Daño,Judelle Stephen T.
MT-1201
EXERCISE No. 15
Surface Coatings

1.By means of a schematic diagram, show the composition of atypical paint. * A paint is formulated as a mixture of four ingredients: * Binder is the main ingredient of paints. Binders are polymers (resins) forming a continuous film on the substrate surface.Binders are responsible for good adhesion of the coating to the substrate. * Solvent (water or organic solvent) is a medium where the binder, pigment and additives are dispersed in molecular form (true solutions) or ascolloidal dispersions (emulsions or sols). * Pigment is a solid substance dispersed throughout the coating to impart it a color, opacity (hide the substrate surface). * Additives are small amounts of substances modifying the paint properties.

2.Explain the difference between the terms paint, varnish and lacquer * Paints will have pigments, that is coloring molecules that are in suspension in a liquid (but not dissolved). Pigments are more stable than dyes, but you have to work harder to keep them in suspension, what is why one has to stir paint to make it uniform.

* Varnish is a clear, hard solution that is principally applied to wood to give it a glossy finish while forming a protective film around it. Varnish consists of a resin, a drying oil and a thinner or solvent. Since varnishes have very little color, they can also be applied over a wood stain to enhance the shine of the wood.
What is Lacquer?

* Lacquer is a type of solvent-based product that is made by dissolving nitrocellulose together with plasticizers and pigments in a mixture of volatile solvents. Lacquer also contains a solution of shellac in alcohol that creates a synthetic coating, causing it to form a high gloss surface. The name lacquer derives from the Portuguese name 'lac,' which is a form of resin expelled from certain insects.
3.What are the main functions of the ff. Constituents of paints?
a.)pigment c.)solvent
b.)binder d.)additives

* Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food and other materials. * The binder in the paint system plays a key role in terms of determining the pigment and the type of solvent in which it is dissolved. A common choice for a solvent is water as it is compatible with most polymers, except some toners. * Solvents are used in paint manufacture to dissolve the different compounds used in the paint formulation such as colour and binder, making the paint the correct consistency for application. Once the paint has been applied the solvent evaporates, allowing the resin and pigment to produce a film of paint and to dry rapidly. Without solvents it would be impossible to produce durable, decorative and, in particular, glossy paints for use both indoors and outdoors to withstand all conditions.

* Dow Corning offers additives for solvent-borne, water-borne, solventless and radiation cure systems. They are compatible with a wide array of binder systems and diluents. Many offer multiple benefits, and all are effective at low concentrations.
4.For each of the ff. Types of paints, give specific properties and related application
TYPES:
ARCYLIC PHENOLIC EPOXY OILS ALKYD

PROPERTIES * Acrylic paints are an art and commercial product that people put on different surfaces to add color or, in some cases, achieve a special effect. Essentially mixtures made with plastic and pigment, they are suitable for a variety of projects ranging from house painting to fine arts. Although their chemical properties can create problems, such as difficulty cleaning, many people like them for their positive qualities, such as their ability to resist water after drying. Experts are still examining how they hold up over time. * Phenolic resins offer such favorable properties as heat resistance, flame retardancy, low smoking, adhesiveness, good mechanical strength and good electrical properties, and great potential for modification. Commercial production of phenolic resins began in the early 20th century. Over this nearly 100-year history, phenolic resins have been used with good results in an incredible array of applications.
Today, phenolic resins play a crucial role in a wide range of industries. For example, they are used as a binger for abrasives and as an electronics material. * Epoxy paints consist of two components that react with each other to form a hard, inert coating. Part A typically consists of an epoxy resin with pigments & extenders and Part B is the epoxy-curing agent, often called the hardener. Epoxy paints are typically referred to as anticorrosive barrier coatings. The excellent adhesion of epoxies coatings is due to the strong polar bonds it forms with the surfaces when it comes in contact and cures on a surface. The cross-linking reaction of epoxies for the most part is independent of the surrounding environment except temperature. * The information on the label will tell you a lot about the paint:- the name of the pigment or pigments used, followed by the pigment number i.e. Burnt Umber is PBr 7 - PBr stands for Pigment Brown, PY Pigment Yellow and so on.
The label also tells you about the vehicle or binder the paint has been made with, the vehicle is often Linseed Oil, although Safflower Oil is regularly used for light colours.Another symbol or wording is used, to state whether the paint is opaque, semi-opaque or transparent. A caution notice if it is required * Alkyd paints are durable and resistant to wear-and-tear. These paints are widely preferred for high traffic areas in a home such as hallways and play rooms for children. Also, these paints are resistant to humidity and moisture. As a result, they are good choices for kitchens, bathrooms and also cabinets and furniture. The lustrous finish is also resistant to stains. The paint can be wiped down for easy cleaning. Stains are not absorbed easily and discoloration does not set in. The paint retains a uniform sheen for a long time.
APPLICATION/USES
* Acrylic paint can be used for craft projects and home decorating. The colors will stay true and will not yellow, so your painted treasures will look good for many years after their completion. * The term "phenolic" is used to refer to a few different substances made with phenol, an organic compound. It can describe a type of resin used to create various consumer items and is the name given to a class of plant-based chemical compounds. It can also refer to carbolic acid, an organic material that has been used in various medical and cleaning products. * Epoxy paint is one of several types of paint you have almost certainly encountered, whether you are aware you have or not. This paint is very common in industrial and commercial buildings, especially as a paint for concrete flooring. Like other paints, epoxy can be decorative, but most often it is used for practical reasons * Commonly used drying oils include linseed oil, poppy seed oil, walnut oil, and safflower oil. The oil may be boiled with a resin, such as pine resin or frankincense to create a varnish; often prized for its body and gloss. Different oils confer various properties to the oil paint, such as less yellowing or different drying times. Certain differences are also visible in the sheen of the paints depending on the oil. * Alkyd paints are also used by artists when painting oil paintings. They are able to be thinned if the painter so desires and are also compatible with other oil based paints giving the artist more freedom of choice. Some types of alkyd paints also dry slower than others which is an advantage to some artists while working on their paintings.
5.What are the main functions of the ff. Types of paints?
a.)prime b.)undercoat c.)finishing coat or finishes

* All incomplete surfaces are required to be primed prior to painting, including dry walls, concrete, wood, and metal. Application of paint to unprimed surfaces may cause additional peeling and development of cracks, compared to when the paint is applied to suitably primed surfaces. Therefore, though this process of priming may cause additional expenditures, preferably it must not be omitted. * Surfaces that have been previously painted may not need priming, unless the oil based paints are being changed to latex paint, or the paint already applied has deteriorated. The surfaces that have deteriorated should be cleaned suitably before the application of primer. * Undercoat is any coating applied to a surface after priming and before the finish coat. It is matt with a high content of pigment and extender and a color approaching or helping that of the finish coat. Undercoats have many functions, they increase the thickness of the overall film, they hide the color of the primer or the previous layer on the existing substrate, and they are generally tinted in a similar color range as the topcoat. Varnish undercoats have less oil per unit of resin than varnish finishes. * The function of a finish coating like paint or varnish over an epoxy barrier coat, is to decorate the surface and protect the epoxy from sunlight. In doing so, the finish coating extends the life of the epoxy moisture barrier, which, in turn provides a stable base that extends the life of the finish coating. Together the two form a protective system far more durable than either coating by itself.

6.Give the composition and specific uses of latex paint.
Composition
* Like all other latex paints, acrylic latex paint uses water as the solvent. The binder, or the solid, in acrylic latex paint is the resin acrylic. The binder holds together the color pigments, the solvent and other components of the paint. Acrylic resin provides superior durability and adhesiveness to acrylic latex paint, which makes it the preferred choice over oil paints that show more inclination to chip and crack over time. Acrylic latex paints can contain varying amounts or percentages of acrylic. The paints that are 100 percent acrylic do not use any other resins in combination with the acrylic. These paints are the most expensive and of the highest class.

Specific uses * Latex paint is a water-based paint that comes in different finishes, including flat, semi-gloss and glossy. Outdoor and indoor latex paints are available and can be tinted to any color. Latex paints make up about 75% of the paint market, with the other 25% being oil-based paints. There are many advantages to latex paint that make it a good choice to use on many different surfaces.
7.Describe and Give the causes of the ff. Paint film defects or failures
a.)blistering c.)cracking e.)wrinkling
b.)chalking d.)flaking

* The most common cause of blistering is applying paint to a damp or wet surface. Allow the substrate to dry completely before priming and painting. If there is a continual moisture problem (in a leaky basement, for example), it must be corrected before painting. * Chalking is the formation of fine powder on the surface of the paint film due to weathering. Chalking can cause color fading. All paints chalk to some degree, it is a normal, desirable way for the paint film to wear away and provide a good surface for future repainting. * Cracking affects paint whether through poor application or normal wear and tear, a host of factors can cause paint to fail. Looking at the symptoms is a way to find out why your paint has not functioned correctly. Call a professional painting service to fix up problem areas, and read this short guide to learn about the causes of common paint problems. * Painting interior and exterior walls of a house is hard work. You might have scraped off loose paint, prepped surfaces properly, and still the paint started cracking and flaking within a year. Unfortunately, there are many causes for flaking paint, such as cheap paint, old paint, inadequate surface prep or weather conditions. It is devastating to watch all the hard work in painting a house go to waste; however, learning about potential causes of paint failure before the paint job is started, or learning how to fix flaking and cracking can help overcome this problem. * Wrinkling can occur is you apply paint too thickly (more likely when using alkyd or oil-based paints).
Painting during extremely hot weather or cool damp weather causes the paint film to dry faster on top than on the bottom, which can lead to wrinkling. Uncured paint that is exposed to high humidity levels is also susceptible to wrinkling.Another possible cause of wrinkling is applying a top coat of paint to insufficiently cured primer.Finally, painting over contaminated surface (e.g., dirt or wax) may also lead to this condition.

8.Name the constituents of varnish and give the function of each.
Violin
* Violin varnishing is a multi-step process involving some or all of the following: primer, sealer, ground, color coats, and clear topcoat. Some systems use a drying oil varnish as described below, while others use spirit (or solvent) varnish. Touchup in repair or restoration is only done with spirit varnish.
Resin
* Most resin or "gum" varnishes consist of a natural, plant- or insect-derived substance dissolved in a solvent, called spirit varnish or solvent varnish. The solvent may be alcohol, turpentine, orpetroleum-based. Some resins are soluble in both alcohol and turpentine. Generally, petroleum solvents, i.e. mineral spirits or paint thinner, can substitute for turpentine. The resins include amber,dammar, copal, rosin, sandarac, elemi, benzoin, mastic, balsam, shellac, and a multitude of lacquers.
Shellac
Main article: Shellac * Shellac is a very widely used single-component resin varnish that is alcohol-soluble. It is not used for outdoor surfaces or where it will come into repeated contact with water, such as around a sink or bathtub. The source of shellac resin is a brittle or flaky secretion of the female lac insect, Kerria lacca, found in the forests of Assam and Thailand and harvested from the bark of the trees where she deposits it to provide a sticky hold on the trunk. Shellac is the basis of French polish, which for centuries has been the preferred finish for fine furniture. Specified "dewaxed" shellac has been processed to remove the waxy substances from original shellac and can be used as a primer and sanding-sealer substrate for other finishes such as polyurethanes, alkyds, oils, and acrylics.
Alkyd
* Typically, modern commercially produced varnishes employ some form of alkyd for producing a protective film. Alkyds are chemically modified vegetable oils which operate well in a wide range of conditions and can be engineered to speed up the cure rate and thus harden faster. Better (and more expensive) exterior varnishes employ alkyds made from high performance oils and containUV-absorbers; this improves gloss-retention and extends the lifetime of the finish. Various resins may also be combined with alkyds as part of the formula for typical "oil" varnishes that are commercially available.

Spar varnish * Spar varnish (also called marine varnish) was originally intended for use on ship or boat spars, to protect the timber from the effects of sea and weather. Spars bend under the load of their sails. The primary requirements were water resistance and also elasticity, so as to remain adhering as the spars flexed. Elasticity was a pre-condition for weatherproofing too, as a finish that cracked would then allow water through, even if the remaining film was impermeable. Appearance and gloss was of relatively low value. Modified tung oil and phenolic resins are often used.
Drying oils * By definition, drying oils, such as linseed and tung oil, are not true varnishes though often in modern terms they accomplish the same thing. Drying oils cure through an exothermic reactionbetween the polyunsaturated portion of the oil and oxygen from the air. Originally, the term "varnish" referred to finishes that were made entirely of resin dissolved in suitable solvents, either ethanol (alcohol) or turpentine. The advantage to finishes in previous centuries was that resin varnishes had a very rapid cure rate compared to oils; in most cases they are cured practically as soon as the solvent has fully evaporated. By contrast, untreated or "raw" oils may take weeks or months to cure, depending on ambient temperature and other environmental factors. In modern terms, "boiled" or partially polymerized drying oils with added siccatives or dryers (chemical catalysts) have cure times of less than 24 hours. However, certain non-toxic by-products of the curing process are emitted from the oil film even after it is dry to the touch and over a considerable period of time. It has long been a tradition to combine drying oils with resins to obtain favourable features of both substances.
Polyurethane
* Polyurethane varnishes are typically hard, abrasion-resistant, and durable coatings. They are popular for hardwood floors but are considered by some wood finishers to be difficult or unsuitable for finishing furniture or other detailed pieces. Polyurethanes are comparable in hardness to certain alkyds but generally form a tougher film. Compared to simple oil or shellac varnishes, polyurethane varnish forms a harder, decidedly tougher and more waterproof film. However, a thick film of ordinary polyurethane may de-laminate if subjected to heat or shock, fracturing the film and leaving white patches. This tendency increases with long exposure to sunlight or when it is applied over soft woods like pine. This is also in part due to polyurethane's lesser penetration into the wood. Various priming techniques are employed to overcome this problem, including the use of certain oil varnishes, specified "dewaxed" shellac, clear penetrating epoxy sealer, or "oil-modified" polyurethane designed for the purpose. Polyurethane varnish may also lack the "hand-rubbed" lustre of drying oils such as linseed or tung oil; in contrast, however, it is capable of a much faster and higher "build" of film, accomplishing in two coats what may require multiple applications of oil. Polyurethane may also be applied over a straight oil finish, but because of the relatively slow curing time of oils, the emission of certain chemical byproducts, and the need for exposure to oxygen from the air, care must be taken that the oils are sufficiently cured to accept the polyurethane

Lacquer
Main article: Lacquer * The word lacquer refers to quick-drying, solvent-based varnishes or paints. Although their names may be similarly derived, lacquer is not the same as shellac and is not dissolved in alcohol. Lacquer is dissolved in lacquer thinner, which is a highly flammable solvent typically containing butyl acetate and xylene or toluene. Lacquer is typically sprayed on, within a spray booth that evacuates overspray and minimizes the risk of combustion. * Outside America, the rule of thumb is that a clear wood finish formulated to be sprayed is a lacquer, but if it is formulated to be brushed on then it is a varnish. Thus, by far most pieces of wooden furniture are lacquered. * Lacquer may be considered different from varnish because it can be re-dissolved later by a solvent (such as the one it was dissolved in when it was applied) and does not chemically change to a solid like other varnishes.[3]
Acrylic
* Acrylic varnishes are typically water-borne varnishes with the lowest refractive index of all finishes[citation needed] and high transparency. They resist yellowing. Acrylics have the advantage of water clean-up and lack of solvent fumes, but typically do not penetrate into wood as well as oils. They sometimes lack the brushability and self-leveling qualities of solvent-based varnishes. Generally they have good UV-resistance.
Two-part
* Various epoxies have been formulated as varnishes or floor finishes whereby two components are mixed directly before application. Often, the two parts are of equal volume and are referred to as "part A" and "part B". True polyurethanes are two-part systems. All two-part epoxies have a "pot-life" or "working time" during which the epoxy can be used. Usually the pot-life is a matter of a few hours but is also highly temperature dependent. Both water-borne and solvent-based epoxies are used.
Conversion
* Used when a fast-curing, tough, hard finish is desired, such as for kitchen cabinets and office furniture. Comes in two parts: a resin and an acid catalyst. The first is a blend of an amino resin and an alkyd. The acid catalyst is added right before application in a set ratio determined by the manufacturer. Most produce minimal yellowing. There are, however, two downsides to this finish. The first is that as the finish cures, it gives off formaldehyde, which is toxic and carcinogenic. The second is that the finish can crack or craze if too many coats are applied.
9.Name the constituents of lacquers and give the function of each.
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Nitrocellulose lacquers * Quick-drying solvent-based lacquers that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulostic materials, were developed in the early 1920s, and extensively used in the automobile industry for 30 years. Prior to their introduction, mass-produced automotive finishes were limited in colour, with Japan Black being the fastest drying and thus most popular. General Motors Oakland automobile brand automobile was the first (1923) to introduce one of the new fast drying nitrocelluous lacquers, a bright blue, produced by DuPont under their Duco tradename.
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Acrylic lacquers * Lacquers using acrylic resin, a synthetic polymer, were developed in the 1950s. Acrylic resin is colourless, transparent thermoplastic, obtained by the polymerization of derivatives of acrylic acid. Acrylic is also used in enamel paints, which have the advantage of not needing to be buffed to obtain a shine. Enamels, however, are slow drying. The advantage of acrylic lacquer is its exceptionally fast drying time. The use of lacquers in automobile finishes was discontinued when tougher, more durable, weather- and chemical-resistant two-component polyurethane coatings were developed. The system usually consists of a primer, colour coat and clear topcoat, commonly known as clear coat finishes.
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Water-based lacquer * Due to health risks and environmental considerations involved in the use of solvent-based lacquers, much work has gone into the development of water-based lacquers. Such lacquers are considerably less toxic and more environmentally friendly, and in many cases, produce acceptable results. More and more water-based coloured lacquers are replacing solvent-based clear and coloured lacquers in underhood and interior applications in the automobile and other similar industrial applications. Water based lacquers are used extensively in wood furniture finishing as well.[citation needed]
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Japanning * Just as china is a common name for porcelain, japanning is an old name to describe the European technique to imitate Asian lacquerware.[11] As Asian and Indian lacquer work became popular in England, France, the Netherlands, and Spain in the 17th century the Europeans developed imitations that were effectively a different technique of lacquering. The European technique, which is used on furniture and other objects, uses finishes that have a resin base similar to shellac. The technique, which became known as japanning, involves applying several coats of varnish which are each heat-dried and polished. In the 18th century this type of lacquering gained a large popular following. Although traditionally a pottery and wood coating, japanning was the popular (mostly black) coating of the accelerating metalware industry; and by the twentieth century the term was freely applied to coatings based on various varnishes and lacquers besides the traditional shellac.
10.Differentiate the ff. Types of varnish.
a.)spar varnish c.)furniture varnish
b.)floor varnish

* The furniture varnish is basically the easiest varnish in term application. It drying faster and most proper for furniture finish.

* The floor varnish has medium elasticity and strong enough tho withstand the abrasion since the activity on the floor.

* The spar varnish is varnish that is designed for finish the outdoor uses.It is more durable and strong to withstand the outside weather, but it need longer time to dry.

Daño, Judelle Stephen T.
MT-1201
Exercise No. 16
Wood Preservatives

1.Define the term “wood preservative”. * The term wood preservatives defines that the wood preservation is the process of preserving wood from the wood destroying agents like insects or fungus so that the life span of the wood can be extended.
2.Explain the desirable characteristics of wood preservative.
Preservative must perform their function throughout the service life of the product under the variety of exposure conditions. Hence it should have following characteristics: * High toxicity against fungi and or insect attack * High level of permanency under all service condition. * High degree of stability during treatment i.e. resistance to decomposition at normal treatment temperatures. * High level of penetrability. * It should not add to the inflammability of the wood; should rather increase the natural resistance of timber against fire. * It should not be harmful to human beings and other livestock. They must be relatively free from objectionable qualities in handling and use. * The environmental damage should be a minimum.

3.Name the important constituents of the common types of wood preservative.
Standard wood preservatives used in water solution include: * Acid Copper Chromate (ACC): Acid copper chromate (ACC) contains 31.8% copper oxide and 68.2% chromium trioxide * Ammoniacal Copper Zinc Arsenate (ACZA): ACZA should contain approximately 50% copper oxide, 25% zinc oxide, and 25% arsenic pentoxide dissolved in a solution of ammonia in water. * Chromated Copper Arsenate (CCA): It is one of the oldest and commonest types of water borne preservatives. This is the compound of Copper, Arsenic and Chromium. In the treatment, Copper works as the primary fungicide, arsenic as a secondary fungicides and an insecticide. During the rainfall, arsenic might leach out and can harm the environment; therefore it is not wise to use CCA treated wood in residential and commercial constructions. * Borate Preservatives: Borate preservatives are readily soluble in water, are highly leachable, and should only be used above ground where the wood is protected from wetting. Borates are odorless and can be sprayed, brushed, or injected. Borate treated wood is of low toxicity to humans and does not contain Copper or other heavy metals. In this chemical, Boric acid, Oxides and Salts (Borate) are effective wood preservatives. * Coal tar Creosote: It is the residual product from the distillation and processing of coal tar which is normally black or brownish in colour. It is high toxic to wood destroying organisms, permanent, easy to apply and relatively cheap. This has been commonly used in utility poles such as electricity pole, telephone poles and railway sleepers. * Other Creosotes: Creosotes distilled from tars other than coal tar are used to some extent for wood preservation. These include wood-tar creosote, oil-tar creosote, and water–gas-tar creosote. These creosotes protect wood from decay and insect attack but are generally less effective than coal-tar creosote. * Pentachlorophenol: It is also being used commonly which is manufactured by the direct chlorination of phenol or a mixture of phenol and lower chlorinated phenols.

4.Give the advantages ,disadvantages and uses of each type.

* Advantages: its less harmful to environment
Disadvantages: produces less electricity compared to other resources, difficult to find in some places. * The process of wood preservation, or treating it with a chemical or natural preservative, has the advantage of extending the practical life of the wood product and enhances its resistance to fungus, mold, or insects. * The disadvantage may be initial cost, exposure to the treatment chemicals, and disposal of treated wood without harm to the environment.
USES
* Wood preservatives containing ACC are only registered for industrial and commercial uses. ACC treated wood contains hexavalent chromium or chromium (VI). Chromium (VI) is a chemical in the highest EPA toxicity category for oral, dermal, and inhalation toxicity and is also a strong skin sensitizer. * ACQ wood preservatives (types A, B, C, and D) are composed of copper oxide and a quaternary ammonia compound. The absence of chemicals like arsenic or chromium has made ACQ one of the most widely used residential wood preservatives. The EPA has registered ACQ wood treatments for use on lumber, fence posts, decking, landscape ties, utility poles, marine pilings, and other uses * Cu-HDO is an outdoor wood preservative composed of copper (Cu) and N-cyclohexyl-diazeniumdioxide (HDO). Cu-HDO is used for pressure-treatment of lumber, poles, millwork, and piles. Cu-HDO is not likely to move through soils and contaminate groundwater. Cu-HDO is highly toxic to aquatic organisms, so it is not allowed in aquatic areas. * Borate wood preservatives are composed of naturally occurring minerals that protect wood from fungus, termites, and other wood-decomposing organisms. Borate wood preservatives are comprised of disodium octoborate tetrahydrate. Borate wood preservatives are low-toxicity treatments used primarily on indoor wood that is protected from weather. * Chromated copper arsenate (CCA) wood preservatives contain chromium, copper andarsenic. Pressure-treated wood containing CCA is no longer used in most residential settings. The chemicals in CCA-treated wood have been shown to leach into the surrounding environment and can transfer to the skin when people touch the wood. CCA residues on the skin typically result in minimal exposure. However, eating, smoking or children's hand-to-mouth activity can lead to ingestion of the chemicals. * Copper azole-treated wood is greenish-brown and has little to no odor. Type A (also known as CBA-A) contains copper, boric acid, and tebuconazole. Type B (also known as CA-B) contains higher concentrations of copper and tebuconazole but no boric acid. * Creosote-treated wood has either a thick black mixture of coal tar chemicals on the wood or the clear to yellowish greasy resin of the creosote bush. Many railroad ties are treated with creosote or pentachlorophenol. Creosote-treated wood can leach chemicals that may dissolve in water, move through soil and contaminate groundwater. * Cyproconazole is a water-based fungicide used to protect above-ground wood. Cyproconazole does not protect wood from insects. Although cyproconazole is used as a fungicide on some crops, many of the wood preservative formulations are not intended for use on wood that comes in contact with food. * Micronized copper wood treatments are new versions of the ACQ and CAformulations. The main difference in these new versions is the use of very small particles of solid copper, usually copper carbonate, rather than soluble copper in the solution being injected into the wood. * Pentachlorophenol is a restricted use pesticide and is used industrially as a wood preservative for utility poles, railroad ties, and wharf pilings. Pentachlorophenol was widely used as wood preservative until 1987 when its use was restricted to certified applicators. * Propiconazole is designed to prevent wood decay from fungus. Propiconazole does not protect wood against insect damage, so it is only intended to treat above-ground wood. Propiconazole is also used as a fungicide on turf and ornamental plants, numerous food and feed crops, and as an antimicrobial preservative for other materials.
5.Explain the effect of wood preservative in wood. * Insects and mold can damage wood over time. To prevent that damage, wood is often treated with pesticides. Treated wood is commonly used to build telephone poles, road signs and marine pilings as well as decks, play structures and raised garden beds. Several wood preservatives are registered with the EPA, each with different uses and potential risks.Wood preservatives can extend the life of wood and reduce the need for forest resources, but proper use is important. Some preservatives can slowly leach into the surrounding soil or water. Sometimes, touching the wood can leave residue on exposed skin. Use the resources below to learn about selecting and using treated wood properly.

Daño,Judelle Stephen T.
MT-1201
Exercise No. 17
Refrigerants

1.Explain the difference between a refrigerant and a circulating cooling medium.
Refrigerants. A refrigerant is the primary working fluid used for absorbing and transmitting heatin a refrigeration system. Refrigerants absorb heat at a low temperature and low pressure andrelease heat at a higher temperature and pressure. Most refrigerants undergo phase changes duringheat absorption—evaporation—and heat releasing—condensation.