A newly developed thermal embossing technique combines the advantageous characteristics of separator, mini-pleat thread and forming techniques. Without using any foreign materials as spacers, pleats can be made up to 280 mm deep, thus enabling the production of disposal-friendly filters with low pressure drops. The V-shaped pleat geometry inherent in the process ensures a homogeneous flow through the filter medium, and low-turbulence downstream flow. The new multi-scan test is employed for quality assurance and filter testing to the specifications laid down in the new DIN 24183 and EN 1822 standards, using sophisticated measuring technology and a 31-channel condensation nuclei counter battery.