How to apply sealant? Sealing skills determine the life of the sealant!

After choosing the right sealant and handling the base surface, the sealant application technique is the key to success or failure! Just squeeze out a line of sealant and expect it to be watertight? That’s a big mistake. The wrong shape and thickness will cause the sealant to bear huge stress and easily crack and fail.

Core skills: shape and thickness

Depth-to-width ratio is the golden rule: For common joints (3-12mm wide), the depth of the sealant should be half of its width (such as a 6mm wide joint, the depth of the sealant is about 3mm). Too shallow will result in insufficient strength, too deep will result in waste and difficult to cure.

Contacting both sides is the key: Make sure that the sealant is in good contact and bonding with both sides of the joint at the same time, which is the core of forming an effective seal.

Avoid “point contact”: It is a common mistake to only apply glue to the bottom of the joint without contacting the two sides (like a “lying 7”), and this kind of bonding is extremely fragile.

Backing material is essential: When the joint depth is too large (usually >10mm) or the depth-to-width ratio needs to be controlled, be sure to use a closed-cell foam stick as a backing. It can prevent three-sided bonding (causing stress concentration), save glue, and help form an ideal concave meniscus shape.

Perfect finishing: Use a scraper or finger (dip in soapy water to prevent sticking) to flatten and compact the colloid to form a slightly concave “concave meniscus”, which can reduce stress and extend life.

One-sentence secret: Apply the sealant well, remember “the depth is half the width, and both sides must be glued firmly”!