Clogged Holes
Clogged holes are a defect caused by molten zinc metal not draining adequately and partially or completely filling holes with excess zinc. Molten zinc will not drain easily from holes less than 3/10 (8mm) in diameter due to the viscosity of zinc metal. A good example is the screen shown to the right. Clogged holes can be minimized by making all holes as large as possible; regardless, clogged holes less than 1/2 in diameter are not a cause for rejection, unless it prevents the part from being used for its intended purpose.
© 2026 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.