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In need of a lusterless/dull electroless nickel

Q. My name is Aaron Stinson. I am the Quality Manager and NDT Level III at a Metal Finishing shop. We have been requested to process some parts to ASTM B733 (ELECTROLESS NICKEL) but the customer requires a dull low luster finish. The sample part provided is extremely dull compared to the EN I am used to seeing. I would describe its appearance as resembling a piece of Lead. The main objective is to be non-reflective. I have tried a few different products provided by well known suppliers to no avail and could really use some advice. We currently use a mid-phos semi bright EN bath and it is way to bright for this application. I've tried baking, raising the pH, and extended pickling. I have exhausted the little intelligence I have and would greatly appreciate suggestions. Thanks,

Aaron Stinson
Plater, Manager at plating shop, anodizer - Vonore Tennessee USA
February 17, 2011

A. Step one would be to grit blast the part with a fine aluminum oxide. Next, take a spent EN solution and dissolve some aluminum in it. You will get a gray to dull gray. At least we did. James Watts - Navarre, Florida February 18, 2011 A. You can try several things besides trying to find a chemistry or supplier that suits your needs. 1- Sand blast before plating. 2- Dip in diluted nitric acid (30%). This treatment will produce a dark color and a fine smut which can be wiped off if necessary. 3- If the parts are already plated and difficult to strip and re-process, sand blast them with very fine sand (i.e. 240) at low pressure (50-60 psi) and see if the plate resists. If it doesn't increase pressure and keep going, you're in step 1. G. Marrufo-Mexico Guillermo Marrufo Monterrey, NL, Mexico February 18, 2011 A. Hi Aaron, You may consider: either to roughen substrate metal (usually copper) with etchant prior EN to make the EN deposit look more dull or to apply mild nickel etchant on EN deposit (to etch away a few microinch EN) to make it become dull Regards, David David Shiu - Singapore February 18, 2011

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Want to do GREY Electroless Nickel Plating

Q.
I am interested in learning the Process of GREY COLOURED ELECTROLESS NICKEL PLATING on Steel Parts. I also want to know which Chemicals should I purchase and from where ?

I want to do it myself in my shop. Please advise at the earliest.

HARI OM VERMA
Product engineer - CHANDIGARH - India
October 26, 2017