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- 2. How to measure water vapor transmission rate ? (WVTR)
- We recommend the method based on ASTM F 1249-90 that uses MOCON equipment. Otherwise bag method, which applies water absorbent of CaCl2 inside the bag that is made out of TECHBARRIER
 , is available, too. General method for WVTR measuring "Cup method", however, is NOT recommendable due to the big mistakes.
| Notes: |
| a) |
Sample piece: must not have any scratched defect or folded part. |
| b) |
Pre-conditioning is essential to obtain reliable data. 170 hour-pre-conditioning is recommendable for 40 , 90%RH actual measuring condition. |
| c) |
Sample piece: should be fixed in a cell as the following figure then stored in a climate chamber that is conditioned 40, 90%RH. |
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| d) |
Bag Method: need approximately 170 hour-pre-conditioning before the actual measurement. |
| e) |
Bag Method: needs weight measuring of bags every 1 or 2 days after pre-conditioning. WVTR can be obtained by the data of transition. |
| f) |
Face direction:
TECHBARRIER-S is especially sensitive against its SiOx surface direction as a laminated film. In case of dry contents, fixing should be as well as the following figure. |
| g) |
Example of making bag. |
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