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KTA-TATOR, INC.
Corporate Headquarters
115 Technology Drive
Pittsburgh, PA 15275
Phone: 412.788.1300
Fax: 412.788.1306
E-mail: info@kta.com

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1-800-KTA-GAGE
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The KTA Challenge #16
What Caused This Failure?
Win a $500 KTA gift certificate redeemable
for KTA products or services


Photograph #1	Photograph #2

Problem: A moisture cure urethane ((MCU) primer and finish coat were applied to an existing steel roof. Wholesale disbonding between the new coats of MCU occurred within one year.

Background and clues:

Failure involves a two-coat MCU system applied in the field.
The specification required pressure washing and the application of an MCU primer (aromatic) and MCU finish (aliphatic). Application was to be in accordance with the coating manufacturers' instructions.
Both coats were applied by spray.
The work was done in July and August. The finish was applied within two to three weeks after the application of the primer. The surface of the primer was blown down with clean, dry, compressed air prior to the application of the finish.
Wholesale peeling of the MCU finish from the primer was observed the following spring.
The field investigation revealed:
1. The MCU primer was well adherent to the original coating and to any areas of bare steel that had been present.
2. The thickness of both coats was within the manufacturer's recommendations.
3. Pinholes were visible in both coats of MCU across the entire roof.
4. The adhesion between coats was poor, even in areas where the finish coat had not yet spontaneously disbonded and appeared to be intact.
5. Fine white deposits were visible on the backside of disbonded chips.

Click here to e-mail us and tell us why you think the coating failed. Send your answer to us before 5pm EST on Wednesday, May 14, 2008. Don't forget to include your name and phone number. The winner will be selected at random from all of those who provide the correct answer. The answer and winner will be posted on the web site Thursday, May 15, 2008.

A new challenge will be posted the beginning of each month.

*The $500.00 gift certificate is redeemable for any KTA product or service.