TAPPI TIP 0304-69
Understanding wet strength: what are MRA, WRA, and WPA?
| Organization: | TAPPI |
| Publication Date: | 1 January 2011 |
| Status: | active |
| Page Count: | 3 |
scope:
To determine the "wet strength" needs of a corrugated box plant, one must first define the level of "wet strength" needed. Generally, the industry has accepted three levels of "wet strength" adhesive.
1. Moisture Resistant (MRA) - used for the lightest possible applications.
2. Water Resistant (WRA) - medium level of performance.
3. Waterproof (WPA) - highest level of performance.
This Technical Information Paper will identify the key characteristics of each type of "wet strength" adhesive and when it would be used. Proper test methods to determine the level of water resistance of a particular box wil be discussed.
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