title: Drip bloodstain appearance on inclined apparel fabrics: Effect of prior-laundering, fibre content and fabric structure.
abstract: The interaction of blood and fabrics is currently a 'hot topic', since the understanding and interpretation of these stains is still in its infancy. A recent simplified perpendicular impact experimental programme considering bloodstains generated on fabrics laid the foundations for understanding more complex scenarios. Blood rarely impacts apparel fabrics perpendicular; therefore a systematic study was conducted to characterise the appearance of drip stains on inclined fabrics. The final drip stain appearance for 45° and 15° impact angles on torso apparel fabrics (100% cotton plain woven, 100% polyester plain woven, a blend of polyester and cotton plain woven and 100% cotton single jersey knit) that had been laundered for six, 26 and 52 cycles prior to testing was investigated. The relationship between drop parameters (height and volume), angle and the stain characteristics (parent stain area, axis 1 and 2 and number of satellite stains) for each fabric was examined using analysis of variance. The appearance of the drip stains on these fabrics was distorted, in comparison to drip stains on hard-smooth surface. Examining the parent stain allowed for classification of stains occurring at an angle, however the same could not be said for the satellite stains produced. All of the dried stains visible on the surface of the fabric were larger than just after the impacting event, indicating within fabric spreading of blood due to capillary force (wicking). The cotton-containing fabrics spread the blood within the fabrics in all directions along the stain's circumference, while spreading within the polyester plain woven fabric occurred in only the weft (width of the fabric) and warp (length) directions. Laundering affected the formation of bloodstain on the blend plain woven fabric at both impact angles, although not all characteristics were significantly affected for the three impact conditions considered. The bloodstain characteristics varied due to the fibre content and fabric structure for both impact angles investigated. It is therefore necessary to consider the age of the fabric (which is fabric specific), the fibre type (including blends) and the fabric structure, before interpreting bloodstain patterns. An understanding of this simplified inclined drip stain interaction has been investigated to generate a basis for more complex interactions, such as spatter bloodstains.
authors.affiliation: Sir John Walsh Research Institute, University of Otago, Dunedin 9054, New Zealand; Institute of Environmental Science and Research (ESR) Ltd., P.O. Box 29-181, Christchurch 8540, New Zealand. Electronic address: tc.decastro@gmail.com.
authors.forename: Therese C
authors.initials: TC
authors.lastname: de Castro
authors.affiliation: Impact and Amour Group, Centre for Defence Engineering, Cranfield University at the Defence Academy of the United Kingdom, Shrivenham, SN6 8LA, United Kingdom.
authors.forename: Debra J
authors.initials: DJ
authors.lastname: Carr
authors.affiliation: Institute of Environmental Science and Research (ESR) Ltd., P.O. Box 29-181, Christchurch 8540, New Zealand.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Taylor
authors.affiliation: Sir John Walsh Research Institute, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Jules A
authors.initials: JA
authors.lastname: Kieser
authors.affiliation: Oral Sciences, Discipline of Periodontics, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Warwick
authors.initials: W
authors.lastname: Duncan
mesh_terms: D000818:Animals; D001801:Blood Stains; D003020:Clothing; D005554:Forensic Medicine; D007846:Laundering; D023421:Models, Animal; D055585:Physical Phenomena
keywords: Elliptical stains; Impact angles; Wetting; Wicking