The difference of anti-corrosion mechanism
What is the difference between ROVAL and conventional paint?
A conventional paint film acts as a surface barrier to water and air. This is called “anti-corrosion by barrier protection.”But once the film is damaged or has deteriorated, rust develops in that area and begins to spread underneath the film.
ROVAL protects steel by the mechanism of electrochemical reaction, employing the self-sacrificing property of zinc.
In the case of steel only, the reaction between the anode and the cathode occurs on the surface of the steel and rustoccurs. However, when steel and zinc in close contact, the zinc side becomes the anode, and the zinc protects the steel
by rusting instead of the iron.
Even when a ROVAL film is damaged, rust will not spread due to the presence of the surrounding zinc particles.

ROVAL(80μm)

Epoxy paint+ Urethane topcoat

JIS anti-corrosion paint+ Phtalic topcoat

No rust is found.

Rust from cross-cut.

Rust spread overthe substrate.

Enlarged photo

Enlarged photo

Enlarged photo

Rust does not spreadfrom cross-cut.

Rust from cross-cut spreads.

Rust is foundother than cross-cut.

Beforeexposure

After36 months
exposure

Exposethe steel
substrates(cross-cut part)(cross-cut part)(cross-cut part)ROVAL vs Normal paints Anti-corrosion mechanism
ROVAL

Normal paints(An�-corrosion by electrochemical reac�on)(An�-corrosion by barrier protec�on)

Mechanisms of Anti-corrosion
Sulfurous acid gas
CO2 gasWaterSunlight(UV rays)

Water may penetrate throughthe zinc dusts on the steel
surfaces, but the steel isprotected by the electrochemicalreac�on of zinc.

Sulfurous acid gas
CO2 gas

Paint ﬁlm provides protec�on toa metal surface by shielding itfrom water/air.

Normal paints

Secondary layer
Primer

Steel

Steel

Water

Sunlight(UV rays)

Top-coa�ng

ROVAL ﬁlm

Sulfurous acid gas
CO2 gas

Water

Sunlight(UV rays)

Steel

The oxidiza�on of zinc forms
corrosion products which act asa protec�ve barrier against air
and moisture improvingan�-corrosion performance.

Sulfurous acid gas
CO2 gasSunlight(UV rays)

A protec�ve barrier deteriorates
with exposure.

Sunlight(UV rays)

Rust will develop and creep
under the paint ﬁlm.

SteelCorrosion productIf rust should develop on
damaged or thinly covered
surfaces, electrochemicalreac�on prevents rust fromcreeping under the paint ﬁlm.

Water

Sulfurous acid gas
CO2 gasWater

Red Rust
Steel

SteelRust

MaintenanceA�er removing white rust withhand tools, reapply ROVAL tothe exis�ng ﬁlm.
(In case of red rust, remove withpower tools.)

Preparation
Hand tool
Power tool

Preparation

Old ﬁlms

Sandblas�ng
Power tool

SteelLowcost

No need to remove old ﬁlm

Easy
applica�onReapplying

Red Rust

High cost
Steel

Reapplying

Complexapplica�onTop-coa�ngSecondary layer
PrimerSteel

New ROVAL ﬁlm
Old ROVAL ﬁlm

A�er completely removing allold ﬁlm and red rust withsandblast or power tools, apply
primer, intermediate coat, andtopcoat.

Steel
鉄

The zinc protects the iron by rusting instead of the ironPrepare two steel plates and immerse one in salt water. On the other steel plate, put a slab of zincand immerse in salt water.
After 2 weeks, only the steel plate without zinc has rusted. On the other hand, the steel plate carrying
a slab of zinc has not rusted.
This experiment shows the zinc protects the iron by rusting instead of the iron.
Only steel plate

Steel plate + Zinc

After 2 weeks

We succeeded in raising the dry film zinc content to 96% by mixing a large amount of zinc powder
into a special resin.
Our competitors usually use around 70 to 80% zinc in their products, but we use a staggering 96%.
ROVAL is a paint that can make the most of the anti-corrosion ability of zinc.
Cross-sectional photograph of theROVAL coating film (x1000)

Zinc powder

Steel surface

Cold Galvanizing CompoundZincContent

96 %