A good primer or bonding agent must do more than simply wet the surface. It needs to spread evenly, penetrate or anchor appropriately to the substrate, create a stable intermediate layer, and improve the adhesion of the next material—whether that is putty, plaster, mortar, tile adhesive, or paint.
In practical formulation work, primer and bonding-agent performance depends on the balance of viscosity control, film formation, surface wetting, adhesion support, and foam control. MikaZone’s public content does not present a dedicated primer formulation page that we could verify, but it repeatedly shows these same functions across related materials. Its HEC pages position HEC as a core thickener for water-based coatings and paints; its PVA page highlights bonding strength and film formation; and its wall-putty application guide explicitly says to apply a bonding primer on weak or porous substrates before further finishing.