September 1, 1995


Jerome H. Ludwig
8840 N. 57th Street
Paradise Valley, Arizona 85253

Dear Mr. Ludwig:

         I am happy to advise  you that you have been  selected  by the Board of
Directors (the "Board") of H.E.R.C.  Products  Incorporated (the "Company"),  to
receive a  non-incentive  stock  option  and that on August 18,  1995,  you were
granted an option to  purchase  One  Hundred  Thousand  (100,000)  shares of the
Company's  Common  Stock,  $.01 par  value,  at a price of $3.625 per share (the
"Stock").  The option  granted to you is subject to the terms and conditions set
forth in this letter (the "Agreement").

         The Board has imposed the following  terms and  conditions  relating to
your option and its exercise:

         1. You may exercise your option,  only in accordance  with  Paragraph 3
below,  by delivery to the Company (in care of its  Secretary)  at the principal
offices of the Company,  presently  located at 3622 North 34th Avenue,  Phoenix,
Arizona 85017,  written  irrevocable  notice of exercise in the form attached to
this letter as Exhibit A.  specifying the number of shares with respect to which
the option is being  exercised,  together with payment of the exercise price for
those  shares in cash or by check.  Any other form of  exercise or tender may be
refused  by  the  Company,  acting  through  the  Board  or  otherwise,  in  its
discretion.

         2. Your  option is not  transferable  other than by will or the laws of
descent and distribution and is exercisable,  during your lifetime, only by you.
You may not assign or otherwise transfer or encumber your option or any interest
in your option to any person in any way.

         3.       (a) Your options shall vest on August 18, 1996.

                  (b)  Notwithstanding  any other  provision  of this  Agreement
         (other than  Paragraph  3(h)  below),  your  option,  to the extent not
         previously  exercised,  shall  automatically  terminate  and  be  of no
         further force or effect as to all remaining  shares of Stock as of five
         o'clock p.m., M.S.T., on August 18, 1999.

                  (c) In the event you leave the  employment  of the Company for
         any  reason  whatsoever,   including   termination  by  your  voluntary
         resignation or at the direction of the Company,  with or without cause,
         or of your death or Permanent Disability,  then, at your option, or the
         option  of  your   personal   representative,   you  or  your  personal
         representative  may  exercise  the option to the extent  vested and not
         previously  exercised or expired,  such exercise to occur no later than
         sixty (60) days following your last day of employment  with the Company
         or the date of your death or Permanent Disability,  as applicable,  and
         the  Company  (or its  nominee)  shall  have  the  right  (but  not the
         obligation)  to  purchase  any  shares of Stock  acquired  pursuant  to
         exercise  of  options  under  the Plan  held by you  (including  shares
         acquired  pursuant to this  sentence) at a price equal to the Appraised
         Value per share of such Stock,  determined in accordance with Paragraph
         3(e).  The  Company  (or its  nominee)  shall  exercise  this  right to
         repurchase  the  shares  of Stock,  if at all,  within  six (6)  months
         following  the  date of the  termination  of your  employment  with the
         Company  by  delivering  written  notice  of  exercise  to you or  your
         personal representative.  Payment on such exercise by the Company shall
         be made in not more than five equal  annual  installments  of principal
         and accrued  interest (at an annual interest rate,  adjusted on a daily
         basis,  equal to the prime rate of interest publicly  announced an such
         from time to time by Bank One in Phoenix, Arizona due commencing on the
         Company's  (or  its  nominee's)  purchase  and on  the  next  four  (4)
         anniversaries of such purchase. The date for consummating such purchase
         shall be the sixtieth  (60th) day  following  delivery of the Company's
         notice of exercise,  provided  that such date may be extended by you or
         your personal representative by written notice to a date not later than
         the earlier of ten (10)days after all holding periods under

Jerome H. Ludwig
September 1, 1995
Page 2

         Section 422A of the Internal  Revenue Code expire or  consummation of a
         transaction (e.g., merger, consolidation, stock sale) pursuant to which
         the holder of your shares would be entitled to receive consideration of
         any kind.

                  (d) In the event  any  shares of Stock  acquired  pursuant  to
         exercise  of  options  hereunder  or any  interest  therein,  are to be
         transferred,   voluntarily   or   involuntarily   (including,   without
         limitation,  any sale,  encumbrance,  foreclosure  or  transfer in lieu
         thereof,  or by operation  of law, any division of marital  property on
         account of divorce or legal  separation  being deemed a "transfer"  for
         purposes hereof, but excluding transfers to which Paragraph 3(c) hereof
         applies),  the  Company  (or its  nominee)  shall have a right of first
         refusal as follows: You (or the holder of such shares if not you) shall
         give the Company advance written notice  detailing all the terms of the
         proposed  transfer.  The Company (or its nominees) shall have the right
         (but not the obligation), exercisable upon delivery to the transferring
         shareholder  of written  notice of  acceptance  within thirty (30) days
         following receipt of the notice of proposed  transfer  described in the
         preceding  sentence,  to  repurchase  all or any of such  shares on the
         terms and  conditions  set-forth in such notice;  provided that the per
         share  purchase  price  shall be the lesser of (i) the price,  plus the
         Appraised Value of any non-cash consideration (determined in accordance
         with  the  procedures  specified  in  Paragraph  3(e)  below)  (or,  if
         applicable,  110% of the loan amount), stated in the notice or (ii) the
         Appraised Value of the shares,  determined in accordance with Paragraph
         3(e) (and shall be the Appraised  Value,  determined in accordance with
         Paragraph   3(e),  in  the  event  of  a  transfer  not  involving  any
         consideration);  and provided  further than the purchase price shall be
         payable,  at the election of the Company (or its  nominees),  either on
         the terms set forth in the  transferor's  notice or in up to five equal
         annual  installments  of principal  and accrued  interest (at an annual
         interest  rate,  adjusted on a daily basis,  equal to the prime rate of
         interest  publicly  announced  as such from time to time by Bank One in
         Phoenix,  Arizona) due  commencing on the Company's (or its  nominee's)
         purchase and on the next four (4)  anniversaries of such purchase.  The
         date for  consummating  such purchase shall be the sixtieth  (60th) day
         following  delivery  of the  Company's  (or its  nominees')  notice  of
         exercise,  provided that such date may be extended by the  transferring
         shareholder  by written  notice to a date not later than the earlier of
         ten (10) days after all holding  periods under Section 422A of the Code
         expire.  Failure by the Company (or its nominees)  (without  default by
         the  transferring  shareholder) to close such purchase within the above
         60 day period  shall  give the  transferring  shareholder  the right to
         transfer such shares or interest therein on the terms and to the person
         described in the notice during the 60 days following  expiration of the
         original 60-day period; provided that the shares or interest therein to
         be transferred shall for all purposes remain subject to this Agreement.
         If the transferring shareholder fails to close the proposed transfer on
         those terms within such second  60-day  period,  the proposed  transfer
         shall  again  be  subject  to  the  terms  of  this   Paragraph   3(d).
         Notwithstanding  the  foregoing,  such  shares  may be  transferred  or
         retransferred  without invoking this right of first refusal between you
         and trusts of which you and/or your  spouse are the sole  beneficiaries
         by giving  prior  written  notice  certifying  such a transfer is to be
         made;  provided  that  following any such  transfer,  such shares shall
         remain  subject  to this  right  of  first  refusal  and all the  other
         provisions of this agreement.

                  (e) The  "Appraised  Value" of a share of the Stock shall mean
         that value which is determined  pursuant to this  Paragraph  3(e).  The
         Appraised  Value  may  be  mutually  agreed  upon  by the  selling  and
         acquiring  parties  of the  shares  of  Stock.  If the  parties  cannot
         mutually  agree on the  Appraised  Value of a share of Stock within ten
         (10) days after  delivery of a written notice of exercise of a purchase
         right or obligation  hereunder,  then the Appraised Value of a share of
         Stock  shall  be  equal  to the  fair  market  value  of such  share as
         determined as of the date of  termination of your  employment  with the
         Company and in the  following  manner:  the fair market  value shall be
         determined  by a Board of  Arbitration  comprised of three (3) members,
         one of whom shall be selected by the selling  party and another of whom
         shall be selected by the  acquiring  party.  The third arbiter shall be
         appointed  by the two  arbiters  so  selected.  If either side fails to
         select an arbiter within fifteen (15) days after written  request to do
         so, then the other  party's  arbiter shall  unilaterally  establish the
         Appraised Value in a written  opinion.  The decision of the majority of
         said arbiters, or of the single arbiter if applicable, shall be binding
         upon the parties  hereto.  If no two arbiters  agree upon a single fair
         market value, it shall be the arithmetic average of the values

Jerome H. Ludwig
September 1, 1995
Page 3

         determined  by the two arbiters  whose  estimates are closest in value,
         which  average  value  shall be binding  upon the parties  hereto.  The
         arbiters  shall  render  a  written  decision  and  shall  conduct  all
         proceedings  pursuant to the Uniform  Arbitration Act as adopted in the
         State  of  Arizona  and to the  then  existing  rules  of the  American
         Arbitration Association governing commercial transactions to the extent
         such rules are not inconsistent with such Act and this Agreement. Costs
         of  arbitration  shall be  borne  as  determined  by the  arbiters.  In
         determining  the Appraised  Value, no value shall be placed on the good
         will or name of the Company  (except that good will may be valued at an
         amount not exceeding its unamortized cost to the extent it represents a
         cost to the  Company,  and all shares  shall be valued  equally,  i.e.,
         without regard to majority or minority status of such shares.

                  (f)  "Permanent  Disability"  means  that you (1) are  under a
         legal  decree  of  incapacity  or  disability  pursuant  to title 14 of
         Arizona Revised Statutes or other applicable  statutes the date of such
         decree  being deemed to be the date on which such  disability  occurred
         for purposes of this agreement), or (2) submit any claim for disability
         insurance  benefits or for early  distribution  of the  amounts  from a
         qualified pension or profit-sharing  plan maintained by the Corporation
         on account of disability (the date of the earliest of such claims shall
         be the date on which such disability shall be deemed to have occurred),
         or (3) are  determined to be disabled  pursuant to a  Determination  of
         Disability.  A determination of Disability  means a determination  that
         you,  because of a medically  determinable  disease,  injury,  or other
         mental or physical disability,  are unable to perform substantially all
         of your  regular  duties  and that such  disability  is  determined  or
         reasonably  expected  to last at least  twelve  (12)  months,  based on
         then-available  medical  information.  The  Determination of Disability
         will  be  based  on the  written  opinion  of the  physician  regularly
         attending  you.  If the  Company  disagrees  with the  opinion  of such
         physician  (the First  Physician"),  it may  engage at its own  expense
         another  physician (the "Second  Physician") to examine you. The Second
         Physician  shall confer with the First  Physician and, if they together
         agree  in  writing  that  you are or are not  disabled,  their  written
         opinion  shall be conclusive  as to such  disability.  If the First and
         Second  Physicians do not agree,  they shall choose a third  consulting
         physician (the expense of which shall be borne by the Company), and the
         written  opinion of a majority of these three (3)  physicians  shall be
         conclusive as to such disability. The date of any written opinion which
         is conclusive to such disability is the date on which such  disability,
         if that is the  conclusion,  will be deemed to have occurred unless the
         opinion  expressly  establishes the date of occurrence.  In conjunction
         with this  Section,  you  consent to such  examination,  to furnish any
         medical information requested by any examining physician,  and to waive
         any  applicable  physician-patient  privilege that may arise because of
         such examination.  All physicians  except the First Physician  selected
         hereunder must be board-certified in the specialty most closely related
         to the nature of the disability alleged to exist.

                  (g) For so long as the Company's right to repurchase the Stock
         as set forth in this  Paragraph 3 remains  effective,  neither you, nor
         your personal representative(s),  devisee(s), heir(s), successor(s), or
         assignee(s)  shall sell,  assign or  otherwise  transfer  any shares of
         Stock or interest  therein without  obtaining the written  agreement of
         the purchaser, assignee or transferee that the shares remain subject to
         this repurchase  right, and you evidencing the Stock may be legended to
         reflect the foregoing restrictions.

                  (h) In its sole discretion,  the Board may waive or accelerate
         vesting of options, or waive or extend expiration dates, other than the
         final expiration date.

         4. The Company will reserve or keep  available at all times  sufficient
shares of its common  stock to permit the  exercise of your option and all other
options granted or to be granted.

         5. It is contemplated that the common stock in the Company to be issued
to you upon exercise of your option will not be registered  under the Securities
Act of 1933, as amended (the "Act") or any applicable  state securities laws, in
reliance  on  exemptions  from  registration  thereunder.  If in the  opinion of
counsel  satisfactory  to the Company no  exemption  from  registration  is then
available,  or if such issuance is otherwise in violation of  applicable  law at
the time  purchase  rights are exercised  under this option,  then the Company's
obligation  to issue  shares of its common  stock upon  exercise  of your option
shall  terminate.  If such an  exemption  is  available  in the  opinion of such
counsel,  and such issuance is not 

Jerome H. Ludwig
September 1, 1995
Page 4

otherwise   in   violation   of   applicable   law   you   (or   your   personal
representative(s),  devisee(s),  or  heir(s))  will  deliver to the Company as a
condition  precedent to giving notice of each  exercise,  an  investment  letter
agreement  in form and  substance  satisfactory  to the  Company  to enable  the
Company to comply  with the Act or other  applicable  securities  laws and which
may,  among other  things,  limit or condition the right to dispose of shares of
Stock  acquired by exercise  of your  option  will be  permitted  only if in the
opinion  of counsel  satisfactory  to the  Company  Ouch  disposition  is not in
violation  of the  Act,  any  applicable  state  securities  laws  or any  other
applicable law, regulation or rule, and you (or your personal representative(s),
devisee(s),  or heirs(s))  deliver to the Company a letter agreement in form and
substance  satisfactory to the Company  whereby your  successor(s) or assign (6)
agrees to be bound by the terms and  conditions  of  paragraph  3 above and this
Paragraph 5. You (and your personal representative(s),  devisee(s), or heirs(s))
agree  to pay all  costs  of  obtaining  any  legal  opinions  and all  costs in
connection  with  proposed  exercise  of your option or  dispositions  of shares
acquired pursuant to your option.

         6. You agree to pay to the Company or to make arrangements satisfactory
to the Board to pay to the Company,  at such time as any income is recognized by
you with respect to this option, any Federal,  state, or local taxes of any kind
required by law to be withheld  on such income by the  Company.  In the event of
disposition or other transfer by you of common stock issued to you upon exercise
of your options,  you agree to provide to the Company  promptly  written  notice
describing in reasonable  detail the disposition or transfer,  including without
limitation the sale price, if any, and date of transfer or disposition.

         7. This option  granted to you is governed by, and shall be interpreted
according to, the laws of the State of Arizona.

         8. Each  party  hereto  agrees to do all such  things and take all such
actions,  and to make, execute and deliver such other documents and instruments,
as shall be reasonably requested to carry out the provisions, intent and purpose
of this Agreement.

         This  letter  only  grants the  options  described  above and is not an
employment  agreement or a promise or assurance of continued  employment for any
period of time including any period of time necessary to permit full exercise of
the options under Paragraph 1 above.


















         Please  acknowledge  your  receipt of this  letter,  together  with the
materials  referred to herein and your  agreement to the terms and conditions of
your option as set forth herein by signing the enclosed  copy of this letter and
returning  it promptly to the  Secretary of the Company at the address set forth
in Section 1 of this letter.  Any questions  concerning  any matter  relating to
your non-incentive stock option should also be addressed to the Secretary.

                                              Very truly yours,

                                              H.E.R.C. Products Incorporated

Jerome H. Ludwig
September 1, 1995
Page 5





                                              By  /s/ Gary S. Glatter
                                                  ------------------------------

                                              Its      Chief Operating Officer
                                                  ------------------------------





ACCEPTED AND AGREED:




/s/ Jerome Ludwig
- ------------------------------------
Jerome Ludwig






















                                   EXHIBIT "A"

                          NOTICE OF EXERCISE OF OPTION
              TO PURCHASE SHARES OF H.E.R.C. PRODUCTS INCORPORATED
                          AND RECORD OF STOCK TRANSFER

         I hereby  exercise my Stock Option  granted  pursuant to a letter dated
September  1, 1995 (the  "Agreement")  subject  to all the terms and  provisions
referred  to in  the  Agreement,  and  notify  you  of  my  desire  to  purchase
_______________  shares of Common Stock of H.E.R.C.  Products  Incorporated (the

Jerome H. Ludwig
September 1, 1995
Page 6

"Company")  which were  offered to me  pursuant to said  Option.  Enclosed is my
check in the sum of $______________ in full payment for such shares.

         I hereby  represent that the __________  shares of the Company's Common
Stock to be  delivered  to me  pursuant to the  above-mentioned  exercise of the
Option  granted  to me  on  August  18,  1995  are  being  acquired  by me as an
investment  and  not  with a view  to,  or for  sale  in  connection  with,  the
distribution  of any such shares.  I also  represent  that I have read and fully
understand the Agreement,  including  without  limitation  the  restrictions  on
transfer of the shares hereby being acquired and the Company's repurchase rights
with  respect  to  such  shares.  I  agree  to  indemnify  the  Company  and its
subsidiaries, together with their respective officers and directors, against any
and all liabilities, losses, damages and expenses (including reasonable attorney
fees) arising from or in connection  with any  disposition  of the shares hereby
being acquired,  or any interest therein, in violation of applicable  securities
laws or  regulations.  I further  represent that I have been given access to all
information  necessary to allow me to make a decision as to the  advisability of
an  investment in the  Company's  stock and the value of such stock,  and that I
have the skill and experience necessary to make such decision.

         DATED:_____________________, 19 ___ .



                                               _________________________________
                                               Employee 's Signature



                                               _________________________________
                                               Signature of Employee's Spouse



Receipt is hereby acknowledged of the delivery to me by _____________________ on
_______________  of stock  certificates  for  _______  shares  of  Common  Stock
purchased by me pursuant to the terms and  conditions of the Agreement  referred
to  above,   which  shares  were   transferred   to  me  on  H.E.R.C.   Products
Incorporated's stock record books on _______________, 19___.



                                               _________________________________
                                               Employee