Building Material _ Paint

ATGB1053 BUILDING MATERIALS GROUP ASSIGNMENTS-PAINTS

IntroductionPaint is one of the useful materials for building construction. Generally, it is used to

improve the aesthetic of the building. Besides, special paints are used for protection against rust,

as internal vapour barriers, to protect against radon emissions from radioactive building materials

to seal of volatile formaldehyde in chipboard and more.

Ordinary paint consists of three elements, binder, pigment and solvents. The binder

makes the coat of paint retain its structure, and binds it to the surface to which it is applied.

While the pigment gives the paint colour, also plays a role in its consistency, ease of application,

drying ability, durability, and hardness. The solvent dissolve the paint to make it usable at

normal room temperatures. Moreover, it is possible to add fillers to paint to make more

economical. Some modern paint based on synthetics resins need a large proportion of different

additives in order to achieve technical and aesthetic requirements.

One of the painting methods, Lazure is painting with less pigment; used when the

structure of the material needs to remain visible it can be achieved by using a larger proportion

of solvent in the paint. There are many types of paint; Varnish is the paint without pigment,

while stain is paint with no binder, where the pigment is drawn into the surface.

Special conditions are often required by the materials and components to be treated, and

in relation to their position within or on the building. Factors those are important such as

diffusion through the paint, sensitivity to water, resistance to wear, sensitivity to light, and the

risk of emissions. Interior and exterior paint have a big difference in this respect.

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Many types of paint are mainly based on raw materials from plants, while others are

based on fossil raw materials. Pigments for painting buildings are usually mineral-based.

HistoryPrior to the earliest cave paintings were made by using iron oxide. The ancient Egyptians

developed other paints from pigments in the soil such as yellow, orange, and red. It was the

Romans who gave us purple, a pound of royal purple dye, required the crushing of four million

mollusks. Cochineal red, discovered by the Aztecs, was made using the female cochineal beetle.

A pound of water-soluble extract required about a million insects and it was the Spaniards who

introduced the crimson color to Europe in the 1500's. Later genuine Indian Yellow was produced

from concentrated cows urine which was mixed with mud and transported to London for

purifying, Sap Green from the Blackthorn berry and Sepia Brown from the dried ink sac of

squid.

Paint is made up of a pigment, a binder to hold it together and appropriate thinners to

make it easy to apply. Blue Frit was the first synthetic pigment being produced by the Egyptians

from ground down blue glass 5000 years ago. Before the nineteenth century the word 'paint' was

only applied to oil-bound types; those bound with glue were called 'distemper'.

By 1000 B.C. development of paints and varnishes based on the gum of the acacia tree,

better known as gum Arabic, had been developed. At this time umbers, ocher's and blacks were

readily obtainable, new colors were also discovered - the first was 'Egyptian Blue'; 'Naples

Yellow' dates from around 500 BC and 'red lead' was discovered by accident in about 2500.

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White lead occurred naturally but demand encouraged production of manmade versions.

Vitruvius describes production of white lead in the 2nd century AD.

Before the 16th century, pigment color was largely dependent on dyestuffs which could

be grown in, or were indigenous to Europe and similar temperate regions. Between 1550 and

1850 only the so-called natural dyestuffs were available but the range was greatly extended with

tropical dyestuffs from Central America and India and elsewhere.

In the 17th century the Dutch greatly increased availability of white lead and lowered

cost by invention of the Stack Process. All white lead paints included chalk in their undercoats,

reserving purer white lead for finish coats. In1856 the first real synthetic dye, 'Mauveine', was

discovered by Henry Perkins. It was then realized that a great many dyes could be made

synthetically and cheaply. It was then that Linseed Oil began being mass produced. They also

had pigment grade zinc oxide, which is white paint. Using cast-iron paint mills and zinc-based

pigments, industrialists produced the first washable paint marketed as 'Charlton White' in the

1870's.

The Sherwin-Williams company spent ten years trying to perfect the formula where fine

paint particles would stay suspended in Linseed oil. In 1880 they succeeded in developing a

formula that far exceeded the quality of all paints available at the time. It was then that emulsions

based on similar formulae, were produced and marketed as 'oil bound distempers'. By 1880 the

new paints were readily available in tins, in a wide range of colors, and came to be exported all

over the World.

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The paint trade has change a great deal over the last hundred years. During the 19 th

century, painters prepared the pigments themselves from the raw materials. During the last 30

years everything has been industrialized, including the application of paint, particularly for

windows, doors and outside paneling.

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Types of paintPaint technology is a complicated science. There are many types of paint available today,

some giving different surface finishes, others designed for particular applications. This makes the

selection of paint less straightforward, however selecting the correct type of paint will give a

more satisfactory end result.

Nowadays, all paints basically fall under two binders categories which define their type;

mineral binders and organic binders.

Paints with mineral binders

These types of paints are best suited for painting on mineral surfaces and unplaned timber

surfaces. Most common type are based on binders of lime, cement and water glass, which is

soluble in water. For examples, lime paint, silicate paint, and cement paint.

Binder for lime paint is slaked lime. The pure lime colours give matt, absorbent surfaces

which are difficult to wash and it is porous to vapour and not elastic. The lime paint must be

completely removed before it is being painted over.

Silicate paints can be made by react the waterglass paints with lime on the painted

surface. The paint film forms crystalline layers which has a high resistance against acids. The

best results are achieved on fresh render. This paint is more durable than lime paint and has a

strong resistance to pollution.

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Cement paints usually consists of Portland cements. They can be made by mixing some

lime with a small amount of water and then added to the pigment and water. Their durability and

quality fall somewhere between lime and silicate product.

Paints with organic binders

Organic binders consist of synthetics resins, protein glue, drying oils, tar, natural resin,

cellulose products, starch and emulsion.

Synthetics resins can be divided into thermoplastics and thermosetting products. Alkyde

oil paint is the most important thermosetting product. It is a paint with chemical compound

between linseed oil and the polymer. It is widespread use during 1950s.Less pigment alkyde oil

paint is called a stain. With no pigment, the paint is used as varnished. Its high percentage of

solvent can be a big risk in the working environment because of its emission of solvents.

Protein glue paint cannot be over painted with others type of paint. Two type of paints are

animal glue paint and casein paint. It can be used in emulsion paint and dissolved in water.

Under dry conditions, it is inert and does not lead to electrostatic charging.

Example of drying oil are linseed oil, Chinese tree oil and hemp oil. Linseed oil used in

painting since the beginning of the 17th century and also used for stone facades. It is generally

water prove and dry very slowly.

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Tar is weak brown in colour. Pigment such as English red or ochre is stirred in to give

more beautiful colour. It is impossible to paint others colour on top of it.

Natural resins can be used for varnishing wood, but it is less durable and needs a longer

drying time, and it also more expensive.

Emulsion paints are waterproof and produce a good matt surface. It is very economical.

Sometime, more than one layer of painting is needed to prevent flaking occur.

Stain do not contain added binders. Two main types of stain are chemical and water-

based stain. Chemical stain is based on a colour reaction with substances in the timber. While,

water-based stain is made with pigments that are soluble in water.

Other types of paint

Other types of paint that are available for specific jobs include:

Primer

These can be either oil or water based and are used to seal unpainted surfaces to prevent covering

coats of paint soaking in.

Undercoat

These usually are oil-based, applied on top of the primer. They should be in correct colour to

provide the right colour base for the finishing coats.

Anti-condensation

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It is for use in humid conditions such as in kitchens and bathrooms, this paint ii specially

formulated to prevent the surface becoming cold to the touch and therefore less conducive to

condensation. It is not a cure for condensation, only a way of reducing its effect on painted

surfaces.

Radiator paint

It is used for central heating pipes and radiators and will stand up to the high temperatures

without discolouring as other paints are prone to do.

Fire-retardant

These special paints contain an additive to provide a fire-resistant quality, they do not resist fire

completely, but has a greater flame resistance than ordinary paint and will reduce their spread.

Bituminous

Although often not considered as a paint, bitumen is used where a water proof coating is

required. Bitumen does not dry in the normal sense used with paint, it can crack if stressed when

frozen and will run or at least become sticky to the touch in hot weather. It is thick and usually

black and is used for areas where high water resistance is needed and appearance is not important

- such as on the inside of cast irons guttering and metal cold water tank. Bitumen is difficult to

paint over with conventional paints as the underlying bitumen tends to bleed into the overlaying

paint and will move with temperature changes while the covering paint may not be able to stand

up to the movement.

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Properties

Latex Paint

Top coat latex paints have been around for a long time. Some of the new latex paints provide

an excellent finish. hey consist of pigments suspended in water, therefore, they are thinned

with water instead of mineral spirits or turpentine. These materials are added to the latex to

make it dry faster and make it more durable. Acrylic-based latex paints are fast drying,

washable, durable, and ready to repaint in less than an hour. Some vinyl-based latex paints are

self-priming and fast drying. Rubber-based latex paints are effectively used on metal and

masonry.

Advantages of latex paint:

-comes in gloss, stain, and flat finishes

-dries quickly

-is easy to apply and touch up

-can apply two coats in one day

-cleans up easily

-is non-flammable

-can be used on almost any surface

--can often be washed, depending on type

-spots can be touched up easily

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-sometimes a prime coat is not needed

Disadvantages of latex paint:

-may have to wait 30 days before washing

-does not clean as well as oil-based paints

-must be sanded between coats on new woodwork.

-is not as durable as oil-based paints

-may rust metal

-sometimes does not adhere to glossy surfaces

-some brands yellow with time

-must be stored where it will not freeze

-may become brittle and chip

-generally cannot be used on metal and wood

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Oil-based Paints

These paints are very common on the market. They consist of alkyd resins thinned with solvents

like paint thinner or turpentine.

Advantages of oil-based paint:

-can be purchased from high-gloss to flat finish

-wall easily cleaned after being painted

-may resist chips and mars

-covers some wall imperfections

-resists stains

-may not need a prime coat

Disadvantages of oil-based paint:

-fades faster than latex paint

-hard to touch up

-may become shiny after repeated cleaning

-can discolor if applied over masonry

-thinned with a solvent, therefore more costly

-requires solvent to clean brushes

-flammable

-has an odor when newly applied

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Oil-based LatexDurability Excellent adhesion; better adhesion than latex on

heavily chalked surfaces.Excellent adhesion to most substrates; better elasticity than oil.

Color Retention

Not as good as latex, more likely to chalk and fade in sunny exposure.

Superior resistance to chalking and fading, especially when exposed to bright sun.

Ease of Application

More difficult to apply due to greater "drag," but goes on heavier for better one-coat hiding and coverage.

Goes on smoothly and evenly, with less brush drag.

Mildew Resistance

Vegetable-oil base can provide nutrients for mildew growth; most products contain mildewcide to minimize growth.

Less likely to grow mildew; mildewcide additives discourage mildew growth, help maintain fresh appearance.

Versatility Can be used on most materials, but for new concrete, stucco and other masonry, a sealer or pre-treatment is required; should not be applied directly to galvanized metal.

Can be used on wood, concrete, stucco, brick, galvanized metal, vinyl siding, aluminum siding, etc.

Odor Stronger odor than latex. Very little odor; non-combustible.

Cleanup Turpentine, paint thinner or other solvent. Simple water cleanup.

Drying Time Eight to 24 hours. One to six hours, permitting quick recoating.

Performance Comparison Chart for Top-Quality Paints

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Pros and Cons of Non-Toxic

Paint

Non-toxic paint (also called non-VOC paint) has been gaining popularity since it

was first introduced in the 1960s. Essentially, non-toxic paint is marketed as a safer,

less-polluting solution for interior wall painting and even artistic painting. The absence

of chemical solvents renders it safer for both the environment and for the people that

might otherwise be breathing toxic fumes. Of course, as with any product, there are

both pros and cons to using non-toxic paint.

Obviously, the major pros involve health and the environment. When you use

non-toxic paint on your interior walls or on your canvas, you don't breathe in the fumes

that are emitted by solvent-containing paints as they dry. Some of the most popular

non-VOC paints are made with milk or other organic components that smell better as

you paint and don't release harmful vapours.

The pros of non-toxic paint are especially important for people who have chronic

respiratory problems or allergies. Chemical fumes create more irritants in the air, which

can worsen pre-existing conditions or even create new conditions that are harder to

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control. Even if you use an air purifier and allergen-free furnishings, paint with chemicals

can significantly damage your health.

Other pros of non-toxic paint include price, drying time and disposal, though the

first two are affected largely by the non-VOC paint product you choose. Many of these

alternative paints cost less (especially in bulk), and dry much faster due to their thicker

consistency. Furthermore, you don't have to dispose of non-toxic paint as hazardous

waste, which makes clean-up much easier.

The cons of non-toxic paint are relatively few, but you should consider all aspects

of the paint job before you. For example, it can be difficult to find the specific colors you

need for a painting project when you use non-VOC paint. Every color in the world might

be available, but finding each in the same brand with the same ingredients can be a

chore.

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The usage of paint for building or constructions

Different types of paint have different usage for building or constructions.

Most of the paints with mineral binders are used on mineral surfaces or unplanned

timber surfaces.

Lime paints are used on pure cement or rough timber. It

is being painted in thin coats. Silicate paints can be used on all

mineral surfaces and also on rough wood. While pure cement

paint is mainly used for special treatment of pools and various

concrete structures, with large quantities of added polymers.

Paints with organic binders are mostly used in painting of wood, concrete and render.

Linseed oil is used on wood, concrete, render and to a

certain extent, steel. It can be used out of doors or indoors. Tar is

normally used outdoor so that the polycyclical aromatic

hydrocarbons (PAHs) substances can be filtered into the soil.

While, emulsion paint is used for painting render and concrete

also. Stain is basically used on wood such as spruce or pine.

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Paint is also used for protecting against certain building

materials. Non-ferrous metals may corrode in contact with

alkaline concrete cement or lime mortar, or with acidic gypsum

plasters. Water running off such materials may also be

corrosive. Aluminium and lead must always be protected; zinc,

cadmium and tin need protection in most conditions, copper

rarely. Thick coats of bitumen give suitable protection. Alkali-resisting primers may be used on

alkaline surfaces and will also suffice for the plaster contacts.

Besides, wood, especially western red cedar, Douglas fir, oak and sweet chestnut, may

affect metals. Bitumen, aluminium paint or zinc chromate primers may be used to prevent

contact. Wood primers may not be suitable. Wood treated with copper based preservatives

should not be in contact with aluminium.

The sheen of paint is the amount of light reflected by the surface of a paint finish. There

are four basic sheens, flat, satin, semi gloss and gloss.

Flat Paints exhibit non-reflective properties providing a matte finish. This finish helps

hide surface imperfections, and is normally used for ceilings and walls in areas not subjected to a

lot of wear and tear, dining rooms, living rooms and bedrooms not used by small children.

Satin Finish also know as eggshell finish, provides soft luster sheen similar to that of an

eggshell. A satin finish provides a harder surface finish which is more durable and more stain

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resistant than a flat finish. This durability makes satin paint a good choice for walls in children's

rooms, hallways, stairways and family rooms.

Semi gloss Paints are very durable, they are easier to clean, and are

more stain resistant than satin finish paints. Semi gloss paints are

most often used on heavy wear surfaces or areas that are frequently

cleaned such as kitchens and bathrooms. Semi gloss paint is also

used on wood trim and cabinets.

Gloss Paint is a harder, more durable, more stain

resistant paint finish. It is easier to clean than all the other paint

finishes. Gloss finishes generally make surface imperfections

more noticeable. Gloss finishes are the best choice for heavy

wear areas like kitchens, bathrooms, furniture and cabinets,

floors, stairs, handrails, high traffic doors and trim.

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Conclusion

Paints are very useful and important in not only building construction but also for other purposes.

However, they bring a lot of environment issues to human. When the paint is manufactured,

some toxic substances can also be produced to the surrounding at the same time. When painting

also, some of them that contain VOC’s (Volatile Organic Compounds) will release low level

toxic emissions into the air for years after application. These VOCs are a major contributor to

low-level atmospheric pollution and the use of these compounds leads to global warming. It is

also a major cause of ‘sick building syndrome’, asthma, allergies and chemical sensitivities.

Now, this issue can be solved by using low-VOC and zero-VOC paints and finishes. Most paint

manufacturers now produce one or more non-VOC variety of paint. These new paints are

durable, cost-effective and less harmful to human and environmental health.

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References:

Building Materials/essential information from Building Research establishment,

Lancaster: MTP Construction, 1973

The Ecology of Building Materials, Bjorne Berge, Architectural Press

Architect’s Pocket Book, Charlotte Baden-Powell, 3rd Edition, Architectural

Press/Elsevier

http://www.diydata.com/materials/paints/paints.php

http://www.hytechsales.com/howtopaint/paint_types.htm

http://www.brendasemanick.com/art/historyofpaint.htm

http://homerepair.about.com/od/interiorhomerepair/ss/paint_6.htm

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http://homerepair.about.com/od/interiorhomerepair/ss/paint_6.htm

http://www.brendasemanick.com/art/historyofpaint.htm

http://www.hytechsales.com/howtopaint/paint_types.html

http://www.diydata.com/materials/paints/paints.php

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Building Material _ Paint