Sopro VF HF 420 – VarioFlex® High Strength Flexible Tile Adhesive

An extra-rapid-set, early-high-strength, flexible, cementitious floating-bed tile adhesive allowing early loading, for efficient tile laying and particularly suitable for dishing prone resin-bonded tiles*) using the thin-bed method. Low-chromate to Regulation (EC) No 1907/2006, Annex XVII.  Tested to C2 EF, DIN EN 12004.

Field Of Application

For dishing-prone resin-bonded tiles1), cast stone and terrazzo tiles, earthenware, stoneware and fully vitrified stoneware tiles, mosaic, terracotta, discoloration-resistant natural stone units in marble, granite etc. Also suitable as a bonding and contact layer in conjunction with the thick-bed method, e.g. for rapid set mortars incorporating Sopro Rapidur® B1 turbo binder. In commercial and industrial facilities, hospitals, public buildings, airports, railway stations etc.

Suitable Substrates

Min. 3-month-old concrete; calcium sulphate screeds; mastic asphalt screeds (indoors); board subfloors; cement screeds; heated floor constructions (cement and calcium sulphate screeds); strong existing ceramic, natural stone, terrazzo or cast stone coverings; timber substrates (in conjunction with Sopro FDP 558 tile insulation board); waterproof membranes.


Rapid crystalline water binding and very early strengths achieved by Sopro VF HF 420 make it ideal for rapid, dishing-free laying of resin-bonded1), natural stone and cast stone units. As a floating-bed adhesive, Sopro VF HF 420 ensures full rear-face wetting of tiles, exceptionally high frost resistance for covering system and uniform load transmission to the substrate. For trouble-free laying of large-format fully vitrified stoneware tiles up to 1.0 m² in size on calcium sulphate screeds pretreated with undiluted Sopro GD 749 primer. For larger formats, calcium sulphate screeds should be pretreated with Sopro MGR 637 multi-purpose primer or Sopro EPG 522 epoxy primer. Sopro VF HF 420 offers good workability and achieves a high coverage. Ideal for rapid tile laying on tightly scheduled projects.

Related Downloads

icon-pdf TDS Sopro VF HF 420 – VarioFlex® High Strength Flexible Tile Adhesive


icon-pdf TDS SMET_Tiling Onto Calcium Sulphate Floor Screed_System I

icon-pdf SMET Professional Tiling Systems Brochure


Featured Benefits of SoprVF HF 420 – VarioFlex® High Strength Flexible Tile Adhesive

• Extra-rapid-set
• Early high strength, achieving tensile adhesion strengths ≥ 1.0 N/mm² after only 3 hours
• Rapid crystalline water binding
• High reliability through full rear-face wetting and contact adhesion
• Ideal for fast-track or tightly scheduled schemes, e. g. weekend supermarket refurbishments
• Floating-bed floor laying, indoors and outdoors
• Through the addition of 30 % Sopro QS 511 coarse silica sand, Sopro VF HF 420 is also suitable for 5 – 20 mm coat thicknesses
• Reduced-dust
• EMICODE system of GEV (German Association for Control of Emissions in Products for Flooring Installation): EC1PLUS R (“very-low-emission-plus”) rating
• DGNB (German Sustainable Building Council): Top quality level 4, Line 8 **)

Technical Details Sopro VF HF 420 – VarioFlex® High Strength Flexible Tile Adhesive

Coat Thickness Max. 5 mm in compacted adhesive bed
Mixing Ratio (water only) 5.5 – 6.0 ltr water: 25 kg Sopro VF HF 420
Coverage Approx. 1.4 kg/m² per mm coat thickness
Maturing Time 3-5 minutes
Pot Life 30–45 minutes; stiffened mortar must not be retempered by addition of water or fresh mortar to restore workability.
Open Time Approx. 30 mins
Walkable / Groutable After approx. 2 hours or after setting of adhesive; take measures to spread loads over the floor.
Loading After approx. 5 hours;

In commercial facilities  – After approx. 2 days

In areas subject to high wet exposure – After approx. 3 days

For underwater applications – After approx. 10 days

In conjunction with floor heating – After approx. 14 days

Specified Times Apply for normal temperature range of +23°C and 50% relative humidity; higher temperatures shorten and lower temperatures lengthen these times
Application Temperatue Between +5°C and max. +25°C air and substrate
Tools/ Tool Cleaning Mixing attachment, notched trowel with suitable serration (tooth size up to 12 mm); wash tools with water immediately after use.
Packaging 25kg bag

Available in 25kg bags with 40 bags per pallet.

* Please consult SMET technical support team prior to laying resin-bonded tiles.
** Based on DGNB (German Sustainable Building Council) criterion ‘ENV1.2 Local Environmental Impact’ (2015 version).

For other adhesives from SMET.