Critical Cleaning in Controlled
A Q&A about cleaning systems, solvents, and vapor degreasing.
Image: MicroCare Corp.
Q. What exactly do you mean by the term “critical cleaning”?
Here at MicroCare, we define “critical cleaning” as those
factory environments in which a cleaning failure could
result in extraordinary costs, product failures, legal action,
product recalls, or even potentially the loss of life. Critical
cleaning environments permit
zero failures. When it’s got to be
perfect, every time, that’s critical.
Q. How does critical cleaning differ from precision cleaning?
Precision cleaning is a less-critical
process. It can tolerate some
proportion of cleaning failures.
The many degrees of cleaning
are defined by one crucial ques-
tion: “What does it cost when the
cleaning isn’t perfect?”
Imagine a person working in
a Class 1,000 cleanroom making
medical devices. An undetected
cleaning problem can lead to
product failures or bacterial
growth. We’re talking infections,
additional surgery, lawsuits,
recalls, reputations tarnished. It’s
major; it’s catastrophic; it’s critical.
Q. Companies have been cleaning in controlled environments for years. So what’s driving this change?
The difference today is many of the tried-and-true cleaning answers used in those cleanrooms today soon may not
work or may not be available. The processes companies
have used for years even may not be obtainable at any price.
A great example is in electronics, and the continued
miniaturization of new products which makes cleaning
much more difficult. These smaller, denser, more complex
electronics are much harder to clean, and the old techniques ain’t going to get it done. So let me put it to you
straight: the old answers are going away.
Q. Is going “green” the problem? Is it also the answer?
There are huge pressures on companies to become more
“green.” Many regulators want companies to minimize use
of smog-producing chemicals, called “volatile organic com-
pounds” and the most popular VOC is simply alcohol. The
European REACH regulations, new toxicity research, and
simple economics also are forcing vendors to reformulate or
even to withdraw products altogether. For example, Asahi
Glass has pulled from the market their popular cleaner,
HCFC-225, to comply with the Montreal Protocol. Using
alcohol in California is almost impossible today.
At the same time, water-cleaning is losing its economic
and environmental advantage. Water-cleaning systems
generally have been getting bigger to accommodate the
tougher cleaning problems. These super-sized machines
have trouble fitting conveniently into the expensive floor
space of a cleanroom. They also use more electricity
(which contributes to global warming) and release hot,
humid air into the humidity-controlled environment of
In contrast, low surface tension, non-flammable cleaning fluids easily can achieve cleanroom performance standards, even in relatively small machines. They cut water
consumption completely and cut electricity consumption
by 70%. They reduce consumables and simplify maintenance. They don’t require a protective bubble of space,
wiring, and plumbing around them. Vapor degreasers simply are very flexible. It’s a win-win for everybody.
Q. These systems sound remarkable. Why don’t we hear
more about the capabilities of vapor degreasing?
When I explain vapor degreasing to young engineers
— say, people under 35 — they think I’m Professor
Dumbledore. The process sounds like magic. But it’s
not. It’s just simple thermodynamics, and in a properly
engineered system it works great. And, not too long
ago, it worked everywhere. Vapor degreasing was widely
used through the 1980s. Virtually every factory had a
vapor degreaser; they were fast, effective, and cheap.
This was a thoroughly well-proven technology and
every old-timer today probably remembers one from
their early years.
But there’s a catch. With vapor degreasing, you need
both good hardware and good cleaning fluids to make it
all work. But as late as the 1990s, the most popular fluids
were all ozone-depleting substances. So when the solvents
went away, the machines went with them.
Q. What do these machines look like?
In general, there are three types of vapor degreasers. The
most common is the batch-style, open-top degreaser in
which the parts are moved vertically in and out of the
cleaning chambers. These can be as small as a 4-liter
machine that fits on a desktop, and as big as a 5,000-liter
system into which you could insert a jet engine. These