Frequently Asked Questions

How exactly is Fosroc Lokset applied to stop an actively flowing water leak in a basement wall and how long does the repair take?

Stopping an active water leak with Fosroc Lokset requires a specific, hands-on technique that is straightforward once understood. The procedure is as follows. First, prepare the crack or defect by chipping and widening the leaking crack to a V or box profile (minimum 25 mm wide and 25 mm deep) using a chipping hammer or angle grinder — this provides the volume for the Lokset plug and the depth needed for adhesion. Removing loose concrete around the crack during this preparation is important — loose material allows the Lokset to shift under water pressure when being held. Second, mix the Lokset: take a small quantity of Lokset powder in the palm of a gloved hand or in a container, add the minimum amount of clean water to form a stiff putty (or mix with some of the seeping water if available), and knead to a homogeneous consistency within 30 seconds. Third, form the mixed Lokset into a cone or plug shape in the hands; immediately press the plug firmly into the crack or hole opening, holding it in place with the fingers and applying pressure toward the wall, maintaining pressure for 2 to 4 minutes while the Lokset sets. The water leak should slow and stop as the Lokset fills the void and sets around the flowing water. Fourth, after initial set (the plug will feel noticeably warm and rigid), release manual pressure and check that the leak has stopped. If seepage continues at the edges of the plug, apply additional small pieces of freshly mixed Lokset around the edges. Fifth, after 30 to 60 minutes, apply further repair mortar or waterproofing coating as needed to complete the repair to the finished surface level.

Can Fosroc Lokset be used in a water tank that is in service for drinking water supply and is the material safe for potable water contact?

The suitability of Fosroc Lokset for use in contact with drinking water in a potable water supply tank depends on the specific formulation chemistry and its compliance with Indian and international standards for potable water contact materials. Aluminate cement compounds (the chemistry used in rapid-setting hydraulic cements) have some historical concerns related to the potential release of aluminium ions in contact with water, particularly in newly applied, uncured material — the aluminium ion concentration in water in contact with fresh aluminate cement can be elevated above the WHO guideline values for drinking water immediately after application. Before using Lokset in a potable water tank, the following precautions should be taken: confirm with Fosroc India that the specific Lokset formulation has been evaluated for potable water contact compliance or that there are any specific curing and washing-out requirements before filling; after applying Lokset to repair a leaking potable water tank, the repaired area should cure for a minimum of 7 days in air before the tank is refilled; the first tank fill after repair should be discharged to drain (not used for drinking) to allow any residual surface alkalinity and any potential aluminium leaching to flush from the system; and the water quality (pH, aluminium content) should be checked before the tank is returned to drinking water supply service. For tanks supplying drinking water to a large population or in regulated systems (municipal water utilities), written approval from the water authority for the repair method and materials is advisable before commencing repairs.

What is the difference between Fosroc Lokset and Renderoc Plug and when should each be used for stopping water leaks?

Fosroc Lokset and Renderoc Plug are both rapid-setting cementitious compounds from Fosroc for stopping active water leaks, and they are very similar in concept and application — both are hand-packed plugging materials with rapid set times (minutes) for use against actively flowing water. The distinction between the two products is primarily in the specific formulation — the cement chemistry, the admixture package, and the resulting set time and early strength — with each product representing a formulation variant that may have been optimised for slightly different site conditions, water temperatures, or the specific water chemistry encountered (hard or soft water, acidic or alkaline groundwater). In practice, the selection between Lokset and Renderoc Plug depends on which product is currently listed and available in the Fosroc India product range in the specific packaging and regional supply chain. Space Arc Engineering can confirm which specific rapid-setting leak-stopping product from Fosroc India is currently stocked and available for immediate supply in the Delhi NCR and Ghaziabad market. The application technique and follow-up repair procedure are essentially identical for both products. If both are available and the project has extremely fast-flowing water (more than a trickle), the product with the faster initial set time should be selected — typically confirmed from the technical data sheets by comparing initial set times at the expected water temperature.