JS500
Information
The Most
Frequently Asked Questions About JS
What Is JS5OO?
JS500 is .0003" minimum thickness of electrolytic zinc, which is
yellow dichromated, and then leached back to white in the JS
Solution.
How Does It Work?
The .0003" minimum of electrolytic zinc provides a homogeneous,
solid, covering of sacrificial zinc that is sufficiently thick
as to cover the minor blemishes in steel brought on by working,
that form corrosion sites. The zinc acts as a protection for
steel by reacting with the atmosphere in the preference to the
exposed steel. The better the zinc deposit and the more zinc
present the better the protection. The yellow dichromate
provides a barrier protection to prevent the atmosphere from
reacting with the zinc to give the familiar white corrosion
products, and therefore prolong the life of the zinc. The JS
film works in several ways to further increase this protection
tenfold. The JS enters the passivate gel and replaces the
hexavalent chromium. It also forms a further protective layer on
top of the gel, which is flexible and not easily wetted. The
effect is that humidity runs off the surface so preventing the
formation of an electrolytic corrosive cell. The outer JS layer
also prevents the chromate gel from mechanical damage. The gel
layer adds further protection and in the event of mechanical
damage penetrating the gel it frees up the self healing JS to
react with the zinc surface and prevent further corrosion, and
of course the zinc gives it normal sacrificial protection, aided
by limited free surface.
What Protection Does This Give?
JS will give a minimum of 500 hours to red rust on significant
surfaces, and 96 hours to white rust in the standard salt spray
test. JS will also give a minimum of five cycles in the
Kesternich test.
How Does This Relate To Service?
There is no direct correlation between corrosion tests and real
life.
How Do I Know It Will Meet My Corrosion Protection Needs?
There is no such thing as a corrosion protection agent that
meets all of the conflicting demands of the customer. Toxicity,
dimensional changes, availability, compatibility, and economics
all play their part. What we can say that JS has been in the
field and operating satisfactorily in the automotive,
construction and agricultural and appliance industries for over
ten years. The JS is non-toxic does not significantly change
dimensions, is economical to apply, and is compatible with most
other finishes and metals.
What Drawbacks Does JS Have?
It can only be painted if specially pretreated and care has to
be taken to allow for the inherent characteristics of
electrolytic zinc, such as low current density areas.
How Easily Available Is The Process?
MacDermid Incorporated licenses the process to 20 metal
finishers in the USA and 2 metal finishers in Ontario. The
process is also available in Europe.
What Advantages Does JS Have?
It is non toxic, withstands bending, does not significantly
affect dimensions, readily available, economical in application,
provides adequate corrosion protection, pleasing in appearance,
does not accumulate in recesses, resists abrasion and does not
conduct electricity.
Where Can I Get More Information?
The process was developed in Canada at Torcad, in Toronto
telephone number, (416) 239-3928 or email us at: torcad@bellnet.ca .
Information can also he obtained from MacDermid Incorporated
with offices all over North America, Head Office (203) 575-5600.
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