Gloves and Friction Ridge Skin

[rwh0406]

I am investigating a homicide case in which the victim was bound with construction marking tape, similar to duct tape but with an extremely aggressive glue. There are cotton fibers and a red polymer material on the tape. These findings are consistent with known samples from other work cotton work gloves that have a red polymer hot dipped on the palm side, presumably to increase the ability to grip. The tape was processed with CA/Ardrox. A pattern area developed on the sticky side of the tape that I first thought was friction ridge skin because it included a delta region. After some though and some discussions with my colleagues, I am uncertain. The ridge flow doesn't "feel" right. There is a repetitive sequence in the level 2 details that is not natural.

?????Has anyone ever seen a cotton work glove with a red polymer palm with a man made pattern on the surface that is intended to imitate friction ridge skin.?????

RWH
Connecticut

[Charles Parker]

Do you have a photo?

RWH----I brought up an old post. Does your ridge structure look anythng like the photos in the thread titled "Schallamach Waves"!

[Ernie Hamm]

You could also look at comments and excellent illustrations under the CLPEX thread "Extrusion or Sprue Marks". The type of glove covering you are describing could be in the elastomeric material range and this substance/material can be influenced by forces during the manufacturing process which can result in the formation of surface stress pattern waves/ridges. These are different than Schallamach waves, which are transient in nature as the material is subjected to additional friction abrasion forces.

[rwh0406]

I was able to view some photos of Schallamach waves. These were helpful but did not totally resolve my questions. The pattern area I am looking at is very small -.75x.50. It was removed from a larger clump of tape and the there are indications that it was stretched and had been folded; causing some of the pattern to be a mirror image of the area adjacent to it. The ridges, if that is what they are, have no third level detail. Throughout the pattern there is repetition of the level 2 detail. (bifurcation, ending ridge, bifurcation, ending ridge) This does not look or feel right.
Cotton fibers and red polymer were found on the tape, which would suggest the suspect wore gloves. The tape was extremely sticky and very difficult to handle. Based upon all this, it is my gut feeling that this is some type of pattern produced by contact with a glove. Now all I have to do is prove it.

[Charles Parker]

rwh-----Ernie might be right (he ususally is) and they may be this other form of waves or ridges. I have brought it up to the top because of the images that it contains.

Take a look and see if these are closer to what you are observing.