Law No. 1—The law of minimum voids to be observed in constructing a paint formula—this law having already been accepted as mathematically correct and technically proved in the technology of concrete and cement.
Corollary—The requisite thickness of a paint film together with the utmost attainable strength and impermeability can best be obtained by a properly proportioned blend of pigments of three or more determinate sizes.
AN EXHIBITION OF CERTAIN ANALOGIES GOVERNING THE MANUFACTURE
OF CONCRETE AND OF PAINT
| 1 | Concrete aggregate = solids + vehicle | Paint aggregate = solids + vehicle | |
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| 2 | | Solids | = | coarse | + | medium | + | fine | | | (stone) | | (gravel) | | (sand) |
| | Solids | = | coarse | + | medium | + | fine | | (pigments | ⎧ | pulverized | ⎫ | { | precipi-
tated | } | (fume) | | ⎨ | cryst'lline | ⎬ | | ⎩ | (etc.) | ⎭ |
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| | |
| 3 | | Vehicle = | | = | reactive binder | + | evapor'g thinner | | { | cement and com-
bining water | } | (excess water) |
| | Vehicle = | | = | reactive binder | + | evaporating thinner | | | (linseed oil) | | (volatiles) |
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| 4 | | Solids | + | compacting | = | | | | (tamping) | | | = | elimination of accidental voids | + | | + | proper adhesive contact | |
| | Solids | + | compacting | = | | | | (brushing) | | | = | elimination of accidental voids | + | | + | proper adhesive contact | |
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| 5 | Vehicle + reaction = hydrosilicates, etc. | Vehicle + reaction = linoxyn |
| | (setting) | (drying) | |
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| 6 | | Solids + vehicle + | | + | lubrication | + | chemical reaction | = | | = | final product | { | solidified binder | + | } | | + solids |
| | Solids + vehicle + | | + | lubrication | + | chemical reaction | = | | = | final product | { | solidified binder | + | } | | + solids |
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| | |
| 7 | Final product = concrete | Final product = paint coating | |
| | | (of max. strength | ⎧ | shearing | ⎫ | | ⎨ | tensile | ⎬ | | ⎩ | crushing, etc. | ⎭ |
| | (of maximum | ⎧ | strength | ⎫ | | ⎨ | impermeability | ⎬ | | ⎩ | durability | ⎭ |
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| | **** | **** | |
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| If we assume for both paint and concrete |
| | proper lubrication | |
| | proper proportion of vehicle and solids | |
| Then the essential difference between a thin film of |
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| Concrete | and | Paint |
| | is | |
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| Cement Binder | Linoxyn Binder |
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| | Disadvantages | |
| | Non-elastic and hence an impracticable binder for a film to protect non-similar structuralsurfaces. | Slowly perishable from oxidation by the air. | |
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| | Advantages | |
| | Durable and with the qualities of a natural mineral. | Semi-elastic and therefore a practicable binder for a film to protect structural surfaces. | |
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| Postulate (def. Webster's Dictionary—A self-evident problem) |
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| Postulate No. 1—The organic linoxyn or semi-elastic binder of thepaint vehicle (unlike the cement binder) is perishable and its purity,strength and protection from attack means life to the paint coating,and hence the life of the oil is the life of the paint. |
| Postulate No. 2—The inorganic or powdered mineral solids of a paintcoating will crumble unless held together by the binder, but theimperishable pigments must be so ground and blended in the binder thatthey will protect the binder and present the greatest possible solidfront to the atmospheric attack. |
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| | **** | **** | |
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| A paint, to secure the greatest protection and life for the linoxyn,together with the durable qualities of cement, |
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| | Therefore |
| |
| | Should expose to air decay |
| | within limits of physical strength | within limits required for elasticity, | |
| | The greatest amount of pigm't material | etc. The least amount of exposed linoxyn | |
| | (which is) | or | |
| | Durable and with the inert qualities ofnatural mineral | Considering the linoxyn present between pigment particles as the void or point of attack, | |
| | Then | |
| the minimum exposure of linoxyn | |
| | or minimum voids obtainable by proportioned pigments of different particlesizes. | |
Law No. 2—The law of the flat arch in paint coatings—i.e., the fact that in studying the fundamental physical principles governing the strength and durability of a paint coating it is necessary to regard the coating as consisting of a series of flat arches, in which the pigment particles of largest characteristic size serve as the piers or supports for the flat arches of which the continuous film is composed.
Corollary A—The strength and durability of a paint coating is determined by the strength and durability of the piers or supports (which consist of the characteristic pigment particles of the largest size).
Corollary B—Owing to their inherent strength and durability the pigment particles of largest characteristic size which serve as supports for the paint coating should consist, in part at least, of chemically inert pigments, such as natural crystalline barium sulphate, calcium carbonate, magnesium silicate, etc.
Corollary C—It follows directly that the thickness of a paint coating is determined by the particles of pigments having the largest characteristic size, even if that pigment be present only in moderate percentage. Upon this principle depends the comparatively great thickness of film and moderate spreading rate of paints composed of such pigments as basic carbonate—white lead, red lead, barytes, etc., and the strongly contrasted thinness of film and high spreading rate of paints composed of the sublimated pigments such as lamp black, zinc oxide, basic sulphate—white lead, zinc-lead white, leaded zinc, etc.
In commenting upon the announced laws set forth above, Heckel says: “The recognition of these laws was an exercise of pure deduction. Paint manufacturers before Mr. Perry’s announcement were producing paints containing three or more pigments with particles of varying characteristic sizes; but their procedure was based largely on empirical knowledge, the result of accumulated experience, due to a conscientious endeavor to produce the highest type of paints for economic service. In the absence of any law to govern or to limit the use of the reinforcing pigments, inexperienced manufacturers had brought upon the market paints which were badly proportioned as to the several pigments, or burdened beyond the limits of effectiveness with reinforcing pigments. To all paint manufacturers Perry rendered a substantial service in deducing for them the laws set forth in his address. In the results following a recognition of these laws there was nothing new or startling, but Perry was the first to give the principles from which it can be determined in advance whether a paint formula will prove to be physically good or bad in practice.