Long open time adhesive HB Fuller Köracoll WB 20

      What makes the HB Fuller Köracoll WB 20 adhesive different?

The Köracoll WB 20 is the reference in the H.B. Fuller water-based adhesive range that offers the longest positioning time: up to 30 minutes with one-sided application and 80 minutes with two-sided contact bonding. That is its defining characteristic, and it is what makes it the right choice as soon as the part to be bonded is large, heavy or difficult to present in a single move.

With a fast-grab adhesive, a part placed slightly off is a part lost. Here the operator keeps control: the piece can be laid down, lifted, realigned and pressed without degrading final adhesion. This long open time is achieved with a 78 % solids content, the highest in the range, which limits the amount of water to be driven off despite the extended working window.

A second argument is compliance. The WB 20 is the only reference in the range to carry EMICODE EC1 for very low volatile organic compound emissions, Giscode D1 for the least restrictive class of the German hazard scale and conformity with DIN EN 12529 for castor chair traffic. It is also compatible with underfloor heating.

Adezif supplies this adhesive as an official H.B. Fuller distributor within its range of industrial glues.

      What applications is the Köracoll WB 20 used for?

The Köracoll WB 20 comes into its own whenever positioning time becomes the deciding criterion: assembling full-format panels, bonding coverings across their whole surface, or presenting parts that a single operator cannot lay down in one movement.

• Insulation boards both thermal and acoustic bonded onto wood, metal or concrete

• Decorative laminate onto wooden panel or onto sheet metal

• Floor and textile coverings including carpets and acoustic underlays

• Sandwich panels and interior fit-out including vehicle conversion work

Conversely, if the assembly has to hold immediately without clamping, the reference to choose is the Helmitin 38151, with its contact set in 20 to 40 minutes on porous and non-porous substrates alike. Between the two references the deciding factor is neither the substrate nor the final strength but the time the operator actually needs.

      How is the Köracoll WB 20 adhesive applied?

There are two methods, and the method chosen is what sets the time available. With one-sided wet bonding the adhesive is spread on a single substrate and the part is laid within 30 minutes. With two-sided contact bonding both faces are coated and assembly can take place up to 80 minutes after application. The adhesive is spread with a roller a brush or an A2 notched trowel.

Consumption falls between 200 and 400 g/m² depending on substrate porosity and on the tool used. The processing range is +10 to +30 °C: below 10 °C the water no longer escapes properly and the film does not form.

Initial cure takes 3 to 8 hours, during which the assembly must carry no mechanical load. Fresh squeeze-out is cleaned off with water; once dry it calls for a dedicated cleaning solvent.

Like every dispersion adhesive the WB 20 requires at least one absorbent substrate in the bonded pair so that the water can escape. Two closed substrates face to face will block drying and a long open time does not compensate for that. Surface preparation before bonding and the surface energy of the materials remain the two parameters that decide whether the assembly succeeds.

Storage must be frost-free and always above +10 °C. A single freeze cycle destroys the dispersion irreversibly.

      What are the technical specifications of the Köracoll WB 20?

The values below come from the manufacturer's technical documentation. They are indicative and must be confirmed by trials on your own substrate pairs.

To request the full technical data sheet or a sample of the Köracoll WB 20, contact the Adezif team with your substrate pairs, your line speed and the final strength you expect.

Technical data taken from the documentation of the manufacturer H.B. Fuller Kömmerling, cross-checked against two European specialist distributors and verified on 5 November 2026. Processing values are indicative and do not remove the need for validation trials on your own substrates.