Exhibit 10.15.6
SIXTH AMENDMENT TO THE
RPM INTERNATIONAL INC. 1997 RESTRICTED STOCK PLAN
     THIS SIXTH AMENDMENT to the RPM International Inc. 1997 Restricted Stock
Plan is executed by RPM International Inc. (hereinafter referred to as the
“Company”) as of the date set forth below.
WITNESSETH:
     WHEREAS, the Company adopted and maintains the RPM International Inc. 1997
Restricted Stock Plan (hereinafter referred to as the “Plan”) for the benefit of
certain of its employees and certain employees of the Company’s subsidiaries;
and
     WHEREAS, the Company reserved the right, pursuant to Section 8 of the Plan,
to make certain amendments thereto; and
     WHEREAS, it is the desire of the Company to amend the Plan so that, upon
lapse of restrictions on stock awarded thereunder, the Company or the escrow
agent shall automatically sell the number of shares necessary to generate
sufficient proceeds to satisfy the grantee’s minimum tax liability arising from
the lapse of restrictions;
     NOW, THEREFORE, pursuant to Section 8 of the Plan and effective as of the
date hereof, the Company hereby amends the Plan as follows:
     1. Section 5.1 of the Plan is hereby amended by the deletion of Section 5.1
in its entirety and the substitution in lieu thereof of a new Section 5.1 to
read as follows:
     “5.1 The Shares shall not be sold, transferred or otherwise disposed of and
shall not be pledged or otherwise hypothecated (and any such sale, transfer or
other disposition, pledge or other hypothecation being hereinafter referred to
as “to dispose of” or a “disposition”) until the earliest of (a) the later of
either the employee’s termination of

 

--------------------------------------------------------------------------------

 

employment with the Company and any of its subsidiaries or the lapse of the
right of the Company to a return of such Shares pursuant to Section 5.2 below;
(b) a change in control that occurs with respect to the Company; or (c) the
termination of the Plan. Notwithstanding the foregoing, but subject to the
terms, conditions and restrictions specified under this Plan, after the date
that a participant’s Shares become nonforfeitable in accordance with Article 5
or Article 6, and provided that the participant has not surrendered the Shares
in accordance with Section 11.3, the Company or the escrow agent (as the case
may be) shall sell the fewest number of such Shares with respect to which
restrictions have lapsed necessary for the proceeds of such sale to equal (or
exceed by not more than the actual sale price of a single Share) the
participant’s minimum tax liability determined by multiplying (A) the aggregate
minimum marginal federal and applicable state and local income tax rates on the
date of the lapse of restrictions; by (B) the total number of Shares with
respect to which restrictions have lapsed. The Company or the escrow agent (as
the case may be) shall withhold the proceeds of such sale for purposes of
satisfying the participant’s federal, state and local income taxes resulting
from the lapse of restrictions. The Company or the escrow agent (as the case may
be) shall deliver the proceeds of the sale of Shares to the Internal Revenue
Service and/or other taxing authority in satisfaction of the participant’s tax
liability arising from the lapse of restrictions. The participant shall provide
the Committee, the Company and/or the escrow agent with such stock powers and
additional information or documents as may be necessary for the Committee, the
Company and/or the escrow agent to discharge their obligations under this
Section.”

2

--------------------------------------------------------------------------------

 

     IN WITNESS WHEREOF, RPM International Inc., by its officer duly authorized,
has caused this Sixth Amendment to the RPM International Inc. 1997 Restricted
Stock Plan to be signed effective as of September 1, 2006.

                  RPM INTERNATIONAL INC.    
 
           
 
  By:   /s/ Ronald A. Rice    
 
           
 
      Ronald A. Rice    
 
           
 
  Its:   Senior Vice President — Administration    
 
           

3