Skinprint inking means
US 2723476 A
Description (OCR text may contain errors)
Nov. 15, 1955 c. B. LYON 2,723,476
SKINPRINT INKING MEANS Filed Jan. 28, 1954 FIG. I
INVENTOR. CLIFFORD B. LYON ATTORNEYS United States Patent Ofiice 2,723,476 Patented Nov. 15, 1955 SKINPRINT INKING MEANS Clifford B. Lyon, Sandusky, Ohio, assignor to Fingerprint Identification Service Co., Sandusky, Ohio, a corporation of Ohio Application January 28, 1954, SerialNo. 406,699 2 Claims. (Cl. 41-1) The present invention relates to skinprinting and more particularly to novel inking means and method for taking fingerprints, footprints, or other identifying skinprints. This application is a continuation-in-part of my co-pending application Serial No. 262,862, filed December 21, 1951, now abandoned.
Any procedure which is set up for routine accumulation of sample prints must meet the requirements of good definition. Usually sample prints are taken by employing glass plates upon which a film of ink is rolled or otherwise evenly distributed. The portion of the skin to be printed is then placed on or (to record a larger skin area) rolled across the inked plate under firm pressure to pick up the ink for printing, care being taken to avoid any smudging motion while the skin surface is being pressed on the plate. While adequate definition may be obtained by this method, the prints must be taken slowly and deliberately. To avoid smudging, cooperation or at least passivity is necessary on the part of the subject. Moreover, the procedure is awkward and slow in that it is necessary to re-distribute the ink on any portion of the glass plate surface between printing operations utilizing that portion of the surface.
Positive fingerprint identification is today essential in crime detection and is also highly important in the field of disaster relief. Despite its drawbacks, the'glass plate procedure has been widely employed for these purposes because of the importance of obtaining adequate sample print definition. The method, although cumbersome, is workable because the subjects are either adults or children of at least school age and because speed in taking the prints is not essential, although it maybe very desirable where prints of large numbers of people-are to be taken at a given time.
In recent years, a means of positive mother-infant identification has become increasingly important as the number of births occurring in hospitals rather than homes and the capacity of individual maternity hospitals has increased. Modern obstetrical practice is to confine the mother for less than half the time that she would have been confined a decade ago. This fast turnover of obstetrical cases is reflected in busy delivery rooms, crowded infant wards and multiplied opportunities for incorrect tagging of mothers and infants. Particularly under these conditions andfor purposes-of positive identification, it. is desirable to use fingerprints and footprints if well defined prints may be taken immediately after birth without special preparation and unwieldy apparatus. To have an attending nurse record on a single card, immediately after birth, her own print, the mothers print, and the infants print virtually eliminates any chance of mother-infant confusion. However, messy and unhandy roller-inked plates do not lend themselves to delivery room use. Moreover, even if glass plates are used, adequate print definition is not attained and the incidence of smudged prints is high because of the difiiculty of maintaining steady firm pressure of the squirming infants sole on the inked plate. Also, as a preliminary to taking the prints, the vernix or waxy coating on the newborn infants skin must be carefully and deliberately cleaned off. As a result, footprinting of newborn infants has been heretofore limited to souvenir purposes. Definition is no problem in prints taken merely for this purpose and, consequently, it is usually most convenient to utilize conventional fabric-surfaced wet inking pads.
I have discovered that the provision of a plate having a smooth surface and a very fine porous structure and impregnated but not covered with the proper non-drying ink will render an inking surface which will give very superior definition and with which several thousand prints may be taken consecutively. My invention gives such superior definition that not only are the lines and whorls of prints consistently distinct, but even the pattern of pore formation in each ridge is easily visible, so that a single ridge may be used for positive identification if a complete print is not available. As more fully set forth below, the inking surface I have provided is sensitive to very light skin contact which, in conjunction with the effect of body heat,
actually draws out the ink onto the ridges of the skin. Be-
cause of the light pressure required and the heat-respon-' sive drawing action, there is no tendency to flood the valleys in the skin pattern and the ink is transferred only to those skin portions actually in contact with the smooth inking plate surface.
My invention may be used with particular advantage in connection with mother-infant identification. The inking plate may be used conveniently and re-used many times to provide well defined. prints. After simply wiping the vernix from the newborn infants feet with a clean cloth, they are lightly held momentarily against the inking plate to allow ink transfer by body-heat induced capillary action. These prints, together with the mothers thumb print and the attendant nurses thumb print are then recorded together on one or more single pieces of paper. Due to the definiteness of the pattern and the absence of valley flooding, the transfer to polished paper is perfect for identification purposes and the residuum of ink left on the skin is so insignificant that is unnecessary to wash it off. The entire process requires but a few moments time and entails no preparation ,or cleaningv up. Use of my invention avoids the obliterating eifect of pronounced pressure or slipping of the skin surface on an inked pad or plate and. the print definition attained is well above the standard required for identification purposes. In fact, a skin surface may be put in contact with the plate contemplated by my invention and then the skin surface may be deliberately drawn across the plate without destroying print definition. Such a procedure in conventional skinprinting devices. and methods results in smudging and obliteration of the print for all practical purposes.
Other objects and advantages of my invention will appear from a complete reading of the specification and from the drawings inwhich:
Figure 1 is? a schematic cross-sectional view of an inking plate made according to my invention.
Figure 2 is a perspective view of the inking plate.
Figure 3 is a view of. the inking plate mounted in a suitable case.
The plate illustrated in Figures 1 and 2 comprises a permeable calcium sulfate slab 10 having extremely small ink absorbing interstices. The slab is permeated with an ink 12 in such a manner that the ink is distributed throughout the body of the slab but is not normally present on the slab surface 11, as will be more fully explained below. Previous skin inking devices have utilized wet inking surfaces which present the liquid ink directly to the skin upon initiation of skin contact. In contrast, the present invention provides a smooth, normally dry inking surface to which ink is supplied upon skin contact. In the present invention the ink is supplied only to those portions of the inking surface in actual contact with the high points or ridges of the skin.
The ink withdrawing action obtained by using a calcium sulfate pad is very fast, occurring in a fraction of a second. Moreover, the calcium sulfate slab may-be readily cast with a smooth surface by using a smooth non-sticking mold, preferably a mold made of methyl methacrylate or another of the acrylic resin thermoplastics. Other mold materials which require surface lubricants to prevent sticking are to be avoided because the surface lubricant will subsequently interfere with the withdrawing of the ink upon skin contact.
To make the plaster slab, water is added to dehydrated calcium sulfate (plaster of Paris) and the mix is poured into the mold and allowed to dry for 24 hours to form a large, fine-pored, permeable plate. Pore size may be increased or decreased by increasing or decreasing the ratio of water in the mix. The dried plate is cut to size and the individual slabs are suspended in a bath of ink so that the ink may permeate the slab from both sides. A slab one eighth of an inch thick should require about 48 hours to become totally saturated with ink, the degree of saturation being determinable by weighing. If the required time for total saturation varies widely from 48 hours, improper pore size is indicated. In such a case, the water ratio in subsequent mixes is varied until a proper pore size is indicated by an elapsed time for total saturation of approximately 48 hours.
After saturation, excess ink is removed from the plate surface by pressing an absorbent paper or other absorbent material on the surface, care should be taken during this operation to avoid any rubbing which would tend to destroy the smooth cast surface of the slab. After a few moments contact the absorbent paper is removed from the surface. The plate will thereupon dry up on the surface to present a lusterless, non-specular top plane with no suggestion of the glistening appearance of a Wet slab.
To obtain the withdrawing action, I have found it preferable to employ a liquid petrolatum base or other mineral oil base aniline dye ink of relatively high velocity. Carbon black inks should be avoided because the permeable slab will precipitate out the carbon, and the liquid withdrawn upon skin contact will have a weak color unsuitable for identification printing. Inks prepared according to the following formulations within the indicated ranges have been found to be fully satisfactory in the practice of the invention:
Certified Drug and Cosmetic Red No. 18 or Nigrosine Within the indicated ranges, the percentages are preferably chosen so that the viscosity of the resulting dye solution (ink) in seconds of flow through a number 4 Ford cup is as follows:
. Sec. Red at F Black at 82 F 29.5
In use, the surface of my inking slab remains normally dry. However, skin contact with the slab surface quickly induces a rise of ink from the slab interior to those points on the slab surface in contact with the skin. This rise apparently involves a capillary action incident to the disturbance of the surface tension equilibrium of the ink caused by the contact of warm skin. The capillary action appears to be coupled with an expressing action caused by the transfer of body heat to those portions of the ink and slab in the immediate vicinity of the contacting skin. An object at room temperature pressed on the surface of the dry-surfaced slab will pick up only a very faint film of ink through the combined effects of capillary action and mechanical pressure. However, a finger or other skin surface held in light brief contact with the slab will pick up a definite deposit of ink which, upon transfer to paper, produces a print of superior definition.
A suitable case such as that illustrated in Figure 3 may be provided to house my inking slab. To minimize the possibility of damage to the slab, the base 13 of the case may be constructed to snugly fit the slab and to closely conform to the bottom surface of the slab in order to obtain uniform support. The interior dimensions of the lid 14 may also be as closely tailored as practicable to the upper portion of the slab, with only a very slight spacing between the lid 14 and the surface 11 in the closed position.
Any polished oil absorbent paper is satisfactory for receiving prints taken on my inking slab. A high chrome coat paper has been found to be particularly satisfactory.
From the above disclosure, it will be apparent that many modifications in the disclosed specific embodiment of my invention will suggest themselves. In particular, various inks may be employed. Accordingly, the scope of my invention is to be defined solely by the following claims.
What is claimed is:
1. A skinprinting device comprising a porous slab of calcium sulfate dihydrate, a liquid petrolatum base aniline dye ink interstitially dispersed throughout said slab, the relationship between the porosity of the slab and the viscosity of the ink being such as to cause a large face of said slab to present a smooth normally non-glistening surface of dry appearance.
2. A skinprinting device comprising a porous slab of calcium sulfate dihydrate, a mineral oil base ink interstitially dispersed throughout said slab, the relationship between the porosity of the slab and the viscosity of the ink being such as to cause a large face of said slab to present a smooth normally non-glistening surface of dry appearance.
References Cited in the file of this patent UNITED STATES PATENTS 1,241,322 Woody Sept. 25, 1917 2,041,740 Beckman May 26, 1936 2,353,877 Chollar July 18, 1944