US2316041A - Process for simulating hammered metal - Google Patents

Description

Patented Apr. 6, 1943 v raocass roa smom'rmo am ss METAL I Gerald E. E. I. do

ama, rum, Mica, asslgnoi' to.

Pont "de Nemours a company, Wilmlngton, Del.. a corporationof Delaware No Drawing. Application mach 12, 1940.

Serial No. 323,533

- This invention relates'to improvementsiin the finishing of metal, wood and other surfacesto simulate hammered metal and multi-toned metallic effects.

Heretofore various methods have been known therim of the-crater "the granular ing two medium wet coats of the metallic paint v for producing two-toned finishes and some. of l theseme thods produce two-toned'metallic effects. Practically all of them, however, require the use of two or more paint products and require at least two separate and distinct finishing operations. The methods involving a'single finishing operation gressively changing in the liquid state, rendering them impractical for continuous application or repair-.0! previous nnish'in case of damage.

One. of the objects of this invention is to produce from a single'liquid paint, supplemented with a spatterfcoat of thinner; uneven surface other object of a finish having an anda multi toned effect. this invention is to provide a have the disadvantage of pro-- Y of the thinner.

coating. composition which, when applied to a suitablebase material; will-Idryl -to a-prot'ective coating which simulates the appearance of. hammered -meta-l'. 1 A still further-object" of" this invention-is' to provide aJcoating technique which enables; the economical. production-"of a} ham rne redmetal. finish or multltoned efiectt Still another object of this invention is the provision of compositions capable of" producing such'an improved finish. Other objects will be apparent as the; description of' the' inventlon proceeds.

These objects. are accomplished by incorporating in a thin'oleoresinous; resinou's or'nitrocellulose vehicle as a'base' powder or paste and applying the paint or a I granular pigment, and lacquerj by spraying, dip-- material; a flake metallic pigment composing-the central portion. I f Best results have been obtained by first applyor lacquersufiicientlyheavy to cover uniformly solid in color, in each rial has time to set, 'due-to loss of the volatile constituents, applyingthe droplets of thinner to the surface with a. special spatter gun or equip ment adjusted for this effect. The hammered effect develops'alr'nost immediately at the impact The compositions which maybe used. for carrying out this process may-vary greatly as totheir ingredients and proportions. It has, for example,

been found that good results can ,be obtained by using, as the clear vehicle, either oleoresinous varnishes, alkyd resins of the oil modified type, or clear nitrocellulose lacquers. .Thevehicles can-be chosen'so as to be suitable for .-air .dr

ing, ,for bakin'gor for both.

'I'he basematerial may be either pigmented or unpl'gmented,- asdesired. In order, however, to

produce a finish simulating more closely a gen- .uine hammered metal finish, it is desirable to have the base material pgmented by grinding it I with -a pigment 'or' dye designed to give an approping or brushing in such a manner as tofirst produce a smooth uniform coating, sufficiently ,"heavy to cover the surface, followed, in five to "sixjt'yseconds for the nitrocellulose and resinous "products, and from four .to. thirty minutes for erial, with a-coat of thinner the paint or lacquer in the net instead, of by the conventional mist coating methods. These droplets of thinner, upon strik- 1' nner as to strike the surface form of small dropthe paint or lacquer, spreadput. to form spots or small areas having ridges atthe edge's of the {areas-with the. central portion or crater of these v having the color of the finely; divided metal,

,jwhile the edges-or rim of "the craterhasthecblor pot the granular pigment :or dye' -us ed, .thus pro,-

J'du'cing a hammered effect. This isdireotlyl-oppoasite to prior art wherein the-metaljmigrates to 'prlate tin-t totheresulting finish. It is essential that a metallic bronze minum powder produces the best results because "it tends. to fioat or leaf readily and because its I simulation of a hammered color produces a closer metal effect than do merated.

The metalpowders or pastes used are coated with a fatty acid or soap and may be of the formcommercially available. powder per gallon of finished composition depends upon the particular metal, powder or paste employed and also may bevaried to produce d ifferentrefiects. .It has been found that from of 1% to 40% by weight of metal powdermay be use forjvarious effects, but the mostpractical and preferred.- range of metal powder is r-.-om ap'-. proximately 1%' to 5%, t,

Theamounft oi granular the other powders enupigment also varies.

greatly with the hiding power of the partcular pigment employed and with the efiect desired.

. Good results have been obtainedfrom A of 1% to'30%.,with the most satisfactory results and preferred range from 2% to 15% of pigment;

coat, and, before the mate- The quantity of metai In the manufacture of the composition, it is relatively unimportant whether the pigmented enamel is added to the metallic flake or vice versa. The finished product is held in this state until required for application, at which time solvent is added to reduce the material within the range of good spraying consistency and the material sprayed, as described in the foregoing,

The spatter coat of thinner is then applied, the action of the droplets producing the hammered effect. Best results are obtained with a spray gun fitted with. a spatter cap, although any type of equipment so adjusted or regulated as to spray in the form of droplets, rather than by a fine mist, will produce entirely satisfactory results. The thinner referred to above is composed of two or more miscible solvents, having relatively rapid rates of evaporation. The function of the thinner is to serve as a medium of movement in which the metallic particles concentrate towards the center and float towards the surface of each individual droplet, due to the violent and rapid ebullition of the volatilesolvent. As a preferred thinner, I use a mixture consisting of equal parts by volume of denatured alcohol, methyl ethyl ketone and V. M. 8: P. naphtha. It is evident that a thinner, consisting of variations in the above combination or the solvents embracing slowly volatile or highly volatile solvents, or a single solvent, may be used, if desired.

As an example of a preferred coating composition spattered with thinner, the following pigmented resinous base material has been successfully applied:

Example I Per cent Bone black 3.18 Iron oxide. 1.94 Ferrite yellow .96 Extra fine lining A1 flake 2.31 Alkyd resin 33.61 Solvent 58.00

The alkyd resin of this example consisted of a blend of two synthetic resins, one being a linseed oil modified alkyd resin, and the other being a linseed and China-wood oil modified alkyd resin. These resins may be prepared by any method known in the art, but should preferably have a low acid number.

This material was applied on a smooth steel panl with a spray gun using 12-lb. fluid and 65-70 lb. air, holding the nozzle 12-15 inches from the surfaces. This enamel was immediately spattered with thinner using the combination consisting of ethyl alcohol, methyl ethyl ketone and V. M. 8; P. naphtha inequal parts by volume The spatter coat was applied with a regular spatter gun using approximately 2-lb. fluid pressure and less than 15-lb. air pressure. The resulting film, after baking one hour at 225 F. showed a series of areas varying from 4 to /4 of an inch in diameter. The craters of the areas contained a high concentration of aluminum particles, tinted reddish gray, while the rim of the craters contained the base'color of the pigment combination. This material can be modifled, by incorporating suitable driers, to produce a satisfactory effect and hard film onair drying.

Example II The following formula illustrates one embodiment of the invention in which nitrocellulose lacquer is used to produce an effect which closeapplied to metal, wood or other surfaces:

Per cent Nitrocellulose 17.06 Coconut oil modified alkyd resin 8.46 Malic acid -L. .30 Dibutyl phthalate 3.63 Extra fine lining aluminum paste 1.62 Bone black 2.37 Titanium dioxide 1.55 Ramapo blue .23 Blown castor oil 2.44 Combined solvent and diluent; 62.34

"This resin is produced in any known manner and may cgliitrain approximately 34% coconut oil and 66% alkyd This lacquer was applied to the surface. asdescribed in Example I, and the spatter coat of thinner sprayed immediately afterward. The resulting film, simulating a hammered appearance, was baked one hour at F. to produce a hard fllm, although similar results can be obtained by air drying.

Example III Bone black 17.00

Extra fine lining aluminum paste (66.5%

T. S.) 1.87 China-wood oil-limed rosin varnish (thirty gallon length-51% non-volatile) 49.44? Limed rosin (56% non-volatile) 10.33 Lead-manganese drier V. M. 8: P. n p 5.09 Mineral spir 15.68

The above paint, when applied on a steel surface, as previously described, and baked one hour at 225 F., produces a hard, dark gunmetal film, simulating a hammered finish.

While I have illustrated the invention with a resinous composition, a nitrocellulose lacquer, and an oil varnish vehicle, it is to be understood that the invention is not limited to the specific examples nor to the specific resin, cellulose derivative, or oil, since other resins which are capable of forming a durable film may be used. Likewise other cellulose derivatives such as cellulose acetate or cellulose ethers either alone or in combination with natural or synthetic resins are likewise suitable as far as producing the desired appearance is concerned. In place of China-wood oil, I may use linseed oil vehicles which may likewise contain resins.

While it is usually preferred to decorate wood, metal, or similar rigid bodies with a metallic finish, it is to be understood that the invention is not limited to these materials since paper, fabric of all kinds, and even other materials may be treated provided the surface'is supported until the finish is sufiiciently dry to prevent running or sticking when rolled.

V mered metal finish It is apparent that many widely diirerent embodiments 01' this invention may be made without departing from the spirit and scope thereof and therefore it is not intended to be limited except as indicated in the appended claims.

Iclaim:

1. The process of producing a simulated hamwhich comprises applying to a rigid base a substantial film of a composition containing a film-forming agent, at least one volatile solvent, 2-15% granular pigment, and from 15% of a flake metallic powder, allowing the film to partially set by evaporation of the solvent, immediately thereafter spattering thereon a composition consisting of highly volatile s01- vents for the film-forming agent, substantially in the form of coarse droplets under a fluid pressure of about 2 lbs. and an air pressure of less than 15 lbs. per sq. in. whereby the spattered solvent dissolves the fihn-forming agent and thereby forms apparent metallic craters, and drying the same to a hard finish.

2. The process 01' claim 1 in which the said solvent consists essentially of alcohol, 'methyl'ethyl ketone, and naphtha.

GERALD E. ARMENTROU'I'.