How to Measure Adhesion 8:50
Measuring Coating Adhesion to Metals, Concrete, and more with the PosiTest AT from DeFelsko- the Measure of Quality.
The PosiTest AT-M is a rugged, mechanical pull-off adhesion tester designed for reliable, accurate measurements of coating bond strength. Compact and field-ready, it delivers consistent results without reliance on electronics or batteries, making it a dependable choice for inspectors working in challenging environments.
By applying hydraulic pressure manually, the PoiTest AT-M gives operators full control while maintaining compliance with international standards. It’s an ideal solution for contractors, inspectors, and quality assurance professionals who need a cost-effective, durable, and trustworthy tool for routine adhesion testing.
Supplied exclusively in the UK by DFT Instruments, and supported by our DeFelsko Authorised Service Centre (DASC), every AT-M comes fully calibrated, certified, and backed by expert UK support and fast local service.
PosiTest AT-M Features
- Manual hydraulic pump designed to apply smooth and continuous pressure with a single stroke
- Pull Rate Indicator to manually monitor and adjust the rate of pull
- Internal memory stores maximum pull-off pressure, rate of pull, test duration and dolly size for up to 200 pulls
- Compatible with PosiSoft Desktop for viewing, printing and storing measurement data
Why Testing Matters
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Verify Coating Performance – Adhesion strength is essential for long-term protection and durability.
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Identify Application Issues – Detect weak bonding caused by poor surface prep, primers, or environmental conditions.
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Compliance with Standards – Meets requirements of ISO 4624 and ASTM D4541 for pull-off testing.
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Support Quality Assurance – Generate documented evidence of coating adhesion for audits and contracts.
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Reduce Risk of Failures – Spot problems before coatings fail in service, saving money and reputation.
Why Choose DFT?
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Official UK Distributor – Genuine DeFelsko instruments, supplied with full traceability.
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Authorised UK Service Centre (DASC) – Local calibration and repair, no need to ship overseas.
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Certified Accuracy – Supplied with a calibration certificate traceable to UKAS/NIST standards.
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Fast Turnaround – Most recalibrations and repairs completed in one working day.
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Technical Guidance – Our team provides practical advice on best testing practices and probe selection.
Helpful PosiTest Adhesion Testing Videos
PosiTest AT Self-Alignment Feature 2:50
A helpful video showing the self-alignment feature. Both the PosiTest AT-M Manual and PosiTest AT-A Automatic models compensate for misalignment.
Manual Adhesion Tester 9:29
Instructional video for the PosiTest AT-M Manual Adhesion Tester
Features & Benefits
Easy Operation
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Manual hydraulic pump applies smooth, even pressure.
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Clear pull-rate indicator helps operators maintain uniform testing speed.
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Simple control and lightweight design make it highly portable for site work.
Built for the Field
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IP65-rated enclosure for dust, water, and weather resistance.
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Rugged construction for dependable use in harsh conditions.
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Supplied in a protective hard-shell carrying case.
Reliable Accuracy
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Calibrated and certified to ±1% accuracy with NIST traceable load cell.
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Self-aligning aluminium dollies ensure accurate measurements on smooth or uneven surfaces.
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Complies with ISO and ASTM adhesion testing standards.
Flexible Testing Options
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Compatible with multiple dolly sizes (10, 14, 20, and 50 mm).
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Versatile enough for coatings on metals, concrete, wood, and plastics.
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Records maximum pull-off pressure, dolly size, pull rate, and test duration.
Practical Data Management
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Internal memory stores up to 200 results for later review.
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Data can be transferred to PC via USB and managed with PosiSoft software.
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Results include fracture type classification for quality documentation.
Models
| Specification | ATM20 | ATM50 | ATM50T (EN 12004-2) | ATM50C (ASTM C1583 / EN 1542) |
|---|---|---|---|---|
| Dolly Size & Stand-Off | 20 mm | 50 mm | 50 × 50 mm Plate | 50 mm |
| Typical Applications | Higher bond-strength coatings on metals | Lower bond-strength coatings on wood, concrete, and plastic | Cementitious adhesives for tiles | Concrete surfaces and overlays |
| Range | 0.7 – 20 MPa 100 – 3000 psi |
0.1 – 3.3 MPa 16 – 480 psi |
0.1 – 2.585 MPa 13 – 375 psi |
0.1 – 3.3 MPa 16 – 480 psi |
| Resolution | 0.01 MPa (1 psi) | 0.01 MPa (1 psi) | 0.01 MPa (1 psi) | 0.01 MPa (1 psi) |
| Accuracy | ±1% Full Scale | ±1% Full Scale | ±1% Full Scale | ±1% Full Scale |
| Included Dollies | Ø20 mm aluminium (20 pcs) | Ø50 mm aluminium (8 pcs) | 50 × 50 mm steel plates (4 pcs, with threaded post) | Ø50 mm steel (4 pcs, ≥25 mm thickness) |
| Cutting Tool | 20 mm hole saw | 50 mm hole saw | – | 50 mm diamond-grit hole saw with arbor |
Typical Applications
Protective coatings on structural steel
Concrete surfaces, overlays, and flooring systems
Automotive and aerospace coatings
Marine protective systems
Plastics, timber, and composite substrates
FAQ’s
Is the PosiTest AT-M suitable for field use?
Yes. The AT-M is designed for on-site testing in real-world conditions. With a tough, sealed enclosure and heavy-duty hydraulic pump, it is dustproof, weather-resistant, and impact-tolerant (IP65 rated). It is compact enough for easy transport and reliable enough for daily site inspections.
Do the kits come with dollies?
Every AT-M kit includes self-aligning dollies manufactured to precise standards. The 20 mm and 50 mm versions use aluminium dollies, while the 50 × 50 mm Tile and 50 mm C1583 kits are supplied with steel dollies. These are single-use fixtures, eliminating cleaning between tests and allowing you to retain them as permanent evidence of adhesion checks.
What adhesive should be used?
The standard kit comes with a two-part epoxy adhesive that is effective across most coatings and substrates. For specialist coatings or situations requiring faster curing, other adhesives may be suitable — our team can advise on alternatives that maintain accuracy and compatibility.
Is the Manual model as accurate as the Automatic?
Yes. Both AT-M and PosiTest AT-A models are calibrated to ±1% accuracy. The difference lies in operation: the AT-M uses a manual hydraulic pump, giving the user direct control of the pull rate. This makes it reliable for fieldwork, though the automatic model provides greater consistency where repeatability is critical.
When should I use 20 mm versus 50 mm dollies?
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20 mm dollies are recommended for high-strength coatings on metals.
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50 mm dollies are better suited for lower-strength coatings applied to concrete, timber, or composites.
Choosing the correct size ensures accurate measurement across different substrates.
Can the PosiTest AT-M be used on pipes or curved surfaces?
Yes, for larger diameters. Users report good results on pipes above 200 mm in diameter. Smaller diameters may be possible using 10 mm or 14 mm dollies, though all international standards require the use of flat dollies for compliance.
How many readings can the AT-M store?
The PosiTest AT-M can save up to 200 measurements in its internal memory, including maximum pull pressure, dolly size, test duration, and fracture type. Results can be exported to PC via USB for further reporting with PosiSoft software.
What is the lowest adhesion strength the AT-M can measure?
The AT-M can record values below 16 psi when used carefully, unlike the Automatic model which has a fixed priming pressure. This makes it especially useful when testing low-bond coatings on softer substrates.
Can I speed up adhesive curing?
The supplied epoxy typically cures within 24–48 hours. If faster testing is required, cyanoacrylate (superglue) adhesives can be used for lower-strength coatings. Always ensure the adhesive is suitable for both the coating and the dolly material.
What substrate thickness is required?
No strict minimum is specified, but thin or flexible substrates can deform under load, affecting results. ISO 16276 recommends 3 mm minimum for steel. For thinner materials, secure the specimen against a backing or support to prevent bending during testing.
Can I use the AT-M on brittle or flexible materials?
Adhesion testing is intended for rigid surfaces. Flexible materials may distort the results, while brittle substrates can crack or break under the pull-off force. In such cases, results may reflect substrate failure rather than true coating adhesion.
Does the PosiTest AT-M come calibrated?
Yes. Every AT-M is supplied calibrated and ready to use, with a long-form Certificate of Calibration traceable to UKAS/NIST/PTB standards. This certificate includes actual test readings, offering full compliance assurance.
Is training required to use this gauge?
No. This gauge is straightforward to operate, supported by clear instructions and quick-start guides. Our UK team is always available for advice, and tutorial videos are provided to demonstrate correct testing methods.
Still need assistance?
If you encounter issues, consult the troubleshooting guide or contact our support team. As the UK’s DeFelsko Authorised Service Centre (DASC), DFT Instruments provides calibration, repairs, and expert technical help locally.
Find out more about the PosiTest AT-A and all the features that come with it
Every PosiTest AT-M kit includes:
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Manual Adhesion Tester (AT-M)
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Rechargeable hydraulic pump system
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Selection of dollies (varies by model)
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Cutting tool
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Adhesive with mixing sticks and palettes
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Abrasive pad and cotton swabs
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USB cable and PosiSoft software
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Instruction manual and quick reference guide
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Certificate of Calibration (traceable to NIST/UKAS)
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Protective carrying case
The PosiTest AT-M combines mechanical simplicity with reliable accuracy, making it a trusted choice for inspectors who need a robust, easy-to-use adhesion tester.
📞 To enquire about this product, contact us today on: 01442 879494 or Complete the form.