But for a Smut
What is the best chemical pre-treatment for hard chrome plating?
Q. We do hard chrome plating (conventional). What is the best chemical pre-treatment for hard chrome plating? We currently use an aluminum oxide blast and a reverse sulfuric etch. We are concerned about the smut created by the reverse sulfuric etch. We manually scrub the smut off with Scotch-Brite. Is there a chemical desmut that may work? We run mostly carbon steels and some stainless steels. —H.R.
A. Over the years I have seen many different approaches to removing smut from carbon steel parts prior to plating. Sadly, I am not aware of any “silver bullets” for desmutting of parts. Some people suggest a cyanide-based formulation while others talk about using acid/surfactant formulations to do the job. I suggest that, as a start, you should consider using a chromic acid reverse etch for your carbon steel parts. One formulation for chromic acid reverse etch bath is 26 to 30 ounces per gallon and an operating temperature close to that of the plating bath temperature. Typically, an etch of 15 to 30 seconds at one amp should be adequate.
If you want to investigate various other types of formulations for desmutting, try a Google search using the terms “desmutting carbon steel” or “desmutting stainless steel.”
Related Content
-
Products Finishing Reveals 2023 Qualifying Top Shops
Each year PF conducts its Top Shops Benchmarking Survey, offering shops a tool to better understand their overall performance in the industry. The program also recognizes shops that meet a set of criteria to qualify as Top Shops.
-
Possibilities From Electroplating 3D Printed Plastic Parts
Adding layers of nickel or copper to 3D printed polymer can impart desired properties such as electrical conductivity, EMI shielding, abrasion resistance and improved strength — approaching and even exceeding 3D printed metal, according to RePliForm.
-
Advantages to Pumped Eductor Agitation
Not all agitation methods are created equally. Pumped agitation with eductor nozzles can improve process tanks and quickly show a reduction in operating costs while keeping staff safe, following environmental legislation and preventing pollution.