Unit 2-F Flashcards by christopher waygood

What finishes can be used for metal?

Cellulose and acrylic paints
Electroplating
Dip coating
Powder coating
Varnishing
Galvanising
Anodising
Cathodic protection

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How do cellulose and acrylic paint protect metal?

Oil or water based and form a protective layer over the metal

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What are the benefits of cellulose and acrylic paints?

Protects ferrous metals from rust
Improves aesthetics (range of colours and textures)

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What is electroplating?

Applying a thin layer of metal to the surface of another

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How does electroplating work?

Both metals submerged in electrolyte
Plating metal at anode
Metal to be plated at cathode

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What metals are commonly electroplated?

Jewellery can be electroplated with gold or silver

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What are the benefits of electroplating?

Improves wear resistance (plated with wear resistant metal)
Enhances electrical conductivity (plated with good conductor)
Improves surface finish

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What metals can be electroplates?

Gold
Silver
Copper
Platinum
Chromium
Brass
Zinc – corrosion resistant and non-toxic

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How does dip coating work?

Metal heated and dipped into plastic powder
Metal is then reheated to join plastic to surface

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What are the benefits of dip coating?

Increases aesthetic appeal
Protects the metal
Stop metal scratching other objects
Provides comfortable grip

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What plastics are used for dip coating?

Rubber based – soft, flexible
PVC based – thick, durable
Vinyl based – chemical and abrasion resistance
Polyurethane based – durable, wear and chemical resistance

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How does powder coating work?

Charged plastic powder sprayed onto surface of metal
Plastic is then heated to set it hard

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What are the benefits of powder coating?

Durable and hard finish
Corrosion resistance
Improves aesthetics

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What plastics are used for powder coating?

Polyester
Polyurethane
Epoxy
Acrylic

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How does varnishing protect metal?

Solvent and binding agent mixture
Solvent evaporates leaving protective film

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What are the benefits of varnishing?

Protection from elements
Adds aesthetic appeal to attractive metals

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How does galvanising work?

Steel must be cleaned with no oxide layer
Steel dipped in molten zinc
Zinc bonds to surface to protect the steel

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What are the benefits of galvanising?

Protects from rust
Increases the lifespan of the steel

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How does anodising work?

Current is passed through aluminium in an acid bath to oxidize the surface

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What are the benefits of anodising?

Enhances hardness and toughness
Improves wear resistance
Can provide colour

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How does cathodic protection work?

Either: structure made into a cathode and connected to an anode
Or: metal is coated in sacrificial metal which will be corroded

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What metals can be cathodically protected?

Steel structures which are submerged in water or soil

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What are the benefits of cathodic protection?

Greatly reduces the corrosion of steel parts

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What metals are used in cathodic protection?

Saved metal – steel
Sacrificial metal – zinc or aluminium

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What finishes can be applied to plastics?

Acrylic spray paint Overmoulding

What are self-finishes?

Polymers often do not need any extra finishing Textures can be added to the mould Colours are added during manufacture

What is overmoulding?

Adding more polymer over the top of initial product

What plastics can be used for overmoulding?

TPE (thermoplastic elastomer)

What are the benefits of overmoulding?

Adds grip or texture Adds colour to draw attention

What is an alternative to overmoulding?

Twin shot injection – two injection points for 2 polymers

What are the benefits of acrylic spray paint?

Cost affective – easy to change colour Adds aesthetic appeal

What finishes can be applied to protect woods?

Polyurethane varnish Water based paints Wax Yacht varnish Danish oil Teak oil Pressure treating

What finished can be applied for aesthetics of wood?

Colour wash Stains

What is wet rot?

Moisture absorbed by wood Wood breaks down and becomes soft and crumbly

What is dry rot?

Fast spreading fungus makes wood dry and powdery

How can insects damage wood?

Woodworm attacks soft and hard wood Deathwatch beetle larvae attack hardwood

How does polyurethane varnish protect wood?

Leaves a plastic coating on the wood

How is polyurethane varnish applied?

With a brush in the direction of the grain

What are the benefits of polyurethane varnish?

Hard Tough Heatproof Waterproof Clear so grain can be seen

How should wood be prepared for water-based paints?

Knots treated Primed with undercoat

What are the benefits of stains?

Enhance the grain Makes cheap wood look more expensive

What are the benefits of water-based paint?

Protection and colour Surface is stronger and harder Protects from moisture

What are the benefits of colour wash?

Enhances aesthetics Allows grain to show Can add vintage look

How is colour wash applied?

With a sponge

How is wax applied?

With brush or cloth Buffed to produce a high gloss finish

What are the benefits of wax?

Natural grain can be seen Increases surface hardness and toughness

How is yacht varnish applied?

With a brush or sprayed

What are the benefits of yacht varnish?

Increases toughness and hardness Increases weather resistance

How is Danish oil applied?

With a cloth in the direction of the grain Left for 5 mins Excess is removed

What are the benefits of Danish oil?

Maintains natural appearance Multiple layers build waterproof finish

How is teak oil applied?

With a cloth in the direction of the grain Left for 5 mins Excess is removed

What are the benefits of teak oil?

Improves weather resistance Protects from fungal or insect attack Increases aesthetic appeal

For which woods should you use Danish vs teak oil?

Teak oil is for oily woods like teak

How is pressure treating done?

Timber into vacuum chamber Wood is flooded with copper sulphate Vacuum removes excess preservative Wood is left to dry

What are the benefits of pressure treating?

Copper is a good fungicidal Resists rotting

What plastics are used for encapsulation lamination?

Mainly PET

What finishes can be applied to papers and boards?

Lamination (encapsulation and surface coating) Embossing Debossing Varnishing Foil blocking Screen printing Flexographic printing Offset lithographic printing Digital printing

What are the benefits of encapsulation lamination?

Protects from moisture Increases lifespan

What plastics are used for surface coating lamination?

Usually PP with an adhesive

How is surface coating lamination done?

Sprayed on or applied with a roller

What are the benefits of surface coating lamination?

Provides UV protection Protects from moisture

What is embossing?

Stamping raised designs into material Uses a male and female die to emboss the substrate

What are the benefits of embossing?

Aesthetic appeal

What is debossing?

Stamping sunk design into material

What are the benefits of debossing?

Aesthetic appeal

What are the benefits of varnishing?

Protects from UV, fingerprints and dirt Words and symbols can be made using spot varnishing

What is foil blocking?

Applying foil in a specific pattern using a die Die is heated to bond the foil to the material

What are the benefits of foil blocking?

Aesthetic appeal

What is screen printing?

Ink is spread on a mesh with a negative stencil Material is placed below, and ink is transferred using squeegee

What are the benefits of screen printing?

Good for small batches Minimal setup cost

What is flexographic printing?

Uses CMYK and multiple rollers to transfer ink to a cylinder with the design Ink is then transferred to the material

What are the benefits of flexographic printing?

Very cost efficient High speed Good quality Continuous printing possible

What is offset lithographic printing?

Design is etched on an aluminium plate Multiple rollers transfer the ink to the material

What are the benefits of offset lithographic printing?

High image quality Long life process Can be used on canvas, cloth and wood - Edits are expensive and time consuming

What are the benefits of digital printing?

Fast and efficient Customisation quick and easy Can be used for high and low volume

What is a holographic finish?

A very high gloss finish

Unit 2-F Flashcards

(77 cards)