Wood Finishing

Question 1

Purposes of finishing wood

Answer 1

Prevent the wood from absorbing moisture

Protect against decay

Protect against insect attack

Enhance the natural appearance of the final product

Question 2

Methods of degradation of natural wood - wet rot

Answer 2

alternating wetness and dryness results in the absorption of moisture

Despite the surface drying out, moisture remains below

Leads to break down of fibres and fungus spreads through the wood

The wood becomes soft, wet and crumbly

Question 3

Methods of natural wood degradation - dry rot

Answer 3

Fast-spreading fungus causes dry rot

This quickly turns the wood into a dry, soft, powdery state

Question 4

Methods of natural wood degradation - insect attack

Answer 4

Furniture beetle (woodworm) attacks softwood and hardwood

Deathwatch beetle attacks hardwood

Both lay their eggs in cracks in the wood

Hatched larvae eats into the wood creating tunnels

Developed beetles eat their way out via a flight hole

Question 5

Before applying a wood finish

Answer 5

Smooth the surface - planing and/or sanding with glass paper (in the direction of the grain)

Remove all dust with a cloth before a finish is applied

Question 6

Polyurethane varnish (acrylic varnish) properties

Answer 6

Available in gloss, satin and matte

Provides a hard, tough, heatproof, waterproof finish

Clear finish allows the grain to remain visible

Question 7

Water-based paints properties

Answer 7

Available in gloss, satin, matt and metallic effect

Applied for indoor and outdoor use

Predominantly for softwoods

Makes surfaces more aesthetically pleasing, tougher, harder and resistant to moisture

Question 8

Stains properties

Answer 8

Helps colour and enhance the grain

Can make inexpensive wood look more valuable

No specific protection properties

Question 9

Colour wash

Answer 9

Applied with a wet sponge and available in many different colours

Helps colour the wood to make it more aesthetically pleasing or to add vintage style whilst allowing the grain to show

Question 10

Wax properties

Answer 10

Can be buffed to provide a high-gloss finish

Increases surface hardness and toughness

Clear finish allows the grain to remain to be visible

Usually for indoor products

Question 11

Yacht varnish

Answer 11

Available in high gloss and satin

Applied via brush or sprayed directly onto the wood

Suitable for woods that are always outside

Increases toughness, hardness and weather resistance

Question 12

Danish oil properties

Answer 12

Available in clear and colour tints

Enhances the grain, not hardwearing but regular application builds up a matt, water-resistant finish

Question 13

Teak oil properties

Answer 13

Available in clear tint

Used for naturally oily woods

Used for outdoor products to improve weather resistant and resistance to fungal and insect attack

Aesthetically pleasing as grain is enhanced

Question 14

Pressure treating

Answer 14

Wood is placed in a pressure vessel containing a solution copper sulphate and other preserving salts

Vacuum and pressure are controlled to force the preservative deep into the fibres of the wood and then the wood is steam dried

Helps protect for rot, insect and fungal attack and weathering for up to 50 years

Question 15

Polyurethane varnish application process

Answer 15

Apply a thin coat with a brush - in the direction of the grain

Several thin coats applied - using fine-grade sandpaper between coats

Question 16

Water-based paints application process

Answer 16

Applied using a brush, rolled or spray

Primer -> undercoat -> paint finish

Wood knots should be treated with knotting solution - prevents the resin oozing out and spoiling the finish

Question 17

Stains application process

Answer 17

Applied with a brush, roller or spray

Surfaces should be grease-free before application

Question 18

Wax application process

Answer 18

Applied with a brush or stockinet cloth

Once dry, buffed with a clean lint-free cloth

Available in clear or coloured

Question 19

Danish oil application process

Answer 19

Apply with a lint-free cloth rubbing into the surface in the direction of the grain

Leave the wood to absorb the oil for 5 minutes

Then remove excess oil

Lightly sand or rub with wire wool between coats

Question 20

Teak oil application process

Answer 20

Apply to surface with lint-free cloth - rub the oil into the surface along the grain

Leave for 5 mins for the wood to absorb the oil - then wipe away excess

Question 21

Wood finishes

Answer 21

Polyurethane/acrylic varnish

Water-based paints

Stains

Colour wash

Wax

Yacht varnish

Danish oil

Teak oil

Pressure treating

Question 22

Pressure treating application process

Answer 22

Wood is stacked on a trolley and wheeled into the chamber

Air is removed by a vacuum pump

Treatment solution then fills the tank

Pressure is increased to force the treatment solution into the wood and remaining solution is removed

Final vacuum pump and then the wood is left to dry