US1949781A - Tarnishproof cloth - Google Patents

Description

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March 6, 1934. A. D. CHAMPLIN 1,949,781

TARNISHPROOF CLOTH Filed March 8, 1933 2l. PiiizSERViNG, DISINFECTIMG ND'SlEHiLIZiiG.

l. GECIILC Viana U, vu-x UNITED STATES PATENT FFICE 4 Claims.

My invention relates to improvements in tarnish proof cloth. It is well known that silver Ware will tarnish on exposure to the ordinary atmosphere even if wrapped with the standard type of paper or fabric. This tarnishing is due to sulphur in some form present in the air, often to free sulphur, but more often to free hydrogen sulphide which becomes volatilized from the sulphur, or often in a lesser degree sulphur dioxide or other sulphur compounds. I am aware that others have impregnated fabrics with substances such as silver oxide, lead acetate, etc. in which it is claimed that the sulphur has a greater ainity for the base of the salt, or metal with which the cloth has been impregnated than it has for the silver underneath. All these salts of which I am aware, however, make when acted upon by the sulphur or its compounds an insoluble sulphide impregnated in the cloth. These insoluble sulphides are of all sorts of colors, such as being black for silver and lead, white for zinc, etc. Sulphides when formed in use aiect the pure white of the fabric, o-r any shade it may be dyed, in factI where silver oxide is used it is only possij ble to obtain a dark brown.

An object of my invention is to irnpregnate the wrapping fabric with a solution of soluble substances which will not form the sulphide, but will transfer the sulphur or its compound into a soluble colorless medium in the fabricwithout tarnishing the silver.

These and such other objects of my invention as may hereinafter appear will be best understood from a description of an embodiment thereof, such as is shown in the accompanying draw- 111g.

'I'he drawing is a perspective View of a piece of silver wrapping fabric constructed in accordance with my invention and impregnated with the desired solution.

While any type of fabric, paper, textile, or otherwise, may be employed for wrapping the silver I preferably employ a so called naped or pile, textile fibre woven fabric, as I find this more readily absorbs the desired amount of solution. I then suitably impregnate this fabric, so that the desired reagents are absorbed in the fabric by passing it through a padding machine, spraying it on, soaking it in, or in any of the other ways well known to the trade. In order to absorb the sulphur I preferably employ a salt formed of a base having a greater afnity for free sulphur than the silver but incapable of forming a permanent sulphide therewith. While any salt of this general description may be employed, I preferably employ aluminum sulphate. When this is attacked by sulphur or hydrogen of sulphide, it immediately tends to temporarily form aluminum sulphide. I also impregnate the fabric with an excess of an oxygen container reagent, preferably one formed of an alkaline base, such as borax and I also impregnate the fabric with a deliquescent salt, such as sodium sulphate. A fifteen per cent solution of aluminum sulphate, borax and sodium sulphate is mixed up for impregnation on the goods and preferably containing an excess of borax and sodium sulphate. While any other type of an oxygen container agent may be used, I preferably employ borax and while any salt of an alkaline deliquescent salt may be employed I have achieved best results by employing sodium sulphate. The reaction between the base having a greater affinity for free sulphur than the silver and the borax appears to be as follows:

It is known that while this reaction tends to form aluminum sulphide it will not be fo-rmed, but that the aluminum sulphide will immediately be broken down by the excess of water present into aluminum hydroxide and hydrogen sulphite as follows:

It is also known that aluminum hydrate is soluble in boric acid and the boric acid in the solution will immediately dissolve the aluminum hydrate therein. Whatever sulphur is therefore present will be created into hydrogen sulphide and this and any additional hydrogen sulphide in the air will be absorbed by the borax, namely, the oxidizing agent and the sodium sulphate in the following manner:

NA2B407 -I-HzS -l- 5H2O :NAzS -l-HaBOs thereby immediately forming soluble sodium sulphide which of itself is readily dissolved in the solution which the deliquescent salt keeps in the fabric. The alkaline deliquescent salt also functions of itself to dissolve any free I-IzS as follows:

the H2SO4 being immediately dissolved by the excess of alkaline salt present so as not to weaken the fabric. The deliquescent salt also functions to capture and entrain any free SO2 or other types of sulphur oxide or free sulphur salt present. It is apparent therefore that I get rid of the sulphur or its compounds in the air in an entirely different manner than anyone hitherto by providing a deliquescent solution in the fabric which will function instead of forming an insoluble colored sulphide to form a soluble colorless sulphur salt which becomes readily absorbed and dissolved in the excess of alkaline salt and deliquescent salt solution at all times present in the fabric. It is obvious that in employing this solution that the soluble sulphur salt will not in any way affect the silver in use, but will prevent the tarnishing and will not in any manner affect the color of any dyestuff or white finish put on the fabric. It is apparent therefore that I have provided a novel type of tarnish proof fabric which will actually prevent the formation of the tarnishing silver sulphide, at the same time permitting the cloth to be bleached or dyed in any desired shade.

It is alsoapparent that the deliquescent salt will keep the solution moist and hydroscopic so that the solution is always active in the cloth and will not dry up, fall out or evaporate.

It is understood that my invention is not limited to the specific embodiment described and that various deviations may be made therefrom without departing from the spirit and scope of the appended claims.

What I claim is:

1. A fabric for protecting silverware from tarnish comprising a material suitable for wrapping impregnated with a solution of a salt formed of a base having a greater affinity for free sulphur or its compounds than the silver but incapable of forming apermanent insoluble sulphide therewith and an excess of sodium sulphate.

2. A fabric for protecting silverware from tarnish comprising a material suitable for wrapping, impregnated with a solution of a salt formed of a base having a greater affinity for free sulphur or its compounds than the silver but incapable of forming a permanent insoluble sulphide therewith and sodium sulphate.

3. A fabric for protecting silverware from tarnish, comprising a material suitable for Wrapping, impregnated with aluminum sulphate and an excess of borax and sodiumjl'plat 4. A fabric for proteting'silverware from tarnish comprising a material suitable for wrapping, impregnated with aluminum sulphate, borax and sodium sulphate. Y

1 ARTHUR D. CHAMPLIN.

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