Water and the Plating Process: Part 1

It may seem fairly obvious to most readers, but water plays an integral role in the plating process. Whether it’s the rinse tanks, or the process tanks, water is in every bath. It may come as no surprise to you that the different types of water will interact with the plating process in different ways. In this series of blog posts, we will delve into each type of water and how it interacts with the process, starting with hard water.

Hard Water

As you may recall, hard water is characterized by its mineral content. These minerals, typically calcium and magnesium, can cause several issues. Let’s first look at the cleaner baths. Hard water, when used in cleaner baths, can prevent saponification. Saponification is the process by which the cleaner reacts with the soil on the surface of the part and allows it to be pulled off the part into the cleaner solution, thus cleaning the part. With that in mind, it becomes pretty clear why we would not want this process to be prevented. Now, I don’t want to make you think that this happens immediately. In fact, the cleaner will do us the favor of softening the water, at the expense of cleaner bath life. By this softening, hard water will cause a large amount of sludge to be formed in the bottom of the tank, in addition to the normal sludge formation in emulsion type cleaners.

Hard Water in Rinse Tanks

Let’s move onto talking about hard water in the rinse tanks. Hard water will affect the rinsing process in a few different ways. First, hard water already has a fair amount of “stuff” in solution. This means that it will be limited in the amount of soil that it can rinse off the surface of the part. If it fails to rinse the entirety of soil/chemicals off the surface of the part, that “stuff” is going to be carried further into the next process tank, leading to issues down the line.

Hard Water in Plating Tanks

Speaking of process tanks, what will hard water do in the plating tank? This is harder to answer in a very general sense, since different cations (the minerals in the hard water) will affect plating tanks differently. Generally, you can expect to see roughness in the deposit, a dull overall deposit, lower anode efficiency, and possible the evolution of sludge in the bottom of the tank. Because of these possible issues, which can cause a lot of headaches, it is best to avoid hard water when making up a plating tank. This advice can be translated to post-treatment tanks as well. In general, your plating tanks and post treatment tanks should be as clean as possible, since they are the last things to touch the parts.

In short, hard water is less than ideal in all aspects of the plating process. This is due to its high levels of reactive cations. These cations can cause sludge buildup in most of the tanks on the line, can lead to the formation of lime deposits in pipes, and negatively impact the appearance of the plating deposit. Because of this, it is recommended that you avoid hard water whenever possible and economical.

Look out for Water and the Plating Process: Part 2, about soft water and the plating process. For a much more in-depth discussion on water and the plating process, please contact either the Asterion main office or your friendly Asterion rep.