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                                                                     Exhibit 4.1

OI

CUSIP 687836 20 5
SEE REVERSE FOR CERTAIN DEFINITIONS

INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

CLASS B COMMON STOCK PAR VALUE $0.01
This CERTIFIES that


is the owner of

FULLY PAID AND NON-ASSESSABLE SHARES OF THE CLASS B COMMON STOCK OF owner of

OSCA, Inc., transferable on the books of the Corporation by the owner in person,
or by duly authorized attorney, upon surrender of this certificate properly
endorsed. This certificate and the shares represented hereby are subject to all
the terms, conditions and limitations of the Certificate of Incorporation and
all amendments thereto and supplements thereof. This certificate is not valid
until countersigned and registered by the Transfer Agent and Registrar. WITNESS
the facsimile seal of the Corporation and the facsimile signatures of its duly
authorized officers.

Dated:

/s/ Steven J. Brading
Secretary

/s/ Robert L. Hollier
President and Cheif Executive Officer

Countersigned and Registered:
     Norwest Bank
     (Minnesota, N.A.)

Transfer Agent
and Registrar,
By

Authorized Officer

OSCA, Inc.
         The Corporation will furnish WITHOUT CHARGE to EACH STOCKHOLDER WHO SO
REQUESTS, A FULL STATEMENT OF THE DESIGNATIONS, PREFERENCES AND RELATIVE,
PARTICIPATING, OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OR SERIES
THEREOF AUTHORIZED TO BE ISSUED AND THE QUALIFICATIONS, LIMITATIONS OR
RESTRICTIONS OF SUCH PREFERENCES AND/OR RIGHTS.

         The following abbreviations, when used in the inscription on the face
of this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM    -  as tenants in common   UNIF GIFT MIN ACT- ..... Custodian .....
                                           (Cust)       (Minor)
TEN ENT    -  as tenants by the entireties
                                           under Uniform Gifts to Minors
JT WROS    -  as joint tenants with right
              of survivorship and not as       Act ..........................
              tenants in common                    (State)

Additional abbreviations may also be used though not in the above list.

For value received, .......................hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE
                               .................................................

 ................................................................................

 ................................................................................

 ................................................................................

 ..........................................................................Shares
of Class B Common Stock represented by the within Certificate, and do
hereby irrevocably

constitute and appoint  ........................................................

 ........................................................................Attorney
to transfer the said Shares on the books of the within-named corporation with
full power of substitution in the premises.

Dated........................


                            ............................................



         NOTICE: The signature to this assignment must correspond with the name
as written upon the face of the certificate in every particular, without
alteration or enlargement or any change whatsoever.