Why can’t I specify the finish I want with Hot Dip Galvanized Steel? It’s a question that doesn’t have a simple answer. The ACA covers the influencing factors in this interesting article. The initial appearance of HDG steel is largely determined by the metallurgical reaction between the zinc and the steel. To find out what the 4 key influencing factors are and what to expect, over time as the oxidisation process occurs, take a look at this article.