There are 3 main types of finishing.
Self finishing - Materials that do not require a finish.
Self coloured - Materials produced in the required colour.
Applied finish - A surface finish to enhance or preserve.
FOR PAPER AND BOARD.
LETTERPRESS. Paper is pressed against the plates holding the letters. It is still used today for specialist printing such as wedding invitations, but it can usually only print one colour at a time.
LAMINATING. There are two main lamination methods in relation to papers and boards.
Lamination via encapsulation
Lamination via a surface coating
EMBOSSING. This creates a raised design on the surface. It also can have a practical application such as applying braille to packaging.
DEBOSSING. This is the opposite of embossing and produces an indented depression rather than a raised surface.
FOIL BLOCKING. This process involves the application of heat and pressure to a metallic paper (foil) to create areas of depth and texture.
VARNISHING, UV VARNISHING AND SPOT VARNISHING.
Varnish is a clear ink used on pre-coated papers to provide aesthetics and protect it from dirt and fingerprints. It is available in gloss, satin and matt finishes.
UV varnishing provides a smooth finish and is cured using UV light once the ink has dried.
Spot varnishing is applied to specific areas to make text or logos stand out. It can be done with normal or UV varnish.
PRINTING PROCESSES.
SCREEN PRINTING. (Art process)
transfer of designs onto paper and fabrics.
transfer of designs onto ceramics.
printed circuits for electronics products.
the process was originally called silkscreen printing as ink was forced through a template via a silk screen and squeegee.
PAD PRINTING.
Pad printing is often compared with screen printing. Pad printing is how lego figures are printed. y using pad, printing by pressing it on the surface.
FLEXOGRAPHY. It is a relief printing process similar to letterpress but in this case raised text and images are photo etched onto a rubber material which is glued onto steel rollers.
This process is primarily used for packaging, carrier bags but also books and magazines.
OFFSET LITHOGRAPHY. It is probably the most versatile (universal) and economic of the commercial printing processes and uses the same four colours (CMYK) through a series of up to five presses.
Offset lithography is often used to print high-quality promotional materials
ELECTRO-PHOTOGRAPHIC PRINTING. Process involves the depositing of toner into the paper or card. Dry or liquid toners can be used but they are fixed by heat.
INKJET PRINTING. Process involves spraying electrostatically charged ink droplets directly onto the paper relying on absorption to fix the inks.
FINISHES FOR POLYMERS.
Adding colour during the moulding process can be done because polymers are synthetically produced.
Polymers are self- finishing.
With sheet materials this is often a perfectly smooth mirror-like finish, however, they can also have textures to give a frosted look or any other texture that is also in the mould.
Polymers are self coloured.
ACRYLIC SPRAY.
Although polymers are self-finishing it may still be necessary to apply a different colour or surface finish for aesthetic or practical reasons. Acrylic paint is a fast drying, water soluble paint that becomes water resistant when dry. It is readily available in a wide range of colours including pearlescent, metallic and fluorescent.
OVERMOULDING. (TPE) - Thermoplastic elastomers.
It is when a second polymer is moulded over a specific part of a product.
There are two main ways of doing this:
Use two injection moulds
Twin shot injection moulding
GEL COATS CAN BE ADDED TO MOULDS WHEN LAMINATING GRP.
GRP - Glass fibre reinforced plastic.
SMART PIGMENT.
By replacing traditional pigments with smart pigments we can affect the colour of a materials by subjecting them to heat or light.
Smart pigments have a variety of practical uses and can be incorporated into fabrics and polymers in the same way that you might mix in a paint or dye to colour a material while it is being formed.
THERMOCHROMIC PIGMENT.
Thermochromic pigments change colour when exposed to heat. Common examples are baby spoons, kettles and thermometers.
PHOTORESCENT PIGMENT.
Phosphorescent materials have the unique ability to absorb light and then use that light to provide low level illumination in dark or low light conditions.
FOR METALS.
Purpose of Paints:
Provide color and sometimes a textured finish to metals.
Act as a barrier against corrosion for metals like steel and iron.
Preparation:
Cleaning the metal surface, de-greasing the surface, applying a primer to help the paint adhere properly.
Surface:
Undercoat - Applied to get a full, rich color.
Color Layer - Main paint layer providing the desired color.
Clear Lacquer - Applied over the paint for a shiny finish, commonly used on cars and other glossy products.
ELECTROPLATING.
Purposes of electroplating coating:
- Coat a cheaper metal with a layer of another metal.
- Provide protection and improve appearance.
Examples of it are silver-plated teapots or gold-plated cheap jewelry
Process is:
1. Submerging the metal product in a solution with tiny particles of the coating metal, applying an electric current, coating metal and becomes electroplated.
POLYMER DIP COATING.
This coating ir suitable for products like wire coat hangers and outdoor equipment.
Process is - heating the metal product, dipping the hot metal into a tank of fine polymer powder with air blown in to ensure even distribution and metal melting the powder, creating a tight and even polymer coating.
METAL DIP COATING.
Purpose is to coat metal products by dipping them into molten metal. It is commonly used to protect cheap metals like low-carbon steel from rust.
Process is dipping the metal product into a tank of molten plating metal. This action creates a protective layer against corrosion. As an example - food cans are often tin-plated because tin doesn't react much with food.
Using a Zinc plating is known as Galvanizing. It is used to produce car bodies, buckets, screws, hinges and much more. It give a corrosion resistant finish.
POWDER COATING.
Powder coating gives a better finish than dip coating. It works by spraying a negatively charged item with positively charged powder, which sticks to it. The item is then baked in an oven, turning the powder into a smooth coating.
This method is used for coating chair and table legs, as well as many household metal items like fridges and washing machines.
VARNISHING.
This coation for metal gives it a clear finish and helps prevent rust. It is applied like paint or spray. Varnish is just clear paint without color. For a finer finish, a clear lacquer can also be used.
SEALANTS.
Metal sealants are strong coatings that protect polished surfaces from damage and tarnishing. Silicon-based sealants are often used in cars to protect against weather and rust. They are usually applied with a cloth or machine pad to create a film, left to cure for 15 minutes, and then buffed to a shine.
PRESERVATIVES.
Metal preservatives protect metal surfaces temporarily or after processing. They are great for molds and dies to prevent fingerprints. They can be applied with a cloth, spray, or by dipping the metal.
ANODIZING.
This process is quite same as giving aluminum an extra tough skin. It's a way to make aluminum products stronger and more durable. It's kind of painting, but instead of just covering the surface, it actually gets into the aluminum itself. After anodizing, you can add a layer of lacquer or varnish to keep it looking nice and protected.
CATHODIC PROTECTION.
All metals have a natural voltage and when two different metals are joined together there is an electrical current. If water is present at the joint it results in the formation of an electrochemical cell and one of the metals will corrode.
Cathodic protection is a method used to control the rate of corrosion. The main use is to protect steel structures buried in soil or immersed in water such as pipelines, ships and offshore platforms.
Wood is prone to damage from moisture, bugs, and weathering, despite its natural appeal. Adding wood stains or color washes can enhance its look, often with varnish for extra protection.
It's vital for wood finishes to preserve the material, as it can degrade in dry or wet conditions, leading to rot.
Here's a rundown of the main wood finishes. Their use depends on what the item is for and how it should look. For example, a chopping board shouldn't be oiled or waxed to avoid contaminating food, whereas a cricket bat is oiled because varnish would wear off during play.