06
BIR TLE Y GA LVA N IZ IN G | GALVANI ZI NG PROC ESS
THE PROCESS
The galvanizing reaction will only occur on a chemically
clean surface. Therefore most of the preparation work is
done with this objective in mind. In common with most
coating processes the secret to achieving a good quality
coating lies in the preparation of the surface of the iron or
steel. It is essential that this is free of grease, dirt and scale
before galvanizing. This type of contamination is removed
by a variety of processes. Common practice is to degrease
using an alkaline or acid degreasing solution into which the
component is dipped.
The article is then rinsed in cold water and then dipped in
hydrochloric acid at ambient temperature to remove rust
and mill scale. Welding slag, paint and heavy grease will not
be removed by the above cleaning steps and should be
removed before the work is sent to the galvanizer.
After a further rinsing operation, the components will then
commonly undergo a fluxing procedure. This is normally
applied by dipping in a flux solution - usually out 30%
zinc ammonium chloride at around 65-80°C. The fluxing
operation removes any of the last traces of oxide from the
surface of the component and allows the molten zinc to
wet the steel.
For more information about galvanizing please visit
the Galvanizers Association website:
Birtley Galvanizing Factory
www.galvanizing.org.uk