So you decided to purchase an immersion wort chiller but you can't decide between copper or stainless steel. We all know how cool stainless is but which is the better choice?
When it comes down to which will cool your wort quicker, copper immersion chillers is the clear choice. The heat exchange copper provides is superior to stainless thereby providing quicker cool downs which help reduce DMS and provides better cold break. Fast cooling is also imperative to reduce wort temperature to under 175° in order to halt isomerization and lock in your bitterness.
So why stainless steel you may ask? Well, it has excellent corrosion resistance, it's easy to clean, and will last a lifetime. Another advantage of stainless over copper is that copper can develop a greenish-blue toxic oxide called Verdigris. Though it's easily removed from copper, if left on when immersed in wort it can contaminate your beer.
High copper cost have made stainless steel wort chillers more attractive price wise, and a proper sized stainless steel chiller will do an adequate job of cooling wort. But when it comes down to which will cool your wort quicker, copper is the better choice.