Best Industrial Sealants: Types, Comparison, and How to Choose

The best industrial sealant depends entirely on the joint, the substrate, and the environment. Silicone wins on temperature and UV resistance, polyurethane on abrasion and paintability, epoxy on structural strength, MS-polymer on all-around versatility, and butyl on low-cost waterproofing. There is no single best product, only the best match for your application.

This guide compares the main sealant chemistries by measurable properties, names the governing standards, and gives a use-case quick-pick so procurement and maintenance teams can specify with confidence rather than guesswork.

Best sealant by use case: quick-pick guide

Most buyers arrive with an application, not a chemistry, in mind. This table maps common industrial requirements to the chemistry that fits best.

What industrial sealants do, and how they differ from adhesives

Industrial sealants fill and seal gaps between surfaces to block the passage of air, moisture, dust, and chemicals. While many sealants also bond, their primary job is to create a flexible, durable barrier that accommodates joint movement without failing.

The distinction from an adhesive matters. An adhesive is engineered primarily for bond strength to hold parts together. A sealant is engineered primarily for flexibility and environmental resistance to keep a joint sealed as it expands and contracts. Many modern products, such as MS-polymers, do both.

Two standards govern most elastomeric joint sealants. ASTM C920 classifies sealants by type, grade, class, and use. ISO 11600 classifies them by movement capability, with classes such as 12.5, 25, and 50 indicating the percentage of joint movement the sealant can absorb.

Sealant types compared: Properties at a glance

This is the core selection reference. Each chemistry is compared on the properties that determine performance: service temperature, movement capability, cure, substrates, and best application.

Silicone sealants

Silicone is the benchmark for temperature and weather performance. It stays flexible across an exceptionally wide range. Silicone handles the widest temperature range, from about −50°C to 150°C, without losing flexibility, which makes it ideal for outdoor and industrial settings. High-temperature grades extend further still.

Its other advantages are UV stability and movement. Some silicone formulations allow up to ±50% joint movement, and silicone offers excellent UV resistance without yellowing or degrading over time. The main trade-offs: most silicones cannot be painted, and they skin over within roughly 30 minutes and fully cure in 24 to 48 hours. Neutral-cure grades are gentler on metal and concrete; acetoxy grades cure faster on glass and ceramic.

Polyurethane sealants

Polyurethane is the workhorse for concrete, abrasion, and paintable joints. It bonds aggressively to porous substrates and resists mechanical wear. Polyurethane bonds exceptionally to porous and non-porous materials without primer, with movement capability typically around ±25 to 35%, and most polyurethane sealants can be painted once cured.

Cure and durability differ from silicone. Polyurethane skins over in 2 to 4 hours and cures in about 7 days, and it may yellow or degrade under long-term UV exposure. That UV sensitivity is why polyurethane is favored for concrete joints, industrial flooring, and structural joints rather than sun-exposed façades. Polyurethane sealants account for roughly 40% of joint sealant applications in commercial construction.

Epoxy sealants

Epoxy is the choice when structural strength and chemical resistance outweigh flexibility. As a two-part chemical-cure system, it forms rigid, high-strength bonds. Epoxy adhesives are a common structural-grade choice known for strong bonds, and they bond best to similar substrates such as glass, metal, and wood.

Because epoxy cures rigid rather than elastic, it is not suited to moving joints. Its strengths are structural repairs, chemical-resistant coatings, and electronics. In electronics, epoxy is widely used because of its non-conductive nature for sealing PCBs and integrated circuits. This corrects a common misconception: epoxy, not acrylic, is the structural bonder for metal and concrete.

MS-polymer (modified silane) sealants

MS-polymer is the modern all-rounder, engineered to capture the best of silicone and polyurethane. MS-polymer technology blends the strengths of silicone and polyurethane into a sealant that is flexible, adhesive, and environmentally friendly, curing on contact with airborne moisture without releasing isocyanates or solvents.

Its standout trait is adhesion. MS-polymer sealants bond to a wide range of substrates, including glass, stainless steel, PVC, ABS, and wood, without needing a primer first, and they perform well outdoors without yellowing or cracking. Low-VOC, paintable, and primer less, MS-polymer is increasingly specified where versatility and environmental compliance both matter.

Butyl and acrylic sealants

Two budget-friendly chemistries cover specific niches. Butyl provides reliable, low-cost waterproofing with strong adhesion to porous and non-porous surfaces, making it a staple for roofing, automotive, and construction sealing. It softens in extreme heat, so it suits moderate-temperature service.

Acrylic is the economical interior caulk. It is easy to apply, paintable, and adheres to common building materials, but it has limited movement capability and degrades in high-moisture or extreme-temperature conditions. Acrylic sealants are commonly used for caulking, jointing, and grouting household joints, but are not advised on glass panes due to their flexibility limits.

How to choose the right sealant

Match the sealant to four variables in this order, and the right chemistry usually becomes obvious.

1. Environment. Assess exposure to UV, moisture, temperature extremes, and chemicals. Silicone leads for heat and UV; polyurethane handles mechanical stress; epoxy resists chemicals.

2. Substrate. Confirm adhesion to your actual materials. Silicone and polymer-based sealants are typically used for metal joints, epoxy and polymer sealants suit porous materials and concrete, and epoxy bonds structurally to metal, concrete, and glass. MS-polymer adheres to most substrates without primer.

3. Joint movement. For expansion joints and anything that flexes, choose a high-movement chemistry. Silicone commonly meets ISO 11600 Class 50 or 100, while polyurethane typically meets Class 25, so silicone suits long-term façade movement and polyurethane suits structural joints.

4. Application and cure. Factor in how it is applied and how fast it must cure. Acrylic and butyl apply easily by gun; epoxy needs two-part mixing; silicone cures faster than polyurethane. Confirm paintability if color matching matters, since most silicones cannot be painted.

Best practices for application

Even the right sealant fails if applied poorly. Four steps protect the bond.

• Prepare the surface. Clean, dry, and degrease the substrate. Contamination is the leading cause of premature sealant failure, so this step is non-negotiable.
• Design the joint correctly. Use a backer rod to control sealant depth and achieve the proper width-to-depth ratio. Prime porous substrates where the manufacturer specifies it.
• Apply evenly and tool the bead. Lay a continuous bead and tool it to ensure full contact with both joint faces. Gaps and voids create weak points that fail under movement.
• Allow full cure. Follow the manufacturer's skin-over and full-cure times. Rushing cure compromises strength, and cure times vary widely, from 24 hours for silicone to about 7 days for polyurethane.

Frequently Asked Questions

What is the best industrial sealant?

There is no single best sealant. Silicone is best for high temperature, UV, and weather; epoxy for structural strength and chemical resistance; polyurethane for abrasion and paintable concrete joints; MS-polymer for all-around primerless versatility; and butyl for low-cost waterproofing. Match the chemistry to your substrate, environment, and joint movement.

What is the difference between silicone and polyurethane sealant?

Silicone offers superior temperature range, UV stability, and movement capability (up to ISO Class 50), but it cannot usually be painted. Polyurethane offers stronger abrasion resistance, paintability, and excellent adhesion to concrete, but it degrades under long-term UV. Choose silicone for façades and wet areas, polyurethane for concrete and structural joints.

What is MS-polymer sealant?

MS-polymer (modified silane) is a hybrid chemistry that combines the flexibility and UV resistance of silicone with the adhesion of polyurethane. It bonds to most substrates without primer, is low-VOC and paintable, and releases no isocyanates or solvents, which makes it a versatile modern choice.

Which sealant is best for expansion joints?

Choose a high-movement chemistry. Silicone (ISO 11600 Class 50 or higher) handles the greatest joint movement for façades, while polyurethane (Class 25) suits structural and concrete expansion joints that also need abrasion resistance.

What sealant bonds best to metal?

Silicone and MS-polymer adhere well to metal for flexible sealing, while epoxy provides the strongest structural bond to metal where rigidity is acceptable. Neutral-cure silicone is preferred over acetoxy on metal to avoid corrosion.

What do ASTM C920 and ISO 11600 mean?

ASTM C920 is the U.S. standard classifying elastomeric joint sealants by type, grade, class, and use. ISO 11600 is the international standard classifying sealants by movement capability, with class numbers such as 25 or 50 indicating the percentage of joint movement the sealant can withstand.

Source industrial sealants through eINDUSTRIFY

eINDUSTRIFY is a premier global B2B marketplace for industrial supplies, connecting procurement, MRO, and plant teams with vetted suppliers across every sealant chemistry. Every seller is vetted, so you source genuine, standard-compliant silicone, polyurethane, epoxy, MS-polymer, butyl, and specialty sealants, with the ability to compare brands and technical specs in one place.

Browse the Adhesives, Sealants & Tape category for the full range, plus related Paints & Coatings and Seals, Gaskets & O-Rings categories. For bulk orders, technical selection help, or hard-to-find formulations, submit an RFQ and our team will match you to the right suppliers with fast price comparison. Call +1-888-774-7632 or email info@eindustrify.com to get started.

Tags: industrial sealants silicone sealant polyurethane sealant MS-polymer sealant selection ASTM C920