Filters "Red tape" - ashless, made of filter paper type FB, corresponding to GOST 12026-76. This type of paper provides fast filtration and is made of special refined pulp. After annealing in a crucible at a temperature of 800°C, the filter itself leaves practically no ash and can be used for gravimetric analysis.
Red Tape filters can be used to filter hot acidic or alkaline solutions. Such resistance to aggressive media is explained by the fact that the filter paper from which these filters are made was previously impregnated with synthetic resins.
These filters allow high precision quantitative analysis. They are in the shape of a circle. Diameter - 110 mm.