Blade Coating Bases are those various pastes, fats and lards that provide a stable grease able to withstand the addition of alchemical ingredients without losing viscosity. The bases easily spread over the entire length of the weapon, distributing the powerful ingredients evenly for maximum results. Care should be taken, however, not to touch one's eyes or other sensitive body parts until thoroughly washing your hands.
Standard quality allows up to 3 ingredients. (This quality of base is not found in the game.)
Dog tallow is actually required for a quest: The Dogcatcher of Vizima. It can be found in many places, but Salamandra bodies are a good bet, as is Shani's house, though the exact location within Shani's house varies. It will also appear in the crypt inside the sewers, near the Aard Circle of Elements. Of course, there is always the option to kill the hapless animals under cover of night.