Abstract: A method of manufacturing an annular seal for a heat recuperator tube end is disclosed as comprising loosely wrapping without appreciable tension at least one layer of a compressible and resilient blanket of unbonded ceramic fibers about an annular forming mandrel, stabilizing the inner area of the fiber layer, thereafter compressing the fibers to decrease their volume while not destroying the recuperative ability of the fibers to resiliently expand back to a volume substantially greater than their compressed volume when the compression is released by wrapping a retainer exteriorly of the fibers to compress them and to temporarily retain them in compressed condition, the retainer being destructable at operating temperatures of the tube ends of the recuperator in which the seal is to be used. A specific wrapping process utilizing overlapping sheets of heat destructable wrapping material is disclosed.