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Differences Between Clear Zinc and Yellow Zinc

I would like to know what advantages there may be to having parts yellow zinc plated as opposed to clear zinc plated. On some parts that we paint after clear zinc plating we have a problem with out gassing. Would changing to yellow zinc help in this matter?

Steve Callier
P&A Metal Fab Inc. - Portland, OR, USA
2001

Hi,

The biggest advantage of yellow passivation is the additional corrosion protection it offers. If your "blisters" are caused by the surface being too smooth after clear passivation then the yellow passivation will solve your problem, but in most cases the problem is deeper: the cleaning was not good enough and the heat lifts the plating off the article. If you can lift some of the paint off you can see: if the zinc coating is on the base metal then your problem was the passivation, if the zinc metal comes off with the paint then you have a cleaning problem.

Good luck!

Trudy Kastner
Chemserve Systems - Durban , South Africa
2001