Substrate
Adhesive and surface render can be used on mineral substrates as well as on dry, gypsum-containing substrates. The substrate must be even, clean, load-bearing, and suitable for bonding the boards. Old paints, salts, bitumen coatings, etc. must be removed. If necessary, the substrate can be pretreated with Fescon Silicate primer to equalise absorption. The substrate must be moistened (to a matte-damp condition) before installing the boards. Any damage or water leaks in the substrate must be repaired before the installation of the silicate boards.
Substrates containing gypsum must be removed in areas where there is a risk of moisture penetration through the substrate. The remaining gypsum plaster layer must be at least 10 mm thick. Thinner gypsum layers are not suitable as a base for the installation of the silicate board system.
Mixing
Pour approximately 10 litres of clean tap water into the mixing container. Add 20 kg of Adhesive and surface render and mix mechanically. Mixing time must be at least 3 minutes. Allow the mortar to stand for a short while, then remix. Prepare only as much material as can be used within approximately 2 hours. Do not retemper hardened mortar with water or fresh material. Higher temperature and lower relative humidity will accelerate drying.
Before applying the finishing coat or the next board layer, treat the surface with Fescon Silicate primer (2 parts Silicate Primer to 1 part water).
Board installation and furface finishing
Apply Adhesive and surface render to both the wall and the back side of the silicate board using a notched trowel (recommended notch size 8–10 mm) in a horizontal direction to ensure full adhesion to the substrate (make a test application if necessary). The boards must be installed quickly so that the adhesive does not form a skin. Press the board firmly against the substrate with the palms of your hands. Avoid using excessive force to prevent the board from cracking.
Apply a new 2–3 mm thick layer of Adhesive and surface render on top of the installed boards and embed an alkali-resistant glass fibre mesh (7 × 7 mm). Overlap the mesh by 10 cm. Apply an additional 2–3 mm finishing layer on top and smooth the surface.
Tool cleaning
Clean tools with clean water immediately after use.
Storage and handling of waste
See the separate storage and disposal instructions https://www.fescon.fi/en/material-bank