Finishes Flashcards
paper and board polymers metals
name 5 finishing processes for paper/board
- embossing
- laminating
- debossing
- varnishing
- foil blocking
what is the difference between embossing and debossing?
- embossing makes a 3D pattern on the surface
- debossing puts the pattern underneath the surface
what is embossing and debossing used for?
- braille on medicine
- add texture to board
- add status to paper
how does embossing work?
- substrate stamped between 2 shaped steel plates using heat and pressure
- plates shape fibres without cutting or ripping the substrate
what is blind embossing?
no ink is applied
what is foil blocking?
a dry decorative process where coloured metallic foils are applied to paper and board
what is the foil blocking process steps?
- metal dye is heated [100-200 degrees]
- foil stamped onto substrate
- heat and pressure bonds the foil to substrate
what process can foil blocking be used with?
embossing
what properties does lamination give to paper and boards?
- durability
- tear proof
- wipe clean
what is lamination? [paper]
when a polymer film is bonded to the front and back of a substrate
what finishes are the films available in? [6]
- matte
- gloss
- silk
- metallic
- holographic
- soft touch
what is encapsulation and how is the process carried out?
- use a desktop laminator
- paper placed in plastic pouch and fed into machine
- machine puts it under heat and pressure
- plastic fuses to paper leaving a transparent margin
properties of encapsulation lamination
- not versatile
- quick
- convenient
- durable
- protects edges from moisture
what do varnishes do?
add a protective barrier and different finishes/textures
how is varnish applied? [form]
- liquid form
- printed on
what is the name when varnish is applied in certain areas?
spot varnishing
what is the difference between water based and solvent varnishes?
water based - dry quickly , eco friendly
solvent- toxic, cheaper
how does UV varnish cure?
under UV light
why are acrylic spray paints used?
to protect and colour moulded plastic parts/products
properties of acrylic spray paint
- water based
- fast drying
- UV protection
- weather resistance
where are acrylic spay paints used?
- mass produced ABS parts
- car parts [bumpers]
how do you prepare ABS for spray paint?
- washed and dried
- surface scraped
- cleaned again to remove dust
- primer applied and left to dry
- several even coats of paint applied
what are thermoplastic elastomers called and used for?
overmouldings - additional grip and texture and indicate where to hold
uses of overmouldings
- tool handles
- sport equipment
- toothbrushes
- torches
- power cables
how are overmoulds made?
-injection moulding
either two separate moulds or a duel cavity mould [continuous production]
when are gel coatings used?
- part of layup process
- creates rigid GRP shell
- creates coloured finish
what is the process of gel coating?
- pigment added to polymer resin
- applied to inside of mould and cured before layup process
- creates a pre-coloured high shine surface finish
what are the two finish categories?
- protection
- aesthetic
why are solvent based spray paints not environmentally friendly?
contain VOC [volatile organic compounds]
what are volatile organic compounds?
gases emitted into the air that are toxic or pollutants
what are thermochromic pigments?
added to polymers to create a colourful reaction to thermal changes
uses of thermochromic pigment
- baby cups
- plastic cutlery
- thermometers
what are phosphorescent pigments?
pigments charged by exposure to light
how do phosphorescent pigments work?
release light energy stored in the dark [glow in the dark]
uses for phosphorescent pigments
- watch faces
- toys
- ceiling stars
- frisbees
- balls
what are the 2 reasons for metal finishes?
enhance appearance and prevent corrosion
what are the 11 metal finishes?
- cellulose and acrylic paint
- electroplating and galvanising
- sealants and preservatives
- anodising
- plating
- dip and powder coating
- cathodic protection
what do cellulose and acrylic painting do to metal?
provide colour and protect against corrosion
how do you prepare metal for painting?
- work piece prepared and degreased
- key applied so paint will stick
- paint applied
properties of cellulose paint [cars]
- fast drying [contains solvent]
- contains VOCs
- needs multiple coats for high quality finish
properties of acrylic paint
- water based
- durable
- hard wearing
- requires heat
- needs professional equipment
- 24 hrs to cure
uses for acrylic paint
- bikes
- roofing sheets
- window frames
what is electroplating?
coating a cheap base metal with desired metal
how does electroplating work?
- negative electrode is the object that’s being plated
- positive electrode is the coating metal
- electrolyte is solution of coating metal
what is galvanization?
when steel or iron is coated with zinc for protection
what does the zinc do in galvanization?
- forms zinc carbonate when exposed to air or water
- resistant to corrosion and tough
what are the two methods of galvanizing?
electroplating and hot dipping
what is the hot dipping process?
- workpiece cleaned during 4 stage process
- dipped into 830-850 degree zinc bath
- cooled, cleaned and inspected
what is good about hot dipping?
- good for large objects
- thicker overall coverage
what are sealants?
block the passage of air or fluids through metal joints
what do sealants prevent?
- prevent decay, weathering and corrosion
- polymer based
what are preservatives?
provide a temporary or long term protection for metal surfaces
where are preservatives and what do they do?
-used in moulds and dies to prevent atmospheric corrosion or condensation
uses of preservatives
machine beds [smooth frictionless]
stabilize rust
how are preservatives applied? [5]
- bonding
- electrostatic
- spraying
- immersion
- cloth
what is anodising?
a process used to make a hard wearing and corrosion resistant surface on aluminum
how does anodising work?
- aluminum workpiece immersed in electrolyte
- current passed through
- cathode placed in a tank
- workpiece is anode
what metals can be anodised?
magnesium, titanium and aluminum
what is the anodising process?
- electrochemical
- oxygen ions are released from electrolyte
- o2 ions combine with aluminum ions
- results in an aluminum oxide layer that thickens and protects the surface
properties of anodising? [4]
- colouration
- wear resistant
- improved lubrication
- increased electrical insulation
properties of plating?
- increases the wear resistance and lubricity
- thermal barrier improved conductivity
what is the plating process?
- heated coating metal evaporates upwards
- it cools and fuses to the component [called deposit]
- physical water vapor deposition [PVD]
uses of plating
- solar panels
- surgical implants
- jewellery
- coated cutting tools
what does dip coating do?
provides a thick, wear resistant, water resistant and air tight finish
what is the dip coating process?
- metal heated to 230 degrees
- dipped into tank of fluidised polymer powder
- warm air blows around the tank
- heat from metal melts polymer so it bonds to surface
- cools and solidifies
what does powder coating do?
provides an even coating that’s more hard wearing than paint
what is the powder coating process?
- workpiece statically charged
- powder paint sprayed through air gun
- charge creates strong attraction between powder and workpiece
- workpiece baked to melt the coating to the metal
what is cathodic protection?
when sacrificial anodes are used to control the corrosion of the metal surface
what is the cathodic protection process?
- metal turns into the cathode of electrochemical cell
- sacrificial metal turns into anode
- bonds to the surface so it corrodes instead of metal
uses of cathodic protection
boat hulls
fuel pipes
oil rig foundations
why are finishes applied to wood?
improve aesthetics and performance
what do finishes do? [6]
- change the colour
- enhance natural grain
- add texture
- moisture resistance
- seals to make easier to clean and protect from airborne pollutants
how is wood prepared for finishing?
- sanded along the grain
- remove surface dust by methylated spirits
- finish applied
How can finishes be applied to wood?
cloth, brush, roller, pad, spray
pressure treatment by professionals
what are the 8 finishes?
- colour wash
- wax finishes
- danish oil
- teak oil
- stains
- water based paints
- acrylic varnish
- polyurethane varnish
what are the 2 finish categories?
water based
solvent based
what is Polyurethane varnish and its properties?
liquid plastic suspended in a carrier
- satin, matte or gloss
- tough
- hard wearing
- heat, water and chemical resistant
- clear or tinted
positives and negatives of water based Polyurethane varnish
- good quality finish
- water based is good for environment
- safer
- wood looks fake
- not UV resistant
positives and negatives of solvent based Polyurethane varnish
- durable
- long drying times
- health risks
- Not UV resistant
what is the appearance of acrylic varnish?
milky-white but dries clear
properties of acrylic varnish
- fast drying time
- doesn’t yellow
- durable
- hard wearing
- less resistant to heat and solvents
- non toxic
- odour free
uses of Polyurethane varnish
boats and wooden floors
what are water based paints used for?
- applying opaque colour to wood
- interior wood work and furniture
properties of water based paints
- available in any colour
- can be watered down
- low odour
- low level of VOCs
- hard wearing
- quick drying
- easy to use and clean up
what are many water based paints certified as?
toy safe
what is recommended when using water based paints?
primer and undercoat
what do stains do?
apply colour to paint whilst keeping natural wood grain
positive and negative for stains
provide an aesthetic finish
no protection against decay or degradation
what stains are available?
- bright colours
- natural wood tones
- soft woods
- hard woods
what do colour washes do?
give an artistic, destressed look to accentuate details
how are colour washes applied?
- applied to painted surface
- wiped away with a rag while wet
- most of wash is removed but leaves some finish and texture
are colour washes protective or aesthetic?
purely aesthetic
wax finish properties
- limited protection against moisture, heat and scratches
- food safe
- non toxic
how is wax applied?
- lint free cloth and left to sink in
- residual wax buffed up to shine
- several coats applied
what do oils do?
replace natural oils lost over time
properties of oil
- little heat, scratch or liquid protection
- non toxic and wood safe [raw]
what is Danish oil made from?
oil and varnish
properties of Danish oil? [+ 1 use]
-enhances woods beauty
-water resistant
-durable, satin finish
-used as a primer
-food safe when fully cured
toys
where is teak oil commonly used?
hard woods
properties of teak oil
- UV protection
- indoor and outdoor uses
- not good for high sheen
- not for high traffic areas
- cannot be glued
uses of teak oil
- boats
- garden furniture
what preservative is added to treated timber?
antimicrobial copper based preservative
where is pressure treated wood used?
when exposed to constant weathering and fungal/insect attacks
uses of pressure treated wood
landscaping
fencing
playgrounds
what is the process name for pressure treatment?
Tanalising
what is tanalising?
- uses pressurized treatment vessel
- forces preservative chemicals deep into the wood
