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                                                                   EXHIBIT 10(a)

                               FOURTH AMENDMENT TO
                           CREDIT AGREEMENT AND WAIVER



        THIS FOURTH AMENDMENT ("Amendment") dated as of March 31, 2003, by and
among the borrowers listed on Schedule 1 (collectively "Companies") and Comerica
Bank, a Michigan banking corporation ("Bank").

                                    RECITALS:

        A. Companies and Bank entered into a Credit Agreement dated as of April
25, 2001 which was amended by three amendments ("Agreement").

        B. Companies and Bank desire to amend the Agreement as hereinafter set
forth.

        NOW, THEREFORE, the parties agree as follows:

        1. The definitions of Consolidated Adjusted Net Income, Consolidated
Cash Flow Coverage Ratio (Environmental), Measuring Period and Revolving Credit
Maturity Date set forth in Section 1 of the Agreement are amended to read in
their entireties as follows and the definition of Consolidated Cash Flow
Coverage Ratio (Operating) is deleted:

               "Consolidated Adjusted Net Income" shall mean as of any date of
        determination thereof net income from continuing operations of Detrex
        and its consolidated Subsidiaries for the applicable Measuring Period
        (determined without giving effect to extraordinary gains or
        extraordinary losses), determined in accordance with GAAP, as
        consolidated in accordance with GAAP, less to the extent added in
        calculating such net income, the amount of any recoveries in
        environmental reserves (net of applicable taxes) and plus to the extent
        deducted in calculating such net income, the amount of any non-cash
        environmental expense accrued to environmental reserves (net of
        applicable taxes), any charges taken in connection with the closing of
        any facility of Detrex or any of its Subsidiaries, and any non-cash
        pension expense.

               "Consolidated Cash Flow Coverage Ratio (Environmental)" shall
        mean as of any date of determination thereof, a ratio, the numerator of
        which is Consolidated Adjusted Net Income for the applicable Measuring
        Period, plus depreciation and amortization expenses for such period, of
        Detrex and its consolidated Subsidiaries and the denominator of which is
        the sum of unfunded Capital Expenditures, payments on capital leases and
        dividends paid or payable during such period, of Detrex and its
        consolidated Subsidiaries plus the amount of all payments of principal
        paid or payable by Detrex and its consolidated Subsidiaries during such
        period, plus, to the extent not reflected in the calculation of
        Consolidated Adjusted Net Income, the amount of any cash expenditures


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        during such period by Detrex and its consolidated Subsidiaries which are
        deductions from long term or short term environmental reserves and all
        cash pension expenditures, all as determined in accordance with GAAP, as
        consolidated in accordance with GAAP.

                "Measuring Period" shall for any date of the determination
        ending on or before December 31, 2003, the period from January 1, 2003
        through such date of determination and for any date of determination
        occurring after December 31, 2003 shall mean the four preceding fiscal
        quarters ending on such date.

                "Revolving Credit Maturity Date" shall mean May 1, 2004.

        2. Section 9.1 of the Agreement is amended to read in its entirety as
follows:

               "Permit the Consolidated Cash Flow Coverage Ratio (Environmental)
        at any time to be less than the following amounts during the periods
        specified below:

<TABLE>
<S><C>
               June 30, 2003 through September 29, 2003          0.8 to 1.0
               September 30, 2003 through December 30, 2003      0.9 to 1.0
               December 31, 2003 and thereafter                  1.0 to 1.0"
</TABLE>


        3. Section 9.2 of the Agreement is amended to read in its entirety as
follows:

           "Permit Consolidated Tangible Net Worth at any time to be less
        than $5,840,000."

        4. Companies violated the provisions of Section 9.2 for the period ended
December 31, 2002 and the provisions of Sections 9.1 and 9.2 for the period
ended March 31, 2003 ("Covenant Violations"). Bank hereby waives any event of
default arising from the Covenant Violations. This waiver shall not act as a
consent or waiver of any other transaction, act or omission, whether related or
unrelated thereto, including any noncompliance with such covenants for any
period other than the periods ended on December 31, 2002 and March 31, 2003, as
applicable. This waiver shall not extend to or affect any obligation, covenant,
agreement or default not expressly waived hereby.

        5. Companies hereby represent and warrant that, after giving effect to
the amendments and waiver contained herein, (a) execution, delivery and
performance of this Amendment and any other documents and instruments required
under this Amendment or the Agreement are within each Company's corporate
powers, have been duly authorized, are not in contravention of law or the terms
of any Company's Articles of Incorporation or Bylaws, and do not require the
consent or approval of any governmental body, agency, or authority; and this
Amendment and any other documents and instruments required under this Amendment
or the Agreement, will be valid and binding in accordance with their terms; (b)
the continuing representations and warranties of each Company set forth in
Sections 7.1 through 7.15 of the Agreement are true and correct on and as of the
date hereof with the same force and effect as made on and as of the date hereof;
(c) the continuing representations and warranties of each


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Company set forth in Section 7.16 of the Agreement are true and correct as of
the date hereof with respect to the most recent financial statements furnished
to the Bank by Companies in accordance with Section 8.1 of the Agreement; and
(d) no Event of Default (as defined in the Agreement) or condition or event
which, with the giving of notice or the running of time, or both, would
constitute an Event of Default under the Agreement, as hereby amended, has
occurred and is continuing as of the date hereof.

        6. Except as expressly provided herein, all of the terms and conditions
of the Agreement remain unchanged and in full force and effect.

        7. This Amendment shall be effective upon execution of this Agreement by
Companies and the Bank.

        IN WITNESS the due execution hereof as of the day and year first above
written.

COMERICA BANK                               DETREX CORPORATION



By:__________________________________       By:_________________________________
                                                   Robert M. Currie

Its:__________________________________      Its:   Secretary


                                            THE ELCO CORPORATION



                                            By:_________________________________
                                                   Robert M. Currie

                                            Its:   Secretary



                                            HARVEL PLASTICS, INC.



                                            By:_________________________________


                                            Its:________________________________



                                            S.O. REALTY, INC.



                                            By:_________________________________
                                                   Robert M. Currie

                                            Its:   Secretary





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                                   SCHEDULE 1



Detrex Corporation

The Elco Corporation

Harvel Plastics, Inc.

S.O. Realty, Inc.





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