Bonding agent and primer systems

SikaCem Cementitious Bonding Slurry is a polymer-modified, two-component bonding slurry in the Sika construction range. Applied by brush or roller to the prepared substrate immediately before the render coat, it provides a bonding layer that mechanically and chemically keys the render to substrates that would otherwise have insufficient absorption for direct render application — including dense concrete, smooth blockwork, and previously painted surfaces where the paint film has been removed but the surface remains sealed. The slurry is mixed from a cementitious powder and a liquid polymer component, applied as a textured coating to the substrate, and the render coat is applied into the wet slurry before it sets ('wet-on-wet'). This wet-on-wet application is critical — if the slurry is allowed to dry before the render is applied, it acts as a debonding layer rather than a bonding agent. Confirm current product name and wet-on-wet application timing with Sika Australia before specifying.

Mapei provides two bonding agent options for render adhesion improvement: Planicrete (a liquid acrylic copolymer added to the cement/sand mix as a bonding admixture) and Primer 3296 (an acrylic primer applied to the substrate surface before render). Planicrete is mixed with water and OPC to form a cementitious slurry that is applied to the substrate and allowed to become tacky before the render is applied ('tacky-on-tacky' or dry-to-touch depending on substrate). Primer 3296 is an acrylic primer applied and allowed to dry before render. In Australian strata render remediation, Mapei Planicrete is used by contractors working within the Mapei supply chain for bonding agent applications where a cementitious slurry approach is preferred. Primer 3296 suits applications where a dried acrylic primer is preferred over a wet-on-wet slurry approach. Confirm current product names, application method, and open time with Mapei Australia before specifying.

Fosroc's bonding agent range for render and mortar adhesion comprises Nitobond AR (acrylic bonding agent) and Nitobond EP (epoxy bonding agent for higher-performance applications). Nitobond AR is the standard bonding agent used with the Renderoc render and repair mortar range — applied to the substrate surface to improve adhesion of Renderoc mortars to dense, smooth, or low-absorption concrete and masonry. Nitobond EP is a two-component epoxy bonding agent specified for more demanding applications where a higher bond strength is required, or where the substrate is smooth hard concrete with very low absorption. In Australian Class 2 strata facade remediation, Fosroc Nitobond AR is specified as the bonding agent for Renderoc render systems. The integrated Fosroc system — Nitobond AR bonding agent plus Renderoc render — is the preferred approach for contractors who work within the Fosroc supply ecosystem and require documented system compatibility and warranty support. Confirm current product names, application method, and compatibility with the Renderoc render grade being used with Fosroc Australia before specifying.