INDUSTRIAL TECHNOLOGYTIMBER
ASSOCIATED THEORY
TOPIC 5
Wood Finishing
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INTRODUCTION
STAINING TIMBER
HOW FINISHES
WORK
TYPES OF
POLYURETHANE
SURFACE
PREPARATION
APPLYING
POLYURETHANE
TYPES OF
ABRASIVES
MISCELANEOUS
FINISHES
REPAIRING MINOR
DEFECTS
BIBLIOGRAPHY
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Wood Finishing
Introduction
There are three main stages to the successful
completion of a wood project:
Stage 1
Planning & Design
Stage 2
Material preparation & Construction
Stage 3
Application of a Protective Finish
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Wood Finishing
Introduction
Although wood is durable and resistant to a fair
absorbent
amount of wear and tear the surface is ………………..
protected
and needs to be ………………..
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Wood Finishing
Introduction
stain
Spilt food, dirt and hand marks tend to ……………….
dull
and ……………
the surface.
roughen the
Water raises the grain and tends to ……………..
surface. Alternatively, excessive dehydration will
shrink
split
cause the timber to ………………..
and ……………...
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If left untreated the timber fades, & cracks
appear.
before
after
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Wood Finishing
How Finishes Work.
A protective finish seals the surface of the timber in
one of two ways.
1.
Saturating the fibres and filling the pores
2.
Bonding to the surface in a tough,
flexible film.
The latter method is usually quicker as it can be
performed in a single operation.
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Wood Finishing
The nature of the project, and where it will be
the type of finish
used will determine ………………………………
Outdoor projects require a finish that will
moisture
ultra violet light
resist ………………and
the effects of …………………………
Indoor projects may be less durable, but are
decorative
often ………………………
and a finish is chosen
beauty of the timber
that enhances the natural ……………………………....
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Wood Finishing
This outdoor
setting needs a
finish that will
resist moisture
and ultra violet
rays.
Unfortunately,
nothing will
stop it from
fading
eventually.
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Wood Finishing
Surface Preparation
The quality of the finished surface depends on
many factors, the first of which is good
surface preparation
………………………………………
Generally, the more care taken with surface
finish
preparation, the better will be the final……………
Defects that are present on the surface will
clear finishes
usually show up under ………………………….
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Wood Finishing
Surface Preparation
Sanding: This is the name given to the process
of smoothing timber by actually “scratching”
abrasive paper
the surface with…………………………..
Abrasive paper was originally made from
sand hence the term ……………………….
sanding
……………,
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Wood Finishing
Surface Preparation
Abrasives consist of small particles of crushed
grit that is glued to a backing sheet. The
cloth
backing sheet may be ……………….
or
paper
………………..
glass
Abrasives are made from crushed ……………,
garnet or other…………………………………
synthetic material
………………
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Wood Finishing
Abrasives can be wrapped
around various shaped
blocks for hand sanding.
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Wood Finishing
Or they can be attached to
the base plate of Belt sanders
And orbital sanders
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Wood Finishing
Abrasives are graded by number. The larger
the grit particles
the number the smaller ………………………………
Abrasives are available in sheets, or they may be
machines
made into belts for different sanding …………………….
They may also be purchased as discs or small
round cylinders for special situations.
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Wood Finishing
These are the most common “grits” used at AHS.
Number
40
80
100
120
180
240
320
Common Use
Belt Sander- very coarse
Removing plane marks
Hand or orbital sanding
Hand or orbital sanding
Final hand or orbital sanding
Smoothing after 1st coat
Smoothing after 2nd coat
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Wood Finishing
On the back of the abrasive paper is information
pertaining to:
The brand of the abrasive
The material used for the abrasive
The grit of the abrasive
Important: Whenever possible sand in the
direction of the grain of the timber.
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Wood Finishing
Important: Whenever possible sand in the
direction of the grain of the timber.
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Wood Finishing
Types of Abrasives
TYPE
PROPERTIES
GARNET
Orange natural Softwood
mineral,
furniture
friable
ALUMINIUM Very tough,
OXIDE
block shaped
grit
SILICON
Shiny, black
CARBIDE
very hard
particles
USES
Best all purpose
woodworking
abrasive
Rubbing back a
polyurethane
finish.
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Wood Finishing
Repairing Minor Defects
Timber is a natural material, and often it is
necessary to disguise natural defects before
adding the final finish. In other cases it may be
poor workmanship
necessary to repair………………………………………
There are a number techniques that can be used
to disguise faults in timber, but they must be
before the finish is applied
carried out …………………………………………………
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Wood Finishing
Wood putty or stopper Available in a range of
timber colours, and can be pressed into small
gaps and cracks.
Method
Press putty into joint with clean
flexible knife. Leave slightly raised. Sand off
when dry.
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Wood Finishing
Matching timber colours A small amount of
stain may be mixed with the putty to get a
better colour match.
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Wood Finishing
Inserting a Plug Cut a hole with a plug cutter
directly over the defect. Insert a plug of the
same timber with the grain running in the same
direction. Alternatively, insert a different
coloured plug as a “feature”.
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Wood Finishing
Staining Timber
Timber may be stained before a protective finish is
applied. This is carried out for the following
reasons:
1.
To even out the variations in colour that
occur naturally with some timbers.
2.
To make an inexpensive timber look like an
exotic species of timber.
EXTRA…
This slide and the following two slides show
different stains that can be applied to pine to
make it look like an expensive alternative
timber.
Brandy Stain (pine)
Antique Stain (pine)
Sierra Brown Stain (pine)
Provincial Stain (pine)
Honey Stain (pine)
Salem Stain (pine)
Chocolate Stain (pine)
Vintage Stain (pine)
Auburn Stain (pine)
Hickory Stain (pine)
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Wood Finishing
Test a small amount of
stain on a piece of timber
similar to your project to
gauge the colour of the
finish. Several stains may
be tested on a “test strip”
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Wood Finishing
Staining Timber
Stains can be applied with a brush or a rag.
Wipe along the grain and wipe off excess with
smooth even strokes. Wear gloves.
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Wood Finishing
Types of Polyurethane
Oil-based, thin
with mineral
turps.
Oil-based
gel
Water-based,
clean up with
water.
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Wood Finishing
Applying Polyurethane
Or applied with a
cotton pad.
Polyurethane may
be brushed on…….
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Wood Finishing
Applying Polyurethane
A foam pad or applicator
is good for large flat
surfaces.
Spraying is a good
method for fiddly
jobs.
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Wood Finishing
Applying Polyurethane
Lightly sand the surface between each coat
using 320 grit aluminium oxide or
carborundum.
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Wood Finishing
Applying Polyurethane
After the final coat has hardened
Scandanavian oil or a wax can be rubbed
into the surface.
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Wood Finishing
There are many other types of finishes that
may be applied to timber. Some of these
include….
French polish
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Wood Finishing
There are many other types of finishes that
may be applied to timber. Some of these
include….
Tung oil
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Wood Finishing
There are many other types of finishes that
may be applied to timber. Some of these
include….
Canauba wax
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Wood Finishing
And of course paint.
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Wood Finishing
Bibliography & other Resources
These two are
available from the school library
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Wood Finishing
Bibliography & other Resources
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Wood Finishing
Bibliography & other Resources
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Wood Finishing
Bibliography & other Resources
The end of
Topic 5