Reasons for Applying Surface Treatments or Finishes
- Protection: Prevents corrosion, decay, or surface damage (e.g. rust on metals,
rot in timber).
- Durability: Increases the product’s resistance to wear, weather, or moisture.
- Aesthetics: Enhances the visual appearance (colour, texture, gloss).
- Functionality: May add non-slip surfaces, electrical insulation, or hygiene
coatings.
Preparing a Material for Treatment or Finish
Before applying any surface treatment or finish, materials must be properly prepared:
- Cleaning: Remove grease, dust, or residues (e.g. with white spirit or mild
detergent).
- Sanding: Smooth the surface using sandpaper to remove rough edges or previous
finishes.
- Degreasing: Particularly important for metals before painting or coating.
- Priming: Applying a primer coat ensures better adhesion of paint or varnish and
improves finish quality.
- Masking: Use masking tape to protect areas that should not be coated.
Common Surface Treatments and Finishes
Timber
- Paint: Adds colour and protects from moisture; usually needs primer and
undercoat first.
- Varnish: Transparent finish that highlights grain and provides water
resistance.
- Wax: Enhances texture and gives a soft finish; suitable for indoor furniture.
- Oil (e.g. Danish or linseed): Soaks into wood and protects from inside; good
for outdoor use.
- Stain: Changes colour without hiding the grain; often combined with varnish or
wax.
- Preservative: Protects against fungal decay and insects, especially for
exterior use.
Metal
- Paint: Protects against rust and adds colour; often used with a primer.
- Powder Coating: Dry powder is electrostatically applied and cured with heat.
Durable and even finish.
- Galvanising: Steel coated with a layer of zinc to prevent corrosion.
- Electroplating: A decorative and protective metal layer applied using
electrolysis (e.g. chrome or nickel).
- Anodising: Used mainly on aluminium to thicken oxide layer and add colour.
Polymers
- Polishing: Improves surface shine on acrylic and other thermoplastics.
- Painting: Requires surface keying (light sanding) and a compatible primer.
- Surface Texturing: Achieved during moulding or with embossing/etching for grip
or style.
How to Apply a Surface Treatment or Finish
- Brush application: Suitable for paints, oils, and varnishes. Easy to control
but may leave brush marks.
- Spray application: Provides a smoother, even finish; requires good ventilation
and protective equipment.
- Dip coating: Metal is heated and dipped into polymer powder that melts and
coats the surface.
- Electroplating/anodising: Done using electrical current in a chemical bath;
requires specific setup.
- Powder coating: Uses a spray gun and curing oven; provides tough, even
protection.
Summary
Choosing the right surface treatment or finish depends on the material, environment, product use, and
desired appearance. Effective preparation and correct application are essential for achieving
long-lasting and visually appealing results.
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