My response in the February issue regarding General Motors specification GMW 3359 for non-electrolytically applied zinc-rich coatings was incorrect. Here is the correct answer:
Using a non-electrolytic process greatly reduces problems associated with hydrogen embrittlement of steel components. This specification discusses the application of zinc-rich solvent or water-based coatings, typically using spray or dip-spin processes. The standard is available for a fee from engineers.ihs.com.
The dip-spin process is good for small parts and is conceptually simple. Parts are loaded into a suitable carrier, dipped into a solution and then spun at high speed to ensure that all of the components in the container are coated. The typical process sequence is: cleaning and pretreatment, coating application and oven curing, then a second coating and oven curing, if needed.