Substrate preparation (by intended use)

For good adhesion, the base layer needs to be carefully prepared. Whether it’s concrete, wood, particleboard, OSB, drywall, metal, PVC, or old cladding, the substrate surface must be smooth, clean, dry, rigid, and load-bearing. Once these conditions are met, improving adhesion by applying a primer is recommended. The primer’s role is to even out water absorption across the surface.

Weber’s GR 100 primer (supplied in 5 kg buckets, as a homogeneous powder with a maximum grain size of 1 mm) is based on synthetic resins with mineral additives and can be applied to any surface, before cladding or leveling. It’s used for wall and floor cladding, indoors and outdoors, wherever water absorption is excessively high or low (e.g. concrete, masonry, dry plaster, drywall).

Primer is applied at temperatures between 5-30°C. Working in rainy weather or under direct sunlight should be avoided. After application, the surface stays rough. Good results are also obtained applying it over old ceramic or mosaic tiles, OSB, wood, or PVC; the key condition is that the surface must not deform. It improves adhesion on the surfaces it’s applied to.

It’s prepared by pouring a 5 kg bag of powder into 6 liters of clean, cold water. Mix by hand or with an electric mixer. Let it rest for 10 minutes, then mix again. This produces a homogeneous mixture that can be applied with a wide brush or paintbrush. It needs to be re-mixed periodically during use, to avoid settling. Catalog consumption is 0.15-0.20 kg/m² per coat.

One bucket is enough to cover about 30 m² in a single coat. The product is non-toxic, but it’s classed as corrosive and can cause serious eye damage, so it must be handled carefully. The surface can be used once it’s fully dry.