Finishes (timbers/ metals)

Question 1

threat to timbers ( Wet rot)

Answer 1

water is absorbed into the wood which breaks down the fibres of the wood and encourages fungal growth
the timber becomes soft, wet and crumbly

Question 2

threat to timbers ( Dry rot)

Answer 2

fast spreading fungi infect dry timber making the wood dry, soft and powdery

Question 3

Threat to timbers ( Insect attack)

Answer 3

woodworm attacks softwood and hardwood
deathwatch beetle attacks hardwood
both lay eggs in the wood which hatch and eat through the wood leaving holes and tunnels which weaken it

Question 4

Polyurethane/ Acrylic varnish (timbers)

Answer 4

hard, water proof, tough and clear finish so the grain is still visible

Question 5

Water based paints (timbers)

Answer 5

provides protection and colour
paint seals the surface while allowing customisation of aesthetics
generally used on less attractive softwood

Question 6

Stains (timbers)

Answer 6

improves colour and enhances grain
colour cheap wood to look like expensive hardwood
have no protective properties

Question 7

Colour wash (timbers)

Answer 7

Colours wood while allowing the grain to still be visible

Question 8

wax (timbers)

Answer 8

can be clear or coloured
high gloss finish
increases surface hardness and toughness

Question 9

Yacht varnish (timbers)

Answer 9

protects timbers in an outdoor environment (e.g. boats, window frames ect)
increases toughness, hardness and weather resistance

Question 10

Danish oil (timbers)

Answer 10

can be clear or colour tint
maintains natural appearance of timber
soaks into wood and enhances grain

DISADVANTAGES
not hard wearing
needs regular coats to build up water resistant finish

Question 11

Teak oil (timbers)

Answer 11

used for outdoor wood
improves weather resistance and protects against insect and fungal attack
enhances grain

Question 12

Pressure treating (timbers)

Answer 12

Wood is placed in a pressure vessel with copper sulphate salts
heat and pressure force preservatives into the timber
protects against rot, fungi and insects for up to 50 years
used in decking and bridge construction ect

Question 13

cellulose and acrylic paints (metals)

Answer 13

covers the surface of the metal and prevents corrosions
provides aesthetic colour and texture

Question 14

Electroplating (metals)

Answer 14

electrolysis is used to coat the outside of a metal with a different one to improve aesthetics and protect the surface
the object acts as a cathode in the electrolysis setup, when the current flows metal ions in the electrolyte cover the cathode

Question 15

Polymer dip coating (metals)

Answer 15

metal is heated to 230 C
dipped into powdered polymer which melts and coats the metal.
the polymer powder is suspended in a liquid like state by jets of air (fluidisation bath)

Question 16

metal dip coating (metals)

Answer 16

metals are dipped into tanks of molten metal coating them as they cool
covers the surface in a corrosion resistant layer
often zinc (460 C) or tin (320 C) is used

Question 17

Powder coating (metals)

Answer 17

the metal is negatively statically charged
positively charged thermoset polymer is sprayed throw an air gun and is attracted to the surface of the metal
the product is heated in an oven to melt the powder and give an even coat

Question 18

Metal varnish (metals)

Answer 18

a clear surface protection which stops corrosion and scratching while the metal is still clearly visible

Question 19

Sealants (metals)

Answer 19

tough polymer sealant completely protects the metal from the environment allowing it to be used in an outdoor environment with the metal still being visible

Question 20

Preservatives (metals)

Answer 20

provides temporary protection to machinery parts to ensure they are not damaged or there surfaces distorted at any point in manufacturing (e.g. moulds and dies )