Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a wood treating and
coating composition affording improved durability, water-
repellence and aesthetic appearance. The coating
composition permits treatment of wood with preservation of
the natural grain appearance, when colored, while
protecting against the effects of the elements.
A large number of stains or coatings is currently ~ -~
available for the treatment of dressed lumber and ~inished
wood for external and internal applications, including
acrylic coatings, latex coatings, lacquer, lacquer
cellulose, epoxy resin, so-called liquid plastic, varnish ~
resin, and numerous oil-pigmented stains. All such ;~; n-
products suffer from some drawbacks and limitations
(especially when used outdoors), such as limited
durability, undue opacity, dullness of finished surface,
deterioration of aesthetic appearanoe in a relatively short
period of time, lack of breathability, cracking,
evaporation and flaking, light-degradability, shrinkage and ~-
unsuitability for external use, leading to the need for
periodic re-application or replacement.
Shellac has been employed for many years as a
wood caatling sub~s,ta~ce ,or~ as a component in coating
compositions. For example, Canadian Patent No. 1346
describes a composition for mixing with paint and
co~prising water, shellac, washing soda and linseed oil.
Patent No. 13935 discloses a paint composition containing
resin, shellac, camphor, castor oil and glycerin. Patent
No. 16492 describes a coating composition containing
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shellac, beeswax, whiting and alcohol, while Patent No.
53510 describes a paint composition containing methyl
alcohol, shellac, pine resin, camphor and gum arabic.
Patent No. 60431 describes a paint containing shellac,
methylated spirits, pigment and varnish.
Moreover, Canadian Patent No. 217,435 discloses a
wood filler composition comprising beeswax, paraffin wax,
turpentine, linseed oil, varnish, Japan drier and shellac.
Finally, Patent No. 510,480 describes a staining
and filling coating composition for wood containing a
solvent mixture of butanol, shellac, ethanol, manilla gum,
silica, talc, neutral stain filler, dye, ethyleneglycol
ether and thinner.
Shellac alone as a coating material would dry too
fast and modification of the drying characteristics of
shellac might impair the coating qualities thereof.
It is accordingly an object of the present
invention to provide a wood coating composition which
avoids or mitigates the disadvantages and shortcomings of
currently available products and which affords an improved
coating providing durability, breathability, water-
repellence and attractlivle ! aesthetic appearance, while
retaining sufficient transparency to permit visibility of
the natural grain structure of the wood.
It is a further object of the invention to
provide a wood treating and coating composition which is
compatible with existing wood preservative compositions and
which, furthermore, can be pigmented or dye colored.
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Accordingly, one aspect of the invention provides
a wood coating composition, which comprises: (a) ~rom 5 to
20 lbs of a raw or refined shellac, (b) from 1 to 3
gallons of a nut tree oil, preferably selected from castor
oil, tung oil, cashew nut oil, china nut oil, pine oil, and
mixtures thereof, (c) from 0.5 to 1.5 gallons of a drier,
preferably selected from Japan drier, cobalt naphthenate
drier and monosec drier, (d) from 0.05 to 2, preferably
0.5 to 1.5 gallons of a glycol, preferably ethylene glycol,
and (e) a balance of an alcohol, such as methanol,
ethanol, isopropanol `or butanol or mixtures thereof or
methyl hydrate.
If desired, the composition can further
incorporate an alcohol-based stain or ink, a dye, a
pigment, a preservative and/or an anti-fungicide.
A further aspect of the invention provides a
water-based wood coating and treating composition,
comprising a formulation as defined above in association
with an emulsifier, which composition can be diluted with a
desired volume of water.
Another aspect of the invention provides a
process for formulating .a water-based preservative
composition for treating wood which comprises: (i) mixing
together the above specified ingredients (a) to (e) in
amounts falling within the ranges specified, (ii)
thereafter adding the emulsifier and the water, (iii)
allowing the resultant water-based composition to stand for
a sufficient period of time, and (iv) admixing the water-
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based composition with a wood preservative, such as an
aqueous solution of copper chromite and copper arsenite.
The coating composition of the invention
preferably contains about 10 pounds of raw or refined
shellac dissolved in about 3 gallons of methyl alcohol,
about 2 gallons of castor oil, about 0.5 gallon of monosec
drier or cobalt naphthenate drier, about 0.5 gallon of
ethylene glycol, about 1 gallon of alcohol-based stain and,
additionally, about 2 to 3 gallons of the alcohol.
Preferred alcohol components include methanol alone, and
mixtures of methanol/ethanol, methanol/isopropanol and
methanol/butanol, for instance in 60/40 ratio by volume
percent. Another preferred alcohol mixture is
butanol/ethanol/isopropanol of 60/20/20 parts by volume.
In the composition of the invention, the
properti~s of the shellac are modified by the remaining
ingredients, so as to permit exterior use of the
¢omposition primarily on wood and wood products, but also
on brick, cement, metal and fiberglass. This is achieved
partly by the use of a larger than usual proportion of the
drier, which functions to harden the finish. The presence
of the nut tree o~ assists in absorption of the shellac
into the wood and improves the sheen of the finished wood
product. It further improves the body of the liquid
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25 composition which assists in application thereof and - ~
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affords improved elasticity, strength and durability to the -~
shellac when compounded with the dryers. The nut oil
inhibits the degree of drying of the finish so that, ~ ~
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although the coating feels dry to the touch, it never dries
completely hard but retains elasticity for expansion and
contraction due to temperature change of the coated
substrate.
The function of the glycol, such as ethylene
glycol, is to assist in the admixture of the shellac, drier
and nut tree oil and further acts as a fire retardant. It
should also be noted that shellac itself is a generally
non-flammable substance. Moreover, the presence of
ethylene glycol assists spreadability when the composition
is pigmented or dyed and blends the dye or stain so that it
does not separate from the composition or cause streaking,
thereby giving rise to a coating which is uniform in color.
The alcohol functions as a solvent for the
shellac and, further, as a thinner for the overall
composition. A preferred drier is Japan drier, which is a
varnish containing a large percentage of resins and driers
used as a liquid drier for paints and coating compositions.
The amount of Japan drier in the composition of the
invention is relatively larger than has been used
conventionally, which assists in modification of the
properties of the, nut qil and shellac and results in an
improved sheen, water-repellence and aesthetic appearance
of the coatings.
The composition of the invention can also include
a non-toxic preservative, pesticide or fungicide, such as
oxine copper, as well as a stain or pigment permitting a
final composition affording a wide range of wood-simulating
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or other colours, while remaining a completely non-toxic,
preservative coating.
The coatings obtained employing the composition
of the invention are not only water-repellant but also
water-proof, while permitting breathability of the
underlying wood. They are therefore of particular use in
applications near water, such as pool patio decks, boat
decks and any location in which show wood is located near
water. The extremely tough properties of the resultant
coatings are ideal for walking areas, such as decks and
patios, and present a durable, smooth, water-proof surface.
However, the composition can be employed equally well for
interior applications, such as interior mall show wood,
wood panelling and unfinished furniture.
15A particularly advantageous embodiment of the
invention relates to the conversion of the composition of -
the invention into a water-based form, which is compatible
with existing wood preservative compositions containing
copper chromite/copper arsenite (CCA). The conversion is
achieved by adding to the composition of the invention a
suitable quantity of an emulsifier, e.g. from 0.1 to 10% by
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volume~ more preferably!from 0.5 to 5% by volume. Suitable
emulsifiers include alkanolamines, preferably
triethanolamine. Thereafter a suitable quantity of water is
added and the resultant formulation is mixed with a water-
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based CCA-containing formulation. It is important for the
mixture of the composition of the invention and emulsifier
and water to stand for a period of time, for instance about
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24 hours or more prior to admixture with the CCA-containing
solution.
The resultant formulation can also include a
pigment or dye, which can be present in sufficient
concentration to result in masking of the characteristic
blue-green colour of CCA-containing products, so that the
final pressurized coating on wood can be obtained in any
desired colour and provide a durable, attractive and
preservative finish to the wood. Treatment of wood in this
manner can be carried out, for instance, in the pressure
treating lumber plant in advance of sale when used in
conjunction with CCA pressure treatment or other pressure
treatment formulae, or can be applied to a finished wood
structure or product.
Thus, in essence, the composition of the
invention employs shellac, which is a completely non~
durable and generally unacceptable material for exterior
wood use, and which has been modified and formulated
together with the remaining ingredients to produce a
composition providing extremely affordable exterior wood
coatings fully impervious to the elements, when not
converted to ai ,water-based form. In summary, !the
composition of the invention seals and water-proofs wood,
permits stain-finishing in different colours or a clear,
natural finish, and is transparent even with dye color
added, or semi-transparent when pigmented, thereby
; permitting the wood grain to show, is more durable and
lasts longer than existing exterior coatings, does not
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darken when re-coated unlike other outside coatings and
stains, affords a significant degree of fire retardancy, is
non-toxic and environmentally safe in being formulated
primarily from organic materials, and can be converted to a
water-based form which provides a medium for colour and
sealer and which can be employed in conjunction with
currently available pressure-treating preservatives, such
as CCA, to produce an aesthetic, preservative, coloured
finish in pressurized wood.
The following Examples illustrates the invention.
EXAMPLE 1
10 pounds of shellac flakes were dissolved in
from 1 to 2 gallons of methyl alcohol and 2 to 4 quarts of
triethanolamine was mixed in with vigorous stirring. 2
gallons of castor oil, 2 quarts of cobalt naphthenate drier
(monosec) and from 2 to 3 quarts of ethylene glycol and 1
to 2 quarts of butyl glycol (Cellosolve) were added with
- vigorous mixing. If desired, an alcohol solvent, tinting
stain, alcohol aniline stain, ink stain or dye stain can be
added to provide a desired degree of colouring.
This formulation can be used for wood treating
~and coating. The triethanolamine emulsifier can be
replaced by monoethanolamine or a mixture of equal parts of
triethanolamine and butyl glycol. The methyl alcohol can
b- replaced by similar amounts of ethanol, isopropanol,
butanol or amyl alcohol or mixtures of some or all thereof.
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EXAMPLE 2
A wood coating composition was prepared with the
following formulation:
Shellac flakes10 lbs
Castor oil 4 quarts
Cobalt naphthenate2 quarts
Ethylene glycol2 quarts
Methyl alcohol based stain 1 gallon
(concentrated to a desired
lo depth of color)
Methyl alcohol2 gallons
The ingredients are mixed as described in Example
1 to provide about 7 gallons of a transparent wood coating
formulation.
EXAMPLE 3
A water based wood coating composition was
prepared by dissolving lO lbs of shellac flakes in the
minimum sufficient amount of methyl alcohol (approximately
1 to 2 gallons). From about 3 to 4 quarts of
triethanolamine was mixed in which vigorous stirring and
the mixture was allowed to stand. If desired, the
triethanolamine can be partly or wholly replaced by
monoethanolamine or partly replaced by butyl glycol. 2
gallons of castor oil, 2 quarts of cobalt naphthenate and 2
quarts of ethylene glycol were then admixed with vigorous
stirring. The product is allowed to stand for a further 24
hours.
`From 5 to lO gallons of warm water are then added
with vigorous stirring to provide a water-based
composition. This composition can be mixed with a CCA-
containing preservative composition prior to use, or CCA in
an amount of about l to 5% by volume, preferably about 2
l/2~ by volume, can be added to the composition of this
example to provide a wood coating and preserving
formulation. If desired, a cellulose lacquer can also be
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added to the formulation. - ~ ~
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The composition of the invention when used in
conjunction with a CCA-containing product acts as a water-
soluble, oil medium for color to mix with the CCA and
eliminates the harsh drying of the basic CCA-containing
product, thereby reducing the risk of wood rot between
pressure treating and drying in the lumber yard. The
product will seal the pressure-treated wood when dry and
provide water-repellency, thus eliminating the necessity
of re-coating the pressure-treated wood with a water
sealer. It further provides an aesthetic finished
appearance to the lumber, as opposed to a dry look and can
be provided with a range of colours, substantially
eliminating the characteristic blue-green coloration of the
CCA-containing product.
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