What’s the difference? As you can see in the image, the materials designed for the superficial filtration block the particles on their surface, while those designed for deep filtration allow the penetration of particles within their own thickness. Frequently the accumulated particles act as an additional filter element, and thus allow to increase the separation efficiency. It is important to highlight that, compared to an increase of efficiency, there is also an increase of the pressure drop, which make necessary to clean or replace the filter element. As you may have guessed, given the lower penetration of particles, the materials that promote surface filtration are easier to clean and last longer. On the other hand, materials that promote deep filtration are difficult to keep clean. The cartridges exploit both of the filtration mechanisms described above: surface filtration, for example, is generally applied in sandblasting processes, with the use of paper cartridges. Bags, on the other hand, use only deep filtration. Before talking about the factors to take into consideration to choose between a bag or cartridge dedusting filter, it is necessary to do a in-depth analysis on the characteristics of the filter elements.