<PAGE>   1
                                                                   EXHIBIT 10.66


THE SECURITIES OFFERED HEREBY HAVE NOT BEEN REGISTERED WITH NOR APPROVED OR
DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES
REGULATORY AUTHORITY, NOR HAS ANY SUCH AUTHORITY PASSED UPON THE ACCURACY OR
ADEQUACY OF THIS SUBSCRIPTION AGREEMENT OR THE MERITS OF THIS OFFERING. NO
TRANSFER OF ANY SECURITIES OFFERED HEREBY SHALL BE PERMITTED UNTIL THE
TRANSFEROR SHALL HAVE COMPLIED WITH ALL RESTRICTIONS ON TRANSFER SET FORTH
HEREIN AND SUCH SECURITIES HAVE BEEN REGISTERED UNDER SUCH ACTS OR UNTIL THE
COMPANY SHALL HAVE RECEIVED A FAVORABLE OPINION FROM LEGAL COUNSEL ACCEPTABLE TO
THE COMPANY TO THE EFFECT THAT SUCH TRANSFER IS EXEMPT FROM REGISTRATION UNDER
SUCH ACTS. ANY REPRESENTATION CONTRARY TO THE ABOVE IS UNLAWFUL.

                         FORM OF SUBSCRIPTION AGREEMENT


Denali Incorporated
1360 Post Oak Blvd., Suite 2250
Houston, Texas  77056-3023

Ladies and Gentlemen:

    The undersigned (the "Undersigned") understands that Denali Incorporated, a
Delaware corporation (the "Company"), is offering for sale (the "Offering") an
aggregate of 489,190 shares of its Common Stock, $.01 par value (the "Common
Stock"). The Undersigned further understands that the Offering is being made
without registration of the Common Stock under the Securities Act of 1933, as
amended (the "Securities Act"), and is being made only to Accredited Investors
(as defined in Rule 501 of Regulation D under the Securities Act). The number of
shares of Common Stock offered to the Undersigned is set forth underneath the
Undersigned's name on the signature page hereof.

1)   Subscription. Subject to the terms and conditions hereof, the Undersigned
     hereby irrevocably subscribes for and agrees to purchase from the Company
     the number of shares of Common Stock set forth underneath the Undersigned's
     name on the signature page attached hereto, for a cash purchase price of
     $9.25 per share (the "Purchase Price"). The Undersigned agrees to deliver
     the Purchase Price to the Company in cash or check within five days after
     being so requested by the Chairman of the Board or the President of the
     Company. The Undersigned understands that separate Subscription Agreements
     will be executed with other purchasers for the remainder of the shares of
     Common Stock to be sold in this Offering.

2)   Acceptance of Subscription.

     a)   The Undersigned understands and acknowledges that (i) subject to
          paragraph 2(b) below, the Company has the unconditional right,
          exercisable in its sole and absolute discretion,


<PAGE>   2

          to accept or reject this Subscription Agreement, in whole or in part,
          (ii) subscriptions need not be accepted in the order received, (iii)
          all subscriptions are subject to prior sale and to withdrawal,
          modification or cancellation of the Offering by the Company, (iv) no
          subscription shall be valid unless and until accepted by the Company,
          (v) this Subscription Agreement shall be deemed to be accepted by the
          Company only when it is signed by an authorized officer of the Company
          on behalf of the Company, and (vi) notwithstanding anything in this
          Subscription Agreement to the contrary, the Company shall have no
          obligation to issue shares of Common Stock to any person to whom the
          issuance of the shares of Common Stock would constitute a violation of
          the Securities Act or any state securities laws. The Company will
          deliver certificates representing the shares of Common Stock purchased
          by the Undersigned to the Undersigned promptly after the later of the
          acceptance of this Subscription Agreement by the Company (the "Time of
          Acceptance") or the tendering by the Undersigned of the Purchase
          Price.

     b)   If the acquisition of Welna N.V. is not consummated (the "Welna
          Acquisition"), the undersigned will not be required to purchase any
          shares of Common Stock subject to the Subscription Agreement.

3)   Use of Proceeds. The Company will use the proceeds of this Subscription
     Agreement for general working capital needs of the Company, including to
     fund a portion of the Welna Acquisition.

4)   Representations, Warranties and Covenants of the Company. As of the Time of
     Acceptance, the Company represents and warrants to and covenants with the
     Undersigned as follows:

     a)   The Company is duly incorporated, validly existing and in good
          standing under the laws of the State of Delaware, with full power and
          authority to conduct its business as it is currently being conducted
          and to own its assets.

     b)   The Company has duly authorized the issuance and sale of up to an
          aggregate of $5 million in shares of Common Stock at a purchase price
          of $9.25 per share.

     c)   The Common Stock, when issued and paid for, will represent validly
          authorized, duly issued and fully paid and non-assessable shares of
          Common Stock of the Company.

     d)   Since June 30, 1998, the Company has filed all forms, reports or other
          documents required to be filed with the Securities and Exchange
          Commission (the "Commission"), including (i) all Annual Reports on
          Form 10-K, (ii) all Quarterly Reports on Form 10-Q, (iii) all proxy
          statements relating to meetings of shareholders and (iv) all Current
          Reports on Form 8-K (collectively, the "Company SEC Reports"). The
          Company SEC Reports were prepared in all material respects in
          accordance with the Securities Exchange Act of 1934, as amended, and
          the Company SEC Reports did not at the time they were filed contain
          any untrue statement of a material fact or omit to state a material
          fact required to


<PAGE>   3

          make the statement therein, in light of the circumstances under which
          they were made, not misleading.

5)   Representations, Warranties and Covenants of the Undersigned. The
     Undersigned hereby represents and warrants to and covenants with the
     Company and to each officer, director and agent of the Company as follows:

     a)   General:

          i)   The Undersigned has all requisite authority to enter into this
               Subscription Agreement and to perform all the obligations
               required to be performed by the Undersigned hereunder.

          ii)  The Undersigned is the sole party in interest and is not
               acquiring the Common Stock as an agent or otherwise for any other
               person. The Undersigned is a resident of the state set forth
               below his, her or its name on the signature page hereto and (A)
               if a corporation, partnership, trust or other form of business
               organization, it has its principal office within such state; (B)
               if an individual, he or she has his or her principal residence in
               such state; and (C) if a corporation, partnership, trust or other
               form of business organization which was organized for the
               specific purpose of acquiring the Common Stock, all of the
               beneficial owners are residents of such state.

     b)   Information Concerning the Company:

          i)   The Undersigned is familiar with the business and financial
               condition, properties, operations and prospects of the Company,
               and has been afforded the opportunity to ask questions of, and
               has received satisfactory answers from, the Company's officers
               and directors, or other persons acting on the Company's behalf,
               concerning the business and financial condition, properties,
               operations and prospects of the Company and concerning the terms
               and conditions of the Offering.

          ii)  The Undersigned understands that, unless the Undersigned notifies
               the Company in writing to the contrary before the Time of
               Acceptance, all the representations and warranties contained in
               this Subscription Agreement will be deemed to have been
               reaffirmed and confirmed as of the Time of Acceptance, taking
               into account all information received by the Undersigned.

          iii) The Undersigned understands that the purchase of the Common Stock
               involves various risks and that no assurance can be given as to
               the future value of any investment in the Common Stock or the
               future financial condition or results of operations of the
               Company.

          iv)  The Undersigned is relying solely on the representations and
               warranties and other information contained herein and the answers
               to questions with respect thereto furnished to the Undersigned by
               the Company. No representations or warranties have



<PAGE>   4

               been made to the Undersigned by the Company as to the tax
               consequences of this investment or as to profits, losses or cash
               flow which may be received or sustained as a result of this
               investment.

          v)   All documents, records and books pertaining to a proposed
               investment in the Common Stock which the Undersigned has
               requested have been made available to the Undersigned.

     c)   Status of the Undersigned:

          i)   The Undersigned has had the opportunity to consult with the
               Undersigned's own attorney and/or accountant regarding the
               Undersigned's investment in the Common Stock and their
               suitability for purchase by the Undersigned, and to the extent
               necessary, the Undersigned has retained, at the Undersigned's own
               expense, and relied upon, appropriate professional advice
               regarding the investment, tax and legal merits, risks and
               consequences of this Subscription Agreement and of purchasing and
               owning the Common Stock.

          ii)  The Undersigned represents that the Undersigned is (PLEASE
               INITIAL EACH CATEGORY BELOW WHICH IS APPLICABLE TO THE
               UNDERSIGNED):

         (  )       (A)  a natural person whose individual net worth, or joint
                    net worth with his or her spouse, exceeds $1,000,000
                    (including the value of homes, home furnishings and personal
                    automobiles);

         (  )       (B)  a natural person who had an individual income in excess
                    of $200,000 in each of the last two years or joint income
                    with his or her spouse in excess of $300,000 in each of the
                    last two years and who reasonably expects to reach the same
                    level of individual or joint income this year. For purposes
                    of the Offering, individual income shall equal adjusted
                    gross income, as reported in the Undersigned's federal
                    income tax return, less any income attributable to a spouse
                    or to property owned by the spouse, and as may be further
                    adjusted in accordance with the rules, regulations and
                    releases of the Commission;

         (  )       (C)  any entity in which all of the equity owners are
                    accredited investors.

          iii) The Undersigned agrees to furnish any additional information
               requested to assure compliance with applicable federal and state
               securities laws in connection with the purchase and sale of the
               Common Stock.

     d)   Restrictions on Transfer or Sale of the Common Stock:

          i)   The Undersigned is acquiring the Common Stock subscribed for
               solely for the Undersigned's own beneficial account, for
               investment purposes, and not with a view to, or for resale in
               connection with, any distribution of the Common Stock. The
               Undersigned understands that the offer and sale of the Common
               Stock has not been

<PAGE>   5

               registered under the Securities Act or any state securities laws
               by reason of specific exemptions under the provisions thereof
               which depend in part upon the investment intent of the
               Undersigned and the other representations made by the Undersigned
               in this Subscription Agreement. The Undersigned understands that
               the Company is relying upon the representations, covenants and
               agreements contained in this Subscription Agreement (and any
               supplemental information) for the purpose of determining whether
               this transaction meets the requirements for such exemptions.

          ii)  The Undersigned understands that the shares of Common Stock are
               "restricted securities" under applicable federal securities laws
               and that the Securities Act and the rules of the Commission
               provide in substance that the Undersigned may dispose of the
               Common Stock only pursuant to an effective registration statement
               under the Securities Act or an exemption therefrom, and the
               Undersigned understands that the Company has no obligation or
               intention to register any of the Common Stock purchased by the
               Undersigned hereunder, or to take action so as to permit sales
               pursuant to the Securities Act (including Rule 144 thereunder).
               Accordingly, the Undersigned understands that under the
               Commission's rules, the Undersigned may dispose of the Common
               Stock only in "private placements" which are exempt from
               registration under the Securities Act, in which event the
               transferee will acquire "restricted securities" subject to the
               same limitations as in the hands of the Undersigned or pursuant
               to Rule 144 under the Securities Act. As a consequence, the
               Undersigned must bear the economic risks of the investment in the
               Common Stock for an indefinite period of time.

          iii) The Undersigned agrees: (A) that the Undersigned will not sell,
               assign, pledge, give, transfer or otherwise dispose of the Common
               Stock, or make any offer or attempt to do any of the foregoing,
               except pursuant to a registration of the Common Stock under the
               Securities Act and all applicable state securities laws or in a
               transaction which is exempt from the registration provisions of
               the Securities Act and all applicable state securities laws; (B)
               that the Company and any transfer agent for the Common Stock
               shall not be required to give effect to any purported transfer of
               any of the Common Stock except upon compliance with the foregoing
               restrictions and the receipt of a favorable opinion of counsel
               satisfactory to the Company and/or evidence satisfactory to the
               Company that such restrictions have been complied with; and (C)
               that a legend in substantially the following form will be placed
               on the certificates representing the Common Stock:

          iv)  THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
               REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY
               NOT BE SOLD, PLEDGED, TRANSFERRED OR OTHERWISE DISPOSED OF EXCEPT
               IN ACCORDANCE WITH SUCH ACT AND THE RULES AND REGULATIONS
               THEREUNDER AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES
               LAWS. THE COMPANY WILL NOT TRANSFER SUCH SECURITIES EXCEPT UPON
               RECEIPT OF A FAVORABLE OPINION OF COUNSEL AND/OR EVIDENCE
               SATISFACTORY TO THE COMPANY THAT

<PAGE>   6

               THE REGISTRATION PROVISIONS OF SUCH ACT HAVE BEEN COMPLIED WITH
               OR THAT SUCH REGISTRATION IS NOT REQUIRED AND THAT SUCH TRANSFER
               WILL NOT VIOLATE ANY APPLICABLE STATE SECURITIES LAWS.

          v)   The Undersigned has not offered or sold any portion of the
               subscribed for Common Stock and has no present intention of
               dividing such Common Stock either currently or after the passage
               of a fixed or determinable period of time or upon the occurrence
               or nonoccurrence of any predetermined event or circumstance.

6)   Survival; Indemnification. All representations, warranties and covenants
     contained in this Subscription Agreement and the indemnification contained
     in this Section 6 shall survive (i) the acceptance of this Subscription
     Agreement by the Company, (ii) changes in the transactions, documents and
     instruments described herein which are not material or which are to the
     benefit of the Undersigned, and (iii) the death or disability of the
     Undersigned. The Undersigned acknowledges the meaning and legal
     consequences of the representations, warranties and covenants in Section 6
     hereof and that the Company has relied upon such representations,
     warranties and covenants in determining the Undersigned's qualification and
     suitability to purchase the Common Stock. The Undersigned hereby agrees to
     indemnify, defend and hold harmless the Company, its officers, directors,
     employees, agents and controlling persons, from and against any and all
     losses, claims, damages, liabilities, expenses (including attorneys' fees
     and disbursements), judgments or amounts paid in settlement of actions
     arising out of or resulting from the untruth of any representation of the
     Undersigned herein or the breach of any warranty or covenant herein by the
     Undersigned. Notwithstanding the foregoing, however, no representation,
     warranty, covenant or acknowledgment made herein by the Undersigned shall
     in any manner be deemed to constitute a waiver of any rights granted to it
     under the Securities Act or state securities laws.

7)   Conditions to Obligations of the Undersigned and the Company. The
     obligations of the Undersigned to purchase and pay for the Common Stock
     specified herein and of the Company to sell such Common Stock are subject
     to the condition that the representations and warranties of the Company
     contained in Section 4 hereof and of the Undersigned contained in Section 5
     hereof shall be true and correct on and as of the Time of Acceptance in all
     respects with the same effect as though such representations and warranties
     had been made on and as of the Time of Acceptance.

8)   Notices. All notices and other communications provided for herein shall be
     in writing and shall be deemed to have been duly given if delivered
     personally or sent by registered or certified mail, return receipt
     requested, postage prepaid:

<PAGE>   7

     a)   if to the Company, to the following address:

          Denali Incorporated
          1360 Post Oak Boulevard, Suite 2250
          Houston, Texas  77056-3023
          Attention:  Mel Carter

     b)   if to the Undersigned, to the address set forth on the signature page
          hereto;

     c)   or at such other address as either party shall have specified by
          notice in writing to the other.

9)   Notification of Changes. The Undersigned agrees and covenants to notify the
     Company immediately upon the occurrence of any event prior to the Time of
     Acceptance which would cause any representation, warranty, covenant or
     other statement contained in this Subscription Agreement to be false or
     incorrect or of any change in any statement made herein occurring prior to
     the Time of Acceptance.

10)  Assignability. This Subscription Agreement is not assignable by the
     Undersigned, and may not be modified, waived or terminated except by an
     instrument in writing signed by the party against whom enforcement of such
     modification, waiver or termination is sought.

11)  Binding Effect. Except as otherwise provided herein, this Subscription
     Agreement shall be binding upon and inure to the benefit of the parties and
     their heirs, executors, administrators, successors, legal representatives
     and assigns, and the agreements, representations, warranties and
     acknowledgments contained herein shall be deemed to be made by and be
     binding upon such heirs, executors, administrators, successors, legal
     representatives and assigns.

12)  Obligations Irrevocable. The obligations of the Undersigned shall be
     irrevocable, except with the consent of the Company, until the Time of
     Acceptance or earlier termination of the Offering.

13)  Entire Agreement. This Subscription Agreement constitutes the entire
     agreement of the Undersigned and the Company relating to the matters
     contained herein, superseding all prior contracts or agreements, whether
     oral or written.

14)  Governing Law. This Subscription Agreement shall be governed by and
     construed in accordance with the laws of the State of Texas, as such law
     applies to agreements between Texas residents entered into and to be
     performed entirely within Texas, exclusive of any conflicts of law
     principles; and the parties hereto agree that the state and federal courts
     situated in Harris County, Texas shall have personal jurisdiction over the
     parties hereto to hear all disputes arising under this Subscription
     Agreement. This Subscription Agreement is to be at least partially
     performed in Harris County, Texas and, as such, the parties agree that
     venue shall be proper with the state or federal courts in Harris County,
     Texas to hear such disputes. If any party is not able to effect service of
     process upon any other party with

<PAGE>   8

     respect to such disputes, such other party expressly agrees that the
     Secretary of State for the State of Texas shall be an agent for such other
     party to receive service of process on behalf of such other party with
     respect to such disputes.

15)  Severability. If any provision of this Subscription Agreement or the
     application thereof to the Undersigned or any circumstance shall be held
     invalid or unenforceable to any extent, the remainder of this Subscription
     Agreement and the application of such provision to other subscriptions or
     circumstances shall not be affected thereby and shall be enforced to the
     greatest extent permitted by law.

16)  Headings. The headings in this Subscription Agreement are inserted for
     convenience and identification only and are not intended to describe,
     interpret, define, or limit the scope, extent or intent of this
     Subscription Agreement or any provision hereof.

17)  Counterparts. This Subscription Agreement may be executed in any number of
     counterparts, each of which when so executed and delivered shall be deemed
     to be an original and all of which together shall be deemed to be one and
     the same agreement.

18)  Documents Being Tendered. The Undersigned hereby tenders (or has previously
     tendered) two completed and executed copies of this Subscription Agreement
     (one of which will be executed by a representative of the Company and
     returned to the Undersigned upon acceptance) and will tender, within five
     days of being so requested by the Chairman of the Board or President of the
     Company, cash or a check payable to "Denali Incorporated" for the Purchase
     Price as defined in Section 1 hereof (if payment is to be made other than
     by wire transfer).

         NOTE: PLEASE BE CERTAIN YOU HAVE INITIALED THE APPROPRIATE CATEGORY OF
ACCREDITED INVESTOR IN SECTION 6(c).


<PAGE>   9


         IN WITNESS WHEREOF, the Undersigned has executed this Subscription
Agreement this _____ day of __________, 1999.

TYPE OF OWNERSHIP (Check One):

( )  INDIVIDUAL OWNERSHIP (one signature required)

( )  TRUST, AGENT OR OTHER PERSON ACTING IN A REPRESENTATIVE CAPACITY (List
     the name of the person or entity who will be the record holder and provide
     (i) copy of trust agreement, power of attorney or other instrument granting
     the power and authority to subscribe, or (ii) an opinion of counsel as to
     such power and authority)

( )  JOINT TENANTS WITH RIGHT OF SURVIVORSHIP (both or all parties must sign)

( )  COMMUNITY PROPERTY (one signature required if shares are held in one
     name, i.e., managing spouse; two signatures required if shares are held in
     both names)

( )  TENANTS IN COMMON (both or all parties must sign) (Can only be used if
     parties are related and living in same household)

( )  CORPORATION (please include copies of the corporation's Articles of
     Incorporation and bylaws)

( )  PARTNERSHIP (include copy of Partnership Agreement authorizing signature)


<PAGE>   10



         (1) If a Partnership, Corporation or other qualified association, the
signature should be in the name of such entity followed by the authorized
signature and title of the person signing.

         (2) Second signature required for any joint investment.

Name of Investor:

Signature:
           ----------------------------------
   Title:
Address:
Social Security or Tax I.D. No.:
                                 -----------------------------------

If joint investment:
                      ----------------------------------------------

     Name of additional investor:
                                  ----------------------------------

         Signature:
                        --------------------------------------------

         Title (if applicable):
                                ------------------------------------

         Address:
                  --------------------------------------------------

         Social Security or Tax I.D. No.:
                                          --------------------------

No. of shares of Common Stock subscribed for:
                                                 -------------------

Accepted by Denali Incorporated

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


<PAGE>   11

                                                                       EXHIBIT A


                           FORM OF ACQUISITION ABSTRACT


                                     [date]


Canadian Imperial Bank of Commerce, as Administrative Agent
   for the financial institutions party to the
   Credit Agreement referred to below
425 Lexington Avenue
New York, New York 10017

Attention:        Mr. Michael Daven

Ladies and Gentlemen:


         The undersigned refers to the Credit Agreement dated as of January 12,
1999 (as amended, restated, modified, or supplemented from time to time, the
"Credit Agreement", the defined terms of which are used herein unless otherwise
defined herein), among Denali Incorporated (the "Borrower"), the financial
institutions party thereto (the "Lenders"), Canadian Imperial Bank of Commerce,
as a administrative agent for the Lenders ("Administrative Agent") and ING
(U.S.) Capital LLC, as a documentation agent.

         The Borrower intends to make a Permitted Acquisition (the "Proposed
Acquisition"), and in connection therewith hereby certifies the following to the
Administrative Agent and the Lenders:

         1. Attached hereto as Exhibit A is a summary of the proposed Permitted
Acquisition, including a description of the business operations and assets to be
acquired, the rationale for the acquisition, strategic reasons for the
acquisition and the consideration to be paid (including assumed indebtedness,
stock, earn-outs, liabilities and subordinated debt proposed to be issued in
connection therewith), and such summary fairly presents the contemplated
transaction.

<PAGE>   12

         2. Attached hereto as Exhibit B are historical financial statements
regarding the Acquired Business covering the period of the most recently
completed twelve calendar months of the Borrower, the Borrower's proposed
adjustments to the historical financial statements reflecting nonrecurring
expenses and income, and historical proforma financial statements for the
operations to be acquired in the proposed Permitted Acquisition giving effect to
such adjustments.

         3. Attached hereto as Exhibit C are consolidated historical proforma
financial statements for the Borrower for the most recently completed four
fiscal quarters of the Borrower giving effect to the proposed Permitted
Acquisition as set forth in the historical proforma financial statements
described in paragraph 2 above.

         4. Attached hereto as Exhibit D is a completed Borrowers Base
Certificate and certificate of a Responsible Officer of the Borrower,
demonstrating the Borrower's compliance with the covenants contained in Section
10.1 and the requirements of the definition of "Permitted Acquisition" of the
Credit Agreement on a proforma basis after giving effect to the proposed
Permitted Acquisition in accordance with the consolidated historical proforma
financial statements described in paragraph 3 above.

         5. The following sets forth the information to demonstrate compliance
with the requirements of the definition of "Permitted Acquisition" in connection
with the proposed Permitted Acquisition:

                  (a) the Senior Leverage Ratio, as of the last day of the
calendar month preceding the calendar month in which the Acquisition Closing
Date occurs, for the twelve consecutive months immediately preceding such date
(calculated on a pro-forma basis, taking into account the acquisition of the
Acquired Business, as if such Permitted Acquisition had been consummated as of
the first day of such twelve month period) is_______ to 1.00 for such period
[not to be greater than 3.50 to 1.00]; and

                  (b) the Leverage Ratio, as of the last day of the calendar
month preceding the calendar month in which the Acquisition Closing Date occurs,
for the twelve consecutive months immediately preceding such date (calculated on
a pro-forma basis as if such Permitted Acquisition had been consummated as of
the first day of such twelve month period) is________ to 1.00 for such period
{not to be greater than 4.00 to 1.00].


<PAGE>   13



Borrower represents and warrants that it has conducted appropriate customary
environmental, legal, accounting and other diligence in connection with the
proposed acquisition and there are no contingent liabilities, including
environmental liabilities, litigation liabilities, and assumed contractual
liabilities, associated with the Proposed Acquisition that could reasonably be
expected to have a Material Adverse Effect.


     [the Borrower hereby requests the Majority Banks' approval as required by
the definition of "Permitted Acquisitions" of the Credit Agreement.]

     [the Borrower hereby further requests the following waivers and consents in
connection with the Proposed Acquisition.]


                                       Very truly yours,


                                       DENALI INCORPORATED



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