Composition and process for barrier coating and/or cleaning paint masks

An improved aqueous liquid composition for power washing of paint masks contains: organic film-forming polymer, preferably polyacrylamide; inorganic salts, preferably a combination of alkali metal pyrophosphate, metaborate, and tetraborate; and dissolved organic molecules that (i) are hydrocarbons except for having hydroxyl substituents and, optionally, having one or more other types of substituents selected from halogen atoms, keto groups, and aldehydo groups and (ii) have a number ratio of oxygen atoms to carbon atoms that is at least 0.5; and, optionally but preferably, free boric acid.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a composition and process for use with paint 
masks, to provide them with a barrier coating to prevent tight adhesion of 
paint to the masks, clean the masks when paint has accumulated on them, or 
both. Paint masks are solid objects constituted of a material not soluble 
in or otherwise damaged by the paint(s) to be used with the masks. A paint 
mask contains openings and has a surface shape so that it fits closely to 
a surface of another object to be painted with a decorative or functional 
pattern. When paint is then sprayed against or otherwise applied to the 
outer surface of the mask, the paint penetrates to the surface of the 
underlying object only in a pattern that matches that of the hole(s) in 
the mask, while at least some paint normally adheres to the solid parts of 
the mask that define the hole(s) in it. One of the most generally known 
types of paint mask is a stencil suitable for painting numbers and letters 
on flat surfaces such as packing crates. However, much more elaborate 
types of paint masks, many suitable for decoratively painting curved 
surfaces such as those of automobile bodies, are widely used in industry. 
2. Statement of Related Art 
When a paint mask is repeatedly used, the accumulation of paint on it 
eventually reduces the size and often modifies the shape of the pattern 
produced with the mask, as accumulated paint solids come to occupy part of 
the space that was originally part of the hole(s) in the mask. Whenever 
these unwanted modifications of the pattern formed by using the mask 
exceed the tolerance of the user for variation of the pattern produced, 
the mask must be cleaned before being used again. 
Prior to the passage of the Federal Air Quality Act in 1967, accumulated 
paint residues on masks were normally cleaned therefrom by dissolution of 
the paint residues in suitable organic solvents. Substantial emissions of 
solvent vapors into the air resulted. This method became impractical in 
most U.S. urban areas and in many other locations after adoption of the 
limits on solvent emissions now imposed by law. Since that time it has 
become customary to use barrier coating of paint masks that are expected 
to need frequent cleaning. A barrier coating of water soluble material 
applied to a clean paint mask prior to its use permits relatively easy 
removal of accumulated paint residues on the mask by contact with hot 
aqueous solutions which dissolve the underlying barrier coat and thereby 
loosen the paint residues adhered to it, so that the residues can be 
removed by mechanical forces of relatively moderate magnitude. 
Since the publication of U.S. Pat. No. 3,846,172 to Fossati in 1974, it has 
been known that the removal of paint from a previously used mask bearing a 
suitable barrier coating and formation of a new barrier coating on the 
thus cleaned mask can be combined into a single step by treatment with a 
suitable aqueous composition containing film forming ingredients. The 
efficiency of using paint masks has been further increased by the 
introduction of pressure flood mask washing process equipment, which 
conveniently supplies additional mechanical force to increase the removal 
of particularly stubbornly attached types of paint residue. Further 
details are given by D. Crosley, "Barriercoat Process Paint Stripping: 
Mask Washing Without Solvents", Metal Finishing, October 1996, pp. 33-36. 
DESCRIPTION OF THE INVENTION 
Object of the Invention 
The major object of this invention was to provide a more nearly ideally 
performing composition and process for forming effective barrier coats, 
removing accumulated paint residues and barrier coats from masks bearing 
such residues on their barrier coated surfaces, or more preferably, both 
in a single step process. 
Ideal characteristics of a composition for this purpose include: minimal 
foam formation; resistance to growth of any microorganisms that may enter 
the composition from the ambient environment; formation of a film with 
substantially constant thickness and a smooth surface over the entire area 
of application; suitability for completing removal and redeposition in a 
short time, preferably not more than 5 minutes, at a normal operating 
temperature of about 77.degree. C. or less; stability at temperatures up 
to at least 88.degree. C. for an extended length of time; adequate 
detackification of any removed paint residues that have tack, to avoid 
redeposition on the mask(s) being cleaned; formation of a low-slip surface 
on drying, to make handling after treatment less susceptible to problems; 
and avoidance of adverse effects on human health from contacts of the 
composition and/or a film formed from it with human skin, because manual 
handling of the masks is often used as part of the most convenient method 
of removing them from contact with the composition after completion of 
cleaning and formation of a fresh barrier coat and/or of returning 
recoated and dried masks for reuse. Accordingly, the major object of this 
invention is to provide novel compositions and processes that are more 
preferable in at least one of these respects, especially for single step 
processes as noted above, than are the compositions and processes now 
available in the art. 
General Principles of Description 
Except in the claims and the operating examples, or where otherwise 
expressly indicated, all numerical quantities in this description 
indicating amounts of material or conditions of reaction and/or use are to 
be understood as modified by the word "about" in describing the broadest 
scope of the invention. Practice within the numerical limits stated is 
generally preferred, however. Also, throughout the specification, unless 
expressly stated to the contrary: percent, "parts of", and ratio values 
are by weight; the description of a group or class of materials as 
suitable or preferred for a given purpose in connection with the invention 
implies that mixtures of any two or more of the members of the group or 
class are equally suitable or preferred; description of constituents in 
chemical terms refers to the constituents at the time of addition to any 
combination specified in the description or of generation within any 
combination by reactions specified in the description, and does not 
necessarily preclude chemical interactions among the constituents of a 
mixture once mixed; specification of materials in ionic form implies the 
presence of sufficient counterions to produce electrical neutrality for 
the composition as a whole; any counterions thus implicitly specified 
should preferably be selected from among other constituents explicitly 
specified in ionic form, to the extent possible; otherwise such 
counterions may be freely selected, except for avoiding counterions that 
act adversely to the object(s) of the invention; the terms "molecule" and 
"mole" and their grammatical variations may be applied to ionic, 
elemental, or any other type of chemical entities defined by the number of 
atoms of each type present therein, as well as to substances with 
well-defined neutral molecules; the first definition of an acronym or 
other abbreviation applies to all subsequent uses herein of the same 
abbreviation and applies mutatis mutandis to normal grammatical variations 
of the initially defined abbreviation; the term "paint" includes all like 
materials that may be designated by more specialized terms such as 
lacquer, enamel, varnish, shellac, and the like; and the term "polymer" 
includes "oligomer", "homopolymer", "copolymer", "terpolymer", and the 
like. 
SUMMARY OF THE INVENTION 
A composition according to this invention is an aqueous liquid composition 
comprising, preferably consisting essentially of, or still more preferably 
consisting of, water and: 
(A) an amount of a component of dissolved organic film-forming polymer; 
(B) an amount of a component of dissolved inorganic salts; and 
(C) an amount of a component of dissolved organic molecules that (i) are 
hydrocarbons except for having hydroxyl substituents and, optionally, 
having one or more other types of substituents selected from halogen 
atoms, keto groups, and aldehydo groups, (ii) have a number ratio of 
oxygen atoms to carbon atoms that is at least 0.5, and (iii) are not part 
of any of the previously recited components; and, optionally, one or more 
of the following: 
(D) an amount of a component of biocidal material, exclusive of any that 
forms part of any of the previously recited components; 
(E) an amount of a component of wetting agent, exclusive of any that forms 
part of any of the previously recited components; 
(F) an amount of a component of antifoam agent, exclusive of any that forms 
part of any of the previously recited components; and 
(G) an amount of a component of dispersed undissolved finely divided 
solids, exclusive of any that forms part of any of the previously recited 
components. A polymer is defined as "film forming" for the purposes of 
this description if, when a solution or suspension of the polymer in water 
containing at least 20% of the polymer is dried at a temperature of at 
least 25.degree. C. from a liquid film thickness not greater than 1 
millimeter, a continuous and coherent film that is solid at 25.degree. C. 
is produced. 
A composition according to the invention may be ready for immediate use, in 
which instance it may be called a "working composition", or it may be more 
suitable for dilution with water to form such a working composition, in 
which instance the original composition may be called a "concentrate", 
"concentrate composition", or "concentrated composition", all three of 
which terms are considered equivalent in meaning herein. Some compositions 
according to the invention may, of course, be suitable for both uses under 
appropriate conditions. 
A process according to this invention comprises, at a minimum, a step of 
contacting a surface of a solid substrate that is not soluble in a 
composition according to the invention with such a composition for a 
sufficient time to accomplish at least one and preferably both of the 
following: (1) removing from said surface any paint residues present 
thereon and (2) forming on said surface a liquid layer of the composition, 
said liquid layer having the properties that it (2.1) adheres to said 
surface when said solid substrate is removed from contact with any part of 
said composition according to the invention that is not part of said 
liquid layer and (2.2) when dried in place on said surface of said solid 
substrate, forms a solid water soluble coating over said surface. 
Additional steps, which may be conventional per se, can also be part of a 
process according to this invention. 
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
For various reasons, it is often preferred that compositions according to 
the invention be substantially free from various constituents that can 
cause practical difficulties when present. More particularly, with 
increasing preference in the order given and with independent preference 
for each noted component, compositions according to the invention 
preferably contain no more than 4.0, 2.2, 0.90, 0.50, 0.20, 0.12, 0.070, 
0.030, 0.010, 0.0050, 0.0020, 0.0010, 0.00050, 0.00020, or 0.00010 grams 
of constituent per kilogram of total composition (hereinafter usually 
abbreviated as "g/kg") of any of the following: cations selected from the 
group consisting of Zn.sup.+2, Ni.sup.+2, Mn.sup.+2, Co.sup.+2, Cu.sup.+2, 
Fe.sup.+2, Ca.sup.+2, Mg.sup.+2, and all metal cations with a valence of 3 
or higher; sulfate, chloride, bromide, iodide, and nitrate anions; and any 
complexing agents for iron cations that are not part of component (C) as 
defined above. 
Details of preferred compositions according to the invention depend on 
whether the compositions are intended to remove paint residue that include 
water-soluble, or spontaneously water-redispersible, solids as a 
substantial fraction, usually at least 50%, of their total solids content. 
If the paint was applied from aqueous dispersion or solution, residues 
from such paint may well be water-soluble or spontaneously 
water-redispersible, while if the paint was nonaqueous-solvent-borne, its 
residues generally will not be water-soluble or spontaneously 
water-redispersible. If the paint residues to be removed are water-soluble 
or spontaneously water-redispersible, a coagulant is needed to convert 
these residues to a solid phase that can be readily separated from the 
liquid washer composition; otherwise, the dissolved paint residues will 
eventually accumulate with continued use of a composition according to the 
invention until redeposition of paint residues will occur simultaneously 
with formation of a new protective coating in a process according to the 
invention, to an extent that will compromise the protective quality of the 
new coating formed. Also, in order to favor coagulation, somewhat lower 
electrolyte concentrations are preferred when removing paint residues that 
are water-soluble and/or spontaneously water-redispersible. On the other 
hand, if no significant amount of the paint residues is water-soluble or 
water-redispersible, no coagulant is usually needed, because such paint 
residues will not re-enter the liquid phase of a composition according to 
the invention during its use, even in the absence of a coagulant. If all 
the paint residues to be removed are of this type, the compositions 
according to the invention can be made more economical by omitting the 
coagulant. The preferences below will be described for the two extreme 
cases of completely water-soluble and/or spontaneously water-redispersible 
paint residues and completely insoluble and non-redispersing paint solids 
whenever the preferences are different for these two intended uses, but it 
will be understood that one skilled in the art can vary these preferences 
appropriately in a less common case of paint residues that include 
substantial amounts of both types of solid materials. 
Preferred substances for polymer component (A) as described above include 
hydroxyetherified cellulose, polyacrylamide and polymethacrylamide, 
poly{acrylic acid} and poly{methacrylic acid}, poly{vinyl alcohol}, 
polymers of unsaturated quaternary ammonium salt monomers, poly{vinyl 
amine}, water soluble polyamides, poly{vinyl formal}, and poly{ethylene 
oxide}, in each instance with comonomers possible although usually not 
preferred. If the paint residues to be removed are all not water-soluble 
and/or spontaneously water-redispersible, only nonionic polymers are more 
preferred because of their better compatibility with high concentrations 
of inorganic electrolytes; polyacrylamide is most preferred. 
Independently, the weight average molecular weight of the nonionic polymer 
molecules in component (A), which may be designated hereinafter as 
component or subcomponent (A.1) and may constitute all of component (A), 
preferably is at least, with increasing preference in the order given, 
200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, or 
1475 and independently preferably is not more than, with increasing 
preference in the order given, 10.sup.7, 10.sup.6, 10.sup.5, 10.sup.4, 
8000, 6000, 4000, 3000, 2500, 2000, or 1525. 
If all of the paint residues to be removed are water-soluble and/or 
spontaneously water-redispersible, the presence of component (A.1) as 
described above in a composition according to the invention is still 
preferred, but in this instance in combination with a subcomponent (A.2) 
of cationic polymers, preferably those containing quaternary ammonium 
groups. Relative amounts of subcomponents (A.1) and (A.2) preferably are 
such that the ratio of subcomponent (A.1) to subcomponent (A.2) in a 
composition according to this invention preferably is at least, with 
increasing preference in the order given, 0.20:1.0, 0.40:1.0, 0.60:1.0, 
0.80:1.0, 1.00:1.0, 1.20:1.0, 1.40:1.0, 1.50:1.0, 1.60:1.0, 1.70:1.0, 
1.80:1.0, 1.90:1.0, or 1.97:1.0 and independently preferably is not more 
than, with increasing preference in the order given, 20:1.0, 16:1.0, 
12:1.0, 10.0:1.0, 8.0:1.0, 7.9:1.0, 6.0:1.0, 5.0:1.0, 4.4:1.0, 3.8:1.0, 
3.2:1.0, 2.6:1.0, 2.4:1.0, 2.3:1.0, 2.20:1.0, 2.10:1.0, or 2.02:1.0. 
Subcomponent (A.2) is more preferably selected from the group consisting of 
condensation copolymers of organic di-tertiary amines with dichloroethers 
or epichlorohydrin, epichlorohydrin being preferred. The di-tertiary 
amines may be formed in situ by reaction of secondary amines with 
epichlorohydrin. Still more preferably, a third monomer component of 
organic di-primary amines is also used to make the condensation polymers 
for subcomponent (A.2). Independently, the number of carbon atoms between 
functional moieties selected from the group consisting of chloro, epoxide, 
and amino moieties in any difunctional monomer from which such a polymer 
is made is not more than, with increasing preference in the order given, 
6, 4, 3, or 2. Independently of all other preferences, the weight average 
molecular weight of polymeric constituents of subcomponent (A.2) 
preferably is at least, with increasing preference in the order given, 
10.sup.3, 10.sup.4, 10.sup.5, or 10.sup.6 and independently preferably is 
not more than 10.sup.7. If the molecular weight is too low, flocculating 
effectiveness will be reduced, while if the molecular weight is too high 
there is serious danger of gellation of any aqueous solution containing a 
sufficient amount of the polymer to make a preferred concentrate according 
to the invention. The most preferred constituent of subcomponent (A.2) is 
a polymer (in aqueous solution) sold under the name MAGNIFLOC.TM. 577-C by 
Cytec and reported by its supplier to be a polymer of dimethyl amine, 
ethylene diamine, and chlorohydrin. 
In a concentrate according to the invention, when component (A.1) of 
nonionic polymer constitutes all of component (A), the total amount of 
water soluble film-forming polymer component (A), on a solids basis, 
preferably is at least, with increasing preference in the order given, 
4.0, 6.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 14.5, or 14.9% of the 
total composition and independently, primarily for reasons of economy, 
preferably is not more than, with increasing preference in the order 
given, 50, 40, 30, 25, 22, 19, 18.0, 17.0, 16.5, 16.0, 15.5, or 15.1% of 
the total composition. In contrast, if both subcomponents (A.1) and (A.2) 
as defined above are present as part of component (A), the total amount of 
water soluble film-forming polymer component (A), on a solids basis, 
preferably is at least, with increasing preference in the order given, 
6.0, 9.0, 12.0, 13.5, 15.0, 16.5, 18.0, 19.5, 21.0, 22.5, 24.0, 25.0, 
26.0, 27.0, 28.0, 29.0, or 29.7% of the total composition and 
independently, primarily for reasons of economy, preferably is not more 
than, with increasing preference in the order given, 50, 47, 44, 41, 38, 
36, 34.0, 33.0, 32.0, 31.5, 31.0, 30.5, or 30.3% of the total composition. 
The substance(s) and amount(s) used for component (B) preferably should be 
such that the pH of a working composition is between 7.5 and 11. 
Additionally, if component (A) consists of nonionic polymers only, then 
the pH of a working composition preferably is at least, with increasing 
preference in the order given, 7.5, 8.0, 8.2, 8.4, 8.6, 8.8, 8.90, or 9.00 
and independently preferably is not more than, with increasing preference 
in the order given, 11.0, 10.5, 10.0, 9.8, 9.6, 9.50, 9.40, 9.30, 9.20, or 
9.10. These preferred pH levels can be achieved with a wide variety of 
known alkaline salts. However, it has been found that, to optimize the 
properties of a dried barrier coating formed with a composition according 
to the invention, it is preferable for component (B) as defined above to 
contain at least two subcomponents: (B.1) alkali metal phosphate and/or 
condensed phosphate, most preferably pyrophosphate and (B.2) alkali metal 
borate and/or condensed borate, most preferably both borate and 
tetraborate, and the preference for these materials is independent of the 
separate preference for the pH value of a working composition according to 
the invention, because these particular materials appear, for reasons 
unknown, to produce favorable physico-chemical properties in the dried 
film coatings formed. Further and independently, potassium salts are most 
preferred for component (B.1) and for any metaborate content of component 
(B.2), while sodium salts are most preferred for any tetraborate part of 
subcomponent (B.2). The borates and/or the phosphates may be supplied in 
situ by adding the corresponding acid(s) and hydroxide(s) or oxide(s). 
When this method is used, any alkali metal or ammonium hydroxide added to 
a composition according to the invention is assumed to react to the 
fullest extent permitted by stoichiometry with any free boric, phosphoric, 
or condensed boric or phosphoric acid also added to the same composition, 
and any excess of either free acid, oxide, or hydroxide added is assumed 
to remain free in the ultimate composition unless otherwise noted. 
(Reaction with boric acid is assumed to produce metaborates.) 
When component (B) contains subcomponents (B.1) and (B.2) as defined above, 
if component (A) consists solely of nonionic polymers, the molar ratio of 
(B.1) to (B.2) preferably is at least, with increasing preference in the 
order given, 0.10:1.0, 0.20:1.0, 0.40:1.0, 0.50:1.0, 0.60:1.0, 0.70:1.0, 
0.75:1.0, 0.80:1.0, 0.84:1.0, 0.87:1.0, or 0.91:1.0 and independently 
preferably is not more than, with increasing preference in the order 
given, 8.0:1.0, 5.0:1.0, 4.0:1.0, 3.5:1.0, 3.0:1.0, 2.5:1.0, 2.2:1.0, 
1.9:1.0, 1.6:1.0, 1.3:1.0, 1.10:1.0, 1.00:1.0, 0.95:1.0, or 0.93:1.0. 
Independently, if component (A) consists solely of nonionic polymers, the 
molar ratio of BO.sub.2.sup.-1 to B.sub.4 O.sub.7.sup.-2 in a composition 
according to the invention preferably is at least, with increasing 
preference in the order given, 0.090:1.0, 0.150:1.0, 0.20:1.0, 0.30:1.0, 
0.40:1.0, 0.50:1.0, 0.60:1.0, 0.70:1.0, 0.75:1.0, 0.80:1.0, 0.86:1.0, 
0.89:1.0, or 0.91:1.0 and independently preferably is not more than, with 
increasing preference in the order given, 12.0:1.0, 9.0:1.0, 6.0:1.0, 
4.5:1.0, 3.0:1.0, 2.4:1.0, 1.8:1.0, 1.5:1.0, 1.2:1.0, 1.15:1.0, 1.10:1.0, 
1.05:1.0, 1.00:1.0, 0.96:1.0, or 0.92:1.0. 
However, when component (B) contains subcomponents (B.1) and (B.2) as 
defined above and component (A) comprises both subcomponents (A.1) and 
(A.2) as described above, the molar ratio of (B.1) to (B.2) preferably is 
at least, with increasing preference in the order given, 0.020:1.0, 
0.040:1.0, 0.060:1.0, 0.080:1.0, 0.10:1.0, 0.12:1.0, 0.14:1.0, 0.16:1.0, 
0.170:1.0, 0.175:1.0, or 0.180:1.0and independently preferably is not more 
than, with increasing preference in the order given, 1.8:1.0, 1.3:1.0, 
1.0:1.0, 0.80:1.0, 0.50:1.0, 0.40:1.0, 0.35:1.0, 0.30:1.0, 0.27:1.0, 
0.24:1.0, 0.22:1.0, 0.200:1.0, 0.190:1.0, or 0.185:1.0. Independently, 
when component (A) comprises both subcomponents (A.1) and (A.2) as 
described above, the molar ratio of BO.sub.3.sup.-3 to B.sub.4 
O.sub.7.sup.-2 in a composition according to the invention preferably is 
the same as when component (A) includes only nonionic polymers, as set 
forth in detail above. (For the purposes of calculating all of these molar 
ratios, a mole is to be considered as the amount required to contain 
Avogadro's Number, i.e., 6.23.times.10.sup.23, of anions of the type 
specified.) 
Independently of all other stated preferences, the ratio (by weight) of 
total component (B), exclusive of any water of hydration, to component 
(A), measured as non-volatile solids on drying at 100.degree. C. and 
normal atmospheric pressure, when component (A) is constituted exclusively 
of nonionic polymers, preferably is at least, with increasing preference 
in the order given, 0.10:1.0, 0.30:1.0, 0.50:1.0, 0.60:1.0, 0.70:1.0, 
0.80:1.0, 0.85:1.0, 0.90:1.0, or 0.95:1.0 and independently preferably is 
not more than, with increasing preference in the order given, 10:1.0, 
8.0:1.0, 6.0:1.0, 5.0:1.0, 4.0:1.0, 3.0:1.0, 2.5:1.0, 2.0:1.0, 1.7:1.0, 
1.50:1.0, 1.30:1.0, 1.20:1.0, 1.15:1.0, 1.10:1.0, 1.05:1.0, or 1.00:1.0. 
If component (A) comprises both subcomponents (A.1) and (A.2) as described 
above, however, the ratio (by weight) of total component (B), exclusive of 
any water of hydration, to component (A), measured as non-volatile solids 
on drying at 100.degree. C. and normal atmospheric pressure, preferably is 
at least, with increasing preference in the order given, 0.02:1.0, 
0.4:1.0, 0.06:1.0, 0.08:1.0, 0.10:1.0, 0.12:1.0, 0.14:1.0, 0.16:1.0, 
0.170:1.0, 0.180:1.0, 0.190:1.0, 0.200:1.0, 0.210:1.0, or 0.220:1.0 and 
independently preferably is not more than, with increasing preference in 
the order given, 3.0:1.0, 2.0:1.0, 1.5:1.0, 1.0:1.0, 0.80:1.0, 0.60:1.0, 
0.40:1.0, 0.32:1.0, 0.28:1.0, 0.250:1.0, 0.240:1.0, 0.230:1.0, or 
0.226:1.0. 
The function of component (C) is not known in detail, but it has been found 
to be necessary to the practical success of the invention, presumably 
because it affects the bulk and/or surface properties of the protective 
coating formed in some manner that favors facile removal of paint and the 
protective coating together. This component is preferably selected from 
substances that are liquids in pure form at 25.degree. C. and normal 
atmospheric pressure. Independently, at least, with increasing preference 
in the order given, 20, 35, 50, 60, 65, or 70% of it is a subcomponent 
(C.1) selected from molecules in which the number ratio of oxygen atoms to 
carbon atoms is at least, with independent increasing preference in the 
order given, 0.70:1.0, 0.75:1.0, 0.80:1.0, 0.85:1.0, 0.90:1.0, or 
0.95:1.0. Subcomponent (C.1) as thus defined may constitute all of 
component (C), but if it does not, the remainder of component (C) is 
designated as subcomponent (C.2), and it is preferably selected from 
molecules in which the number ratio of oxygen atoms to carbon atoms is 
from 0.65:1.0 to 0.69:1.0. 
Also, independently of any other stated preferences and of one another: 
each of subcomponents (C.1) and (C.2) if present, independently for each, 
or the total component (C) if neither of these subcomponents is present, 
is preferably selected from molecules in which the number of carbon atoms 
is not greater than, with increasing preference in the order given, 8, 6, 
5, 4, or 3 and independently preferably is at least 2 or more preferably 
at least 3; subcomponent (C.1) preferably constitutes at least, with 
increasing preference in the order given, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 
3.5, 4.0, 4.3, 4.6, or 4.9 percent of the total composition and 
independently preferably constitutes not more than, with increasing 
preference in the order given, 20, 16, 12, 10, 8.0, 7.5, 7.0, 6.5, 6.0, 
5.7, 5.4, or 5.1 percent of the total composition; and both subcomponents 
(C.1) and (C.2) are present, in a ratio of (C.1):(C.2) that is at least, 
with increasing preference in the order given, 0.20:1.0, 0.40:1.0, 
0.60:1.0, 0.80:1.0, 1.00:1.0, 1.20:1.0, 1.40:1.0, 1.60:1.0, 1.80:1.0, 
2.00:1.0, 2.10:1.0, 2.20:1.0, 2.30:1.0, 2.40:1.0, or 2.47:1.0 and 
independently preferably is not more than 20:1.0, 15:1.0, 10:1.0, 8.0:1.0, 
6.0:1.0, 5.0:1.0, 4.0:1.0, 3.6:1.0, 3.3:1.0, 3.0:1.0, 2.80:1.0, 2.70:1.0, 
2.60:1.0, or 2.53:1.0. 
Among the optional components of a composition according to the invention 
noted above, only component (D) is normally preferred, and its most 
preferred embodiment, free boric acid, may well have other film modifying 
effects that make it useful in addition to its biocidal properties. In any 
case, a sufficient amount of some biocide to prevent visible growth of 
microorganisms in a composition according to the invention left open to a 
normal ambient atmosphere is normally preferred, because deleterious 
growths, presumably nourished by water soluble polymer component (A) 
and/or organic component (C) are otherwise likely to occur. An amount of 
free boric acid that, when nonionic polymers are the only constituent of 
component (A), has a ratio (by weight) to the total amount of non 
volatiles at 100.degree. C. and normal atmospheric pressure in components 
(A) and (C) that is at least, with increasing preference in the order 
given, 0.004:1.0, 0.006:1.0, 0.008:1.0, 0.010:1.0, 0.015:1.0, 0.020:1.0, 
0.025:1.0, 0.030:1.0, 0.035:1.0, 0.040:1.0, or 0.045:1.0 and independently 
preferably is not more than, with increasing preference in the order 
given, 0.45:1.0, 0.35:1.0, 0.28:1.0, 0.23:1.0, 0.18:1.0, 0.14:1.0, 
0.11:1.0, 0.090:1.0, 0.70:1.0, 0.060:1.0, 0.055:1.0, 0.050:1.0, or 
0.048:1.0 is preferred and will, at least in its most preferred amounts, 
generally have adequate biocidal effect. When component (A) includes both 
subcomponents (A.1) and (A.2), the preferred amount of free boric acid has 
a ratio (by weight) to the total amount of non volatiles at 100.degree. C. 
and normal atmospheric pressure in components (A) and (C) that is at 
least, with increasing preference in the order given, 0.002:1.0, 
0.004:1.0, 0.006:1.0, 0.008:1.0, 0.011:1.0, 0.014:1.0, 0.017:1.0, 
0.020:1.0, 0.022:1.0, 0.024:1.0, or 0.026:1.0 and independently preferably 
is not more than, with increasing preference in the order given, 0.20:1.0, 
0.14:1.0, 0.11:1.0, 0.090:1.0, 0.080:1.0, 0.070:1.0, 0.060:1.0, 0.050:1.0, 
0.045:1.0, 0.040:1.0, 0.035:1.0, 0.030:1.0, or 0.028:1.0. Again, at least 
in the most preferred amounts, the free boric acid will normally have an 
adequate biocidal effect in this type of composition according to the 
invention. However, even if another biocide is used, as is sometimes 
preferred, the above stated amounts of free boric acid preferably are 
still present in a composition according to this invention. 
A working composition according to this invention preferably contains the 
same components that are specified above for concentrate compositions, but 
in an amount that, for components other than water, is at least, with 
increasing preference in the order given, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 
5.0% of the amount stated above for the same component for a concentrate 
composition. Ordinarily, the amount of a component other than water in a 
working composition according to the invention does not, in order to 
achieve satisfactory results, need to be, and therefore preferably is not, 
greater than, with increasing preference in the order given, 15, 12, 10, 
8, 7.0, 6.5, 6.0, or 5.5% of the value specified above for the same 
component in a concentrate composition. However, if extraordinarily 
resistant paints in heavy layers are to be removed, concentrations 
corresponding to a higher fraction of the above noted values for 
concentrate compositions may be preferred. 
When operating a process according to the invention within a temperature 
range from 49.degree. to 82.degree. C. to remove, together with a 
previously applied barrier coating, paint residue accumulations on the 
barrier coating that are from 25 to 508 micrometers (hereinafter usually 
abbreviated as ".mu.") in thickness, by contacting the paint residues with 
a working composition according to the invention that has a concentration 
of a preferred concentrate composition according to the invention as 
described above that is from 5.0 to 25% by volume, it has been found with 
at least one typical paint that the minimum contact time required to 
remove the previously applied barrier coating, together with the paint 
residues on it, can be predicted with fair accuracy by use of the 
following equation: 
EQU R=711-3.36!*{9/5T.sub.1 !+32}-6.80.multidot.P+0.130.multidot.T.sub.2 
where: R is the time in seconds required for removing all of the paint 
residues and the previous barrier coating; T, is the temperature in 
.degree.C. of the composition according to the invention used during the 
process; P is the concentration in volume percent, in the working 
composition, of a preferred concentrate composition as defined above; and 
T.sub.2 is the thickness in .mu.m of the paint residues to be removed. By 
use of this equation, with knowledge of processing costs for a particular 
location and operation, processing conditions for the removal of this 
paint can therefore be economically optimized. With other paints, general 
trends are expected to be the same although exact coefficients would 
probably be different. As a generalization, contact times from 1 to 5 
minutes are normally used. 
Some compositions according to the invention have a tendency to form foams 
readily; this can be a serious practical disadvantage in use of the 
compositions, inasmuch as high pressure spraying is the most common 
commercially practiced method of establishing contact between a paint mask 
washer composition and a paint mask from which paint residues are to be 
removed, and the spray nozzles are usually fed from a reservoir into which 
the liquid runoff from the spraying process is recycled. This mechanical 
arrangement can cause considerable build-up of foam if the mask washer 
composition is prone to foaming. Accordingly, many of the working 
compositions developed during the work that led to this invention were 
subjected to a foam test procedure, which although it does not directly 
simulate commercial conditions, has been found by experience to be 
reliably correlated with foam generation under actual conditions. In this 
test, 100 milliliters (hereinafter usually abbreviated as "ml") of liquid 
to be tested was placed in a glass stoppered graduated cylinder with 250 
ml capacity and shaken vigorously by hand, then put on a horizontal 
surface. The initial foam volume was determined by visual observation of 
the difference between the top of the unfoamed liquid phase and the top of 
the foam, as soon as the drainage of liquid and foam from the walls of the 
cylinder was completed (within 15 seconds after completion of shaking). A 
composition according to the invention preferably generates not more than, 
with increasing preference in the order given, 30, 27, 24, 21, 18, 16, 14, 
12, 10, 8, 6, or 4 ml of foam in this test. If the intended use 
temperature of the composition is known, foaming according to this test 
should be determined at that temperature, because temperature often has a 
strong influence on the amount of foam generated. 
Further appreciation of the present invention may be had from considering 
the following examples and comparison examples which are intended to 
illustrate, but not to limit, the invention.