Glues & Sealants – Are You Stuck?

Glues & Sealants – Are You Stuck?

Glues & Sealants – Are You Stuck?

With so many classes of glues and sealants on the market, how can retail staff respond to customer enquiries with confidence? JOHN POWER goes back to ‘first principles’.

The adhesives/sealants product category is perhaps one of the toughest to master in retail hardware stores, and the difficulty is only compounded whenever new products with fresh capabilities hit the market.

In most cases, customers will know basic information about the types of materials they wish to bond or seal, or the nature of a specific project, so these should be the retailer’s first cues in ascertaining appropriate products or options.

Let’s start with common adhesives/glues and some simple definitions.

Cyanoacrylate – This family of glues includes the popular families of ‘super glues’, which are resilient and quick-drying solutions for a range of DIY tasks involving common materials. Used in comparatively small quantities applied in thin films to facilitate curing, these adhesives react with moisture in the air to harden. Ideal for bonding hard, non-porous materials with low shear strength requirements, including metal, glass, some ceramics and plastic. Generally speaking, super glues are not appropriate for bonding Styrofoam, wood, textiles or fabrics. NB: a variety of new products with ‘gel’ properties are now available to offer easier application on traditionally awkward surfaces – including slightly porous materials and even flexible rubbers – where some gap filling is also required.

Epoxy – Adhesives in this category generally require the admixture of two substances, i.e. a hardening agent and an adhesive resin, to create the finished glue. When combined, the two agents react to form an incredibly tough bond for a range of DIY and professional applications. Epoxies are great for long-term and hardwearing bonds involving metal, ceramics and plastics.

Polyurethane – Also known as ‘expanding glue’ because many products tend to foam and expand during the curing process. This waterproof glue is incredibly strong, but its propensity to expand means it is most appropriate for surfaces that are porous enough to permit a degree of adhesive infusion. Excess glue should be wiped off surfaces before curing is complete (usually within 24 hours).

Polyvinyl Acetate (PVA) – This adhesive, which is often referred to as ‘wood glue’ or ‘craft glue’, is perfect for a variety of projects involving wood, fabrics, papers and cloths.

Hot Glue – These fast-setting glues are most frequently used with a dispenser gun, which heats the tips of glue sticks to melting point. There are two main cautionary notes: be aware that bonds may be unsuitable for tasks involving ongoing exposure to high temperatures; and avoid using hot glue on delicate or porous surfaces where the glue may cause heat damage.

Ideal for bonding ‘problematic’ materials like polystyrene and polyurethane foam products, as well as textiles, paper and leather.

The next step

The above generalities are fine when kindred materials need to be bonded for everyday applications around the house. But what happens when different kinds of materials need to be bonded? Or when bonded materials need to withstand extreme conditions (high heat, saline environments, excessive moisture, etc)?

In such cases, it is easy to imagine a retail salesperson getting stuck very quickly.

The quandary deepens when we realise that multiple types of adhesive might all produce satisfactory results for a desired application.

Various modes of assistance have arisen over the years to address these kinds of selection mysteries, including more helpful labeling policies, more understandable product classifications, improved guidelines on packaging, as well as myriad online support tools.

One of the most valuable of these is the Loctite Product Advisor from Henkel ( This online resource allows users to seek appropriate products according to type of project or materials used. Having chosen which of the two pathways to follow, the user is invited to provide basic information about the project or its materials in just a few steps. The site then offers one or more instant product recommendations for the specific task.

This tool is particularly handy as it addresses both simple and challenging jobs with equal dexterity in a few seconds. Whether used by an inquisitive customer as a preparatory research tool or in-store aid, or by a retail staff member who is unsure about the bonding compatibility of unusual materials, the Product Advisor is a welcome addition to the growing arsenal of online information tools.

Sealants as well

The above database also includes recommendations for sealants – another category that can dumbfound DIYers and even experienced store staff.

Confusingly, sealants and adhesives can share certain characteristics: both may result in airtight or waterproof seals, providing a resilient connection between two or more materials. But sealants are primarily chosen for their gap-filling flexibility rather than brute strength, while adhesives are all about bonding surfaces in a steadfast manner. NB: in circumstances where gaps need to be filled with a permanent and (predominantly) inflexible material, as might apply to gaps in plasterboard walls, users should consider an appropriate filler rather than a sealant. Researchers, it must be observed, continue to cloud the issue by inventing multifunctional products that blur the distinction between adhesives, sealants and fillers!

These days there are two main types of sealant on offer in retail hardware environments:

Silicone – These types of sealants are incredibly common and diverse in their applications. However, as a rule of thumb, silicone sealants are popular for seals involving glass panels, pipes, many bathroom and kitchen applications, and guttering. Silicone sealants are well known for their pliability, making them appropriate for seals in installations like windows that might be prone to expansion and contraction on daily or seasonal cycles. Paintability is another welcome feature of high-quality silicone products.

Polyurethane – Sealants from this family of sealants are typically hardwearing and elastic, delivering tough seals in masonry and brickwork, external cladding and joints.

Of course, there are numerous other specialty sealants available for specific tasks, such as asphalt-based products for roofing, and retail staff should be aware of the precise attributes of these niche ranges.

As an aside, retailers should not forget the obvious add-on sales opportunities relating to tubes of sealant, namely caulk guns, specialist nozzles, applicator tools for smoothing finishes, etc.

The right questions

In summary, the best way to keep clients happy is to ask questions about their projects: What tasks are they hoping to complete? What materials are they bonding or sealing? Does the project involve any extreme conditions? Once these few questions have been addressed, the retailer will be well on the way to finding an appropriate solution. Don’t forget the power of packaging guidelines and online tools to facilitate the process.