SILAC is an acrylic modified silicone water repellent used to render porous exterior building materials water repellent, especially Oamaru stone. Water absorption into the building material is stopped or greatly reduced while water within the material is still able to evaporate out. When applied, SILAC penetrates into the surface sealing smaller pores and lining the larger pores and capillaries with a water repellent resin. SILAC may slightly darken concrete and cement based products to which it is applied. Very dense surfaces treated with SILAC may show a slight gloss. SILAC has excellent alkali and U.V. resistance.
- SILAC is generally used to render vertical and inclined surfaces, such as walls and roofs, water repellent. It can be used on concrete, cement plaster, blockwork, bricks, roofing tiles, fibrous cement and natural stone. It has been used successfully on cracked horizontal surfaces such as balconies as a remedial water repellent.
- Due to the acrylic content of SILAC, it is capable of sealing surfaces which are too porous for treatment with normal water repellents.
- SILAC will lift the colour of exposed aggregate surfaces and is suitable for use as a sealant on slate.
- SILAC is very effective in the protection of tile grout from discoloration on shower floors, benches etc.
- SILAC is very effective on Oamaru stone helping to maintain a clean and waterproof surface and preventing degradation.
- The surfaces to be treated must be free from dust, dirt, efflorescence, moss, lichen and any other material which is likely to prevent or reduce penetration of SILAC into the surface. Previously painted surfaces are unsuitable for treatment unless the coating can be completely removed to permit absorption. Oamaru stone should be washed and allowed to dry thoroughly, unless weathered. It is important to remove any loose dust (from sawing, masonry work, etc) from the pores before application of SILAC.