Why is lead added to the galvanizing bath?
Lead is not purposely added to galvanizing baths, rather it is an impurity in zinc. Different types of zinc have different levels of lead. The specified lead maximums for the various types of zinc can be found in ASTM B6.
Lead does have the beneficial effect of decreasing the surface tension of zinc, which allows it to flow off the steel easier as it is being removed from the kettle. This creates thinner galvanized coatings that have less runs and drips. Bismuth is sometimes added to galvanizing baths to achieve the same effect as lead has when types of zinc are used that have very low levels of lead.
© 2023 American Galvanizers Association. The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.
Comments
tommy v
Galvanized wire seems to develop white spots right out of the kettle. A way to correct the problem has been to increase water flow at the quenching stage. Would welcome ideas on how to prevent these white spots that often are called water spots.
(AGA)
Hi Tommy, assistance with galvanizing process details is available to AGA members only. To become a member: https://galvanizeit.org/about-aga/become-a-member
Harry
Hi, Do you know about any lead free galvanizing? if yes how is it done? Thanks
(AGA)
Hi Harry, All zinc grades contain a small amount of lead, because lead is found in most natural deposits of zinc. Some galvanizers utilize high grade and special high grade zinc ingots which have very low lead content (<0.003 or <0.03%) and are acceptable for most low-lead applications.
Ajay
We had change the zinc cattle with additon of new zinc but we suffer under the problem of zinc pimples and rough surface which can't overcome yet after 7 days could anyone suggest something then plz contact me on my mail
(AGA)
Hi Ajay, We have a guideline for reducing dross pimples which is available to AGA members: https://galvanizeit.org/members/guidelines-notes/dross-pimples-on-finished-product