SiMP-Seal 25 HM | SiMP One-Component Construction Sealant, High Modulus

SiMP-Seal 25 HM is a one-component, gun-grade construction sealant, non-sagging, based on silyl-modified polymer (SiMP) with a high modulus. The product cures under the influence of atmospheric moisture, forming a high-performance compound with long-lasting elasticity and excellent weather and aging resistance. It is solvent-free and isocyanate-free.

• Environmentally Friendly – Solvent-free and isocyanate-free

• No Hazard Warning Symbols Required

• No Air Bubbles – Odorless

• Simultaneous Bonding and Sealing

• Long-lasting Elasticity – Can withstand ±20% joint movement

• Easy Application – Excellent consistency for shaping

• Exceptional Thixotropy – No sagging, quick string-cutting

• Adhesion Without the Need for a Primer on most common building and industrial materials

• Non-Staining on concrete and porous materials

• Excellent Weather and Aging Resistance – Color stability, non-yellowing

• Paintable with various water-based and solvent-based paints (pre-testing recommended)

Applications

SiMP-Seal 25 HM is a versatile, high-performance construction sealant ideal for expansion joints and structural joints in both vertical and horizontal applications, sealing and bonding between different materials, exterior wall joints, and cladding. This product is suitable for sealing metal roofs, gutters, bridge railings, balconies, and waterproofing joints between bricks, masonry, wood, concrete, metals, and window or door frames.

Certifications

Application Instructions

Surfaces must be completely clean, dry, and free of dust or grease. SiMP-Seal 25 HM adheres very well without requiring a primer on most common building materials. If the surface is properly prepared and reinforced, a primer is not necessary. However, some materials like bricks, natural stone, plastics, paints, coatings, and other treatments may create surfaces difficult to bond. Preliminary testing is recommended for these surfaces. Precast concrete panels using release agents other than polyethylene film should be cleaned by sandblasting or mechanical grinding and free from dust.

Recommended application temperature: 15°-25°C. For easier application or in colder weather, store the product at approximately 25°C before use. To ensure the sealant can move freely within the joint, it is important that the sealant does not bond to the bottom of the joint, so a polyethylene backing rod should be placed at the appropriate depth to create the joint correctly. If needed, apply the appropriate primer to the faces of the joint and allow sufficient time for the solvent to evaporate, avoiding the creation of air bubbles in uncured sealant under increasing temperatures. For best performance, apply the sealant when the joint is at the midpoint of its designed expansion and contraction range. Press the sealant into the joint, ensuring it fully contacts both sides of the joint and the backing rod at the bottom. Hold the nozzle in the sealant and continue pumping evenly to avoid trapping air. Avoid overlapping the sealant to prevent air pockets.

Shaping and finishing should be done before the sealant skins over. SiMP-Seal 25 HM can be painted over. It is recommended to test paint compatibility with preliminary tests. Be cautious when using alcohol or alkyd resin-based paints as they may affect the curing process and extend the drying time of the paint. Paint hardness and thickness may reduce the sealant’s elasticity and cause cracking.

Do not cure in the presence of curing silicone sealants. Avoid contact with cleaning solvents during curing. When applying the sealant, ensure no air enters the joint. Since this system cures through moisture, ensure adequate exposure to air.

Cleaning Instructions

Clean tools with acetone or solvents. While the sealant is still uncured, it can be wiped off with paper or fabric. Once cured, it can only be removed using mechanical methods. Avoid direct skin contact by wearing latex, rubber, or polyethylene gloves. If the sealant comes into contact with skin, wash it off immediately with soap and water.

Storage Instructions

SiMP-Seal 25 HM can be stored for 12 months if kept in its original (unopened) packaging at temperatures between 10°C and 25°C, in a dry, cool place. Storage temperatures should not exceed 25°C for long periods. Keep away from damp areas, direct sunlight, and heat sources.