<PAGE>
 
                    U.S. Securities and Exchange Commission
                             Washington, D.C. 20549

                                   FORM 10-Q



[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934


                For the Quarterly Period Ended February 28, 1998



[_]  TRANSITION REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT
     OF 1934


              For the Transition Period from    N/A    to    N/A
                                               -------      -------

                           Commission File No. 1-7755


                                Summa Industries
                (Name of registrant as specified in its charter)



                    California                        95-1240978
         (State or other jurisdiction of            (I.R.S. Employer
         incorporation or organization)          Identification Number)


        21250 Hawthorne Boulevard, Suite 500, Torrance, California 90503
          (Address of principal executive offices, including Zip Code)


                 Registrant's Telephone Number:  (310) 792-7024


Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such report), and (2) has been subject to such filing
requirements for the past 90 days.  Yes  X         No
                                         ---          ---     

The number of shares of common stock outstanding as of March 20, 1998 was
4,238,754.
<PAGE>
 
                                Summa Industries
                                        

                                        
                                     INDEX
<TABLE> 
<CAPTION>                                              
  
     PART I - FINANCIAL INFORMATION                                                              Page
     <S>                                                                                         <C>
     Item 1.  Financial Statements:

          Condensed Consolidated Balance Sheets -
          August 31, 1997 and February 28, 1998 (unaudited)......................................  3

          Condensed Consolidated Statements of Income (unaudited) -
          three months and six months ended February 28, 1997 and 1998...........................  4

          Condensed Consolidated Statements of Cash Flows (unaudited) -
          six months ended February 28, 1997 and 1998............................................  5

          Notes to Condensed Consolidated Financial Statements (unaudited).......................  6

     Item 2.  Management's Discussion and Analysis
             of Financial Condition and Results of Operations....................................  7

     PART II - OTHER INFORMATION................................................................   9 
   
     Item 1.  Legal Proceedings..................................................................  9
     Item 4.  Submission of Matters to a Vote of Security Holders................................  9
     Item 5.  Other Information.................................................................. 10
     Item 6.  Exhibits and Reports on Form 8-K................................................... 10

     Signature Page.............................................................................. 11
</TABLE> 

                                       2
<PAGE>
 
                               SUMMA INDUSTRIES
                     CONDENSED CONSOLIDATED BALANCE SHEETS


<TABLE> 
<CAPTION> 

                                                     August 31, 1997     February 28, 1998
                                                                                (unaudited)
                                                     ---------------     -----------------
<S>                                                  <C>                 <C> 
ASSETS
Current assets:                         
   Cash                                               $ 2,883,000           $   323,000
   Accounts receivable                                  7,023,000            12,872,000
   Inventories                                          3,903,000             9,874,000
   Prepaid expenses and other                           1,647,000             2,073,000
                                                     ---------------     -----------------
        Total current assets                           15,456,000            25,142,000

Property, plant and equipment                          20,248,000            25,992,000
   Less accumulated depreciation                        3,888,000             5,358,000
                                                     ---------------     -----------------
        Net property, plant and equipment              16,360,000            20,634,000
Other assets                                            2,331,000             2,072,000
Goodwill and other intangibles, net                     1,868,000            15,393,000
                                                     ---------------     -----------------
                                                      $36,015,000           $63,241,000
                                                     ===============     =================
LIABILITIES AND SHAREHOLDERS' EQUITY 
Current liabilities:
   Accounts payable                                   $ 2,006,000           $ 5,207,000
   Accrued liabilities                                  2,673,000             4,212,000
   Current maturities of long-term debt                 2,673,000             1,962,000
                                                     ---------------     -----------------
        Total current liabilities                       7,352,000            11,381,000
Long-term debt, net of current maturities               5,571,000            23,402,000
Other long-term liabilities                             2,127,000             3,365,000
                                                     ---------------     -----------------
        Total liabilities                              15,050,000            38,148,000
Shareholders' equity:
   Common stock, par value $.001; 10,000,000 shares
        authorized; issued and outstanding:
          4,099,004 at August 31, 1997
          4,237,504 at February 28, 1998               16,226,000            18,375,000
   Retained earnings                                    4,739,000             6,718,000
                                                     ---------------     -----------------
        Total shareholders' equity                     20,965,000            25,093,000
                                                     ---------------     -----------------
                                                      $36,015,000           $63,241,000
                                                     ===============     =================
      
</TABLE> 

                            See accompanying notes.

                                       3
<PAGE>
 
                               SUMMA INDUSTRIES
                  CONDENSED CONSOLIDATED STATEMENTS OF INCOME
                                  (unaudited)


<TABLE> 
<CAPTION>                                               Three months ended                      Six months ended
                                               -------------------------------------   -------------------------------------
                                               February 28, 1997   February 28, 1998   February 28, 1997   February 28, 1998
                                               -----------------   -----------------   -----------------   -----------------
<S>                                            <C>                 <C>                 <C>                 <C>   
Net sales                                      $13,512,000         $21,183,000         $16,651,000         $38,618,000
Cost of sales                                    9,510,000          14,874,000          11,166,000          26,776,000
                                               -----------------   -----------------   -----------------   -----------------
Gross profit                                     4,002,000           6,309,000           5,485,000          11,842,000
Selling, general and administrative
     and other expenses                          2,840,000           4,246,000           3,991,000           7,836,000
                                               -----------------   -----------------   -----------------   -----------------
Operating income                                 1,162,000           2,063,000           1,494,000           4,006,000
Interest expense, net                              109,000             452,000              81,000             653,000
                                               -----------------   -----------------   -----------------   -----------------
Income before provision for taxes                1,053,000           1,611,000           1,413,000           3,353,000
Provision for income taxes                         424,000             652,000             571,000           1,374,000
                                               -----------------   -----------------   -----------------   -----------------
Net income                                     $   629,000         $   959,000         $   842,000         $ 1,979,000
                                               =================   =================   =================   =================

Net income per common share
     basic                                            $.16                $.23                $.30                $.48 
     diluted                                          $.15                $.21                $.29                $.44
Weighted average common shares outstanding
     basic                                       4,052,000           4,192,000           2,829,000           4,149,000
     diluted                                     4,088,000           4,601,000           2,877,000           4,485,000

</TABLE> 









                            See accompanying notes.







                                       4

<PAGE>
 
                               SUMMA INDUSTRIES
                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                  (unaudited)
<TABLE> 
<CAPTION> 
                                                                                   Six months ended
                                                                       ------------------------------------------
                                                                       February 28, 1997        February 28, 1998
                                                                       -----------------        -----------------
<S>                                                                    <C>                      <C> 
Operating activities:

Net income                                                             $    842,000              $  1,979,000
                                                                       -----------------         ----------------
Adjustments to reconcile net income to net
   cash provided by operating activities:
   Depreciation and amortization                                            835,000                 1,739,000
   Loss (gain) on disposition of property, plant and equipment               (4,000)                  122,000
   Net change in assets and liabilities
      Accounts receivable                                                  (331,000)                 (868,000)
      Inventories                                                             8,000                  (236,000)
      Prepaid expenses and other                                            (62,000)                   88,000
      Accounts payable                                                     (686,000)                  669,000
      Accrued liabilities                                                  (448,000)                 (732,000)
                                                                       -----------------         ----------------
                                                                         
Total adjustments                                                          (688,000)                  782,000
                                                                       -----------------         ----------------

         Net cash provided by operating activities                          154,000                 2,761,000
                                                                       -----------------         ----------------
Investing activities:
   Purchase of business (Note 3)                                              -                   (21,626,000)
   Property, plant & equipment                                             (825,000)               (1,462,000)
   Proceeds from sale of equipment                                            5,000                     1,000
   Net decrease in unexpended revenue bond proceeds                         212,000                   371,000
   Proceeds from cash surrender value of life insurance                      97,000                       -
                                                                       -----------------         ----------------
         Net cash used in investing activities                             (511,000)              (22,716,000)
                                                                       -----------------         ----------------
Financing activities:
   Net proceeds from line of credit                                          55,000                 5,985,000
   Proceeds from issuance of long-term debt                                     -                  13,500,000
   Payments of long-term debt                                              (284,000)               (4,194,000)
   Proceeds from exercise of stock options                                   27,000                   804,000
   Cash acquired from acquisition of businesses, net of cash paid           318,000                 1,300,000
                                                                       -----------------         ----------------

         Net cash provided by financing activities                          116,000                17,395,000
                                                                       -----------------         ----------------
Net decrease in cash                                                       (241,000)               (2,560,000)
Cash at beginning of period                                                 567,000                 2,883,000
                                                                       -----------------         ----------------
Cash at end of period                                                  $    326,000              $    323,000
                                                                       =================         ================
Supplemental cash flow information:
   Cash paid during the period for:
         
         Interest                                                      $     34,000              $    752,000
                                                                       =================         =================
         Income tax                                                    $    665,000              $  1,745,000
                                                                       =================         =================
Non-cash investing and financing activities
   Common stock issued and value assigned to stock options
      for acquisitions (Note 3)                                        $  9,899,000              $  1,345,000
                                                                       =================         =================
Details of acquisitions (Note 3):
   Fair value of assets acquired                                       $ 23,775,000              $ 31,192,000
   Liabilities assumed or incurred                                      (13,681,000)               (8,221,000)
   Common stock issued and value assigned to stock options               (9,899,000)               (1,345,000)
                                                                       -----------------         ------------------
   Cash paid                                                                195,000                21,626,000
   Less cash acquired                                                      (513,000)               (1,300,000)
   Net cash (acquired) used in acquisitions                            $   (318,000)             $ 20,326,000
                                                                       -----------------         ------------------
</TABLE> 
  
                          See accompanying notes.    
<PAGE>
 
                                Summa Industries

              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS


1.   Basis of presentation

     The accompanying condensed consolidated financial statements of Summa
     Industries (the "Company"), some of which are unaudited, have been
     condensed in certain respects and should, therefor, be read in conjunction
     with the audited financial statements and notes related thereto contained
     in the Company's Annual Report on Form 10-K for the year ended August 31,
     1997. In the opinion of the Company, the accompanying unaudited interim
     consolidated financial statements contain all adjustments necessary for a
     fair presentation for the interim period. (See Note 3 below.) The results
     of operations for the three months and six months ended February 28, 1998
     are not necessarily indicative of the results to be expected for the full
     year ending August 31, 1998.

2.   Inventories

     Inventories at August 31, 1997 and February 28, 1998 were as follows:

<TABLE> 
<CAPTION> 

                                                     August 31, 1997           February 28, 1998
                                                                                  (unaudited)
                                                     ---------------           -----------------
                     <S>                             <C>                       <C>
                     Finished goods                      $1,557,000                 $4,968,000 
                     Work in process                        108,000                    209,000
                     Material and parts                   2,238,000                  4,697,000
                                                         ----------                 ----------
                                                         $3,903,000                 $9,874,000
                                                         ==========                 ==========
</TABLE>


3.   Acquisitions

     On October 28, 1997, the Company completed the acquisition of Calnetics
     Corporation ("Calnetics").  The total acquisition cost was $31,192,000,
     consisting of cash due to former Calnetics shareholders of $22,335,000,
     acquisition costs estimated to be $80,000, liabilities assumed or incurred
     of $7,432,000 and an estimated fair value of $1,345,000 for options issued
     in conjunction with the transaction, primarily replacement options issued
     to Calnetics employees who continued with the Company.  The acquisition has
     been accounted for using the purchase method of accounting and,
     accordingly, the purchase price has been allocated to identifiable tangible
     and intangible assets purchased and liabilities assumed or incurred based
     upon their fair value at the date of acquisition.  The excess of the
     purchase price over the fair values of the net assets acquired amounted to
     $13,721,000 and has been recorded as goodwill which is being amortized on a
     straight-line basis over 30 years.

     As a consequence of the acquisition, the consolidated balance sheet of the
     Company at February 28, 1998 includes the balance sheet of Calnetics along
     with preliminary purchase accounting adjustments.  The results of
     operations of Calnetics have been included in the consolidated results of
     operations and the consolidated statements of cash flows of the Company
     since October 28, 1997, the date of the acquisition. The results of
     operations of LexaLite International Corporation ("LexaLite") have been
     included in the consolidated results of operations and the consolidated
     statements of cash flow since November 22, 1996, the date of the
     acquisition of LexaLite.

     The following proforma financial information presents the results of
     operations of the Company with LexaLite and Calnetics as though both
     acquisitions had been made as of September 1, 1996.  Proforma adjustments
     have been made to give the effect to the amortization of goodwill and other
     intangibles, adjustments in depreciation and inventory value, a reduction
     in redundant operating expense, interest expense related to acquisition
     debt, the related tax effects and the effect upon basic and diluted
     earnings per share of the additional shares of stock given in exchange for
     LexaLite stock and of stock options issued in conjunction with the
     acquisitions.

                                       6
<PAGE>
 
     Pro Forma Financial Information (Continued)

<TABLE>
<CAPTION>
                                            Three months ended                                Six months ended
                                   ---------------------------------------     --------------------------------------------
                                   February 28, 1997     February 28, 1998     February 28, 1997          February 28, 1998
                                   -----------------     -----------------     -----------------          -----------------
<S>                                <C>                   <C>                   <C>                        <C>
Net sales                              $22,098,000           $21,183,000           $42,290,000               $44,336,000
Net income                                 773,000               959,000             1,171,000                 2,087,000
                                   =================     =================     =================          =================
Net income per common share
        basic                                 $.19                  $.23                  $.34                      $.50
        diluted                               $.18                  $.21                  $.32                      $.45
</TABLE>

Such proforma results are not necessarily indicative of what the actual
consolidated results of operations might have been if the acquisition had been
effective at the beginning of the periods presented or the results which may be
achieved in the future.

4.   Recent Accounting Pronouncement

     The Company has adopted SFAS No. 128, "Earnings Per Share", issued by the
     Financial Accounting Standards Board ("FASB"), and accordingly has restated
     prior earnings per share.


MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS   OF
OPERATIONS

Statements contained in this Quarterly Report on Form 10-Q that are not purely
historical are forward-looking statements within the meaning of Section 27A of
the Securities Act of 1933 and Section 21E of the Securities Exchange Act of
1934, including but not limited to statements regarding Summa's expectations,
hopes, beliefs, intentions or strategies regarding the future.  Actual results
could differ materially from those projected in any forward-looking statements
as a result of a number of factors, including those detailed in this
"Management's Discussion and Analysis" section and elsewhere herein and in the
Company's Annual Report on Form 10-K for the fiscal year ended August 31, 1997.
The forward-looking statements are made as of the date hereof, and the Company
assumes no obligation to update the forward-looking statements, or to update the
reasons why actual results could differ materially from those projected in the
forward-looking statements.

Results of Operations
---------------------

The following table sets forth certain income information for the Company's
continuing operations as a percent of sales for the quarter and six months ended
February 28, 1997 and February 28, 1998.

<TABLE> 
<CAPTION> 

 
                                              Three months ended                             Six months ended
                                      ---------------------------------------       ---------------------------------------
                                      February 28, 1997     February 28, 1998       February 28, 1997     February 28, 1998
                                      -----------------     -----------------       -----------------     -----------------
<S>                                   <C>                   <C>                     <C>                   <C>
Net sales                                         100.0%                100.0%                  100.0%                100.0%
Cost of sales                                      70.4%                 70.2%                   67.1%                 69.3%
                                      -----------------     -----------------       -----------------     -----------------
Gross profit                                       29.6%                 29.8%                   32.9%                 30.7%
S, G & A and other expenses                        21.0%                 20.1%                   24.0%                 20.3%
                                      -----------------     -----------------       -----------------     -----------------
Operating income                                    8.6%                  9.7%                    9.0%                10.4%
Interest  expense, net                              0.8%                  2.1%                    0.5%                 1.7%
                                      -----------------     -----------------       -----------------     -----------------
Income before provision for taxes                   7.8%                  7.6%                    8.5%                 8.7%
Provision for income taxes                          3.1%                  3.1%                    3.4%                 3.6%
                                      -----------------     -----------------       -----------------     -----------------
Net income                                          4.7%                  4.5%                    5.1%                 5.1%
                                      =================     =================       =================     =================
Effective tax rate                                 40.3%                 40.5%                   40.4%                41.0%
</TABLE>

                                       7
<PAGE>
 
Sales for the second quarter, ended February 28, 1998, increased $7,671,000, or
57% compared to the same period in the prior year, due primarily to the
inclusion of the sales of Calnetics for the full quarter,  which were not
included in the prior year second quarter.  In the aggregate, sales for
previously owned businesses were flat compared to the prior year second quarter.

Sales for the six months ended February 28, 1998 increased $21,967,000, or 132%
compared to the same period in the prior fiscal year, due primarily to the
inclusion of the sales of newly acquired Calnetics for four months and due to
the inclusion of sales of LexaLite for the full six months in the current year
results compared to three months in the prior year six month period.

Consolidated gross profit for the second quarter increased $2,307,000, or 58%
primarily due to the inclusion of the recently acquired Calnetics.  A reduction
in the gross profit percentage resulting from the inclusion of results of the
Calnetics operations, which historically have lower margins, was offset by a
favorable change in product mix and manufacturing cost improvements.

Consolidated gross profit for the six months ended February 28, 1998 increased
$6,357,000, or 116% due to the inclusion of the sales of LexaLite for the full
six months in this year's results compared to three months in the lasts year's
six months and due to the inclusion of four month's results for Calnetics.
Gross profit as a percent of sales decreased from 32.9% to 30.7% for the six
months due to the inclusion of the sales of LexaLite and of Calnetics at
typically lower gross margins than the sales of the businesses owned prior to
the acquisitions of LexaLite and Calnetics.

Operating expenses for the second quarter increased $1,406,000, or 50% from the
comparable prior year quarter, but as a percentage of sales, decreased from 21%
to 20% primarily because of the inclusion of sales and operating expenses of
Calnetics which operates with lower operating expenses as a percentage of sales.
Operating margin increased from 8.6% to 9.7% as a result of the changes in gross
margin and operating expense discussed above.  The increase in net interest
expense incurred in the current periods related to interest expense on debt
acquired with the acquisition of LexaLite and interest on debt incurred in
connection with the acquisition of Calnetics (see "Liquidity and Capital
Resources" below).

Operating expenses for the six months ended February 28, 1998 increased
$3,845,000, or 96% from the prior year six month period primarily because of the
inclusion of the operating expenses of Calnetics for four months and the
inclusion of the operating expenses of LexaLite for the full six months in the
current year compared to three months of the prior year six month period.
Operating margins increased from 9.0% to 10.4% as a result of the changes in
gross margin and operating expense discussed above.  The increase in the
effective tax rate in the current period is primarily associated with the non-
deductible amortization of goodwill related to the recent acquisitions offset by
a lower effective combined state income tax rate.

The Company's backlog, believed to be firm, increased from $6,323,000 at August
31, 1997 to $7,770,000, at February 28, 1998, primarily as a result of the
backlog of newly acquired Calnetics.  The Company's order backlog is not a
significant indicator of future sales volumes.



Liquidity and Capital Resources
-------------------------------

The Company's working capital at February 28, 1998 was $13,761,000 compared to
$8,104,000 at August 31, 1997.  The primary reason for the increase was the
inclusion of the balance sheet of newly acquired Calnetics.

In connection with the acquisition of Calnetics, the Company entered into a new
$34 million credit agreement with a bank.  At February 28, 1998, total
borrowings under the credit agreement were $19,151,000, and the Company had
additional debt of $6,213,000.  The weighted average interest rate for all of
the Company's debt at February 28, 1998 was 7.6%, and unused bank credit totaled
$13,598,000.  All of the Company's assets are pledged to secure the debt
described above.

The Company believes that cash flows from operations and available lines of
credit will be sufficient to fund working capital requirements, planned capital
expenditures and debt service for the next twelve months.

The Company has a strategy of growth by acquisition.  In the event an
acquisition plan is adopted which requires funds

                                       8
<PAGE>
 
exceeding the availability described above, an alternate source of funds to
accomplish the acquisition would have to be developed. The Company has
10,000,000 shares of common stock authorized, of which 4,237,504 shares were
outstanding at February 28, 1998 and 5,000,000 shares of "blank check" preferred
stock authorized of which none is outstanding. The Company could issue
additional shares of common or preferred stock to raise funds.



PART II - OTHER INFORMATION


Item 1.  Legal Proceedings
--------------------------

The Company encounters lawsuits from time to time in the ordinary course of
business, and at February 28, 1998, the Company or its affiliates were parties
to two civil lawsuits as described below.  Although the Company has obtained
liability insurance coverage for each of the past five years, such insurance may
not be available in the future at economically feasible premium rates.
Additionally, some lawsuits filed against the Company in the past have contained
claims not covered by insurance, or have sought damages in excess of policy
limits, and such claims could be filed in the future. Any losses that the
Company may suffer from current or future lawsuits, and the effect such
litigation may have upon the reputation and marketability of the Company's
products, could have a material adverse impact on the future results of
operations, the financial condition and prospects of the Company.

Laitram, et al. v. KVP Systems, Inc., et al. was filed in the U.S. District
--------------------------------------------                               
Court in Eastern Louisiana in September 1993.  The plaintiffs claim KVP has
infringed upon two patents.  The venue was changed to the Federal District Court
in Sacramento, California.  KVP contended the claims were invalid and filed
certain counterclaims.  On April 24, 1997, the District Court ruled that KVP's
products do not infringe plaintiff's patents and also dismissed the
counterclaims.  Both parties have appealed the ruling.  Although the Company
believes it has a reasonable expectation of prevailing on appeal, in the absence
of applicable insurance, the consequences of an adverse determination would be
borne by the Company.

In Wright v. Stang, et al., a piece of pipe, to which a water cannon
   -----------------------                                          
manufactured by Stang was attached, broke, knocking a fireman down.  Since Stang
did not make or supply the pipe which failed, the case was dismissed.
Subsequently, the dismissal was reversed on appeal.  The Company has $2,000,000
in product liability insurance applicable in this case.

Item 2.  Changes in Securities
------------------------------

None.

Item 3.  Default upon Senior Securities
---------------------------------------

None.

Item 4.  Submission of Matters to a Vote of Security Holders
------------------------------------------------------------

At the Company's Annual Meeting of Shareholders held on January 26, 1998, the
following proposals were approved: (a) reincorporation of the Company from the
State of California to the State of Delaware, including separate proposals to
provide the following in the Company's proposed Delaware certificate of
incorporation:  (i) elimination of shareholders' ability to call a special
meeting of the shareholders, and (ii) requirement of a supermajority vote (66-
2/3%) of the shareholders to amend certain provisions of the Company's proposed
Delaware certificate of incorporation and bylaws;  (b) amendment of the
Company's 1995 Stock Option Plan to provide for the issuance of an additional
100,000 options that may be exercised for shares of the Company's Common Stock;
and (c) amendment of the Articles of Incorporation of the Company to provide for
the election of a Board of Directors of not fewer than six nor more than nine
directors divided into two classes, including division of the Board of Directors
into three classes after reincorporation in Delaware.  The Company expects
reincorporation in Delaware to be effective before the end of the current fiscal
year.

                                       9
<PAGE>
 
In addition, the following incumbent directors were nominated for reelection to
the Board of Directors of the Company for the terms indicated.  There were no
other director nominees.  Each was elected for the term indicated and until
their successors are elected and have qualified.

<TABLE>
<CAPTION>  
                                                         Term (years)                      Term (years)
                 Name                             effective January 26, 1998     effective upon reincorporation
                 ----                             --------------------------     -------------------------------
     <S>                                          <C>                            <C> 
     Coalson C. Morris                                          1                                 1
     Michael L. Horst                                           2                                 3
     William R. Zimmerman                                       2                                 3
     James R. Swartwout                                         1                                 1
     David McConaughy                                           2                                 2
     Byron C. Roth                                              1                                 1
     Josh T. Barnes                                             2                                 2
</TABLE> 
 
  
Item 5.  Other Information
--------------------------
 
Prior to October 1986, a previously owned business unit of one of the Company's
subsidiaries operated a facility on property within an area subsequently
designated as a federal Superfund site. The Company learned that hazardous
substances have been identified in the subsurface of the property and that the
current owner has been requested by a state agency to undertake additional
investigation at the property. The Company is also aware that the property has
been subject to a general notice letter issued by the United States
Environmental Protection Agency under the federal Superfund law. The Company, as
the successor to one of several prior operators of the property, may be held
responsible for the contamination at the site regardless of whether its
subsidiary caused the contamination. The Company does not believe it is
responsible for any contamination at the property, and has not been notified or
contacted by any governmental authority in that regard, nor named in any
proceeding relating to the property. However, if the Company were held liable
under federal Superfund law, or other environmental law, or had to defend itself
against such a claim, the consequences could be material to future results of
operations of the Company, but would not be expected to have a material effect
on its financial condition.
 
The Internal Revenue Service ("IRS") has completed its examination regarding the
tax exempt status of one of the Company's industrial revenue bonds. The IRS has
informed the Company that its findings indicate that the bond is not tax exempt
and thus the Company may be required to pay additional interest and/or taxes and
may be required to call the bond in its entirety. The consequences of resolving
this matter are not expected to be material to future results of operations or
to the financial condition of the Company.

 
Item 6.  Exhibits and Reports on Form 8-K
-----------------------------------------
 
  (a)  Exhibits.
 
       27.1  Financial Data Schedule
 
       In addition, each of the exhibits previously filed with the Commission in
connection with (i) the Company's Annual Report on Form 10-K for the fiscal year
ended August 31, 1997 (File No. 1-7755), (ii) the Company's Registration
Statement on Form S-4 (File No. 333-11571), and (iii) the Calnetics' Annual
Report on Form 10-K for the fiscal year ended June 30, 1997 (File No. 0-08767),
as well as Appendix I to the Calnetics' definitive Proxy Statement on Schedule
14A (File No. 0-08767) for the Special Meeting of Shareholders held October 28,
1997, are incorporated herein.

                                       10
<PAGE>
 
  (b)  Current Reports on Form 8-K.
       ---------------------------- 

       None.
 
 
 
                                  SIGNATURES
 
 
Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized on March 20, 1998.
 
 
 
                               Summa Industries
 

/s/ James R. Swartwout                             /s/ Trygve M. Thoresen
----------------------                             ----------------------
James R. Swartwout                                 Trygve M. Thoresen
President and Chief Financial Officer              Vice President and Secretary

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