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HoldTight®102 NO SALT NO RUST ONE STEP |
THE ULTIMATE
CHLORIDE REMOVER
Independent tests confirm that
HoldTight®102 removes ALL chlorides (and other contaminants). It then prevents flash rusting, a simple
and obvious indication that the surface
is clean and ready for coating.
Removing Soluble Salts with
HoldTight®102
Using
three different SSPC-approved tests for
the presence of soluble salts, New York
City Department of Transportation (NYCDoT)
researchers concluded that HoldTight®102 will effectively
achieve zero or undetectable salt
levels.
SSPC-TU
4 Field Methods for Retrieval and Analysis of Soluble Salts on Substrates, sets out guidelines for testing for soluble salts in the field. NYDoT conducted its tests at a Brooklyn site
in accordance with these SSPC guidelines.
All
test samples were taken using the ISO 8502-6 Bresle Sampling Method, as
described in SSPC-TU 4, Section 3.3 - Adhesively Bonded Cell. Then, three different SSPC-approved test procedures
were used to determine the soluble salt levels on the test samples before and
after the application of HoldTight®102 as
recommended by the manufacturer. In
principle any one of the three procedures would have been sufficient. NYCDoT staff used all three, however, as a
multiple cross-check of the results and to confirm with a high degree of
certainty that HoldTight®102 would
effectively remove chlorides.
The
substrates tested were severely corroded steel coupons, approximately 2" thick,
cut from bridge structures removed during repair operations. In each test the sample was first dry
blasted. HoldTight®102 was then used in a potable water wash down at 500
psi, 1-2 gpm, one part HoldTight®102 was
used with 50 parts water. (Note, the
manufacturer recommends this 50:1 dilution of HoldTight®102 as a starting point, especially with dry
blasting. In practice, users report
similar results with 100:1 to 200:1 dilutions depending on the condition of the
surface and the method of surface preparation used. Typically, the more pressure and water used in surface
preparation, the less HoldTight®102 per unit of water needs to be used to achieve
zero or undetectable levels of chlorides.)
The three tests were as follows:
Ø
Kitigawa
Tube method.
Prior to using HoldTight®102 ,
soluble salt levels on the test samples ranged between 200 and 280 ppm, as
measured by an ISO 8502-5 Chloride Ion Detection Tube. These soluble salt
levels were reduced to zero after
the HoldTight®102 wash down. This ISO procedure for testing of soluble
salts is explained in SSPC-TU 4, Section
4.3 - Field Detection of Chloride Ion by Kitigawa Tube.
Ø
Quantab
Strip method. Prior
to using HoldTight®102, soluble salt
levels on the test samples ranged between 200 and 260 ppm, as measured by Quantab Strips in the test procedure described in SSPC-TU 4, Section 4.4 - Field
Detection of Chlorine Ion by Quantab Method.
Soluble salts were undetectable
after the HoldTight®102 wash down.
Ø
Silver
Dichromate (qualitative) method. Soluble salts were also undetectable after the HoldTight®102 wash down as determined
by the ISO 8502-1 Field Test for Iron II Salts in Abrasive Blast Cleaned
Surfaces (Field Test for Soluble Iron Corrosion Products) as described in
SSPC-TU 4, Section 4.8 Qualitative Field Detection of Ferrous Ion.
Similar
results have been reported by users of HoldTight®102 in various other surface
preparation methods and in our own lab tests:
Ø
In water or wet abrasive blasting when HoldTight®102
is used either in the blast water or in the wash down water or in both
Ø
In ultra-high pressure (UHP)
blasting when HoldTight®102 is used, as in dry blasting, after the initial blast
or stripping step in a wash down at a minimum pressure of 500 psi, 1-2 gpm)
HoldTight®102 prevents flash
rusting: the easy way to
determine surface cleanliness.
Simply
put, if flash rust occurs after surface preparation -- even by a method
intended to reduce or remove salts -- you cannot be sure the surface is clean
enough to coat. After working with the
water* to remove contaminants, HoldTight®102
then rapidly evaporates. It
literally lifts the remaining water off the surface, quickly drying the surface
before oxygen in the air has a chance to react with the metal and the water to cause
rust. But if “hygroscopic”
(“water-attracting”) contaminants of any kind remain on the surface, even this quick drying action would not
prevent flash rusting. That’s because
those “suckers” pull moisture out of the air, then they react with the air and
new moisture to cause rust.
So,
if the surface rusts, you may or may not have contaminants. Even if you test for chlorides and find
none, the results may only apply to the specific area of the test. Contaminants may not be spread uniformly
across the surface. The fact is that rust, no matter what its
cause, is typically inconsistent. On the other hand, if the surface does not
rust, you can be very confident that it
is both contaminant- and moisture-free.
Over time, of course, contaminants carried in the air re-contaminate the
surface and then pull moisture out of the air to cause rust. Then you lose your “window” for
coating. With HoldTight®102 that window is usually 2 to 5 days.
_______________
*
HoldTight®102 “works with the water”
in part by dramatically reducing surface tension -- causing the water to spread
much more evenly over the surface, to literally wet the surface more
efficiently. This wetting action
combined with the force of the water under pressure results in much more
efficient cleaning than water alone, even water under very high pressure. Heating the water also reduces surface
tension somewhat, for example, raising water temperature from 20 C (68 F) to
100 C (212 F) reduces surface tension from 72.8 dynes/cm to 58.9 . But at a 1:50 ratio, HoldTight®102 reduces surface tension to 23.4 dynes/cm.