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JUSTONE Flexible Stone can be installed on a suitable metal sandwich-panel face using a three-step system: first apply a compatible epoxy primer; next use Justone's special bonding adhesive to fill the panel grooves and create a flat plane; then use the same specified adhesive to bond the JUSTONE Flexible Stone panels. The metal face must be stable, dry, clean, free of rust and contaminants, and verified for coating compatibility before installation.
The adhesive is not an interchangeable commodity in this assembly. Justone specifies its own bonding adhesive because, after curing, it retains flexibility and elongation that help accommodate service movement caused by temperature change. Product-specific technical data, curing conditions, mock-up results, joints and the panel manufacturer's requirements must still be confirmed for each project.
A metal sandwich panel is different from concrete or cement mortar. Its outer metal skin may contain a factory coating, profiling grooves and local fasteners, and it expands and contracts as temperature changes. The cladding build-up therefore has to do more than simply "stick stone to metal." It must establish adhesion to the actual panel finish, create a continuous flat plane and remain compatible with expected panel movement.
The three layers serve different functions:
| Layer | Primary function | Main site control |
| Epoxy primer | Prepare and seal the metal face, support adhesion and help protect exposed metal from corrosion | Confirm compatibility with the existing factory coating and follow surface-preparation requirements |
| Justone bonding adhesive as leveling layer | Fill panel grooves and create a flat receiving plane | Apply within the permitted thickness and allow it to cure as specified |
| Justone bonding adhesive as fixing layer | Bond the JUSTONE Flexible Stone panel to the prepared surface | Use the specified trowel, coverage, open time and curing conditions |
Justone's public installation guidance identifies steel plates and exterior cladding panels as applicable substrates and notes that different substrates require dedicated primers. It also specifies the use of special adhesive for flexible-stone installation.
Do not apply primer or adhesive until the project team has approved the actual sandwich-panel surface.
Check that the outer sheet is structurally stable and securely fixed. Record:
A primer cannot compensate for loose rust, oil or a failing factory finish. AMPP notes that structural-steel primers support corrosion protection and provide a better surface for subsequent coatings, while primer selection depends on surface preparation, service environment and required life.
Before full installation, obtain written confirmation for:
Use the actual sandwich panel, primer, adhesive, JUSTONE Flexible Stone SKU and joint details. The mock-up should include at least one groove, panel joint, fastener zone and edge detail. Allow the complete system to cure before checking adhesion, flatness, panel alignment and appearance.
Where the project specification requires a quantitative adhesion check, use the agreed pull-off method and acceptance criterion. ASTM D4541 covers pull-off strength evaluation of coating systems from metal substrates, but the project team must define whether and how that method applies to this complete cladding build-up.
Prepare the metal face according to the approved primer technical data sheet. Remove dust, oil, release agents, loose coating and corrosion products. Repair deep scratches and exposed metal using the panel or coating manufacturer's approved method before priming.
Apply the compatible epoxy primer evenly and allow it to cure under the specified temperature and humidity conditions. In this assembly, the primer is used for four practical purposes:
The fourth point should not be presented as a universal property of every epoxy primer. The selected primer must be approved for the actual sandwich-panel coating and the Justone adhesive.
Before moving to Step 2, confirm that:
Metal sandwich panels are commonly profiled rather than flat. JUSTONE Flexible Stone should not be bonded over deep, unsupported grooves without an approved leveling detail.
Use Justone's special bonding adhesive to fill the grooves and create a flat, continuous receiving plane. Apply the material within the product's permitted thickness. If a groove is deeper than the approved single-pass thickness, use the manufacturer-approved multi-layer method or an alternative backing detail rather than applying an uncontrolled thick layer.
Use a straightedge to check the plane in both directions. Allow the leveling layer to cure as stated in the technical data sheet before applying the fixing layer.
A properly leveled substrate helps:
Do not fill over functional panel joints, flashings, weep routes or details that must remain capable of movement or drainage.
Once the leveling layer has cured and the surface is clean, flat and approved, apply Justone's special bonding adhesive using the specified notched trowel. Work within the published open time and install the JUSTONE Flexible Stone panels in the approved sequence.
Justone's general installation guidance recommends applying the special adhesive to the substrate with a V-notched trowel and installing the flexible stone from top to bottom. Press the panel evenly to achieve the required contact without trapping large voids.
During installation:
The primer, leveling layer, fixing layer and JUSTONE Flexible Stone panel operate as one assembly. Substituting an unapproved adhesive changes the adhesion, flexibility, curing, water response and movement behavior of that assembly.
Justone specifies its special bonding adhesive because the cured adhesive remains flexible and has high elongation, helping the system accommodate movement associated with thermal expansion and temperature changes. This is especially relevant on metal skins, which respond quickly to solar heating and cooling.
However, flexibility does not eliminate the need for movement joints or good panel design. The final detailing must account for:
For project submittals, attach the current adhesive technical data sheet and supporting test evidence for elongation, adhesion, water resistance and service-temperature range. Do not rely only on a generic "flexible adhesive" description.
| Error | Why it creates risk | Correct approach |
| Priming over rust, oil or dust | The system bonds to contamination rather than sound metal or coating | Clean, repair and prepare the face before priming |
| Assuming every factory coating accepts epoxy | Coil coatings vary in chemistry and surface energy | Verify compatibility and complete a mock-up |
| Filling deep grooves in one uncontrolled pass | Thick adhesive may cure unevenly, shrink or exceed its approved use | Follow the maximum build or approved multi-layer detail |
| Bonding JUSTONE Flexible Stone directly across panel joints | Metal-panel movement may concentrate stress in the finish | Carry required movement joints through the cladding |
| Replacing the specified adhesive | Changes assembly performance and may invalidate technical support | Use the approved Justone adhesive system |
| Installing before the leveling layer cures | Traps moisture and disturbs the plane | Observe stated cure and recoat times |
| Treating the primer as a rust converter | Active corrosion can continue beneath the assembly | Remove and repair corrosion as specified before coating |
A professional submittal for JUSTONE Flexible Stone over metal sandwich panels should include:
It can be installed on a suitable, stable metal-panel face through an approved primer, leveling and adhesive system. Direct bonding without confirming the panel coating, surface preparation and groove detail is not recommended.
A compatible epoxy primer helps protect properly prepared exposed metal from corrosion, improves the interface for the following layer and seals the prepared face. Its compatibility with the factory coating and Justone adhesive must be confirmed.
No. Rust, loose coating and contamination must be removed or repaired in accordance with the approved surface-preparation method. Primer should not be treated as a substitute for corrosion removal.
Leveling creates a flat and continuous receiving plane, improving adhesive contact, panel alignment and the appearance of the thin finish.
Only an adhesive approved by Justone for this assembly should be used. A substitution changes the assembly's adhesion, flexibility, curing and movement behavior and should undergo written technical review and mock-up testing.
No. Flexible adhesive helps accommodate service movement, but required panel, facade and building movement joints must remain functional and be detailed through the finish.
Follow the current primer and adhesive technical data sheets. Cure time depends on product formulation, applied thickness, temperature, humidity and ventilation; it should not be guessed from a generic schedule.
A representative mock-up is recommended. Where the project specification requires a measured test, agree the test method, substrate condition, cure time and acceptance value before work starts.
Installing JUSTONE Flexible Stone on metal sandwich panels is a controlled three-step process: prime the prepared metal face, level the panel grooves with Justone's special bonding adhesive, and use that specified adhesive again to fix the JUSTONE Flexible Stone panels.
The key is to treat primer, adhesive and veneer as one compatible system. Good results depend on clean and stable metal, approved product compatibility, a flat receiving plane, correct curing and movement-joint detailing, not on adhesive strength alone.
For a project-specific method statement, provide Justone with the sandwich-panel manufacturer, factory-coating type, panel profile, groove depth, elevation drawings, service climate and selected JUSTONE Flexible Stone SKU.
Justone is Thin Flexible Stone Veneer Sheet Supplier in China.The company takes innovation-driven development as its core, regards promoting the progress of the industry as its responsibility, deeply engages in the chemical composite building materials track, and demonstrates its professional expertise in this field.
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