Surface coatings are applied to materials like steel and timber to protect them from corrosion and rotting, to decorate surfaces and add special effects, and to sanitize items by making them easier to clean. Paint consists of a thinner, binder, and pigment and dries through the processes of evaporation, oxidation, and coalescence as the binder particles fuse together into a film. When mixing a two-part coating, it is important to follow the manufacturer's recommendations on ratios and be aware of the mixture's pot life, which refers to the usable life of the mixture before it starts to cure and become unusable.

1. © City of Glasgow College
Charity Number SC0 36198
Surface Coatings

2. To protect – stops steel
corroding, timber rotting
To decorate – improves
appearance, special effects
To sanitise – more hygienic,
easier to clean
To identify – pipework and
other
items
Why apply coatings?

3. Paint is either water-based or
solvent-based. It consists of
three parts:
• thinner
• binder
• pigment.
Paint

4. Evaporation – the
water/solvent
component
evaporates
Oxidation – the
paint
reacts with oxygen in
the air
Coalescence –
binder
particles fuse
together
into a film
How does paint dry?

5. Mixing a two-pack coating
Always
• follow the manufacturer’s
recommendations
• use the correct ratio of base
to hardener
• be aware of the mixture’s pot
life.
What does the term ‘pot life’
mean?

6. Surface coating defects