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                                                                Exhibit 10.20(k)

                                                                  CONFORMED COPY

                             OMNIBUS AMENDMENT NO. 2
                                       TO
                         RECEIVABLES SALE AGREEMENT AND
                         RECEIVABLES PURCHASE AGREEMENT
                       (Arch Chemicals Receivables Corp.)

                  [Sale of Microelectronic Materials Business]

            THIS OMNIBUS AMENDMENT NO. 2 TO RECEIVABLES SALE AGREEMENT AND
RECEIVABLES PURCHASE AGREEMENT is entered into as of November 12, 2004, by and
among ARCH CHEMICALS, INC. ("Arch"), CERTAIN AFFILIATES OF ARCH LISTED ON THE
SIGNATURE PAGES HERETO (each such affiliate, together with Arch, being,
individually, an "Originator" and, collectively, the "Originators"), ARCH
CHEMICALS RECEIVABLES CORP. (the "Seller"), BLUE RIDGE ASSET FUNDING
CORPORATION, THE LIQUIDITY BANKS FROM TIME TO TIME PARTY TO THE CREDIT AND
SECURITY AGREEMENT and WACHOVIA BANK, NATIONAL ASSOCIATION. Capitalized terms
used, but not defined, herein shall have the meanings given to such terms in the
Purchase Agreement referred to below.

            WHEREAS, each Originator and the Seller entered into that certain
Receivables Sale Agreement, dated as of March 19, 2002 (as amended to the date
hereof, the "Original Sale Agreement" and as amended hereby, the "Sale
Agreement");

            WHEREAS, the Seller, Blue Ridge, each other Lender, the Servicer and
the Agent entered into that certain Receivables Purchase Agreement, dated as of
March 19, 2002 (as amended to the date hereof, the "Original Purchase
Agreement", as amended hereby, the "Purchase Agreement", the Original Purchase
Agreement, together with the Original Sale Agreement are referred to herein as
the "Original Agreements" and the Purchase Agreement and the Sale Agreement are
referred to herein as the "Agreements"); and

            WHEREAS, the parties hereto desire to amend each of the Original
Agreements;

            NOW THEREFORE, in consideration of the premises and the other mutual
covenants contained herein, the parties hereto agree as follows:

      SECTION 1. Sale of Microelectronic Materials Business.

      (a) Arch hereby represents and warrants as follows:

            (i) Arch plans to sell, on or before December 31, 2004 (the actual
date of such sale being referred to as the "Sale Date") the majority of its
business of developing, manufacturing, marketing and selling microelectronic
materials products to the microelectronics, semiconductor and other electronic
components industries (the "Microelectronic Materials Business"), including the
stock of Arch Specially Chemicals, Inc. ("ASCI") and the majority of

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the assets of Arch Electronic Chemicals, Inc. ("AEC") and certain assets of Arch
Chemicals Specialty Products, Inc. ("ACSP") each of whom is an Originator;

            (ii) Arch, AEC, ACSP and the Seller each intends to sell all
outstanding Receivables and Related Security relating to the Microelectronic
Materials Business, all of which are currently, and as of the Transfer Date (as
defined below) will be, owned by the Seller (the "Microelectronic Materials
Business Receivables"); and

            (iii) for a period of no more than one hundred twenty (120) days
after the Transfer Date (as defined below) (such period being the "Interim
Period"), collections relating to the Microelectronic Materials Business
Receivables may be sent to a Lock-Box and/or deposited in a Collection Account.

      (b) Arch, ASCI, AEC and ACSP each hereby requests that:

            (i) on November 18, 2004 (the "Transfer Date"), the Seller be
permitted to sell the Microelectronic Materials Business Receivables to Arch,
ASCI, AEC and ACSP, as applicable, for a repurchase price to be determined by
Arch, ASCI, AEC and ACSP, as applicable, and the Seller, subject to approval by
the Agent (the "Repurchase Price");

            (ii) on the Transfer Date, the Agent, Blue Ridge and the Seller each
release their interests in the Microelectronic Materials Business Receivables,
including liens thereon;

            (iii) for the Interim Period, the Agent permit the collections of
the Microelectronic Materials Business Receivables to be made to the Lock-Boxes
and the Collection Accounts; and

            (iv) the Servicer be permitted, on the terms and conditions set
forth herein, to remove from the Collection Accounts upon identification by the
Servicer thereof all Collections received in respect of the Microelectronic
Materials Business Receivables.

      (c) Each Originator (other than ASCI, AEC and ACSP) hereby makes each of
the representations and warranties made by it under Section 2.1 of the Original
Sale Agreement on the date hereof and each Seller Party hereby makes each of the
representations and warranties made by it under Section 5.1 of the Original
Purchase Agreement on the date hereof. All such representations and warranties
shall survive the date hereof. Each Originator (other than ASCI, AEC and ACSP)
hereby represents and warrants that, as of the date hereof, no Termination Event
or Unmatured Termination Event exists. Each of the Seller and the Servicer
hereby represents and warrants that, as of the date hereof, no Amortization
Event or Unmatured Amortization Event exists.

      SECTION 2. Amendments to Original Agreements and Waivers Relating to the
Sale of Microelectronic Materials Business.

      The parties hereto agree that the Original Agreements shall be amended,
modified and supplemented by the following amendments, agreements and waivers,
notwithstanding any provision of any of the Original Agreements to the contrary:

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      (a) Arch agrees that at least two (2) Business Days prior to the Transfer
Date it will provide written notice thereof to the Seller and the Agent, which
notice shall set forth the Transfer Date, the proposed Repurchase Price and the
aggregate Outstanding Balance of the Microelectronic Materials Business
Receivables as of the date of such notice.

      (b) On the Transfer Date (i) each of the Seller Parties shall be deemed to
reaffirm all representations and warranties made by it in Article V of the
Purchase Agreement and to agree that all such covenants, representations and
warranties shall be deemed to have been remade as of the Transfer Date, (ii)
each of the Seller Parties shall be deemed to represent and warrant that no
Amortization Event or Unmatured Amortization Event has occurred and be
continuing as of the Transfer Date, both before and after giving effect to the
sale of the Microelectronic Materials Business, (iii) each of the Originators
shall be deemed to reaffirm all representations and warranties made by it in
Article II of the Sale Agreement and to agree that all such covenants,
representations and warranties shall be deemed to have been remade as of the
Transfer Date and (iv) each of the Originators shall be deemed to represent and
warrant that no Termination Event or Unmatured Termination Event shall have
occurred and be continuing as of the Transfer Date, both before and after giving
effect to the sale of the Microelectronic Materials Business.

      (c) Provided that as of the Transfer no Amortization Event, Unmatured
Amortization, Termination Event or Unmatured Termination has occurred or would
occur as a result of the repurchase of any of the Microelectronic Materials
Business Receivables, then, on the Transfer Date, unless the Agent shall have
notified Arch not later than 2:00 p.m. (New York City time) on the Business Day
immediately preceding the Transfer Date, that the Agent disagrees with the
Repurchase Price, the Seller shall, without further action, irrevocably sell,
transfer and assign to Arch, ASCI, AEC or ACSP, as applicable, upon receipt by
the Seller of the Repurchase Price in accordance with the terms hereof, without
recourse, representation or warranty, all right, title and interest of the
Seller in, to and under all of the Microelectronic Materials Business
Receivables outstanding on the Transfer Date, together with all Related Security
related thereto.

      (d) On the Transfer Date, Arch, as Servicer, shall pay the Repurchase
Price to the Agent's Account by wire transfer in immediately available funds and
the Agent shall apply such amount to the reduction of the Aggregate Invested
Amount, accrued Yield on such amount of the Aggregate Invested Amount so repaid
and accrued Fees on such amount of the Aggregate Invested Amount so repaid.

      (e) Upon receipt by the Agent of the Repurchase Price in the Agent's
Account in immediately available funds by wire transfer, the Agent, the Seller
and Blue Ridge and their respective successors and assigns shall, without
further action, irrevocably release in full each of their respective interests
in all of the Microelectronic Materials Business Receivables and all Related
Security related thereto, including but not limited to any security interests
therein. The Agent and Blue Ridge each agree to take such further actions, at
Arch's sole cost and expense, that Arch may reasonably request to evidence or
confirm such releases, including the preparation and filing of UCC-3 financing
statements relating to the release of interests in the Microelectronic Materials
Business Receivables.

      (f) Arch, in its capacity as Servicer, shall (i) as soon as reasonably
practicable after the Transfer Date (but in no event later than the second
Business Day after the Transfer Date),

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provide written notice to the Seller and the Agent of the final aggregate
Outstanding Balance of all Microelectronic Materials Business Receivables sold
on the Transfer Date (the "Sale Date Microelectronic Materials Business
Receivables Balance") and (ii) from and after the Transfer Date, identify within
two (2) Business Days after receipt, all collections received in any Collection
Account constituting collections received in respect of the Microelectronic
Materials Business Receivables.

      (g) Immediately upon identification of any Collections received in respect
of the Microelectronic Materials Business Receivables, Arch, as Servicer, shall
remove such collections received in respect of the Microelectronic Materials
Business Receivables from the related Collection Account, up to an aggregate
amount at any time not to exceed the Transfer Date Microelectronic Materials
Business Receivables Balance.

      (h) Arch, as Servicer, agrees that it will provide to the Agent on the
first Business Day of each week for each week following the Transfer Date
through and including the earlier of (i) the week in which the last
Microelectronic Materials Business Receivable is paid in full and (ii) the week
in which the 120th day after the Transfer Date occurs, additional written
reporting satisfactory to the Agent relating to the Collections received in
respect of the Microelectronic Materials Business Receivables during the
preceding week.

      (i) Arch agrees that, if the Microelectronic Materials Business
Receivables have not been paid in full by the 120th day after the Transfer Date,
it will send notices to each Obligor of any unpaid Microelectronic Materials
Business Receivable instructing such Obligor to make all payments on such
Microelectronic Materials Business Receivables to such other lock-box or post
office box that is not owned by the Seller as Arch may choose.

      (j) Arch and the Seller each hereby agrees to indemnify (and pay upon
demand to) each Indemnified Party (as defined in the Purchase Agreement) and its
assigns, officers, directors, agents and employees from and against any and all
damages, losses, claims, taxes, liabilities, costs, expenses and for all other
amounts payable, including reasonable attorneys' fees and disbursements awarded
against or incurred by any such Indemnified Party arising out of or related to
any Microelectronic Materials Business Receivables and any Collection relating
to any Microelectronic Materials Business Receivables.

      (k) Subject to the satisfaction of the above terms and conditions and
provided that no Amortization Event or Unmatured Amortization Event has
occurred, the Seller, Blue Ridge and Wachovia, upon receipt of the Repurchase
Price as provided above, shall, without further action, be deemed to waive any
default under the Transaction Documents that may result from the receipt of any
collections received in respect of the Microelectronic Materials Business
Receivables in any Collection Account during the Interim Period; provided,
however, this waiver shall not, except as expressly provided herein, operate as
a waiver of any right, power or remedy of the Agent, any Lender or any other
Secured Party under any of the Transaction Documents.

      (l) Arch hereby agrees to indemnify (and pay upon demand to) Seller and
its assigns, officers, directors, agents and employees (each an "Indemnified
Party") from and against any and all damages, losses, claims, taxes,
liabilities, costs, expenses and for all other amounts payable, including
attorneys' fees and disbursements awarded against or incurred by any

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Indemnified Party arising out of or related to any Microelectronic Materials
Business Receivable or any collection relating to any Microelectronic Materials
Business Receivable, but in each case subject to the limitations on
indemnifications set forth in Sections 6.1(a), (b) and (c) of the Sale
Agreement.

      (m) The Seller, Blue Ridge and the Agent each hereby agrees to the removal
of ASCI, AEC and ACSP as Originators and each of ASCI, AEC and ACSP is hereby
released from all duties, obligations and liabilities as an Originator under the
Original Sale Agreement. Arch hereby agrees to assume, as of the date hereof,
all duties and obligations of each of ASCI, AEC and ACSP that exist as of the
date hereof, including without limitation all liabilities of ASCI, AEC and ACSP
that would otherwise survive termination of the Original Sale Agreement pursuant
to the last sentence of Section 7.10(b) of the Original Sale Agreement and
agrees that it will not assert any defense to any such liability.
Notwithstanding the foregoing, the provisions of Section 7.5 of the Original
Sale Agreement shall, with respect to each of ASCI, AEC and ACSP, survive the
termination of the obligations of each of ASCI, AEC and ACSP under the Original
Sale Agreement.

      (n) ASCI, AEC, ACSP and the Seller each hereby confirms that, upon payment
of the Repurchase Price and the repurchase of the Microelectronic Materials
Business Receivables, each of the Subordinated Notes issued by the Seller to
ASCI, AEC and ACSP will be paid in full and cancelled, and that none of ASCI,
AEC and/or ACSP or any of their respective successors or assigns will have any
rights under such Subordinated Note.

      (o) All references in the Original Sale Agreement to each of ASCI, AEC and
ACSP are hereby deleted.

      (p) Exhibit IV to the Original Purchase Agreement is hereby deleted and
replaced with Exhibit IV to this Amendment.

      SECTION 3. Agreements in Full Force and Effect as Amended.

      (a) Except as specifically amended hereby, each of the Original Agreements
shall remain in full force and effect. This Amendment shall not constitute a
novation of any or all of the Original Agreements, but shall constitute an
amendment of each such Original Agreement only. The parties hereto agree to be
bound by the terms and conditions of each Original Agreement, as amended by this
Amendment, as though such terms and conditions were set forth herein.

      (b) As of the date first set forth above, each reference in the Original
Agreements to "this Agreement", "hereunder", "hereof", "herein" or words of like
import shall mean and be, and any references to such Agreement in any other
document, instrument or agreement executed and/or delivered in connection with
the Original Purchase Agreement shall mean and be, a reference to such Original
Agreement as amended hereby.

      (c) Arch hereby agrees that in addition to any costs otherwise required to
be paid pursuant to the Transaction Documents, Arch shall pay all legal fees and
out-of-pocket expenses of the Agent's counsel, Hunton & Williams, and all audit
fees and due diligence costs incurred by the Agent in connection with the
consummation of this Amendment and the transactions

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contemplated by this Amendment, including, without limitation, in connection
with the Sale Date and the Interim Period.

      SECTION 4. Conditions to Effectiveness of this Amendment.

The amendments set forth herein shall not be effective until the date on which
the Agent shall have received authorized signatures from each of the
Originators, the Servicer and the Seller.

      SECTION 5. Miscellaneous.

      (a) This Amendment may be executed in any number of counterparts, and by
the different parties hereto on the same or separate counterparts, each of which
shall be deemed to be an original instrument but all of which together shall
constitute one and the same agreement. Delivery of an executed counterpart of a
signature page to this Amendment by facsimile shall be as effective as delivery
of a manually executed counterpart of a signature page to this Amendment.

      (b) The descriptive headings of the various sections of this Amendment are
inserted for convenience of reference only and shall not be deemed to affect the
meaning or construction of any of the provisions hereof.

      (c) This Amendment may not be amended or otherwise modified except as
provided in the Agreement.

      (d) THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES UNDER
THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED AND ENFORCED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REFERENCE TO ITS CONFLICT OF LAWS
PROVISIONS (INCLUDING SECTION 5-1401 OF THE GENERAL OBLIGATIONS LAW BUT
OTHERWISE WITHOUT REGARD TO CONFLICTS OF LAW PRINCIPLES).

                   [Remainder of Page Intentionally Left Bank]

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      IN WITNESS WHEREOF, the parties have caused this Amendment to be executed
by their respective officers thereunto duly authorized, as of the date first
above written.

                                        ARCH CHEMICALS RECEIVABLES CORP.,
                                        as the Seller

                                        By: /s/ W. Paul Bush
                                            ------------------------------
                                          Name: W. Paul Bush
                                          Title: VP and Treasurer

                                        ARCH CHEMICALS, INC.,
                                        as an Originator and as the Servicer

                                        By: /s/ W. Paul Bush
                                            ------------------------------
                                          Name: W. Paul Bush
                                          Title: VP and Treasurer

                                        ARCH SPECIALTY CHEMICALS, INC.,
                                        as an Originator

                                        By: /s/ W. Paul Bush
                                            ------------------------------
                                          Name: W. Paul Bush
                                          Title: Treasurer

                                        ARCH CHEMICALS SPECIALTY PRODUCTS, INC.,
                                        as an Originator

                                        By: /s/ W. Paul Bush
                                            ------------------------------
                                          Name: W. Paul Bush
                                          Title: Treasurer

                                        ARCH ELECTRONIC CHEMICALS, INC.,
                                        as an Originator

                                        By: /s/ W. Paul Bush
                                            ------------------------------
                                          Name: W. Paul Bush
                                          Title: Treasurer

   Signature page for Omnibus Amendment No. 2 for Arch Chemicals Receivables
                                 Corp. Facility

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                                         ARCH WOOD PROTECTION, INC.,
                                         as an Originator

                                         By: /s/ W. Paul Bush
                                             ------------------------------
                                           Name: W. Paul Bush
                                           Title: Treasurer

                                         ARCH PERSONAL CARE PRODUCTS, L.P.,
                                         as an Originator
                                         By: Arch PCI, Inc.,
                                         as general partner

                                         By: /s/ W. Paul Bush
                                             ------------------------------
                                           Name: W. Paul Bush
                                           Title: Treasurer

   Signature page for Omnibus Amendment No. 2 for Arch Chemicals Receivables
                                 Corp. Facility

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                                         BLUE RIDGE ASSET FUNDING CORPORATION

                                         BY: Wachovia Capital Markets LLC
                                         as Attorney-in-Fact

                                         By: /s/ Douglas R. Wilson, Sr.
                                             ------------------------------
                                         Name: Douglas R. Wilson, Sr.
                                         Title: Vice President

                                         WACHOVIA BANK, NATIONAL ASSOCIATION
                                         as a Liquidity Bank and as Agent

                                         By: /s/ Gary G. Fleming, Jr.
                                            ----------------------------
                                         Name: Gary G. Fleming, Jr.
                                         Title: Director

   Signature page for Omnibus Amendment No. 2 for Arch Chemicals Receivables
                                 Corp. Facility