Follow us on Twitter Follow us on LinkedIn Like us on Facebook Follow us on Instagram Visit the TPC Store
Search the site




Problem Solving Forum

| More

February 13 - February 17, 2017

Why would a pull-off adhesion test give a high value (no failure) for a solventless epoxy that later showed poor adhesion in service?

More items for Quality Control

Selected Answers

Because the test sample was prepared according to manufacturer's recommendation and in certain environmental conditions as required. The test sample has a small area to apply and monitor epoxy application; but on the job, the applicator may not have met the required environmental conditions, improperly mixed material, and added  thinner to make easy application or evenness in appearance, any of which may may have caused poor adhesion in service.

From simon daly of Hempel A/S on February 14, 2017:
The answers relating to application issues are, of course, very valid; however, there are other fundamentals to consider even if application is applied in approximately the same way as when the high values were achieved. Water absorption and subsequent permeation to the substrate may result in deterioration of some types of adhesive bonds to the substrate, reducing adhesion and ultimately (but not always) the development of blistering. The question does not state where the adhesion is subsequently reduced, whether to the substrate of inter layer; however, the presence of weak intercoat layers (such as those caused by amine bloom) may not necessarily reveal adhesive failure initially but when solubilized by water in the film may show dramatically reduced adhesion. The period of time over which this occurs may be influenced by a number of factors, temperature and thermo-osmosis (the so called "cold-wall" effect) being just two.

From Steve Brunner of WPC Technologies on February 13, 2017:
Often, the high value was done in the lab under ideal conditions and proper mix ratio. Poor adhesion in service can have many variables, including improper mix ratios; coating applied too thick; poor surface preparation; and,  if using heated equipment, the setting was too hot. The best way to obtain adhesion in service similar to that seen in with the test is to read and the manufacturer's application guides.

Please sign in to submit your answer this question    

Tagged categories: Adhesion; Epoxy; Quality control; Testing + Evaluation

Current PSF Question | Submit a PSF Question | Full PSF Archive

KTA-Tator, Inc. - Corporate Office
• Coating failure analysis
• Independent testing
• Accelerated weathering testing
• Abrasives Testing
• Oil & Gas Material Qualification
• A2LA Certificate #2455.01
Contact: Rob Leggat
at 412-788-1300 x176

Fischer Technology Inc.
Highly Repeatable Ultrasonic Wall Thickness Gauge
Detect corrosion by monitoring wall thickness with the compact UMP series from Fischer.

DeFelsko Corporation
PosiTector SST Soluble Salt Tester
Measures the concentration of soluble salts on metal surfaces. Use with all Bresle patch types including the reusable, adhesive-free PosiPatch.

HoldTight Solutions Inc.
Our HoldTight®102 salt remover & flash rust
preventer prevents flash
rust by removing surface contaminants. Contact us
for your nearest distributor.
(800) 319.8802

Mitsubishi Gas Chemical America
Performance Amine 1,3-BAC
A highly reactive cycloaliphatic diamine offering superior performance. Reasonable cost and curing efficacy makes it suitable for all types of epoxy resin applications.

Novatek Corporation
Novatek Corporation, Dustless Coatings Removal
Strip, clean and profile all dust free! Comply with new lead standards. Contact today: (866) 563-7800

Safway Services
Safeguard Assets. Ensure Productivity. HAKI®
Protect assets and equipment. Keep facilities open and operational. Maintain schedules regardless of weather. Ensure smooth and continuous production. Easy to erect. Safway is the primary distributor of HAKI® products including HAKISPAN and HAKITEC® 750 – in North America.

Modern Safety Techniques
Modern Safety Techniques
With our unique LTCat, we can help to provide clean, safe breathing air to your workers. Take a look at our Breathing Air Systems, we supply at least twice as much charcoal as our competitors! Modern

SAFE Systems, Inc.
Portable Blast &
Recovery Equipment
Trailer or skid mounted blast and recovery equipment. Systems designed for maximum versatility, environmental compliance
and overall cost savings.
Call 1-800-634-7278

Axxiom Manufacturing
Schmidt Introduces
the New miniBRS
Reduced in size, it is incredibly easy to maneuver and operate! The perfect alternative to larger blast & recovery units when project space is limited.
Call 1-800-231-2085


Technology Publishing Co., 1501 Reedsdale Street, Suite 2008, Pittsburgh, PA 15233

TEL 1-412-431-8300  • FAX  1-412-431-5428  •  EMAIL

The Technology Publishing Network

Durability + Design PaintSquare the Journal of Protective Coatings & Linings Paint BidTracker

EXPLORE:      JPCL   |   PaintSquare News   |   Interact   |   Buying Guides   |   Webinars   |   Resources   |   Classifieds
REGISTER AND SUBSCRIBE:      Free PaintSquare Registration   |   Subscribe to JPCL   |   Subscribe to PaintSquare News
MORE:      About   |   Privacy policy   |   Terms & conditions   |   Site Map   |   Search   |   Contact Us