There is an old axiom that says polymer coatings bond more strongly to
chromium than to tin. However, I’ve not found any referenced technical
publications that either prove or disprove this saying...
November 2017 SPRAY 39
The interpretation of the graph in Figure 2 is complex and
often leads to the incorrect conclusion that corrosion is prevented
by high pH. Indeed, the curve in Figure 1 is the basis for the
corrosion myth that increasing pH stops TFS and ETP aerosol
container corrosion.
For example, notice in Figure 2 that when the pH is 13, the
corrosion rate is approximately 50 millimeters per year—a very
high corrosion rate. The service lifetime for a 2Q aerosol container
with this high corrosion rate would be approximately two
days. In other words, even though increasing pH does decrease
the corrosion rate, it might not decrease the rate to a low enough
magnitude to result in a commercially acceptable container
service life.
Other ingredients in a formula could change the actual pH
range that produces low corrosion, produce significantly higher or
lower corrosion rates from those in Figure 2 at any given pH, and
change the shape of the pH-corrosion rate curve altogether. In
other words, Figure 2 only illustrates that steel corrosion rates are
a complex function of pH.
Consequently, changing a formula’s pH should be accompanied
with corrosion tests to determine if the pH-change will
increase or decrease TFS container and ETP container steel
corrosion.
Next month we’ll continue the series with a discussion of stainless
steel.
Pair O Docs has a state-of-the art electrochemical corrosion
testing laboratory; please contact me if you would like to know
more about our faster and predictive corrosion testing. You can
also visit our new website which has a short Vision Video that
discusses all our corrosion prevention and control services. Please
also contact me if you would like to a have our Elements of Spray
Package Corrosion short course taught at your R&D facility. Back
issues of Corrosion Corner are available on CD-Rom. Thanks for
your interest and I’ll see you in December. SPRAY
Statement of Ownership, Management, and Circulation
(From U.S.P.S. Form 3526-R)
Publication Title: Spray Technology & Marketing
Publication Number 1055-2340 Filing Date: Sept. 28, 2017
Issue Frequency: Monthly No. Issues Published Annually: 12
Annual Subscription Price: ---
Complete Mailing Address of Office of Publication:
140 Littleton Road, Suite 320, Parsippany, NJ 07054
Complete Mailing Address of Headquarters of Publisher: Same
Full Names and Address of:
Publisher: Cynthia Hundley, Parsippany, NJ 07054
Editor: Ava Caridad, Parsippany, NJ 07054
Owners:
Industry Publications, Inc., 140 Littleton Rd. Suite 320 Parsippany, NJ 07054
Cynthia Hundley, 140 Littleton Road, Suite 320, Parsippany, NJ 07054
Donald J. Farrell, 140 Littleton Road, Suite 320, Parsippany, NJ 07054
Known Bondholders, Mortgagees, and Other Security Holders: None
Extent and Nature of Circulation: Business to Business-Spray Packaging
industry
Issue Date for Circulation Data Below: September 2017
Average No.
copies - 12
month period
Signature: Cynthia Hundley, Publisher, October 1, 2017
September
2016 issue
Total paid and/or requested mailed circulation 4,402 4,437
Free distribution outside the mail (trade shows) 132 400
Total distribution 4,534 4,837
Copies not distributed 40 43
Total 4,574 4,880
Requested or paid electronic copies 1,187 1,095
Total requested copy distribution 5,721 5,932
% Paid or requested circulation 98% 95%