Exhibit 21 THERMO FIBERTEK INC. Subsidiaries of the Registrant At February 23, 2000, the Registrant owned the following companies: NAME STATE OR JURISDICTION PERCENT OF OF INCORPORATION OWNERSHIP - ------------------------------------------------------------------------------------------------------------ AES Equipos y Sistemas S.A. de C.V. Mexico 100 ArcLine Products, Inc. New York 100 Fibertek Construction Company, Inc. Maine 100 Thermo AES Canada Inc. Canada 100 Thermo Black Clawson Inc. Delaware 100 Thermo Black Clawson (China) China 100 Thermo Black Clawson S.A. France 100 Thermo Fibertek Holdings Limited England 100 Thermo Black Clawson Limited England 100 Thermo Fibertek U.K. Limited England 100 D.S.T. Pattern Engineering Company Limited England 100 Vickerys Limited England 100 Winterburn Limited England 100 Thermo Web Systems, Inc. Massachusetts 100 Fiberprep Inc. Delaware 95 (31.05% of which shares are owned directly by E. & M. Lamort, S.A.) Fiberprep Securities Corporation Delaware 100 TMO Lamort Holdings Inc. Delaware 100 E. & M. Lamort, S.A. France 100 Lamort Equipementos Industrials Ltda. Brazil 60* Lamort GmbH Germany 100 Lamort Iberica S.A. Spain 100 Lamort Italia S.R.L. Italy 100 Lamort Paper Services Ltd. England 100 Nordiska Lamort Lodding A.B. Sweden 100 Thermo Fibergen Inc. Delaware 73.58 (additionally 0.11% of the shares are owned directly by Thermo Electron Corporation) Fibergen Securities Corporation Massachusetts 100 GranTek Inc. Wisconsin 100 Next Fiber Products Inc. Delaware 51* *Joint Venture/Partnership