US2082735A - Finger printing method - Google Patents

Description

Patented June 1, 1937 t UNITED STATES PATENT OFFICE FINGER PRINTING METHOD William Heinecke, New York, N. Y., assignor, by mesne assignments, to William N. Dykman, New York, N. Y.

N Drawing. Application May 3, 1934, Serial No. 723,706

3 Claims. (CI. 41-41) This invention relates to finger printing, and. basic acid. The sodium vanadate is alkaline and it comprises a method of obtaining a finger print this acid also serves to neutralize its alkalinity. wherein the finger is moistened with an oxidant It will be noted that instead of smearing the solution and impressed on paper carrying trihyfinger with ink and then transferring the ink to 5 droxybenzoic acid (gallic acid) or another polypaper by pressure, I produce color from colorless 5 phenolic body, thereby producing a colored print, ma erials at he m f impression pe and it further comprises an assemblage of a pad I p d the ink in p I produce it in carrying an alkaline solution of a vanadate, or ing the Print AS a matter of feet e tW reanother like oxidant and a stock of paper sheets agents mentioned, Vanadete and game acid,

carrying trihydroxybenzoic acid, or another polywhen admixed in solution produce an ink. 10 phenol, all as more fully hereinafter set forth and The P p may be Coated With a Sort 0f as claimed. quer containing the trihydroxybenzoic acid, the

Finger prints are usually made with i k or acid being dissolved in a lacquer-like coating carbon black preparations, the carbon being often Composition A SOhltiOh 0f 0011061011 Cotton in in a greasy or oily vehicle, omethin lik i t ethyl acetate or another volatile solvent of the 15 ink. All these methods are open to the objecalcoholic Class. SeTVeS- After application to P p tion of soiling the fingers, of being more or less the Solvent evaporates leaving a coating of D3- uncleanly and of demanding to h ki11 roxylin containing the trihydroxybenzoic acid. A With a smeary ink it is not easy toobtain with 8 d Beating composition is a 4 P cent Solution certainty unblurred sharp prints. Much depends of trihydrexybenzoic d in ethyl a ate with 20 on the finger pressure, or, rather, the correlation an addition 0f 4 D Cent e 'l COttOIl- About between the pressure and the character of the 2 D Cent tartaric acid y be added s a eink. Further, it is important that the prints be bilizer- This composition y be app d t p p fairly uniform in appearance as this facilitates y Ordinary methods. Spraying, brushing, 8

comparison. Sharpness of outline is, however, Beating, 0 instead of using a lacquer the the fundamental requisite; the characteristic p p a be s d w an ary aqu us ridges of the finger surface must stand out clearly u -pi t composition nta tri ydroxyagainst the background. And, a st t d, skill i benzoic acid. As casein coating compositions are required to attain this. alkaline, they are not suitable. A composition of I have discovered a way in which I can produce 2 parts glue. 3 parts y, parts wate 1 part 39 finger prints of greater uniformity of appearance, trihydrOXybenZOic acid and p tartaric d more certainty of outline and capable of easier is Suitable- This Composition y b app t study without the disadvantage of personal inp p y Ordinary Teller Coating means d e convenience or the necessity of any great skill paper afterwards dried.

on the part of the operator. In this method I While I have p fi y S at d trihydroxy produce a print by simple contact of a moistened ZOiC acid gallic acid as used in the present finger t a sensitized urface and t degree of invention and while it possesses distinct advanpressure is no longer an important factor. I use teges Over Other m s, y the P y- & two-liquid process wher in th finger is moishydroxy benzene or naphthalene derivatives, that 40 toned with an oxidant solution, usually a solution i p s/ strike e @0101" With Sodium vehe- 40 of sodium vanadate i glycerin or gylcerin date solution and similar oxidants and may be ethylene glycol and triethanolamine, contained used in this invention {among these applicable in a stamp pad and is then impressed on paper polyphenols: I may Tnentmn: carryingtrihydroxybenzoic acid (gallic acid). P

A colored print is formed at the expense of the 3'4'5tnhydroxy benzmc acld 3-4-5-trihydroxy benzoic ethyl ester vanadate and the trlhydroxybenzolc acid. ThlS color developmentis due to contact and no ex- 3-4 d1hydloxybenzo1c acld (protocatechmc act pressure is required. This gives greater unifig m benzene (pyrocatechmol) formlty of appearance as between successive lrnl methyl 3 5 dihydroxy benzene (01.011101) prints and renders their comparison easier. Trl- 1 2 3 trihydmxy benzene (pyrogallol or hydroxybenzoic acid, being somewhat unstable m acid) when exposed to the atmosphere in the absence 1-3-5-trihydroxy benzene (phloroglucinol) of added free acid, I ordinarily acidulate it with l-3-4-trihydroxy benzene (hydroxy hydroa small amount of tartaric acid or another diquinol) 55 Tannic acids and gallo-tannic acids, that is, tannins which are usually considered to be anhydrides of hydroxybenzoic acids can be used.

In lieu of the tartaric acid for stabilizing the polyphenols, I may use other organic acids. For instance, I may use the following acids: oxalic, malonic, succinic, monomethyl succinic (pyrotartaric acid), dimethyl succinic, glutaric, adipic, suberic, maleic and fumaric. I find that the dibasic acids which contain hydroxyl groups have certain advantages. this class. Also maleic acid (monohydroxy succinic acid) and mesoxalic acid (dihydroXy succinic acid) may be used. I may alsousearomatic carboxylic acids such as phthalic acids.

I find that, on the whole, vanadates give me better colorations with the polyphenols than do other oxidants. Sodium orthovanadate is the most convenient salt. Ammonium vanadate is not very soluble and calcium, etc., vanadates are notcommercially easily obtainable. Sodium orthovanadate dissolved in ordinary commercial glycerin or/and diethylene glycol solution is capable ofdirect application to a stamp pad, and sucha. stamp pad .is used for moistening the finger. A solution of 10. parts commercial sodium vanadate in parts of commercial glycerin is suitable. More suitable still, is an addition of diethylene-glycol-and triethanolamine to this solution. The. purpose of diethylene-glycol as a solvent of nitrocellulose is to cut through the pyroxylin coating, and accelerate the desired reaction.

Whilethe printing method may be used in reverse manner with the oxidantin or on the paper andthe trihydroxybenzoic. acid in the pad, it is not so convenient.

As stated, otherv oxidants may be employed. Among these are thechromates. Sodium chromates used, in the same way as sodium vanadate also. gives colorandagood print. The polyphenolsalso strike a color with ferric chlorid and ferricchlorid may be used. In solution in glycerinon astamp' pad, however, ferric chlorid is not. indefinitely permanent. However, it may be.used and in thisevent, such natural polyphenols astannic. acid may be employed. Paper may be. surfaced orimpregnated with a composition containing extract of gall nuts and a stamp padilsed containing ferric chlorid. In this event, the imprint finally developed is an iron ink of great permanence.

It will be. notedthat in the described method two colorless solutions are used. The moistened finger is not colored nor'does it become colored in making thev fingerprint. Coloration is confined tothe paper. The finger does not become smeared, colored. or stained.

While I-have described the use of paper for the surface to receive the finger print record, othermaterials maybe used. Anodically oxidized thin sheet aluminum or foil is covered with a porous, hard surface which takes up trihydrcxybenzoic acid, etc., and is suitable for taking a finger print. The coating has considerablestiifness and extremely/thin cards may be made using thin foilaluminum; The coating being somewhat acid in its nature, is well adapted to receive trihydroxybenzoic. acid, no added acid stabilizer being then necessary.

Tartaric acid is typical of While I have mentioned finger prints, I wish it to be understood, that by this term I include similar record prints of other portions of the body: thumb prints, palm prints, foot prints, heel prints, etc.

In the operation described specifically I use two colorless substances developing a colored material on contact, this colored material being formed at the expense of the trihydroxybenzoic acid (gallic acid). Other pairs of substances developing colored material of high tinctorial power may however be used. In all cases, one substance is used on the paper and another on the finger, the two on contact developing a colored material of high tinctorial power, the color depending on the particular pair of substances. As such pairs of materials I may use:

Aescioxalic acid 071 1604 de- In the present state of my-knowledge, however, I regard the. pair particularly described, gallic acid and sodium vanadate, as the most generally useful. They producea finger-print of about the right darkness and. of permanent character, neither darkening or lightening in the files. Sometimes, however, the other substances mentioned may be advantageously employed for special reasons.

The present application is a continuation: in

part of myprior application Serial No. 625,198

filedzJuly 27, 1932.

What I claim is:

1. The method of producing finger or likeprints, comprising contacting the finger, or the like, with a surface of an absorbent material impregnated with a, solution of sodium vanadate dissolved in glycerine-diethyleneglycol solution, and then contacting the finger, or the like, with a surface carrying a coating containing trihydroxy benzoicacid,tartaric acid and a thickening agent, the resulting print being a black print.

2. The method as specified in claim 1, in which said first mentioned surface is a stampv pad and said second surface a sheet of paper.

3. The method. of, producing finger or like prints, comprisingzcontacting. the finger, or the like, witha surface of. an absorbent material, impregnated. with a solution of sodium orthovanadate. dissolved in glycerine-diethylene glycol solution, andthencontacting the finger, or the like, with a. surface carrying a coating containing: trihydroxy benzoic acid, astabilizingagent, and 'a'thickening agent, the resulting print being a black-printi WILLIAM HEINECKE;