1. To stop the decay, corrosion or degrade of a material
- To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Why are they needed?
To stop the decay, corrosion or degrade of a material
Wood will decay through wet/dry rot or insect attack
Metals will corrode through rust or electrochemical or chemical attack
Electrochemical occurs when two joined metals react with each other to create a natural voltage. This voltage in the presence of water can cause corrosion
Plastic will degrade over time and expose to a number of elements such as UV and oxygen

2. As well as changing the aesthetics of a product finishes are used to:
- To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Finishes
As well as changing the aesthetics of a product finishes are used to:
Protect the material against corrosion
Make the product water repellent
Improve its resistance to wear and fatigue
Improve its ability to reflect or absorb heat
Improve its ability to insulate against heat or electricity

3. - To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Wood paint
Before paints are applied the wood will need to be prepared be by sanding it down, cleaning it and treating any knots so that the finish is attach to it
The use of a primer is used to prevent other layers absorbing into the wood
As undercoat will help additional layers and a top coat attached better as well as give a better aesthetic finish
Sanding down between layers will also help give a quality finish
Oil-based paints are hardwearing and non porous and so is used inside and outside for coating windows and door frames
Polyurethane paints are good for coating products such as toys. They are extremely hardwearing, tough and stretch-resistant. Polyurethane vanishes are also used if the wood grain is required
Yacht varnish is more appropriately for outdoor products as it is not affected by sunlight (whereas polyurethane varnish is)
Two-stage stain and varnish will both colour and protect wood. They can be used internally and externally. The first layer will contain a colour and will stain the wood. The second will be a varnish which brings out a wood grain under the coloured wood

4. Creosote, Water-soluble, organic solvents and tantalising Creosote
- To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Wood preservatives
There are 4 many types which can all be applied by brush, dipping, spraying or pressure treatment
Creosote, Water-soluble, organic solvents and tantalising
Creosote
Creosote is a tar-oil based preservation
It is a traditional method but is very damaging to the environment
It has now been banned and water-based alternatives are used
These need to be more regularly applied in comparison
Tantalising
This is when a solution of copper sulphate and other salts are impregnated into a timber usually a pressure vessel.
The wood is first dried to remove moisture
Once in the vessel the pressure forces the minerals into the structure of the wood
The wood is then steam dried before being used
Timber treated like this can last up to 50 years

5. - To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Metal finishes
Natural barriers
Ferrous metals will rust if moisture is present
A number of metals will oxidise if damaged or stretched – this protects the metal from further damage
Stainless steel has a natural barrier which prevents oxidisation or rust
Other ferrous metals can go though blueing. This is heating them to 300C plus and then quenching them in oil
This creates a fine oxide layer
Electroplating
This is a method of plating one metal with another
It uses an electrochemical process that allows ions from a coating material to form on a base material to create a coated protective layer
This include chrome plating and silver plating
Anodising
Aluminium can be anodised to give it s more durable and scratch resistant finish
This is done in a similar way to electroplating but a lead is the coating layer
The aluminium is finally sealed afterwards with a lacquer

6. - To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Dipping and Spraying
- Metals can be dipping or sprayed with a material coating when heated
- Galvanising (zinc plating) is done in this way by dipping steel into molten zinc ( C)
- Tin plating is also done in this way with steel ( C)
Enamelling
This is a process of coating metal in a fine glass powder
This is then heating in a kiln so that the glass liquefies and forms a very hard glossy coating on the metal
This is also heat and scratch resistance
Titanium coating
- Due to titanium being so hardwearing it is used to coat tool and kitchen equipment
- This is done via two methods
- Plasma spray
- This uses a super heated inert gas (formed by an electrical arc) to melt fine titanium powder onto a material
- Physical vapour deposition
- This uses a vacuum chamber which has the product placed in it. The coating material is evaporated by intense heat. The atoms of the coating materials are then placed into the chamber and deposit onto the surface of the product.

7. - To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Metal finishes
Painting
As with woods metals have to be prepared before paint is applied
Paraffin-based liquids are use to degrease the metal before it is primed.
Layers of primer, undercoat and topcoat as applied similar to wood
The paint can be brush, rolled or sprayed on
Steel products like car bodies are forgot galvanising before paint to stop corrosion.
Some specialist paints or lacquer can be used directing onto metal without any preparation
Electrostatic coating
This is a system which creates an electrostatic charge between the paint and the product
This means that the paint is attracted to the surface of the metal product so make a secure bond and quality finish
Powder coating
This is a method with statically charge powder particles and then sprays them via an airgun onto the metal product
This give an even coat like electrostatic coating
The product is then placed into an oven or kiln which will bake the powder into the product and create a hard, tough finish
Plastic coating
Plastic dip coating works in the opposite way to powder coating
The metal product is heated up in a oven or kiln (before any finish it applied)
It is then dipped into a fluidised bath of plastic powder
A coat of powder will attach and melt to the surface of the heated product and will cure are the product cools to give a hard and smooth finish

8. - To be able to identify and select a variety of different finishes techniques for wood, metal and plastic
Plastic finishes
Self-finished
Plastics are known as self-finishing
This means that when they are processed into product the moulding and machine used is so high quality they would give a quality surface finish
Self-coloured
Plastic can be pigmented to have different colours
This would be done during the manufacture of the plastic product
Texture
Due to the design of some moulds texture can also be added to plastics
The use of TPE will also have a natural texture to them which is why they are so good for grips and handles
Polymer coating
In a similar way to titanium polymer can use physical vapour deposition to coat product with plastic. This is done with PMMA for glass lenses to make them harder
Overmoulding
This is a process which allows second polymers to be injected over the top of another (plastic component)
This is used add a rubber grip to toothbrushes. The make body is formed first and then the rubber grip is injected in afterwards (and partly embedded in to the body)
Twinshot injection moulding
This is similar to overmoulding but two injectors are used at the same time to inject two different polymers into a single mould
This is used in some phone cases and Ipod cases.