
<PAGE>

                                                                       EXHIBIT C

                  SUPPLEMENTAL  STOCKHOLDERS  AGREEMENT,  dated as of March  15,
1995 (this  "Agreement"),  between ADU ACQUISITION INC., a Delaware  corporation
("Purchaser")  and an  indirect  wholly-owned  subsidiary  of FKI plc, a company
organized  under  the laws of  England  ("Parent"),  and the  persons  listed on
Schedule A hereto (each,  individually,  a "Stockholder" and, collectively,  the
"Stockholders").

                  WHEREAS,  Parent and Purchaser  have entered into an Agreement
and Plan of  Merger,  dated  as of the  date  hereof  (the  "Merger  Agreement";
capitalized  terms not defined in this Agreement  have the meanings  ascribed to
them in the Merger Agreement),  with Amdura Corporation,  a Delaware corporation
(the "Company"),  which provides, among other things, upon the terms and subject
to the  conditions  thereof,  for  the  acquisition  by  Purchaser  of  all  the
outstanding  shares of Common  Stock,  par value $.01 per share,  of the Company
("Company Common Stock") through (a) a tender offer (the "Offer") for all shares
of Company  Common  Stock for the "Per Share  Amount"  (as defined in the Merger
Agreement) and (b) a second-step  merger  pursuant to which Purchaser will merge
with and into the Company (the "Merger") and all  outstanding  shares of Company
Common  Stock  (other than shares of Company  Common  Stock held by Purchaser or
Parent  or any  direct  or  indirect  wholly-owned  subsidiary  of Parent or the
Company and shares of Company  Common Stock held in the treasury of the Company)
will be converted into the right to receive the Per Share Amount in cash; and

                  WHEREAS,   as  of  the  date  hereof,  each  Stockholder  owns
(beneficially  or of record)  the number of shares of Company  Common  Stock set
forth opposite such Stockholder's name on Schedule A hereto; and

                  WHEREAS,  Purchaser and each  Stockholder  have entered into a
Stockholders  Agreement,  dated the date hereof (the "Stockholders  Agreement");
and

                  WHEREAS,  as a  condition  to the  willingness  of Parent  and
Purchaser to enter into the Merger Agreement, Parent and Purchaser have required
that the  Stockholders  agree,  and in order to induce  Parent and  Purchaser to
enter into the Merger Agreement,  each Stockholder has agreed, severally and not
jointly,  to compensate  Purchaser in the event that such  Stockholder  does not
tender pursuant to the Offer,  in accordance with the terms of the  Stockholders
Agreement, all the shares of the Company Common Stock now owned (beneficially or
of  record)  and  which may  hereafter  be  acquired  by each  Stockholder  (the
"Shares").

                  NOW,  THEREFORE,  in  consideration  of the  foregoing and the
mutual covenants and agreements  contained  herein,  and intending to be legally
bound hereby, the parties hereto hereby agree as follows:

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                                    ARTICLE I

               REPRESENTATIONS AND COVENANTS OF THE STOCKHOLDERS

                  SECTION  1.01.  Authority  Relative  to this  Agreement.  Each
Stockholder  represents  and warrants to  Purchaser,  severally and not jointly,
that such  Stockholder  has all  necessary  power and  authority  to execute and
deliver this Agreement,  to perform its obligations  hereunder and to consummate
the transactions  contemplated  hereby;  that the execution and delivery of this
Agreement by such  Stockholder and the  consummation by such  Stockholder of the
transactions  contemplated  hereby have been duly and validly  authorized by all
necessary  corporate  action;  that this  Agreement  has been  duly and  validly
executed and delivered by such Stockholder and, assuming the due  authorization,
execution  and delivery by  Purchaser,  constitutes  a legal,  valid and binding
obligation of such Stockholder,  except to the extent such enforceability may be
limited by bankruptcy, insolvency,  reorganization,  moratorium or other similar
laws relating to or affecting generally the enforcement of creditors' rights and
by the  availability of equitable  remedies;  that the execution and delivery of
this  Agreement  by such  Stockholder  does  not,  and the  performance  of this
Agreement by such  Stockholder will not conflict with or violate the Certificate
of  Incorporation or By-laws of such Stockholder or conflict with or violate any
law, rule, regulation,  order, judgment or decree applicable to such Stockholder
or by which any  property or asset of such  Stockholder  is bound or affected or
require any consent,  approval,  authorization  or permit of, or filing with, or
notification to, any governmental or regulatory authority,  domestic or foreign,
to be obtained or made by such Stockholder  except for applicable  requirements,
if any, of the Exchange Act.


                  SECTION 1.02.  Fee. If the Offer is terminated  because of the
failure of any condition  thereof and a Third Party  Transaction  is consummated
within 180 days  thereafter,  then each  Stockholder  shall pay  Purchaser a fee
equal to: (a) if any Shares of such Stockholder were sold,  exchanged,  disposed
of or cancelled in the Third Party  Transaction,  50% of the excess,  if any, of
(i) the  consideration  per Share received by such Stockholder for the Shares so
sold,  exchanged,  disposed  of or  cancelled  over (ii) the Per  Share  Amount,
multiplied by the number of Shares so sold, exchanged, disposed of or cancelled,
and (b) if no Shares of such  Stockholder were sold,  exchanged,  disposed of or
cancelled  in the  Third  Party  Transaction  but such  Stockholder  received  a
distribution  in  respect  of  its  Shares  as  a  result  of  the  Third  Party
Transaction,  50% of the excess, if any, of (i) the amount per Share distributed
to such Stockholder  divided by the percentage of the consolidated  total assets
of the  Company  disposed of in the Third  Party  Transaction  over (ii) the Per
Share Amount,  multiplied by the percentage of the consolidated  total assets of
the Company disposed of in the Third Party Transaction and then by the number of
Shares  then  owned by such  Stockholder.  Such fee  shall be paid to  Purchaser
promptly (but in no event later than one business day) after such  Stockholder's
receipt of the consideration or distribution.



                                        21

<PAGE>



                                   ARTICLE II

                                 MISCELLANEOUS

                  SECTION 2.01.  Expenses.  Except as otherwise provided herein,
all costs and expenses incurred in connection with the transactions contemplated
by this Agreement shall be paid by the party incurring such expenses.

                  SECTION  2.02.  Further   Assurances.   Each  Stockholder  and
Purchaser  will execute and deliver all such further  documents and  instruments
and take all such further  action as may be necessary in order to consummate the
transactions contemplated hereby.

                  SECTION 2.03. Specific  Performance.  The parties hereto agree
that irreparable damage would occur in the event any provision of this Agreement
was not performed in accordance with the terms hereof and that the parties shall
be entitled  to specific  performance  of the terms  hereof,  in addition to any
other remedy at law or in equity.

                  SECTION 2.04. Entire Agreement. This Agreement constitutes the
entire  agreement  between  Purchaser and the  Stockholders  with respect to the
subject matter hereof and supersedes  all prior  agreements and  understandings,
both written and oral,  between  Purchaser and each  Stockholder with respect to
the subject matter hereof.

                  SECTION 2.05. Assignment. This Agreement shall not be assigned
by operation of law or otherwise  (other than by will or the laws of descent and
distribution),  except  the  Purchaser  may  assign all or any of its rights and
obligations hereunder to any wholly-owned subsidiary of Parent, provided that no
such assignment  shall relieve  Purchaser of its  obligations  hereunder if such
assignee does not perform such obligations.

                  SECTION 2.06.  Parties in Interest.  This  Agreement  shall be
binding upon, inure solely to the benefit of, and be enforceable by, the parties
hereto and their  successors and permitted  assigns.  Nothing in this Agreement,
express or implied,  in intended  to or shall  confer upon any other  person any
right,  benefit  or remedy of any nature  whatsoever  under or by reason of this
Agreement.

                  SECTION 2.07.  Amendment;  Waiver.  This  Agreement may not be
amended  except by an instrument in writing  signed by the parties  hereto.  Any
party hereto may (i) extend the time for the  performance  of any  obligation or
other  act  of  any  other  party  hereto,  (ii)  waive  any  inaccuracy  in the
representations  and warranties  contained  herein or in any document  delivered
pursuant  hereto and (iii) waive  compliance  with any  agreement  or  condition
contained herein other than the condition set forth in Section 1.04 with respect
to satisfaction of the Minimum Condition.  Any such extension or waiver shall be
valid if set forth in an instrument in writing signed by the party or parties to
be bound thereby.

                  SECTION 2.08. Severability.  If any term or other provision of
this Agreement is invalid, illegal or incapable of being enforced by any rule of

                                            22

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law, or public  policy,  all other  conditions  and provisions of this Agreement
shall  nevertheless  remain in full force and effect so long as the  economic or
legal  substance  of this  Agreement  is not  affected in any manner  materially
adverse to any party. Upon such  determination  that any term or other provision
is invalid,  illegal or incapable of being  enforced,  the parties  hereto shall
negotiate  in good faith to modify this  Agreement  so as to effect the original
intent of the parties as closely as possible in a mutually  acceptable manner in
order that the terms of this Agreement remain as originally  contemplated to the
fullest extent possible.

                  SECTION 2.09. Notices. All notices,  requests, claims, demands
and other  communications  hereunder shall be in writing and shall be given (and
shall be deemed to have been duly given upon receipt) by delivery in person,  by
cable,  telecopy,  telegram or telex or by registered or certified mail (postage
prepaid,  return receipt  requested) to the respective  parties at the following
addresses  (or at such  other  address  for a party as shall be  specified  in a
notice given in accordance with this Section 2.09):

                  if to Purchaser:

                           ADU Acquisition Inc.
                           c/o FKI Industries Inc.
                           425 Post Road
                           Fairfield, CT  06430-0970
                           Facsimile No.  (203) 255-7101
                           Attention:  General Counsel

                  with copies to:

                           FKI plc
                           West House
                           King Cross Road
                           Halifax, West Yorkshire  HX1 1EB
                           England
                           Facsimile No.  (011) 44-422-330-407
                           Attention:  Company Secretary

                  and

                           Parson & Brown
                           230 Park Avenue
                           New York, NY  10169
                           Facsimile No.  (212) 682-9112/9113
                           Attention:  James H. Bell, Esq.


                                                 23

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                  if to a Stockholder:

                           to its address set forth on Schedule A hereto.


                  SECTION 2.10.  Governing Law. This Agreement shall be governed
by,  and  construed  in  accordance  with,  the laws of the  State  of  Delaware
applicable to contracts executed in and to be performed in that State.

                  SECTION 2.11. Headings.  The descriptive headings contained in
this  Agreement  are included for  convenience  of reference  only and shall not
affect in any way the meaning or interpretation of this Agreement.

                  SECTION 2.12. Counterparts.  This Agreement may be executed in
one or more  counterparts,  and by the  different  parties  hereto  in  separate
counterparts,  each of which when executed shall be deemed to be an original but
all of which taken together shall constitute one and the same agreement.



                                             24

<PAGE>




                  IN WITNESS WHEREOF,  Purchaser has caused this Agreement to be
executed by its officer  thereunto duly authorized and each Stockholder has duly
executed this Agreement, each as of the date first written above.


                                   ADU ACQUISITION INC.


                                   By:     /s/  Steven D. Jones
                                      ----------------------------------
                                      Name:
                                      Title:



THE STOCKHOLDERS:                  THE INTERNATIONALE NEDERLANDEN (U.S.)
                                   CAPITAL CORPORATION


                                   By:      /s/  Tracey L. Rudd
                                      ----------------------------------
                                      Name:
                                      Title:


                                   ORCAS LIMITED PARTNERSHIP
                                     By:  Archipelago Corp., Its General Partner

                                   By:     /s/  Frederick Whitridge, Jr.
                                      ----------------------------------
                                      Name:
                                      Title:


                                   NETWORK COMPANY II


                                   By:     /s/  John W. Gildea
                                      ----------------------------------
                                      Name:
                                      Title:



                                                25

<PAGE>




                                   SCHEDULE A



                     Name                              Shares

            Internationale Nederlanden (U.S.)
              Capital Corporation                     4,641,535
            Orcas Limited Partnership                 5,149,582
            Network Company II                        1,710,083



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