US1848016A - Metal cleaning compound - Google Patents

Description

Patented 1, 1932 'rs 'r oF-Flca f swam JONES, or'cmmnen, nasmnusms urn. cI-miime oonom 1m m'wis Application am September 1, 1m, Serial Io. 818,115. 'Beuewed January 8, was.

This invention relates to improvements in metal cleaning and more partlcularly to the.

- It is an ob ect of t 's inventlon to provlde removal of tarnish from articles of silver.

Hitherto, one of the most widely used I 5 methods of cleaning gold orsilver articles has been by the use of abrasives, either alone or incorporated in a paste or cloth by means of tallow or other grease. Such abrading process is necessarily slow and has the disadvantage. of abrading or removing a pot-- .tlon of the metal surface as well as the tar-- nish.' A further disadvantage resides in the fact thatit is very diflicult or almost impossible to cleandepressed portions" of embossed or en avedarticles. v 'Another met ed in wide use-is that of dissolving the tarnish in strong, hot so1utiens of cyanides.' Cyanides, as is well known, are extremely oisonous, andcannot be 'handledwith sa ety in the ordinary household. Further, any carelessness m washing off the cleaned articles aftertreat ment might result in the ,fatal .poisoning of anyone using them. In addition, the 'well known. solvent action of cyanides for silver, 'in the presence of air, is a factor to be taken into account. The most commonly used method is to immerse the article to be cleaned in a boil- 3 ing alkaline solution, such as a solution of sodium carbonate, sodium bicarbonate or tri-" sodium phosphate, contained 'in an aluminum pot or like vessel. Ordinary salt may be added to speed up the electrochemical action.- The article to be cleaned must be in electrical contact with the aluminum, either directly or through another piece of metal, so' that an electric current can flow o from the metal to be cleaned to-the aluminum and back to the metal through the elec- I trolyte; This combination forms a short-cir--. .cuit-ed electrolytic cell in which the alumi .num dissolves electrolytically and the sulfide of the tarnished metal is reduced electrochemically to the metal. The sulfide ion liberated unites with the hydrogen. set free to form gaseous hydrogen sulfide. Hydro gen-sulfide has an offensive odor. This old 6o method of cleaning silver leaves themetal jects by providing a com the metal to ing action thereon. I have found that tosea composition of matter .which is adapted to i, remove tarnish from metals, and one which 5 does not require the articles-tobe cleaned to be im.mersed therein. It 1s a further object of this invention to provide a. compositlon of matter which is 'acla ted to remove tarnish from metal and w to slmultaneously neutralize or combine with the hydrogen -sulfide as liberated. "L vAnotherobject of tl lis invention is toprovideacom osition of matter which does not comprise alies or other-caustic, or'poisom' a ous substances and is adapted todetamish metals. r f

, Yet another object "of. this invention is to i 1 provide such a composition of matter as a vendiblearticle, either as a powder, paste,

. or incorporated in a cloth or the like.

I accomplish thwe and other desirable obsition of matter comprising a finely divi ed metalin comoracid salt whose aqueous solution m an acid reaction to litmusfltvith or wlthout a neutral-salt, with or without an anti-odor,

'- and with or without an abrasive, put up either as a, powder, or a paste, or incor orated in a cloth or the like, and adaptedto e activated whenwetr v 1 In the manufacture of the composition comprising my invention '1 use a metal which 4 -I 5 is. sufiicientlyeelectropositive with respect to 5 Q cleaned as to have a detarnis'hcure the best results the metal should be' finely divided, or pulverized if possible. As"

theresult of protracted experiments, I have found that the following metals are suitable for use "in a composition for detarnishing silver or other tarnishable metals or alloys, 1 when taken in conjunction with the acids and acid salts to behereinafter referred to. The metals, in the order of their reducing power, are: magnesium,- zinc, manganese,- cadmium, iron and aluminum. It will, of course, be readily understood that other metals having the desired characteristics may bin'atlon wlth a substantially anhydrous acid. 6

be used, and the foregoing are given merely b way of illustration. The factors of availa ility of materials, cost, ease of processing (grinding, mixing),-stability', reducing power, and hardness enter into the choice of the particular metal to be used,'and such choice will be readily made by those skilled in the art for any given set of conditions.

- In combination with any of the foregoing metals, I make use of a suitable acidor acid salt whose aqueous solution gives an acid reaction to litmus. As I have mentioned above, the particular acid or acid salt chosen must be-readily soluble in water, non-poisonous, non-hydroscopic, commercially available at a moderate price,andofmoderatestrength. If it is to be part of the powder, paste or cloth sold, it must be in the solid form. If it is intended for household use it may be a liquid. For use in powder form acid salts are preferred, since their solutions combine good electrical conductivity. with moderate acidity and therefore give rapid detarnish- {1mg action without excessive generation of eat. 7

. After'numerous experiments, I have found that the following compounds give very satisfactory results in conjunction with the metallic components heretofore described. These com ounds are iven by way of illustration on y, as it will that I may use any compound having like characteristics without departing from the spirit of my invention. The preferred compounds are. as follows; citric acid, tartaric acid, benzoicacid, salicylic acid, sodium acid citrate, potassium acid citrate, sodium acid tartrate, potassium-acid tartrate and monosodium dihydrogen phosphate.

I have also found that the acid .or acid salt may be omitted entirely from the composition in order to avoid any premature reaction between the components. In this case the user can obtain the desired result by adding any appropriate acid solution to the composition at the time of use. I find that that vinegar, lemon juice, sour milk and like acidulated compositions are suitable for use. with the finely divided metals above mentioned. These acid materials are available in every household," and are of relatively low is then taken and the whole is intimatelymixed in a suitable machine such as a ball mill, or the like; To prevent any undesirable premature reaction between the components,

I carry out the grinding and mixing operations under substantially dry conditions. After such treatment, the resulting mixture be readily apparent used.

is packaged or otherwise prepared, as will be described more fully hereinafter.

If it is desired to improve the electrical conductivity of the film of liquid on the surface of the metal being cleaned es eciall where a weak acid is being used, I-a d a sa t to the above described'mixture. 'I find that practically any cheap, non-poisonous, nonhydroscopic, easily soluble neutral salt may be used. Sodiumchloride is the cheapest and most readily available, although I secure eflicient results by the use of any ofsodium citrate, sodium tartarate, or sodium sulfate. It

will be readily apparent that any salt having the desired characteristics can be made use of in the compositions which I have described. Wherean im roved polish is desired, I incorporate an a rasive in the composition.

The abrasive selected must be both soft and chemically inert. I refer touse infusorial earth or some other orm of-silica, although it is to be. understood that any suitable material may be used.

The salt and abrasive, where used, may be incorporated in the mixture during the grinding and mixing operations, or may be added after these steps have been accomplished.

compound, or any suitable chemical reagent which will react with the hydrogen sulfied as it is formed, Another method of eliminating the odor of hydrogen sulfide. is the addition of a masking perfume-such as an essential oil orithe like odoriferous' compound.

To accom lish the removal of the hydrogen sulfid incorporate with the metal-acid composition a small quantit of a substance which is adapted to react wit the gas to form an odorlesg; compound which has no deleterious eflect n the surface of themetal under treatment, I have found that the metals or.

their oxidts which form sulfides insoluble in dilute aci are effective in preventing the escape of ydrogen sulfide, and thus act as an anti-odcir. I- prefer to use copper oxide in .finely divided form, although other metals or their oxides having thedesired properties such as lead or bismuth, for instance, can be As mentiq ned above inthecas of the salt and abrasive additions to the mixture, the anti-odor may be ground up with either of the reacting components, or preliminarily ground and added-in the mixing stage.

The follpw'ing ate preferred examples of compositions which are suitable for use in the powdered form:

Zinc 33.3 Sodium acid tartrate 100.0 Copper oxide 8.4

substantially dry, powdered;

In use, the

metal, acid or mixture of an electropositive acid salt, with or without an of'the neutral salt, anti-odor or abrasive, a ove mentioned, is sprinkled on a damp cloth and applied to 5 1 the artlcle to be cleaned. The operation is very easily performed. There are no caustic alkaline materials or strong acids to corrode the hands of the user; there is no boiling up of the electrolyte; and the articles after cleaning merely require a simple rinsing in tap water to remove thereagents or they can be wiped with a damp cloth.

As noted previously, the acid or acid salt may be omitted from the composition and lemon juice, sour milk), can be used to dampen the cloth upon'which the other ingredients are. sprinkled. the fundamental electrochemical reactions being unchanged.

The powdered composition can in anysuitable manner. taken to have the package substantially ai'r' tight to prevent access of moisture .to the ingredients. For. export trade, which'are excessively damp, it maybe desirable to omit the acid. or acid salt from the composition, the user supplying such omission in the manner designated. .As examples be paekaged o of suitable forms of packages may be men- P g 1 tioned the cans used for ispensm tooth- W111110W be argum nt ha I v p cleaning powders and the hermetical. y sealed f 8 9 2"! which 5 adapted for glassine packets or envelopes. i use 1n the detarmshmg ot metals, and one c Any of the powder compositions made ac- Wi h v ate he ne s ty o 1151112 Q cording to my invention maybe incorporated p a p tu r, e The in a suitable water-soluble vehicle to form 'a D W f 9PNt10n ln d freedom from odorspaste, and the resulting product ut up in and m sslne yhlchj harap rlz s h s jars or collapsible tubes. Thevehici; or bindi QWDO OD' ompri d lf h er used for carrying the powdered ingredi- P 1 1 12 o y Yfi 15 a ents, prepared as above described, is inoor o- 'tmct advanceover the practice of the pr or in any suitable machine, or the ingredients may be wet-ground in the vehicle or binder. care bein taken to exclude moisture. As will be read y understood, the vehicle or hinder used for carrying the powdered ingredients should be a non-aqueous, non-ionizin liquid, having a minimum 0 solvent action on ,-theaci d or acid salt used, and'be readily miscible with water so-that go. it may work by dilutiontherewith, I have found that denatured alcohol and'glycerine are suitable vehicles, but I wish it to be understoodthat these are merely illustrative since other materials having the desired charac- 66 'teristics may be u rated therewith mixture to the as, starch, dextrine or any of the materials mentioned (vinegar,

Care should he or for localities Soap has been widely used as'a vehicle for carrying owdered materials which are to be used as a rasives or the like, but I find that it is not suitable for the purpose of myinvention. This is due to the fact that the use of soap leaves an infinitely thin'saponaceous film on the cleaned metal, which film exerts a deleterious effect on the metal and facilitates further tarnishing.

Where it is desired to impregnate a cloth, paper or like fibrous material with any of the compositions set forth I mix a water soluble gum, such as Karachi gum, the metal and a neutral cloth in'a machine knowntto the textile industry as a padder. The water is removed from thelfabricbyeyaporation. The acid or acid saltis dissolved in a suitable non-ionizing solvent such as denatured alco- ';hol and the resulting solution is applied to the prepared fabric. The aleohol'is removed with solvent recovery. Iuplace of the Karachi gum I may use equivalent materials, such other carbohydrate gums.

As with the powder and the paste modifications of my invention, the acid or acid salt salt with water and apply the may be omitted from the impregnating composition used in connection with the fabric, and the" latter moistened with an appropriate acidulated solution at the time of use. As already noted, vinegar. lemon juice, or sour milk are suitable for this purpose. These materials have been given by way of example only, and 'it is obvious that any suitable fruit juice or the like may be used.

The impregnated fabric can be cut to any suitable size and out up in moisture-proo art.

-Wh. l -1I ism disclosed preferred embodimen sot inn-invention. I wish it to be understood-"that these-are but preferred embodimerits which tvpifv others in which may be incorporated the underlying features 'of'this f -invention. Modifieations1 .m avbe made in the proportions of the incredients used, withof matter for cleaning agent adapted to form inodorous compounds with the. odorous reaction products.

2. A composition of matter for cleaning metal, comprising an intimate mixture of a metal. an acid salt whose aqueous solution gives an acid reaction, and a chemically reactive agent adapted to form inodorous compounds with the odorous reaction products.

3. A composition of matter for cleaning metal, comprising an intimate of a metal, an acid, a chemically reactive agent adapted to form inodorous compounds with the odorous reaction products, and an abrasive. Y 1

4. A composition of matter comprising an intimate m xture of a metal, an acid salt whose aqueous solution gives an acid reac-' tion, a'chemically reactive agent adapted to form inodorous compounds with the odorous m reaction products, and an abrasive.

5. A composition of matter comprising an intimate'mixture-of a met anacid saltwhose aqueous solutiongives ;an acid reaction, a chemically reactive agent adapted to a form inodorous compounds with the odorous reaction products and an abrasive, the whole being finely'divided and incorporated in a non-saponaceous water-soluble binder. 6. An article of manufacture, comprising an intimate and potentially reactive mixture of a metal and an acid salt whose aqueous solution gives an acid reaction bound tosilver, compris' an intimate (Potentially reactive mixture c a metal an a solid acidreactin material.

14. v composition of matter for cleaning silver, comprising an intimate (potentially reactive mixture of a metal an a solid acid, the. whole being finely divided.

i 15. A composition of matter comprising an intimate and potentially reactive mixture of magnesium and sodium hydrogen tartrate.

In testimony whereof I aflix my si ature.

" GRINNELL J O S.

gether' by a non-saponaceous water-soluble v inder and put u in paste form.

7. An article 0 manufacture, comprising an intimate mixture of a metal, an acid salt whose aqueous solution gives an acid reaction and a chemically reactive agent adapted to form inodorous compounds with the odor- 4o ous reaction products bound to ther by a non-saponaceous water-soluble put n2 in .pasteform.

8. composition of matter for cleaning metal, comprising an intimate and potentially-reactive mixture of magnesium and a crystalline acid. l

9. A composition of matter for cleaning metal, comprising an intimate and potentially reactive mixture of magnesium and an an drous acid. t

A composition of matter,'comprisin an intimate mixture ofmagnesium, an aci salt whose aqueous solution givesan acid reaction, and a chemically reactive agent I adapted to form, inodorous compounds with.

the odorous reaction products.

11. A. composition of matter, comprisin an intimate mixture of magnesium, an aci salt, and copper oxide. 12.. A metal cleaning composition comprising finely divided magnesium, having incorporated therewith a substantially dry acid salt whose aqueous solutiongives an acid reaction and copper oxide.

ea 13. A composition of matter tor clieaning mder and