into a large machine known as a Shuggi agglomerator. Inside the agglomerator, sharp, whirling blades mix the material to a fine consistency; the process resembles food being textured inside a food processor.
- After the dry ingredients have been blended, liquid ingredients are sprayed on the dry mix through nozzles fitted into the agglomerator’s walls. The blending continues, causing an exothermic (heat-producing) reaction to occur. The resulting mixture is a hot, viscous liquid similar to gelatin that hasn’t hardened.
- Next, the liquid is allowed to flow out of the agglomerator. As it leaves the machine, it collects on a drying belt where its own heat, exposure to air, and hot air blowers render it friable, easy to crush or crumble. The newly made detergent is then pulverized and pushed through sizing screens that ensure that no large lumps of unmixed product go out to the market. The result of this process is a dry detergent made up of granules of the mixed detergent.
Liquid detergent
If the detergent is to be liquid rather than powder, it is simply mixed back in—after all ingredients are blended—with a solution consisting of water and various chemicals known as solubilizers. The solubilizers help the water and detergent blend together more fully and evenly.
Preparation of explosives
A blasting agent is any material or mixture consisting of a fuel and oxidizer that is intended for blasting and that is not otherwise classified as an explosive. A blasting agent consists primarily of inorganic nitrates (ammonium and sodium nitrates) and carbonaceous fuels. The addition of an explosive ingredient, such as TNT, in sufficient quantity, changes the Classification of the mixture from a blasting agent to an explosive.
Ammonium nitrate, for its weight, supplies more gas upon detonation than any other explosive. In pure form, ammonium nitrate is almost inert (powerless) and is composed of 60 percent Oxygen by weight, 33 percent nitrogen, and seven percent hydrogen. Two characteristics make this compound both unpredictable and dangerous. Ammonium nitrate is water soluble and if uncoated, can attract water from the Atmosphere and slowly dissolve itself. For this reason, most prills have a protective coating of wax or clay which acts as a moisture retardant. The second and most important characteristic is a phenomenon called “cycling.” This is the ability of a material to change its crystal form with temperature. Ammonium nitrate will have one of five crystal forms depending on the temperature. The cycling phenomenon can seriously affect both the storage and performance of any explosive which contains ammonium nitrate. Most dynamites, both regular nitroglycerin or permissibles, contain some percentages of ammonium nitrate, while blasting agents are almost totally comprised of this compound. The cycling effect in dynamite is not due to other ingredients mixed with the ammonium nitrate. For this reason, cycling does not greatly affect dynamite the way it does ANFO.
The two temperatures at which cycling will occur under normal conditions are 0 and 90°F. This is to say that products which are stored over the winter, or for a period of time during the summer, most likely will undergo some amount of cycling. During the summer, in poorly ventilated powder magazines, the cycling temperature may be reached daily.
Properties of explosives
In general, an explosive has four basic characteristics:
- It is a chemical compound or mixture ignited by heat, shock, impact, friction, or a combination of these conditions;
- Upon ignition, it decomposes rapidly in a detonation;
- There is a rapid release of heat and large quantities of high-pressure gases that expand rapidly with sufficient force to overcome confining forces; and
- The energy released by the detonation of explosives produces four basic effects; (a) rock fragmentation; (b) rock displacement; (c) ground vibration; and (d) air blast.
Preparation of paints
Paint is a term used to describe a number of substances that consist of a pigment suspended in a liquid or paste vehicle such as oil or water. With a brush, a roller, or a spray gun, paint is applied in a thin coat to various surfaces such as wood, Metal, or stone. Although its primary purpose is to protect the surface to which it is applied, paint also provides decoration.
A paint is composed of pigments, solvents, resins, and various additives. The pigments give the paint color; solvents make it easier to apply; resins help it dry; and additives serve as everything from fillers to antifungicidal agents. Hundreds of different pigments, both natural and synthetic, exist. The basic white pigment is titanium dioxide, selected for its excellent concealing properties, and black pigment is commonly made from carbon black. Other pigments used to make paint include iron oxide and cadmium sulfide for reds, metallic salts for yellows and oranges, and iron blue and chrome yellows for blues and greens.
Making the paste
Pigment manufacturers send bags of fine grain pigments to paint Plants. There, the pigment is premixed with resin (a wetting agent that assists in moistening the pigment), one or more solvents, and additives to form a paste.
Dispersing the pigment
The paste mixture for most industrial and some consumer paints is now routed into a sand mill, a large cylinder that agitates tiny particles of sand or silica to grind the pigment particles, making them smaller and dispersing them throughout the mixture. The mixture is then filtered to remove the sand particles. Instead of being processed in sand mills, up to 90 percent of the water-based latex paints designed for use by individual homeowners are instead processed in a high-speed dispersion tank. There, the premixed paste is subjected to high-speed agitation by a circular, toothed blade attached to a rotating shaft. This process blends the pigment into the solvent.
Thinning the paste
Whether created by a sand mill or a dispersion tank, the paste must now be thinned to produce the final product. Transferred to large kettles, it is agitated with the proper amount of solvent for the type of paint desired.
Canning the paint
The finished paint product is then pumped into the canning room. For the standard 8 pint (3.78 liter) paint can available to consumers, empty cans are first rolled horizontally onto labels, then set upright so that the paint can be pumped into them. A machine places lids onto the filled cans, and a second machine presses on the lids to seal them. From wire that is fed into it from coils, a bailometer cuts and shapes the handles before hooking them into holes precut in the cans. A certain number of cans (usually four) are then boxed and stacked before being sent to the warehouse.
Properties of paints
- Exterior paint is exposed to all types of varying weather conditions. Exterior paint is therefore required to provide protection against UV radiation of the sun as well as fungal Growth.
- It’s made to combat mildew as well as fading. In addition, they have to be fade resistant as they face very high temperatures.
- The resins used for exterior paint can be softer so that they can withstand temperature changes and ill effects due to exposure to moisture. They are supposed to be flexible and not easily crack on expansion/contraction.
- Exterior paint must be tougher and should be capable of resisting peeling and crumbling.
- Interior paint is more to do with aesthetics and decoration purposes and at the same time, they need to add properties of easy maintenance, wash ability and dampness prevention. It’s designed to withstand abrasion.
- Interior paint is also designed to be more delicate than exterior paint because they occupy the same space as you do.
- Interior paint is so made that they can be scrubbed and can resist staining. Interior paint is formulated to be more resistant to physical damage.
Preparation and properties of varnishes
Wood is valuable for structural purpose and decorative purpose also. Wood has plant origin. The wood used for building construction is known as Timber. Forests produce a huge quantity of timber. Cellulose, Hemicellulose, Lignin and other substances are the constituents of wood. Aliphatic compounds, phenols, fats, waxes, terpenes, terpenoids etc. are found in woods. Stilbenes, Tannins, Flavonoids and Lignanas are phenolic compounds available in woods.
Preparation of varnishes
Drying oil
There are many different types of drying oils, including linseed oil, tung oil, and walnut oil. These contain high levels of polyunsaturated fatty acids.
Resin
Resins that are used in varnishes include amber, kauri gum, dammar, copal, rosin (pine resin), sandarac, balsam, elemi, mastic, and others. Shellac is also a resin. In the 1900s in Canada, resins from local trees were used to finish pianos. As a result, these now antique pianos are considered difficult to refinish. However, shellac can be used over the existing resins provided sufficient time is allowed for thin coats to cure. Thus the original finish can be returned to its original lustre while preserving the color and age-related crackle.
Solvent
Traditionally, natural (organic) turpentine was used as the thinner or solvent, but has been replaced by several mineral-based turpentine substitutes such as white spirit or “paint thinner”, also known as “mineral spirit”.
Spirit varnishes made with alcohol are conveniently prepared and on account of their rapid drying and leaving no disagreeable smell are in frequent use in the household for covering various articles of art. Resin is a class of non-volatile (non-evaporating), solid or semisolid organic substances obtained directly from certain plants as exudations or prepared by polymerization of simple Molecules. Some hard and soft resins used in varnishes are amber, copal, shellac, sandarac, mastic, resin of turpentine, dammar etc. Rosins are classified as pale yellow, yellow, and reddish to yellow, brown or black rosin. If the injection water be not completely expelled the rosin is opaque.
If the essential oils have not been completely eliminated the rosin is viscous and tacky. Spirit varnishes are more or less thin, more or less viscous, colourless or more or less coloured, opaque or transparent solutions, of one or more natural resins, e.g. shellac and shandarac etc., in one more appropriate volatile solvents which leave on Evaporation a thin, more or less resistant film which both adorns and protects the object on which it is applied.
Application of varnish on wood work is carried out in the following steps:
Preparation of surface
The wood surface is made smooth by thoroughly rubbing it by means of sand paper or pumice stone.
Knotting
The process of knotting is carried out exactly in the same way as adopted for painting wood work.
Stopping
Stopping is done by means of hot weak glue size so that pores on the surface are filled up. Alternately, boiled linseed oil can be applied in two coats. The dry surface then be rubbed down with sand paper.
Coat of varnish
On the cleaned surface, two or more coats of varnish are applied. Next coat is applied only when the previous coat has dried up thoroughly.
Properties of varnish
Properties of ideal varnish should be :
- It should give glossy surface. Should be durable.
- It should dry rapidly after application.
- It should not develop cracks after drying.
- It is commonly used on wooden surfaces.
- Colour of varnish should not fade away with time.
- It should not hide the natural grain of inner surface of timber.
,
Dyes are substances that add color to other materials. They are used in a wide variety of products, including clothing, food, cosmetics, and textiles. Dyes can be either natural or synthetic. Natural dyes are derived from plants, animals, or Minerals. Synthetic dyes are made from chemicals.
Natural dyes have been used for centuries. Some of the earliest known dyes were extracted from plants, such as indigo and madder. These dyes were used to color textiles, such as wool and cotton. Natural dyes are often less stable than synthetic dyes, and they can fade or bleed over time. However, they are also often considered to be more environmentally friendly.
Synthetic dyes were first developed in the 19th century. They are much more stable than natural dyes, and they come in a wider range of colors. Synthetic dyes are used in a wide variety of products, including clothing, food, cosmetics, and textiles. However, some synthetic dyes have been linked to Health problems, such as cancer.
Detergents are substances that are used to clean surfaces. They are made up of surfactants, which are molecules that have both water-loving and oil-loving ends. This allows detergents to break down dirt and oil, so that they can be rinsed away with water.
There are three main types of detergents: anionic, cationic, and nonionic. Anionic detergents are the most common type of detergent. They are negatively charged, and they work by attaching to dirt and oil particles. Cationic detergents are positively charged, and they work by repelling dirt and oil particles. Nonionic detergents are neither positively nor negatively charged, and they work by surrounding dirt and oil particles.
Detergents are used in a wide variety of products, including laundry detergent, dishwashing detergent, and hand soap. They are also used in industrial applications, such as cleaning machinery and removing oil spills.
Explosives are substances that can be used to create an explosion. They are used in a variety of applications, including mining, construction, and warfare. Explosives can be either low explosives or high explosives.
Low explosives are also known as propellants. They are used to propel projectiles, such as bullets and rockets. Low explosives are relatively slow-burning, and they produce a lot of pressure. This pressure is used to propel the projectile.
High explosives are also known as detonators. They are used to create a shockwave that can destroy objects. High explosives are very fast-burning, and they produce a lot of heat. This heat can cause objects to melt or vaporize.
Paints are substances that are used to color surfaces. They are made up of pigments, which are substances that give paint its color, and binders, which hold the pigments together. Paints can be either oil-based or water-based.
Oil-based paints are made from a mixture of oil, such as linseed oil, and pigments. They are slow-drying, but they are very durable. Oil-based paints are often used on wood and metal surfaces.
Water-based paints are made from a mixture of water and pigments. They are quick-drying, and they are easy to clean up. Water-based paints are often used on walls and ceilings.
Varnishes are substances that are used to protect and finish wood surfaces. They are made up of a resin, such as polyurethane, and a solvent, such as alcohol. Varnishes can be either oil-based or water-based.
Oil-based varnishes are made from a mixture of oil, such as linseed oil, and a resin. They are slow-drying, but they are very durable. Oil-based varnishes are often used on furniture and floors.
Water-based varnishes are made from a mixture of water and a resin. They are quick-drying, and they are easy to clean up. Water-based varnishes are often used on cabinets and countertops.
Shellac varnishes are made from a resin that is extracted from the lac bug. They are quick-drying, and they provide a natural finish. Shellac varnishes are often used on furniture and Musical instruments.
Dyes
Dyes are substances that are used to color fabrics, paper, and other materials. They are typically organic compounds that are soluble in water or other solvents. Dyes can be natural or synthetic. Natural dyes are derived from plants, animals, or minerals. Synthetic dyes are made from chemicals.
Dyes work by binding to the fibers of the material being dyed. The type of dye used will depend on the material being dyed and the desired color. For example, cotton is typically dyed with natural dyes, while synthetic dyes are often used to dye polyester.
Dyes are an important part of our everyday lives. They are used to color clothing, home furnishings, and even food. Without dyes, our world would be a much more colorless place.
Detergent
Detergent is a substance that is used to clean surfaces. It is typically made from a mixture of surfactants, builders, and other ingredients. Surfactants are molecules that have both water-loving and oil-loving ends. This allows them to surround and remove dirt and oil from surfaces. Builders are substances that help to remove hard water minerals from surfaces. Other ingredients in detergents may include fragrances, dyes, and ENZYMES.
Detergent works by breaking down the Surface Tension of water. This allows the water to more easily penetrate and remove dirt and oil from surfaces. Detergent also helps to suspend dirt and oil in the water so that it can be rinsed away.
Detergent is an important part of our everyday lives. It is used to clean clothes, dishes, and other surfaces. Without detergent, our world would be a much dirtier place.
Explosives
Explosives are substances that can be used to create an explosion. They are typically made from a mixture of fuel and oxidizer. The fuel provides the energy for the explosion, while the oxidizer provides the oxygen that is needed for the fuel to burn. Explosives can be used for a variety of purposes, including mining, construction, and warfare.
Explosives work by creating a rapid expansion of gases. This expansion creates a shockwave that can damage or destroy objects in its path. The amount of damage that is caused by an explosion depends on the type of explosive, the amount of explosive, and the way in which the explosive is detonated.
Explosives are a dangerous substance and should be handled with care. They should only be used by trained professionals.
Paints
Paint is a substance that is used to cover surfaces. It is typically made from a mixture of pigments, binders, and solvents. Pigments are the substances that give paint its color. Binders are the substances that hold the pigment particles together. Solvents are the substances that dissolve the binder and allow the paint to be applied to a surface.
Paint works by forming a thin film on the surface that it is applied to. This film protects the surface from damage and provides a decorative finish. Paint can be applied to a variety of surfaces, including wood, metal, and concrete.
Paint is an important part of our everyday lives. It is used to protect our homes and businesses from the Elements. It is also used to decorate our homes and businesses. Without paint, our world would be a much more drab place.
Varnishes
Varnish is a substance that is used to protect and decorate wood surfaces. It is typically made from a mixture of resins, solvents, and pigments. Resins are the substances that give varnish its hardness and durability. Solvents are the substances that dissolve the resins and allow the varnish to be applied to a surface. Pigments are the substances that give varnish its color.
Varnish works by forming a thin film on the surface of wood. This film protects the wood from damage and provides a decorative finish. Varnish can be applied to a variety of wood surfaces, including furniture, floors, and cabinets.
Varnish is an important part of our everyday lives. It is used to protect our wood furniture and floors from damage. It is also used to give our wood furniture and floors a beautiful finish. Without varnish, our wood furniture and floors would be much more susceptible to damage and would not look as nice.
Which of the following is not a dye?
(A) Indigo
(B) Methylene blue
(C) Ethanol
(D) HennaWhich of the following is not a detergent?
(A) Sodium lauryl sulfate
(B) Sodium dodecylbenzene sulfonate
(C) Sodium carbonate
(D) Sodium bicarbonateWhich of the following is not an explosive?
(A) TNT
(B) C4
(C) Gunpowder
(D) WaterWhich of the following is not a paint?
(A) Oil paint
(B) Acrylic paint
(C) Watercolor paint
(D) Milk paintWhich of the following is not a varnish?
(A) Shellac
(B) Polyurethane varnish
(C) Lacquer
(D) Varnishing spirit
Answers:
1. (C)
2. (C)
3. (D)
4. (D)
5. (D)