Bottom Spray Coating
The innovative solution for making particles functional
The advantage of bottom spray coating (Wurster Processing) is the the coating is very uniformly applied and results in a robust film quality. This method of application is particularly suitable for adding functional coatings to particles to achieve defined and reproducible release profiles for an active substance by way of the coating applied.
In bottom spray coating, the spraying is done from below the product bed up into the product flow. The spray nozzles are integrated into the upward flow of the upbed (part of the bottom plate) and thus completely surrounded by the product. By combining the bottom plate with the Wurster column, a targeted and controlled movement of the particles can be achieved. This is required for the optimal application of coating materials to the particles.
The uniform particle retention times through the spray zone assure homogenous film quality and application volume per individual particles. The particle speed through the Wurster column also generates high kinetic energy in the upbed, which prevents the particles from sticking together prior to carrier solution evaporation. This movement through the upbed allows very small particles to be coated without agglomeration. Since the nozzle is located in the middle of the product flow and sprays uniformly, a premature evaporation of the carrier solution is prevented. The result is an optimally applied film for targeting the intended functions of your product.