MS Polymer, Silicone or PU - which adhesive sealant?
MS Polymer (silane-modified polymer) combines elastic bonding with strong sealing - solvent- and isocyanate-free, paintable and primer-free on many substrates. This guide shows when the hybrid beats silicone and polyurethane, and what matters for selection and application.
View MS Polymer productsWhat is an MS Polymer adhesive sealant?
MS Polymer stands for silane-modified polymer, also called SMP or hybrid polymer. The binder combines the elastic backbone of a polyether with reactive silane groups at the chain ends. These cross-link with atmospheric moisture to form a permanently elastic, tough film - without the drawbacks of pure silicone or polyurethane.
Unlike silicone, MS Polymer contains no silicone oil that contaminates substrates and blocks paint adhesion. Unlike polyurethane, it works without free isocyanates and usually without solvents. Curing runs from the outside in through moisture, typically around 2 to 3 mm within the first 24 hours.
From substrate prep to the cartridge gun - build a reliable bonded joint step by step.
Read the guideMS Polymer, silicone or polyurethane - which one?
All three are one-component, moisture-curing systems, yet they differ clearly in adhesion, paintability and strength. The overview below sorts the typical properties and shows where the hybrid plays to its strengths.
- Choose MS Polymer: elastic, paintable bonding and sealing on mixed substrates, in vehicle and metal fabrication, without primer.
- Choose silicone: high service temperature, sanitary and glazing work, where you do not paint over and need maximum UV and heat resistance.
- Choose polyurethane: high initial and final strength for structural bonds, when isocyanate handling and longer curing are acceptable.
What to watch for in selection and application?
The deciding factors are Shore hardness, sag resistance and cure speed. A low Shore A hardness (around 25 to 40) stays soft and movement-tolerant for expansion joints, while a higher one (around 50 to 60) delivers more bonding strength for load-bearing joints.
- Prepare the substrate clean, free of grease and dust - MS Polymer bonds well but not on release agents.
- Plan a continuous bead or spot bonding; for seals use a triangular or rectangular bead with a matching nozzle.
- For bonds keep a minimum layer thickness of about 2 to 3 mm so the elasticity can absorb movement.
- Overpaint ideally wet-on-wet or after skin formation; test paint compatibility on a sample first.
- Apply the cartridge evenly with a manual or cordless gun; store opened cartridges sealed with the nozzle on.
Cartridge guns, nozzles and smoothing tools for clean seals and bonds.
View accessoriesFrequently asked questions
Can I really paint over MS Polymer?
Yes, most MS Polymers are paintable, often even wet-on-wet. Water-based and many synthetic-resin paints work well. Because paints vary widely, run a compatibility test on a sample area first.
Why is MS Polymer better than silicone for bonding?
MS Polymer offers much higher bonding strength and can be painted over, whereas silicone oil contaminates substrates and blocks paint adhesion. For pure sealing at high heat, however, silicone remains superior.
Is MS Polymer as strong as polyurethane?
High-strength MS Polymers reach very good values, but for purely structural bonds with maximum tensile strength PU is often still a little stronger. MS Polymer scores by being isocyanate- and solvent-free and paintable.
Does MS Polymer need a primer?
On most substrates such as metal, wood, glass and many plastics MS Polymer bonds without primer. On critical plastics or under permanent wet load a primer can further secure adhesion.
Looking for the right MS Polymer adhesive sealant?
We supply elastic, paintable hybrid adhesives and sealants plus cartridge guns and accessories - solvent- and isocyanate-free.
Paintable
Hybrid systems can usually be painted wet-on-wet.
Low emission
Free of solvents and free isocyanates.
Primer-free grip
Reliable adhesion on many substrates without pretreatment.
Expert advice
Our specialists help you choose the right system.