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PLATING Artistic Application of Electroplating Q. I have a slightly unusual application for electroplating: I want to plate a pattern onto the metal cathode, moving a sharp/pointy anode around to trace out the pattern (a non-conductive mask is not possible). However, I can't decide what metal to plate and what solution would be best. I have attempted to plate copper using copper sulfate solution at 237 g/L onto stainless steel, and using a sharp wire as the anode. It has not been very successful so far. Are there any tips you can give with regards to the best materials and solutions? The anode material will likely be platinum, and we do not want it to be consumed in the reaction.—G.M. A. This is an interesting idea, however stainless steel is not the easiest to electroplate because it has oxides on the surface that must be removed before you can get a deposit to adhere to that surface. To start your experimentation, you should use a material like copper or even a typical industrial steel as your base material. Then this base material must be thoroughly cleaned so no oxides are on the surface. There is a process that is routinely used in the plating industry known as brush plating or selective plating. In its simplest form, you use a stylus to plate metal on surfaces that normally cannot be plated in a plating tank. The process is also used for field repair. Normally, a wider stylus or brush is used, but I see no reason why you couldn't use a narrow, pointy stylus. work. Usually for non-critical work, copper is used for this purpose, however. Copper is softer than nickel and easier to machine. But whether this would work for hydraulic cylinders that are a more-critical application is dicey. You don't say whether there are a few pits on the surface of the hydraulic cylinder or if the pits are distributed over the entire surface. If there are only a few pits on the surface, you would save yourself a lot of grinding by selectively plating the pits and building up the deposit in the pitted areas. You would only have to grind the areas that are plated. If the entire cylinder is pitted, the entire cylinder will have to be ground to specification. This is a more labor-intensive process, and your client might not want to drop the money involved. If any readers have a suggestion for solving this problem, please let me know. Researching? Searching for in-depth analysis of a plating process or technology? Look no further than PF's Research and White Paper Zone, an entire section of our site dedicated to free papers and presentations from leading researchers in the finishing industry. pfonline.com/zones/technology Wire Pitting Made in USA Q. We plate a large volume of wire part for one of our customers and have noticed that the amount of pitting has increased dramatically in the last few months. The pits appear to be on one side of the wire. The customer recently told us that the supplier of the wire has recently changed. Is this the cause of the pitting?—J.S. A. Very likely! What is probably happening is that impurities are embedded in the wire during the drawing process. These impurities show up as pits during the plating process. The drawing dies should be checked and a better grade of wire specified. You should also revisit your cleaning process prior to the plating step. Corrosion Pits CLINIC e Will ish W F rom Make You Shine Sta rt to Fin Satinmaster® Non Woven Flap Brush Maroon Very Fine Distributor Net 4x1 x 5/8-11 4x2 x 5/8-11 Super Gold Fine Blue Flash Medium Stock X X X X X X Q. What is the best procedure for replacing hard chrome on carbon steel substrates that have corrosion pits 0.10" in depth? The issue relates to hydraulic cylinder repair where extensive grinding would exceed base material removal tolerances. The vendor has proposed nickel plating and grinding before chrome plating. What are my options in this case?—B.N. A. Filling in pits tends to be a challenge, and a pit with a depth of a 0.10" is even more of a challenge than what is routinely found. The vendor's suggestion of nickel plating the cylinder and then grinding back to specification might Divine offers a full range of non woven and interleaf abrasive flap brushes. • Use to polish, burnish, blend, deburr, satin finish, clean, and brighten stainless steel, aluminum, brass, copper and other alloys. • Gives a uniform and consistent finish over the entire life of the brush. • Excellent for defuzzing wood surfaces. • Stock face widths are 1" and 2". Other widths available up to 42" long. • Core size - 1" ID with a 5/8-11 insert or standard reducer flanges. Interleaf flap brush - coated abrasive interspersed with non woven. Any configuration available. • Provides stock removal while leaving a brushed satin finish. Divine Brothers Company • 200 Seward Ave • Utica, NY 13502 • Tel. 315-797-0470 • 800-642-7456 • Fax 315-797-0058 www.divinebrothers.com • contact@divinebrothers.com PRODUCTS FINISHING — pfonline.com 31