Comparison Of Zinc Coatings

	SHERARDIZING	GALVANIZING	ZINC ELECTROPLATING
ADHESION	EXCELLENT, coating forms an alloy with the substrate.	Good, some alloying the substrate.	Poor, no alloying with substrate.
UNIFORMITY	EXCELLENT, vapour deposition ensures uniformity, ideal for irregularly shaped, recessed and threaded components and close tolerance work.	Poor, molten zinc can lead to build up of coating in drain points.	Poor, preferential deposition on external corners and protrusions and reduced deposition in recesses and internal corners
WEAR RESISTANCE	EXCELLENT, due to the iron content of the coating, it is the hardest of the zinc coatings. The coating can only be removed by chemical or mechanical means.	Good, a tough durable coating but will not withstand forming.	Good, can withstand forming but usually applied to finished components.
POST TREATMENTS	EXCELLENT, forms an excellent key and and accepts top coats without the need for primers or surface finishing.	Poor, requires further processing to ensure adhesion.	Poor, requires further processing to ensure adhesion.
COATING THICKNESS	15-80 microns, thicker coatings possible.	25-140 microns	5-25 microns
HYDROGEN EMBRITTLEMENT	NONE as no acid used and the process is dry and contains no sources of Hydrogen.	DANGER due to acid use.	DANGER due to acid use and presence of Hydrogen in the process.
BRITISH/EUROPEAN STANDARDS	BS 4921/BS EN 13811:2003 - Part 8 BS 7371 PART 8:1998 FOR FASTENERS	BS 729/BS EN ISO 1461 BS 7371 PART 6:1988 FOR FASTENERS	BS1706/BS EN 12329:2000 BS 3382 PART 2 FOR FASTENERS
COST	THE TRUE COST OF PROTECTING COMPONENTS CONSIDERS BOTH THE INITIAL COST AND THE LIFETIME MAINTAINANCE COST. SHERARDIZING PROVIDES AN EFFECTIVE LONG TERM COATING WHICH IS COMPETITIVE ON AN INITIAL COST AND MAINTENANCE BASIS.