Re: Coating Rod Basics

From: Jason DeFontes <jason@defontes.com>
Subject: RE: Coating Rod Basics
Date: Wed, 24 Nov 2004 01:39:53 -0500

> Are there any processes that would be contaminated by the use of a
> stainless-steel rod? So many of the formulas I've been reading warn about
> contamination from iron in the water, etc. I've been wondering if these
> wire-wound coating rods would work, since the way they're designed to
> provide an even coating makes a lot of sense to me.

For one thing, I might add that "stainless steel" is not a uniquely
defined material. It's an alloy containing varying proportions of
chromium and nickel, and there are a few other components that are not
often indicated on the material/product, such as niobium, molybdenum
and titanium. Different components and proportions offer a range of
properties, such as corrosion resistance. I suspect this is why cheap
stainless kitchen wares get rusted rather easily in certain conditions
while high corrosion resistant SS remain rust free. I've seen the same
thing among SS film developing tanks.

I don't know about other processes or countries, but I read that DIN
standard specifies categories of stainless steel material that is
considered suitable for silver gelatin emulsion making
vessels. However, I read more that modern emulsion making vessels are
made from titanium. My vessels are made from glazed ceramic and I'm
generally happy with it, but I want an 18" wok made from
titanium. Very light, good heat conductor, relatively nonstick, and
high corrosion resistance. (last time I checked it's something like
USD600 a piece...)

--
Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)