The Normal Process of Oxydation
The Blanket
Chemical Attack
Water Treatments

The Normal Process of Oxidation

"Metal will oxidize...

With steel it becomes a coat of rust.
With stainless steel it's a dull film."

This is the metal's method of protecting itself. Oxidation occurs until there is a sufficient oxide thickness to protect the base mental. This thickness varies from metal to metal.

When a blanket is intalled on a cylinder, an environment is created between the blanket and the cylinder. This environment interferes with the metal's (cylinder's) ability to build its protective coating by starving the metal surface of oxygen.

Corrosion on
Stainless Steel Cylinder

Corrosion on
Nickel Coated Steel Cylinder

The Blanket

The blanket wicks water into the canvas backing, creating a wet area around its border and a dry area in the center.

Most corrosion occurs in the covered wet areas. On nickel coated steel, the damage is evenly distributed in the wet area. On stainless steel, the damage is spotty with a concentration at the edge of the wet area.

Chemical Attack

Chlorine in incoming water turns into hydrochloric acid when trapped under the blanket. Hydrochloric acid dissolves chrome as well as attacks steel. (Chrome is the active corrosion resistant ingredient in stainless steel.)
Using bleach or acids to clean dampener lines is another method of introducing corrosives to the environment.

Figure 1
During repair, this cylinder was used for 4 days with exposed steel. This is how much corrosion developed in that time.
(See A, B, and C above)

Figure 2
During patent testing, al corrosion was ground off this cylinder area and a blanket treated with Rust Sentry installed. After 30 days the cylinder stayed free of corrosion (rust).
(See D above)

About Water and Water Treatments

Depending on where you are in the country, water condition can be a significant factor in the corrosion of printing cylinders. City water is often treated with clorine in varying levels. Add to that the introduction of fountain solutions containing chemicals or bleach and the problems may multipy.

It might seem logical that filtering your incoming water could solve most of your problems but that isn't necessarily true. In fact, water that is completly pure or treated with a reverse osmosis system is actually more corrosive. The conditions prevailing in your location may need to be analyzed in order to find the cause of corrosion on your cylinders. InPress Solutions. can help you decide what you can do to minimize corrosion problems in your pressroom.

For more information about how

can help you stop corrosion on your blanket cylinders,
just click on the bottle to visit the Rust Sentry website...

U. S. Patent No. 5,366,784