Fibrous product and method and apparatus for making the product

A method of making a nonwoven fibrous insulation product having at least a tri-modal fiber diameter distribution comprising:

• providing a first fiber grouping having a selected fiber diameter distribution primarily for a selected thermal insulating property that forms a generally bell shaped curve at a fiber diameter of about 2 microns;
• providing a second fiber grouping having a selected fiber diameter distribution primarily for a selected rigidity insulating property that forms a generally bell shaped curve at a fiber diameter of about 4 microns;
• providing a third fiber grouping having a selected fiber diameter distribution primarily for a selected recovery insulating property that forms a generally bell shaped curve at a fiber diameter of about 6 microns;
• and
• intermingling and entangling fibers of the first, second, and third fiber groupings in an amount of about 40% by weight of the first fiber grouping, about 30% by weight of the second fiber grouping and about 30% by weight of the third fiber grouping to form a nonwoven fibrous insulation product.