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properties finals > WOOD PRESERVATION > Flashcards

WOOD PRESERVATION Flashcards

1
Q
  • the process of preserving or increasing the life of wood either chemically or mechanically
A

WOOD PRESERVATION

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2
Q

OBJECTIVES OF WOOD PRESERVATION:

A
  • increase durability and service life of wood
  • increase natural resistance to decay
  • stabilize the wood to environmental changes
  • improve surface for mechanical wear
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3
Q
  • chemicals applied to wood to make it more resistant to attacks of agencies of wood deterioration
A

WOOD PRESERVATIVES

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4
Q

REQUIREMENTS OF A GOOD WOOD PRESERVATIVES:

A
  • permanent
  • penetrative
  • safe to handle and use
  • harmless to wood and metal
  • plentiful and available
  • economical
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5
Q

TYPES OF WOOD PRESERVATIVE:

A
  1. Water-borne preservatives (WBP)
  2. Oil-borne preservatives (OBP)
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6
Q

– chemicals that dissolve in water

A

Water-borne preservatives (WBP)

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7
Q

Water-borne preservatives (WBP) :

A

a. Arsenic salts
b. Chromium salts
c. Copper sulfate
d. Borax and boron salts
e. Mercuric chloride
f. Copper chrome arsenate (CCA)
g. Boliden salts
h. Wolman salts

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8
Q

– include by-products of coal distillation, coal tar refining, petroleum refining and wood distillation
- A preservative treatment that is applied to wood in the form of solution in oil

A

Oil-borne preservatives (OBP)

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9
Q

METHODS OF WOOD PRESERVATIVE:

A

a. Brush and spray treatment
b. Dipping
c. Steeping
d. Soaking
e. Kyanizing
f. Hot and cold bath

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10
Q

– brushing or spraying preservatives over the surface of the wood to be treated

A

Brush and spray treatment

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11
Q

– immersing wood in a preservatives (WBP) for a few seconds or minutes

A

Dipping

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12
Q

– process of submerging wood in a tank of preservative in water solution

A

Steeping

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13
Q

– submerging wood on cold OBP for several days

A

Soaking

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14
Q

– steeping wood on mercuric chloride, patented by John Kyan in England in 1832

A

Kyanizing

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15
Q

– involves the immersion of seasoned wood in successive baths of hot and cold wood preservatives

A

Hot and cold bath

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16
Q

PRESSURE PROCESSES OF WOOD PRESERVATION:

A
  1. Full-cell process
  2. Empty-cell process
  3. High pressure sap displacement (HPSD)
17
Q
  • process used when maximum absorption of the preservative is desired
A

Full-cell process

18
Q

Full-cell process:

A

Bethel process

19
Q
  • devised in the 19th century by the U.S. inventor John Bethell
  • sealing the wood in a pressure chamber and applying a vacuum in order to remove air and moisture from the wood cells
A

Bethel process

20
Q
  • part of the preservative forced into the wood under pressure is subsequently recovered, so that the wood cells tends to be coated with preservative rather than filled with it
A

Empty-cell process

21
Q

Empty-cell process:

A

a. Rueping method
b. Lowry method

22
Q
  • patented by Max Rueping of Germany in 1902
  • it involves the application of preliminary air pressure to the wood cells tends to be coated with preservatives
A

Rueping method

23
Q
  • patented by C.B. Lowry in 1906
  • an empty cell process in which the air in the wood is compressed solely by the preservative introduced into the cylinder under pressure
A

Lowry method

24
Q
  • introduced and patented by Dr. Auguste Boucherie (France, 1838)
  • developed by the Forest Products Research Development Institute (FPRDI) in UPLB to be adopted for the use in rural areas
  • a method where the sap from a freshly-felled log is forced out of the wood by a WBP solution introduced under pressure through a cylinder up fitted over one end of the log or pole
A

High pressure sap displacement (HPSD)

25
Q
  • The effectiveness of treatment with a good preservative lies in the amount of preservative absorbed and in depth to which the preservative penetrated, the wood in relation to the conditions of services or hazards of exposure.
A

QUALITY CONTROL IN WOOD PRESERVATION

26
Q
  • the depth of adsorption expressed as the average of the maximum and minimum values of penetration (inches or centimeter)
A

PENETRATION

27
Q
  • amount of preservative absorbed by the wood expressed in terms of weight of preservative per unit volume of wood
A

RETENTION

28
Q

FACTORS THAT INFLUENCE THE TREATABILITY OF A GIVEN PIECE OF WOOD:

A

a. Moisture content
b. Sapwood and heartwood
c. Anatomical features of wood
d. Along the grain penetration is faster and easier than across the grain
e. Treatment process used

29
Q

– seasoned or dried wood are easier to treat except when the process used is diffusion or HPSD method

A

Moisture content

30
Q

– sapwood portion of timber treats easier than the heartwood portion due to the presence of extractives in HW

A

Sapwood and heartwood

31
Q

– wood with larger pores and with less tyloses are easier to treat

A

Anatomical features of wood

32
Q

– pressure process will yield greater absorption and deeper penetration than non-pressure methods

A

Treatment process used

33
Q

_________ penetration is faster and easier than across the grain

A

Along the grain

properties finals (8 decks)

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