Mapei Primer G

Mapei Primer G is a synthetic resin based water-dispersion primer with very low volatile organic compound (VOC) for treating surfaces and to provide uniform absorption in cementitious surfaces.

Primer G is a water dispersion of special synthetic resins which, once applied to any surface, dry to form a flexible, compact, shiny coating which consolidates the surface, where needed. Primer G also improves the adhesion of smoothing compounds, paint, adhesive for wall paper, adhesive for tiles and mortar for renders.
The film of Primer G on the surface of gypsum or cement, prevents any chemical reaction between sulphates and the cement alluminates of the tile adhesives which, in the presence of moisture, leads to the formation of the salt “ettringite’’ which is the cause of tiles breaking away from gypsum substrates. Primer G makes wallpaper stripping far easier and decreases the amount of glue used for paperhanging.

When used before applying sprayable plasters, Primer G prevents over-rapid absorption of water by the substrate, prolongs finishing time and helps prevent shrinkage cracks. When used before the application of self-levelling compounds, Primer G reduces the formation of air bubbles and helps prevent over-rapid drying making self-levelling easier. Primer G is not inflammable and can therefore also be used in closed, unventilated environments without any precautions having to be taken.

Best Uses

Mapei Primer G has a number of priming uses including its suitability for treating gypsum surfaces prior to fixing ceramic tiles, as an anchoring coat for gypsum-based sprayable plasters. Mapei Primer G is also  suitable for improving the bonding of smoothing compounds on cement, gypsum, asphalt, ceramic and marble surfaces cement based and calcium sulphate-based screeds and asphalt, or to provide uniform absorption in cementitious or gypsum surfaces.

Other uses include:

• Preparing cement-based surfaces prior to smoothing with self-levelling or thixotropic smoothing compounds between layers of smoothing compounds once the first coat is perfectly dry
• On gypsum plasters prior to smoothing with cementitious products
• On anhydrite surfaces prior to applying cement based products
• On cementitious renders prior to smoothing with gypsum based products
• On gypsum walls as a fixative for wallpaper adhesives
• Before installing ceramic tiles with cementitious adhesives on:
  – gypsum plasters and sprayed gypsum;
  – prefabricated gypsum panels;
  – fibrous-gypsum panels;
  – anhydrite screeds
• Treating gypsum walls, chipboard, cement fibre boards, foamed concrete, renders etc. prior to papering or painting

Application

The substrate must be clean, dry and free from oils, grease, laitance, residual paint and other loose material. In each case, the manufacturer’s recommendations for gypsum-plaster must be followed, particularly as far as moisture content and level of surface finishing are concerned. Cracks in concrete surfaces must be repaired with Eporip or Epojet. Anhydrite surfaces must be mechanically abraded.

a) As a treatment for ceramic tiles installed on gypsum. Stir the Primer G just before use, spread it uniformly on the surface with a flat brush without diluting it. If the gypsum plaster surface is especially smooth and glossy, it is recommended to abrade it beforehand. Once it has dried fix the tiles.

b) As an anchoring coat for gypsum plasters. Dilute Primer G 1:2 with water and stir well; spread the mix on the surface with a flat brush or spray pump. Apply the
sprayable gypsum as soon as Primer G is dry.

c) As a primer before applying self levelling compounds and thixotropic smoothing compounds from the MAPEI range on: cementitious substrates: dilute Primer G 1:1 or 1:3 with water (depending on the absorption of the substrate). For ceramic, marble and non absorbent substrates: dilute Primer G 1:1 with water. For gypsum based substrate: use Primer G neat;

d) As a primer for wallpaper adhesives: dilute Primer G 1:3 with water

e) As a primer between smoothing layers: dilute Primer G 1:3 with water

Do not apply Primer G in such a quantity that it forms a surface film; dilute with water as appropriate for the absorption of the substrate.