Efflock Hydrophobic Additive

For bathroom tiling, balconies, pool surrounds, and stonemasonry where salt damp or calcium carbonate stains threaten the finish, Hydrophobic Additive provides permanent protection by treating the entire concrete mass. Added directly to the mix, this water-based liquid creates an invisible hydrophobic molecular structure within the pores of cement-based materials to lock out efflorescence without blocking vapour permeability.

What it does

Hydrophobic Additive acts as a bulk impregnating agent that repels liquid water while remaining breathable. By preventing the capillary action that draws moisture through concrete, brick, sandstone, and porous masonry, it stops waterborne salts from migrating to the surface. This mechanical control prevents picture framing in granite and basalt paving, stops salt attack in saline soils, and deprives moss and mould of the moisture required to grow on off-form concrete or brickwork. Unlike topical sealers, bulk impregnation protects the entire mass, meaning the water-repellent performance is unaffected by traffic wear, surface abrasion, or minor movement cracks.

Numbers that matter

• 1:100 dilution ratio: 1 part Hydrophobic Additive to 100 parts clean water (or 100ml per 100L screed mixer capacity) provides a highly concentrated formula that minimizes packaging waste on site.
• 16m² coverage: 1 litre treats approximately 16m² of tiling, which covers a 40mm thick tile screed, tile adhesive, and tile grout based on a 300 x 300 x 10mm floor tile.
• 24-hour rain window: Treated cement-based materials must cure for up to 24 hours before any exposure to rain to ensure the hydrophobic barrier forms correctly.
• 4°C to 35°C application range: Air and substrate temperatures must remain within this window during application and initial curing.

Where to use it

• Tiled wet areas: For screeds, adhesives, and grouts in bathrooms, balconies, patios, stairs, and pool surrounds to prevent efflorescence and protect primary waterproofing membranes from water pooling underneath tiles.
• Stonemasonry and brickwork: Mixed into mortar to form a built-in damp proof course (DPC) that blocks rising damp and salt attack, particularly when using white cement.
• Concrete structures: Protects off-form concrete, post-tension reinforcement pockets, and concrete pavers against freeze-thaw damage and chloride ion absorption.

Installation limits

Always use General Purpose Cement (Type GP) for applications where efflorescence is a risk. Do not use Builders Cement (Type GB); its high proportion of fly ash or blast furnace slag contributes to efflorescence and works against hydrophobic additives.

When mixing tile screed, sand from the building yard carries variable moisture that pre-dilutes the mix. To maintain correct dosage, add Hydrophobic Additive neat to the screed mixer at 100ml per 100L of mixer capacity, then add water to reach the desired consistency. For hand-mixed screeds, pre-gauge in a bucket with a tighter 1:80 or 1:50 dilution to compensate for wet sand.

Latex additives used in cement slurries or tile adhesives will delay the water-repellent performance of Hydrophobic Additive for approximately 6 days. While compatible, the system will not exhibit full hydrophobicity during this initial cure window. If rain enters tile adhesive notches before grouting, extract it with a vacuum and allow it to evaporate fully.

Supervisors should water-test all screeds, mortars, and concrete after 24 hours. A successful mix will show a distinct water-beading effect; if the substrate absorbs water, seek technical advice before proceeding.

Cautions and limitations

• No hydrostatic pressure rating: Hydrophobic Additive does not fill concrete pores and is not rated to resist head pressure under continuous underwater immersion.
• Stain limits: The hydrophobic barrier repels waterborne contaminants but is not effective against oil-based stains.
• Dark grouts: The additive does not resolve or contribute to the patchy appearance or colour-retention issues inherent to dark proprietary grouts.
• Natural stone migration: On highly porous stone or certain dark stones like G684 basalt and sandstone, the additive can migrate from wet bedding screeds or grout into the stone, creating visible dry spots when the stone gets wet. This must be prevented by pre-sealing the stone, or by applying grout across the entire face of the stone rather than just the joints.
• No 6-sided sealing on low porosity: Do not apply sealers to the bedding face of low-porosity stone, as active sealer ingredients sitting on the surface will cause adhesion failure.
• Acid cleaning adjustment: Hydrophobic Additive in mortar repels water but does not repel hydrochloric acid. For face brickwork cleaning, the standard acid-to-water dilution ratio may need to be strengthened to compensate for the water repellency of the mortar joint.