River Marks

River marks may be visible on the fracture edge. A magnifying lens may be used to locate these markings. The pattern shown in the inset illustrates the river markings 'pointing' toward the fracture origin.

Use a permanent marker to place arrows on the part where the river markings indicate origin direction. Follow the river markings through each crack as they may change direction at crack intersections.

After viewing all river markings and labeling them with arrows, search the area they indicate as the initial fracture site. Look for suspect areas. Once a possible initial fracture site has been located wallner lines may be observed. These lines are not always visible, but can increase the likelihood of locating the initial fracture site if found.

If an initial fracture site and the suspect area that is believed responsible for the initial failure, have been located then you should consider modifying the design.

If the checklist has been followed and the initial fracture site has not been located, then you should contact an Eastman representative in your area for assistance.