Painting

Question 1

Paint Compositions

Answer 1

Commonly these include the
* binder
* solvent
* base
* extenders
* pigments
* driers
Although other additives may be incorporated into specialist paints

Question 2

Paint Layers

Answer 2

1. Sealant
2. Filler
3. Primer
4. Undercoat
5. Finish Coat

Question 3

Primer

Answer 3

• The primer grips the substrate to provide protection against corrosion/dampness and to provide a key for remaining coats
• Seals porus surfaces and ensures surfaces do not bleed into paint layers

Question 4

Undercoat

Answer 4

• The undercoat provides good opacity and a good surface which provides a key for the finishing coat
• Should adhere to the primer and be compatible with the top coat
• Lighter than the top coat to prevent showing through

Question 5

Top Coat

Answer 5

• Provides a durable layer of the required colour and texture - glossy, matt, silk
• Should be durable enough to protect the undercoats

Question 6

Paint Preparation For Plaster/Concrete

Answer 6

• Concrete should be at least 28 days old
• Loose motar must be removed with a sraper
• Fill in cracks or use an all body filler to hide any imperfections in formwork

Question 7

Preparation for Painting on Metal Surface

Answer 7

1. Steel -
2. Galvanised Steel -
3. New Ferrous Metal -

Question 8

What to Consider When Preparing Surfaces for Paint

Answer 8

1. Nature of the material to paint which affects time and costs
2. Previous condition of the surface
3. Existence of rust or old paint coats: this is especially relevant if the part is inside or outside, and which is the dominant climate. The level of oxidation can vary (surface, light, medium and strong oxidation)
4. Mechanical conditions that the part may suffer: if the part or surface is exposed to continuous friction, vibration or mechanical impact, this should be considered for the correct pre-treatment to be carried out
5. The size of the surface
6. The cost of the process and application
7. The colour and brightness you want to achieve

Question 9

Paint and Primers

Answer 9

1. Oil paint - A coat of thin primer or prime sealer
2. Emulsion paint - A coat of paint thinned with water
3. Dry distemper- Same distemper thinned with water
4. Size bound distemper - A Coat of clearcole
5. Cement paint and lime wash - Wet the surface before applying

Question 10

Types of Paints

Answer 10

1. Emulsion Paint - Timber, Concrete, Cement, Sand Render
2. Bituminous Paints - Metal
3. Cellulose Paint - Spray
4. Alkyd Resin Paint and Varnish

Question 11

Preparation of Softwood Surface For Painting

Answer 11

1. Knotting
2. Priming
3. Stopping Surface
4. Undercoat (2-5 layers)
5. Finish Coat

Not more than 15% moisture content

Question 12

Reasons for Paint to not Stick to Concrete

Answer 12

1. Moisture Content
2. High Alkaline Content
3. Over porosity
4. Efflorescence
5. Oil and Grease

Question 13

Preparation of Hardwood Surfaces for Painting

Question 14

Special Types of Paints

Answer 14

1. Light Reflecting White paints - white paints with lower light absorbency and greater reflectivity
2. Acrylated Rubber paints- for applications to wet and humid conditions
3. Heat resistant - aluminised paint resistant to temperatures up to 230-260 deg C
4. Flame Retardant - emit non combustible gas when subject to fire
5. Fungicide paints – for areas with recurrent mould
6. Micaceous Iron Oxide paints – for moisture resistence on structural steelwork applications
7. Water repellent/Waterproof paints – for porous surfaces
8. Anti Graffiti – to aid the easy removal of graffiti