Self-supporting filter composite

In a fiber composite for use with a layer of glass fiber which is porous, and wherein said fibers have diameters between about 0.000035 and 0.00015 inch, the combination comprising:

• a) a porous mat of sufficient stiffness as to support said glass fiber layer during use as a filter, said mat consisting of compacted glass fibers, and
• b) an additional porous layer carried by and adhered to the mat to block escape of glass fibers or particles from the filter composite during gas flow therethrough.

In the method of forming a fibrous filter composite, the steps that include

• a) forming a first layer of glass fibers having random orientation, said layer being porous to gas flow therethrough, said first layer fibers having diameters between about 0.000035 and 0.00015 inch,
• b) forming a porous mat and supporting said first layer of fibers at one side of the mat, the mat being of sufficient stiffness as to support the glass fiber layer during use as a filter, the mat comprising compacted glass fibers.

The method of forming a filter that includes:

• a) forming a mat consisting of non-woven glass fibers, and forming a tufted layer of glass fibers on the mat, said fibers in said tufted layer having diameters between about 0.000035 and 0.00015 inch.
• b) and attaching a layer of porous material to a side of the mat,
• c) the overall thickness of the filter being less than about 0.40 inch.