Thin, strong, composite masonry-plastic articles having an earthen body impregnated with an in situ polymerized plastic and a drying oil or semi-drying oil; a mastic for forming a stain resistant grout comprising about 70% to 80% sand and about 20% to 30% of a plastic binder; stain-resistant wall and floor structures comprising said composite articles and grout; and a method for installing such wall and floor structures are described.

BACKGROUND OF THE INVENTION 
The use of earthen tiles, bricks or similar articles as a floor or wall 
covering in high traffic areas has become very popular in recent years. 
However, such floor covering materials are subject to the serious 
disadvantage that they are easily stained or discolored and, therefore, do 
not retain an attractive appearance unless sealed in some way to prevent 
such staining. Previously available sealing materials and techniques have 
provided a protective layer on the surface of the floor covering which is 
subject to wear, particularly in high traffic areas, and must, therefore, 
be periodically renewed. This, of course, entails substantial expense in 
material and labor to maintain an acceptable appearance for such floors. 
Moreover, previously available floor tiles have necessarily been relatively 
thick, e.g. from about 1/2" to about 2" in order to provide sufficient 
breaking strength. Such thicknesses cause problems in installation 
especially in remodeling work and also add to the cost shipping the tiles 
due to the added weight. 
Another serious problem with floors generally composed of floor tiles, is 
that they are generally installed with a cement type grout, which is also 
very susceptible to staining and must, therefore, also be sealed. 
THE PRIOR ART 
Traditional earthen flooring materials such as stone, cement, brick and 
gypsum floor and wall tiles, and bricks required sealing to prevent 
staining and discoloration by a wide variety of materials capable of 
penetrating the porous tiles or bricks and then drying or curing in situ 
to fill and seal the pores of the material and provide a film or layer of 
impregnant on the surface of the tile or brick. Such sealers have 
generally comprised a resin of some sort in a volatile liquid vehicle 
which evaporates or dries to leave a resinous film. Such resinous films 
provide some protection and have proven fairly satisfactory for home use 
in low or moderate traffic areas, but are not sufficiently wear-resistant 
for high traffic areas such as those in public or commercial buildings. 
A process for imparting long lasting gloss, color depth properties, and 
stain resistance to wood tiles for floor and wall covering use is 
described in Bosco U.S. Pat. No. 3,808,032, issued Apr. 30, 1974. This 
process comprises impregnating the wood with a monomer polymerizable by 
organic free radicals, polymerizing the monomer in situ in the wood, and 
thereafter coating the surface of the wood with a penetrating solution 
comprising a drying oil or a semi-drying oil. The polymerization is 
accomplished by exposure to ionizing radiation, and is catalyzed by 
including from about 0.01 to about 0.5 weight percent of a free radical 
polymerization agent in the monomer. The reaction is accelerated by heat. 
Suitable monomers include methyl methacrylate, vinyl chloride, vinyl 
acetate, styrene and mixtures of these monomers. Suitable drying oils 
include soybean, linseed, tall, tung, perilla, oitica, cottonseed, corn, 
sunflower and dehydrated castor oil and mixtures of these oils. The 
preferred drying oil is doubly boiled linseed oil. The oils are applied in 
amounts of about 0.5 to about 2.0 gallons per 6000 square feet of wood 
surface. The penetrating solutions comprise the oil of an organic 
hydrocarbon solvent in an oil to solvent ratio from about 3:1 to 1:3. The 
preferred solvents are naptha, Stoddard solvent and petroleum ether. From 
about 0.01 to about 1 weight percent of a siccative agent such as cobalt, 
lead, zinc and manganese salts may be added to the penetrating solution. 
In this way, wood tiles are obtained which have a permanent gloss, water 
spotting resistance and stain resistance. 
A similar process for making wood-plastic composite tiles is described in 
Bell U.S. Pat. No. 3,808,030, also issued on Apr. 30, 1974. In this 
process a halo-organophosphorous composition is included in the monomer 
before polymerization to impart flame retardancy and to prevent laking of 
the impregnant on the surface of the tiles. It is also noted that the 
penetration of the polymerized plastic is so deep into the wood that the 
tiles may be sanded deeply before finishing by buffing without damaging 
the impregnated plastic. This patent also described preferred finishing 
techniques to produce floor tiles having good wear and stain resistance. 
Barrett U.S. Pat. No. 3,721,579 issued Mar. 20, 1973 describes methods and 
apparatus for impregnating wood or concrete substrates with a monomer and 
polymerizing the monomer in situ by irradiation. This patent teaches how 
to control the temperature and degree of polymerization in order to 
polymerize the monomer in the substrate without polymerizing the monomer 
both surrounding the substrate and how to avoid vaporizing the moisture in 
the wood. This patent also lists a large number of suitable monomers for 
impregnation of the substrates. A large number of substrates are also 
suggested, including preformed concrete shaped in the form of flooring or 
wall tiles. 
Welt U.S. Pat. No. 3,709,719 issued Jan. 9, 1973, describes a process for 
making a masonary-plastic material having a glossy, smooth surface, 
improved wear and resistance properties, and a low porosity, which 
comprises impregnating a masonry material with a monomer which polymerizes 
on exposure to radiation. The masonry material is inserted in a bath of 
monomer and the monomer in the masonry material is polymerized in situ by 
exposing the bath to a source of radiation sufficient to polymerize the 
impregnated monomer but insufficient to polymerize the monomer bath. 
In view of the foregoing, it is apparent that the art has attempted to 
solve the problem of staining and discoloration of floor tiles used in 
high traffic areas. However, the art has not previously solved the problem 
of maintaining a floor of such earthen or brick tiles in attractive 
condition, since it has not found any way to prevent the grout between the 
tiles from becoming stained or discolored. Therefore, even the use of 
stain resistant brick or masonry tiles fail to provide a floor having a 
long lasting attractive appearance since the grouting soon becomes 
discolored. 
It is an object of the present invention, therefore, not only to provide 
relatively thin brick or earthen floor tiles but strong and light earthen 
floor tiles of improved stain resistance, but also to provide stain 
resistant grout and an installed grouted floor or wall which will remain 
undamaged and free of stains or discoloration for prolonged periods of 
time even in high traffic areas. 
It is another object of the invention to provide a thin, stain resistant 
earthen floor which can be installed in a single simple operation. 
SUMMARY OF THE INVENTION 
The present invention relates to composite earthen-plastic articles such as 
tiles or bricks having improved stain resistance and strength, to a novel 
mastic composition for installing the earthen-plastic articles which sets 
up to form a stain-resistant grout, and to the resulting wall or floor 
surfaces which are suitable for use in high traffic areas and which remain 
attractive for long periods of time without special maintenance since both 
the earthen-plastic articles and the grout making up the exposed surfaces 
are stain-resistant. 
The stain-resistance and improved strength of the earthen-plastic articles 
is achieved by double impregnation of the materials. The articles are 
first impregnated with a suitable polymerizable monomer which is then 
polymerized in situ in the body of the earthen article according to 
methods known per se, in the art. This impregnation not only improves the 
stain-resistance of the articles but also their strength, thus permitting 
the use of relatively thin articles even in high traffic areas. The 
resulting plastic-impregnated earthen tile or bricks are then doubly 
impregnated with a penetrating solution of a drying oil or semi-drying oil 
to further improve their stain-resistance. This double impregnation 
extends deeply into the body of the article which may, therefore, be 
ground to achieve a smooth surface and then buffed to achieve a high 
polish or any other desired surface finish. The resulting articles are 
highly stain-resistant and exceed the ANSI specification for strength, 
thus making them suitable for use in paving the walls and floors of high 
traffic areas. The finished articles may be derived from any suitable 
earthen starting material including, without limitation, fired clay based 
brick, unfired non-clay brick derived from gypsum, pumice or the like, 
cement compositions derived from Portland cement, natural stone, slate or 
marble, turquoise, coral or any other fossil, shell or other earthen 
material having acceptable strength when supported on a suitable 
substrate, subflooring or wall board. 
DETAILED DESCRIPTION OF THE INVENTION 
The Earthen-Plastic Articles 
The earthen-plastic articles of the invention having improved 
stain-resistance may be derived from any known earthen article or 
composition; the term "earthen" as used herein being intended to mean any 
solid material derived from the earth or found in nature or similar 
synthetic materials which are sufficiently porous to be impregnated as 
described below. Such materials include without limitation, natural or 
synthetic stone, slate, marble or turquoise, coral or other fossils or 
shells, concrete, Portland or other cement compositions, earthenware of 
any type including fired or unfired clay base or non-clay based bricks, or 
any other earthen composition. The articles are preferably initially 
formed in the desired shape, although they may be cut to shape after 
impregnation. Generally, the articles are formed into thin tiles or bricks 
of the desired size, shape and thickness bofore impregnation. The term 
"thin" as used herein means less than about 1/2", e.g. about 5/16". 
The earthen articles are then impregnated with a suitable polymerizable 
monomer and the monomer is then polymerized in situ within the earthen 
article to form the first stage earthen-plastic articles of the invention. 
These articles are then impregnated with a penetrating solution of a 
drying oil or semi-drying oil and then finished as desired by grinding and 
buffing to form the finished stain-resistant earthen-plastic articles. All 
of this is accomplished in the same way as has been taught in the art 
previously with respect to wood articles in Bell U.S. Pat. No. 3,808,030 
and Bosco U.S. Pat. No. 3,808,032, both issued Apr. 30, 1974; the entire 
disclosure of each of said patents being incorporated herein by reference. 
The impregnation with the selected monomer is carried out in an 
impregnation/irradiation vessel, known in the art per se, of suitable 
dimensions such as a vessel of about 1 ft.times.2 ft.times.18 ft. After 
introducing the articles to be impregnated to the vessel, it is placed in 
a 3' diameter vessel for impregnation. The vessel is then evacuated, 
suitably to about 20-30 millimeters mercury pressure for a suitable 
period, e.g., about 2 hours. The impregnant is then introduced through 
suitable valving to completely immerse the articles. The head space is 
then filled with an inert gas such as nitrogen under pressure, suitably 
about 80 psi for a suitable period of time, e.g. 3 hours. The process gas 
should be free of oxygen since oxygen inhibits the radiation 
polymerization reaction. The period required for suitable impregnation 
will, of course vary with the earthen material depending upon its 
porosity, the viscosity of the monomer and other factors and may be 
determined for each material by trial and error. Generally speaking, an 
impregnation period of about 2 to about 3 hours is generally adequate. 
This time and other conditions may be varied to control the depth of 
impregnation as desired. The viscosity or thickness of the monomer must be 
such that it will penetrate the pores of the particular material to be 
impregnated. 
The pressure is then reduced and the excess monomer is drained from the 
vessel. The vessel containing the monomer-impregnated articles is placed 
in the irradiator. 
The pool irradiator arrangement may suitably be a tank about 26 feet deep 
or more, about 50 feet long and about 22 feet wide filled with water. A 
standard irradiator unit such as a "NEPI" unit or an "NPI" unit may 
suitably be placed on the floor of the pool irradiator. Such irradiator 
source units available from NUMEC produce 500,000 curies of irradiation 
from cobalt 60 and comprise 37 inch pencils arranged in a plaque 12 feet 
by 9 feet. Any other source unit providing equivalent gamma radiation may 
be employed. Such an irradiator arrangement operates at ambient 
temperature and pressure. Handling means are also provided for lowering 
the canister to the proper pool depth and orienting within the zone of 
irradiation. 
The canister is first preferably flushed several times to purge it of 
oxygen. This is suitably accomplished by the use of nitrogen at about 5 
psi. The cover of the canister is then sealed and the canister is lowered 
into the water in the pool and passed slowly through the irradiation zone 
close to the source of irradiation. Irradiation is carried out for a 
predetermined period of time, for example, about 10 hours and provides a 
dose of about 1.7 MRAD. The period of treatment and dosage will, of 
course, vary with the monomer and substrate being impregnated. 
Generally speaking, the dosage required to convert a monomer to a polymer 
varies with the square root of the radiation dose rate. The dosage 
requirement for complete polymerization of the monomer in the masonry 
articles is determined by such factors as the type of earthen in question, 
the type and concentration of the monomer, the presence of impurities, 
such as oxygen for example, in the impregnant or in the masonry or 
environment and the use of irradiation activators. 
The radiation-induced polymerization causes the monomer molecules to become 
linked throughout the earthen article forming a network of polymer that 
envelops the pores of the components thus sealing them in plastic and 
providing stain resistance. Radiation-induced polymerization, proceeds by 
a free radical process, and does not require the addition of either heat 
or catalyst, although both may be used if desired. However, inasmuch as 
the radiation itself acts as a catalyst, it offers a method of controlling 
the exothermic polymerization reaction in the substrate, which is 
difficult to achieve if catalyst and heat are employed. 
Impregnant Materials 
Vinyl monomers are highly suitable, methyl methacrylate (MMA), being 
especially preferred, since it is readily available and easily 
polymerizable. The monomer may be inhibited by Butylate Hydroxide Toluene 
(BHT) at 35 ppm or by other inhibitors known to the art. Known activators 
may also be used if desired. Other vinyl monomers are also very useful 
including the acrylates which are desirable for their elastomeric 
properties. Suitable examples are ethyl acrylate co-polymers with 
vinylidene chloride or acrylonitrile. Acrylonitriles and styrenes are also 
suitable monomers for some applications. The styrenes, however, require 
relatively large radiation doses as much as 20 times that for methyl 
methacrylate. Vinyl chloride is also attractive because of its low cost, 
although it presents handling difficulties known to the art. These 
monomers may also be mixed as desired and may also be diluted with inert 
fillers such as silica or bentonite or the like to reduce cost. 
A wide variety of other additives may be used such as water repellants, 
dyes, fungicides, odorants, bacteriostats and the like. 
Additives may also be used to reduce the heat of polymerization, radiation 
requirements and/or the cost of the impregnant. Certain plasticizers can 
be expected to provide one or all of the foregoing advantages: for 
instance sebacates, adipates, polychlorinated phenyls or phthalates. 
Monomers used for wood and Portland cement impregnation will not work for 
most earthen materials. The pore structure is such that the monomer will 
run from the structure and incomplete impregnation will result. 
A special methyl methacrylate monomer was developed using varying amounts 
of a thickening agent. The amount will vary according to the starting 
material. Thickening agents include long chain acrylics, phosphorus 
organics, or other compatible polymer materials. 
The mastic of the invention is largely composed of sand but has stain 
resistance imparted thereto by the unique combination of about 20 to about 
30% of a suitable stain-resistant plastic binder, preferably an acrylic 
binder such as polyvinylacetate, and several active materials. These 
materials include a surface active agent to aid in achieving an intimate 
wetting or contact with the bricks, tiles or other earthen-plastic 
articles; a lubricant for the sandbinder composition, and plasticizer to 
impart strength. It is also desirable to add an agent to prevent freezing 
of the mastic on storage or during shipping. The resulting mastic when 
used to install the stain-resistant earthen-plastic articles sets up in 
about 4 to about 24 hours on exposure to the air to form a solid grout 
which is also highly stain resistant. 
The resulting wall or floor surfaces of the invention are suitable for use 
even in very high traffic areas, resist damage, and retain an attractive 
appearance despite such traffic for prolonged periods of time due to the 
fact that articles are very strong and both the earthen-plastic articles 
and the grout are highly stain-resistant. 
Generally speaking, the loading of impregnant plastic will suitably vary 
from about 5 to 30% and preferably about 10 to 25% plastic based on the 
weight of the total earthen-plastic article after polymerization.

EXAMPLE 1 
Three hundred fifty square feet of earthen tiles (98% Pumice) were loaded 
into the impregnation irradiation cannister. Tile size 
35/8".times.75/8".times.5/16" thick. After a two hour vacuum of 27" of Hg, 
the monomer was introduced. Monomer consisted of 15% thickening agent, 3% 
crosslinker and 82% methyl methacrylate. A nitrogen over pressure of 80 
psi was maintained for 2 hours to force the liquid into the pores. Excess 
monomer was drained from the vessel and the vessel and product were 
irradiated with a cobalt 60 source to a total dose of 1.7 megarads. 
The resulting product consisting of 74% earthen materials and 26% plastic 
was processed through two single head sanders utilizing 30 and 50 grit 
paper. The sanded composites were continuously contacted with a print 
roller to deposit double boiled linseed oil on the surface. Application 
rate was 6,000 square feet per gallon. After the oil application, the 
samples were buffed and boxed. The resulting product was stain resistant, 
and had structural properties that exceeded ANSI specifications. Thus a 
product that under no situation could be used as a flooring material, was 
converted to a superior flooring material. 
EXAMPLE 2 
Four hundred twenty five square feet of thin fired clay base bricks were 
loaded into the impregnation irradiation cannister. Brick size was 
21/4".times.71/2".times.5/16". After a two hour vacuum of 27" of Hg, the 
monomer was introduced. Monomer consisted of 3% crosslinking agent and 97% 
methyl methacrylate. A nitrogen over pressure of 80 psi was maintained for 
3 hours to force the liquid into the pores. Excess monomer was drained 
from the vessel and the vessel and product was irradiated with a Cobalt 60 
source to a total dose of 1.7 megarads. 
The resulting product consisting of 90% earthen materials and 10% plastic 
was processed through two single head sanders utilizing 30 grit paper. The 
sanded composites were continuously contacted with a print roller to 
deposit double boiled linseed oil on the surface. Application rate was 
4,000 square feet per gallon. After the oil application the samples were 
buffed and boxed. 
The resulting product was stain resistant, and had structural properties 
that exceeded ANSI specifications. Thus a 5/16 inch thick product that 
could not be used as a flooring material was converted to a superior 
flooring material. 
EXAMPLE 3 
Three hundred square feet of coral tile were loaded into the impregnation 
irradiation vessel. Tile size was 6".times.6".times.3/8". After 2 hours 
vacuum of 27" of Hg, the monomer was introduced. Monomer consisted of 10% 
thickening agent, 3% crosslinker and 87% methyl methacrylate. A nitrogen 
over pressure of 80 psi was maintained for 2 hours to force the liquid 
into the pores. Excess monomer was drained from the vessel and the vessel 
and product were irradiated with a Cobalt 60 source to a total dose of 1.7 
megarads. The resulting product consisting of 76% earthen materials and 
24% plastic was processed through two single head sanders utilizing 30 and 
50 grit paper. The sanded composites were continuously contacted with a 
print roller to deposit double boiled linseed oil on the surface. 
Application rate was 5,000 square feet per gallon. After the oil 
application the samples were buffed and boxed. The resulting product was 
stain resistant, and had structural properties that exceeded ANSI 
specifications. Thus a product that under no situation could be used as a 
flooring material was converted to a superior flooring material. 
DOUBLE IMPREGNATION 
The earthen-plastic articles obtained as above have some stain resistance 
but that property is greatly improved by a second impregnation of the 
articles with a penetrating solution of a drying oil or semi-drying oil. 
While such a second impregnation has been suggested previously for wood 
articles in Bosco U.S. Pat. No. 3,808,032 issued Apr. 30, 1970, it was not 
to be expected that impregnation with drying oils or semi-drying oils 
would have a beneficial effect upon the stain resistance of earthen 
articles. 
In accordance with the invention, the earthen-plastic composite is treated 
with a small, controlled amount of a drying or semi-drying oil. The result 
of this treatment is to further coat the pores of the products. The drying 
or semi drying oil becomes absorbed in the pores, and undergoes a 
combination of oxidation and condensation reactions which result in a 
mixture of high molecular weight compounds. 
Suitable drying and semi-drying oils include soybean, linseed, tall, tung, 
perilla, oitica, cottonseed, corn, sunflower, dehydrated castor oil and 
the like. The preferred drying oil is doubly boiled linseed oil. 
While it is greatly preferred to apply the process of the invention to a 
continuous process at the point of manufacture of the earthen-plastic 
composites, it can also be applied very successfully to earthen-plastic 
composite floors or walls which have already been installed. The preferred 
processes are somewhat different when performed "in field," and at point 
of manufacture of the composites. When "in field", it is preferred to 
apply the drying oil or semi-drying oil to the earthen-plastic composite 
in a solvent carrier. Suitable solvent carriers include low boiling 
petroleum distillates, such as mineral spirits, naphtha (VM&P type), 
Stoddard solvent, petroleum ether and the like. The volume ratio of drying 
oil to solvent carrier is suitably from about 3:1 to 1:3 and preferably 
from about 1.5:1 to 1:1.5. The preferred solvent carrier is Stoddard 
solvent. After application, the solvent carrier vaporizes, leaving the 
drying oil or semi-drying oil as a coating on the pores of the 
earthen-plastic article, but does not form a continuous film over the 
entire surface of the composite. 
Any suitable means for applying the required amount of formulation can be 
used. 
In the "in field" case, a sponge mop is one very suitable means, especially 
when the process is being applied to flooring composites already in place. 
The amount of drying oil and solvent carrier formulation applied is 
between one gallon per 1,000 square feet and one gallon per 2,500 square 
feet, preferably one gallon to between 1,300 and 2,000 square feet. 
In the "point of manufacture" case, the drying oil is supplied to the 
surface of the earthen-plastic composite in amounts sufficient to coat the 
individual surface pores, but insufficient to coat the entire surface, 
preferably from about 0.5 to about 2.0, more preferably from about 0.9 to 
about 1.1 gallons of drying or semi-drying oil per 6,000 square feet of 
earthen-plastic composite surface. Preferably, the drying or semi-drying 
oil is applied in a continuous process at speeds and conditions designed 
to insure application of the desired amount of formulation per square 
foot. One suitable means of continuous application is a rubber type print 
roll having a pattern embossed thereon to "print" the formulation in a 
pattern as the masonry-plastic composite is passed under the roller. The 
pressure on the roller preferably can be adjusted to help control the 
application of the desired amount of formulation. 
Optionally, a siccative agent is incorporated in the formulation to 
accelerate the polymerization of the drying or semi-drying oil after it is 
applied to the masonry-plastic composite surface. Suitable siccative 
agents include heavy metal salts, such as naphthenates or neodecanates of 
cobalt, lead, manganese, or zinc and other drying accelerators. Mixtures 
of salts are especially suitable and are preferred. Preferred amounts of 
siccative agent are from about 0.01 to 1 weight percent based on the 
weight of the formulation, and more preferably from about 0.05 to 0.5 
weight percent. 
While not intending to be bound by any theory of the invention, it is 
thought that the drying or semi-drying oil becomes absorbed in the pores 
on the surface of the composite and polymerizes to form a water-resistant 
finish. Without the drying or semi-drying oil treatment, water coming in 
contact with the composite surface has a tendency to penetrate the pores, 
adversely affecting the appearance, gloss and beauty of the composite. The 
drying or semi-drying oil treatment permanently prevents water spots and 
water staining on the earthen-plastic articles. 
After application of the formulation in accordance with the process of the 
invention, it is preferred to again buff the surface to remove any excess 
material. One suitable means for this buffing is use of a nylon pad. To 
obtain the most aesthetically pleasing properties, it is preferred to buff 
one more time with a nylon pad to polish the floor or wall after about 24 
hours from the application of the formulation. Optionally, heat and 
pressure are applied during the buffing and have been noted to have a 
beneficial effect. 
Strength Improvement and Other Properties 
It has been found that the breaking of the new earthen-plastic articles is 
not only greatly increased over that of the unimpregnated starting 
materials, but exceeds by over 60% the (ANSI) Specification for such 
flooring materials. Moreover, the bonding strength and resistance to wear 
of the new articles also greatly exceed the ANSI specifications. Still 
further, the moisture absorption of the new articles is far less than that 
permitted by the ANSI specifications. 
More specifically, the properties of the new articles exceed the ANSI 
specifications as shown in the table below. 
______________________________________ 
PROPERTIES 
ANSI 
Specifi- 
Articles of the Invention 
cation F-Series S-Series 
______________________________________ 
Property 
Bond Strength 50 psi 80 psi 80 psi 
Moisture Absorption 
&lt;5% &lt;0.5% 1.3% 
Break Strength 250 psi 500 psi 400 psi 
Resistance-to-Wear 
35 61 51 
______________________________________ 
The Mastic and Grout 
As noted above, the present invention also includes an improved mastic 
composition for installing the stain-resistant articles which sets up into 
a stain-resistant grout. 
The new mastic is composed largely, i.e. about 70 to 80% by weight, of an 
inert particulate filler such as a suitable sand or silica. The other 
essential ingredient of the mastic is a stain-resistant plastic binder for 
the sand which impart stain-resistance to the grout after it is set. The 
preferred binder is polyvinyl acetate although other equivalent polymers 
may be employed. The mastic contains about 20 to 30% of such a binder. 
Other active additives are included in the mastic. For example, it is 
preferred to include a surface active agent to aid in wetting the surfaces 
of the sand and articles with the mastic binder and impart superior stain 
resistance. Many non-ionic surfactants may be employed for this purpose, 
the alkylphenyl polyether alcohols being especially useful. The preferred 
surfactant, which may be used in amounts up to about 0.5% or more, is 
octylphenoxypolyethoxyethanol which is available commercially under the 
trademark "TRITON X405". This material contains about 40 monomer units per 
molecule. 
It is also desirable to include a lubricant for the sand and binder. 
Suitable lubricants include the polymethyl siloxanes among others known to 
the art. The preferred lubricant is poly dimethyl siloxane which is 
available commercially under the trade designation "Silicone Fluid 
SWS-101" from SWS Silicones Corporation of Adrian, Mich. 
Another desirable component of the mastic is a plasticizer many of which 
are known to the art. The preferred plasticizer is polyoxyethylene aryl 
ether which may be used in amounts up to about 0.5% or more and which is 
available under the trademark "PYCAL 94" from ICI Americas Inc. of 
Wilmington, Del. 
The preferred binder as noted above, is polyvinyl acetate (PVA). An 
especially preferred PVA is a vinyl acetate homopolymer emulsion available 
under the trademark "VINAC XX-210 to 240" which has chemical Abstract 
Registry number 9003-20-7. Other equivalent polyvinyls may also be 
employed if they bind the sand properly and impart stain-resistance to the 
set grout. 
The mastic may also contain various other additives to impart improved 
properties. One such is an anti-freeze stabilizer to prevent freezing of 
the viastic on a storage or shipping. The preferred anti-freeze agent is 
ethylene glycol which may be used in amounts of up to about 1% or more. 
Installation 
The ease and simplicity of installation of the improved stain-resistant 
articles and mastic providing stain-resistant grout constitute one of the 
primary advantages of the invention. Installation may be carried out on 
any suitably stable substrate such as a wood, plywood, masonry stone or 
metal sub-flooring or wood, plywood, chip-board, dry wall or gypsum block 
wall surface. The paste-like mastic composition is simply spread on the 
substrate to a suitable thickness and the impregnated articles, whether 
tiles, bricks or other suitable shaped articles, are placed on the wet 
mastic and imbedded therein by suitable pressure to force displaced mastic 
up around the edges of the tile or brick. The usual grout lines of desired 
width are left between adjacent tiles or bricks. Additional mastic may be 
troweled into the grout lines and leveled and smoothed as necessary to 
provide sufficient grout between adjacent tiles or bricks. Excess mastic 
may be removed from the surface of the masonry articles by wiping in known 
manner. The mastic is then allowed to set to form the stain-resistant 
grout and fully stain-resistant floor and wall surfaces of the invention. 
While setting times will vary, in most cases floors installed in this way 
can be walked on without damage after about 4 to about 24 hours. 
The floor and wall surfaces prepared in this way will provide excellent 
service even in very high traffic areas and will remain undamaged, 
unstained, and attractive for long periods of time. 
While the articles of the invention are normally installed with visible 
grout lines, they may also be installed edge to edge without visible 
intermediate grout. For example, pumice or coral tiles may be closely 
machined to permit closely fitting joints without grout therebetween; the 
only grout being below the tile adjacent the substrate.