Unlike laboratory adhesion tests which use standardized test panels, on-site pull-off testing directly measures the adhesion strength of tiles that have already been installed on your actual project. This makes it the most direct measure of real-world performance available.
How the Test Works
A dolly (metal disc) is bonded to the surface of the installed tile using a high-strength two-component adhesive. After curing, a calibrated pull-off instrument applies a controlled tensile force perpendicular to the tile surface, increasing at a defined rate until failure occurs. The instrument records the peak force at failure and the failure mode.
Failure Modes and What They Mean
- Adhesive failure at tile–adhesive interface: The adhesive did not bond adequately to the back of the tile. Indicates incorrect open time management or low-porosity tile without back-buttering.
- Cohesive failure within adhesive: The adhesive itself split. Indicates either low-strength adhesive or degradation by moisture or thermal cycling.
- Adhesive failure at adhesive–substrate interface: Poor adhesion to the substrate. Often caused by surface contamination, high moisture, or inadequate priming.
- Substrate failure: The substrate material (screed, plaster, concrete) fails before the adhesive. This is typically acceptable if the adhesive bond is stronger than the substrate, but indicates a weak substrate that should be investigated.
When to Commission On-Site Pull-Off Testing
- During quality inspections of large tile installation contracts
- Where tile debonding has been reported to identify the failure mode and responsible party
- As part of a final quality acceptance protocol on high-value commercial projects
- For contractors seeking to demonstrate product performance to clients
Zybuild Quality Hub provides on-site pull-off testing across Hyderabad with same-day preliminary results and a full signed report within 2–3 business days.