Cyanoacrylate can be evaluated on metal, rubber, and plastic, but the correct grade and process depend on the actual surface, joint gap, flexibility, and required cure behavior. TongLin Adhesive recommends treating each material family as a separate validation stream instead of promising universal adhesion from a product name alone.
Start with surface and joint information
Before comparing grades, identify the exact material and finish. A metal with an oil film, a rubber with additives, and a molded plastic with release residue are not equivalent test surfaces. Record:
- material family, coating, hardness or flexibility, and surface finish;
- cleaning method and the time between cleaning and bonding;
- joint gap, overlap area, fixture method, and expected movement;
- application volume, nozzle, handling time, and final test condition.
The surface must be prepared consistently. A stronger-looking result from one coupon can be misleading if its roughness, contamination, or fit is different from the production part.
Use a material-specific comparison
| Substrate family | Main process question | First checks | Boundary to validate |
|---|---|---|---|
| Metal | Is the surface clean and is the joint rigid enough? | Degreasing, fit, dose, and fixture | Coating compatibility, corrosion environment, and final strength |
| Rubber | Can the joint tolerate movement and is the surface additive-free? | Flexibility, surface condition, and cure appearance | Plasticizer effects, peel stress, and aging requirement |
| Plastic | Does the molded surface wet consistently? | Resin type, mold release, gap, and dose | Surface energy, stress cracking risk, and production variation |
For a low-viscosity starting point, consider S505; for more control of the applied bead, consider S508; and for a higher-viscosity comparison, consider S5401. Product data narrows the candidates, but it does not remove the need to validate the customer’s substrates.
Validate the joint, not only the material name
Run repeated samples from the real process and keep preparation, gap, dose, fixture, and conditioning consistent. Compare handling time, appearance, failure mode, and strength after the customer-defined conditioning cycle. If the part is flexible, include the expected movement rather than testing only a rigid pull.
For a private-label product or a packaging format that changes the application, review the cyanoacrylate OEM service. Send metal, rubber, or plastic details plus the joint drawing through Contact; the final recommendation depends on the actual formulation and process.