CLPEX Chat Board

Schallamach Waves

A few months ago Alphabrit posted a photo taken of black electrical tape and Ernie Hamm suggested it might be Schallamach Waves.

About 6 weeks after that posting the lab personnel wanted me to look at something strange. He had a lot of black electrical tape that had been wrapped around bundles of narcotics. These bundles had been wet and had been drying when he removed the tape in attempt to recover friction ridge detail.

Over several feet of this black electrical tape were areas with the following wave like forms. Several of these were photographed and are pictured below. These wave like forms were all visible and at the time these photographs were taken they had not been processed with any physical or chemical means.

I believe these to be some form of Schallamach Waves. Would be interested in any others who might have some knowledge, experience, or photos of the same phenomena who would like to share knowledge, experiences of same.

Sorry Charles,

this doesn't look like a Schallamach pattern at all. Schallamach is wear of rubber objects caused by repeated strain of the rubber itself. It's finer in detail than the patterns on your photographs and it generally goes in one direction.

All the best,

Gerrit

Gerrit, you are correct in that most Schllamach Waves on rubber soles or tires are straight. In what I have read about them (and I have not read a lot by the way), it seems that those who deal with such materials are not sure about how they are formed exactly. One source talks about air flow and we have seen how the wind makes wave forms in the sand or water in the sand on a beach.

http://meetings.aps.org/Meeting/MAR07/Event/58743

I think something of this nature might have occurred here. The material is very soft and pliable and if stretched over the bags and then wetted the adhesive starts to give and any trapped air might create the loss of the adhesion to permit this type of wave form.

Here are some other sources about Schllamach Waves.
http://scitation.aip.org/getabs/servlet ... s&gifs=yes

http://books.google.com/books?id=BOSCzG ... t#PPA50,M1

But the bottom line for me is not the name----we could name them Anomalous Wave Forms (AWF) or even Anomalous Ridge Forms (ARF---here doggy doggy). My main quest is this.

Are these true friction ridge details or are they something different (not made by friction ridge skin)?

If they are true friction ridge detail then no name is necessary.

If they are not true friction ridge detail are they a common occurrence or is this case the only documented one so far?

If they are not true friction ridge detail have other LPE mistaken them for friction ridge detail and have attempted to identify them to suspect of which they do not match and perhaps have provided an incorrect conclusion?

Have you seen this kind of thing before? Has anyone seen this kind of thing before?

Of course we can always debate the name of them, if they have occurred before!

Charles,

During my short stint in Afganistan looking at a lot of tape, I do mean a lot, some of it electrical tape (either red or black) I too saw much of the same waves. There was some discussion about it among some of those with not so much time in prints; however, the bottom line was still that these were waves of some nature and not anything formed by friction ridges. Whenever I have seen friction ridge detail on electrical tape, the difference is easily seen. So obviously this is not an isolated event. And yes, I agree, too, that it has to do with the stretching of the tape. Personally, I find it very interesting. I hope all is well with you.

Danny Lamont
Toney, AL

Brought this up to the top.

Hey Danny, I am doing fine----How are you????