Question 1

What is the difference between powder coating and wet painting?

Accepted Answer

Powder coating uses a dry powder applied electrostatically and then cured in an oven, creating a durable, even finish that is resistant to chipping and corrosion. Wet painting involves liquid paint applied by spraying or brushing, which can be cheaper but is less durable and may contain volatile organic compounds (VOCs). Powder coating is better for high-wear items like bike frames, while wet painting offers more colour options and is easier to touch up.

Question 2

Why is anodising only used on aluminium?

Accepted Answer

Anodising is an electrochemical process that thickens the natural oxide layer on aluminium, making it harder and more corrosion-resistant. Other metals like steel or copper do not form a stable oxide layer that can be thickened in the same way. For steel, galvanising or electroplating is used instead.

Question 3

How do I choose a finish for a product that will be used outdoors?

Accepted Answer

For outdoor use, prioritise finishes that resist UV radiation, moisture, and temperature changes. For metals, consider powder coating or galvanising. For woods, use exterior-grade varnish or paint with UV inhibitors. For polymers, select UV-stabilised grades or apply a protective lacquer. Always test the finish for weather resistance and consider maintenance requirements.

Question 4

What is dip coating and when would I use it?

Accepted Answer

Dip coating involves immersing a component in a liquid coating material (e.g., plastisol) and then curing it. It is used for items with complex shapes, like tool handles or wire racks, to create a thick, even, and insulating layer. It is cost-effective for large volumes but limited to materials that can withstand the dipping process.

Question 5

Can finishes be environmentally friendly?

Accepted Answer

Yes. Water-based paints and powder coatings produce fewer VOCs. Some finishes are biodegradable or made from renewable resources (e.g., linseed oil for wood). Additionally, choosing a durable finish reduces the need for reapplication, saving resources. However, consider the entire life cycle—some eco-friendly finishes may require more energy to apply or be less recyclable.

Question 6

What is the difference between varnish and lacquer?

Accepted Answer

Varnish is a clear finish made from resin, oil, and solvent, providing a hard, protective coating for wood. It penetrates the surface and dries slowly. Lacquer is a fast-drying finish that forms a hard, brittle shell on the surface. Lacquer is easier to apply in thin coats but can be less durable than varnish. Both enhance wood grain and protect against moisture.

Systems: Appropriate surface treatments and finishes that can be applied to components and systems for functional and aesthetic purposes

Topic Overview

Key Concepts

What You Need to Demonstrate

Marking Points

Examiner Tips

Common Mistakes

Frequently Asked Questions

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