You may have heard the term “chemical etching” and think it’s something you’ll only need when you make complicated blacksmithing repairs, but this isn’t necessarily the case. In fact, if you own a small business or an industrial operations department where counterfeiting is common practice, then chemical etching may be exactly what you need. Chemical etching is a process that involves using a corrosive chemical to permanently remove paint from metals without affecting the underlying metal. There are several different types of chemical etching services, including wet and dry methods. The wet method is generally more expensive than the dry method and requires more equipment, chemicals and labor. While the two methods are both effective at removing paint from metals, they have their own unique benefits and drawbacks. Read on to learn more about these differences so that you can decide which service is best for your situation.
WET METHODS
The wet method is perhaps the most well-known type of chemical etching. In this method, the metal is first sprayed with a liquid acid (usually sulfuric acid) and then lightly coated with a base (usually calcium or magnesium hydroxide). This process softens the metal and allows it to be etched with strong and expensive chemicals. This process is useful for removing paint from metals that are difficult or impossible to clean with water-based solvents, such as cast iron, chromium plating, steel, tin and zinc. The benefits of the wet method are obvious: easier access to chemicals and a permanent removal of paint. The downside is that the process is expensive, requires special equipment and can take several days to complete. The dry etching process is similar, but it uses a dry etching acid instead of a wet acid.
DRYING METHODS
The drying method is similar to the wet method, but instead of spraying the metal, the solution is applied by direct contact with the metal. This method is useful for removing paint from metals that are more transparent, such as aluminum, stainless steel, lead and zinc. The benefits of the dry method are that there’s no need to prime (spray) the metal, which makes this etching method less expensive than the wet method, as there’s no removability of the primer. The downside is that there’s no guarantee that the metal you etched will remain etched, making this method less effective than the wet method.
ADVANTAGES OF DRY ETCHING
More effective than the wet method. Dry etching is generally more effective at removing paint than the wet method. The base used in dry etching prevents the metal from bonding with the etching acid, so the process is more selective and less likely to chip off, stain or damage the underlying metal. More selective than the wet method. Whereas the wet method can remove average layer sizes of paint from iron, aluminum, copper, and brass, dry etching only removes the surface layer of the paint. This prevents you from removing the impurities that caused the paint in the first place, such as old grease, dirt, oil, etc. More protective than the wet method. Because dry etching only removes the surface layer of paint, it’s less likely to affect the underlying metal. This makes dry etching a good choice for areas where you want a high level of protection, such as a money clip.
DISADVANTAGES OF DRY ETCHING
More expensive than the wet method. Although dry etching is not as expensive as the wet method, it does have its own set of pros and cons. Dry etching usually costs more than chemical etching because you’re not dealing with as much equipment and chemicals. This also means that dry etching is usually done by a small company with limited equipment and experience. If you decide to go with dry etching, make sure you understand the total cost of ownership over the duration of the project. Loser leaves taint the winner. Because dry etching is less selective than the wet method, it’s possible that you removed some of the more valuable silver from your coin. This is unlikely to be a problem for most applications, but it’s something to be aware of if you’re planning on selling the coin.
Etching is a permanent process that removes traces of paint from metal with a reactive chemical. It’s a great way to permanently remove paint from metal without affecting the underlying metal. Whether you’re going for a specific design or just want to remove a couple of stubborn markings from a coin, chemical etching is the way to go.