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                                                                   EXHIBIT 10.4f


                                 SIXTH AMENDMENT
                                     TO THE
                            STERLING CHEMICALS, INC.
              AMENDED AND RESTATED SALARIED EMPLOYEES' PENSION PLAN


                  WHEREAS, there is reserved to Sterling Chemicals, Inc. (the
"Company") in Section 15.1 of the Sterling Chemicals, Inc. Amended and Restated
Salaried Employees' Pension Plan (the "Plan") the right to amend the Plan;

                  NOW, THEREFORE, Section 2.1 of the Plan is hereby amended by
adding thereto the following:

                  For all purposes of this Plan, an employee of an Employer who
                  is a member of a collective bargaining unit shall not be an
                  eligible employee unless the bargaining agreement with the
                  Employer provides for his coverage.

                  All terms used herein that are defined in the Plan shall have
the same meanings given to such terms in the Plan, except as otherwise expressly
provided herein.

                  Except as amended and modified hereby, the Plan shall continue
in full force and effect and the Plan and this amendment shall be read, taken
and construed as one and the same instrument.

                  This amendment may be executed in several counterparts, each
of which shall be deemed an original, but all of which shall constitute but one
and the same instrument which may be evidenced by any one counterpart.

                  IN WITNESS WHEREOF, the Company has executed this instrument
this _______________, 1999.




                                    STERLING CHEMICALS, INC.


                                    By:
                                       ---------------------
                                    Name:
                                         -------------------
                                    Title:
                                          ------------------