Abstract: A method for encasing a porous body, such as fiberglass, in an envelope of a plastic sheet material in which the plastic material is embedded in the fiberglass without the use of an adhesive material other than the plastic sheet material.

Abstract: A method for encasing a fiberglass mat between a pair of plastic sheets. The fiberglass mat is disposed in a vacuum chamber in which a first sheet is mounted above the mat to form one wall of the chamber. The sheet is heated until it becomes adhesive. A vacuum is applied beneath the sheet to draw it into intimate contact with the mat. The sheet is cooled and trimmed and the mat turned upside down. A second plastic sheet is suspended adjacent the mat and heated until it becomes adhesive. A vacuum is applied beneath the second sheet so that it is drawn toward the first sheet, compressing the fiberglass mat to reduce its thickness. The two sheets are heat sealed around the mat so that it is encased in a compressed condition between the two sheets.