Summary for satin electropolish Discussion
satin electropolish on stainless steel 316 door handles is the core question here, but the answerer says the goal may be mismatched to the process. Ashish asks how to electropolish without the parts brightening and looking polished. In response, AF Kenton agrees with Tony Kenton that a satin finish on stainless steel is achieved by bead blasting, not electropolishing, and says it seems contradictory to expect a satin look from electropolish. The thread also briefly explains that electropolishing is essentially reverse electroplating: the part is made the anode in an acidic bath so burrs and asperities dissolve, usually producing a smoother, brighter surface. The practical takeaway is that if a satin appearance is required, a different finishing method such as bead blasting is more appropriate than trying to force electropolishing to stay dull.
Quickstart:
Electropolishing is a process resembling electroplating in reverse. The components are immersed in an acidic solution, made the anode, and (hopefully) their small burrs and asperities dissolve into the acid, smoothing the finish. Many different metals can be electropolished, with stainless steel being the most common.
Electropolishing may sometimes be more economical than mechanical polishing, but the compelling feature is the nature of the finish. Mechanical polishing always creates a finish resembling (under magnification) a farmer’s plowed field; the scale of the furrows and clods can be reduced but always remains. Electropolished surfaces resemble (under magnification) gentle ocean swells with minimal tooth, no clods to dislodge, and no hiding places.
I’m looking to do satin electropolish on SS 316 door handles. Running into similar issues of the part brightening and looking polished after electropolishing. Any advice on how to electropolish without brightening the part would be appreciated.
Ashish
Shop employee – Delhi, Idia
December 6, 2024
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225 people named Ashish have posted on this site.
A. Hi.
I agree with Tony Kenton that satin finish on stainless steel is achieved by bead blasting, and that it seems contradictory to expect it from electropolishing. Do you have reason to believe that it is possible? Thanks.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Multiple threads merged: please forgive chronology errors and repetition 🙂
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Q. We’ve been trying to achieve a satin finish (think of a #4/180 grit without grain) on 304 stainless using a combination of beadblasting and electropolishing, and hopefully your collective expertise can help guide us in the right direction. This is a decorative finish, not subject to any particular spec other than aesthetics (often the toughest spec of all due to its subjectivity).
We’re starting with 304 bar stock and square tubing, mill finish. rough stuff, indeed. joints are welded and ground flush.
The first samples got a #8 glass beadblast, a pickling, and then spent 8 minutes in the electropolish bath. the electropolishing, as it’s supposed to, did a wonderful job of brightening up the pieces: so much so that every mill mark, pit, and grinding mark was clear as day – and way too bright to fall under my broad definition of ‘satin.’ the effects of the beadblasting were almost entirely washed away.
The electropolisher suggested halving the time in the bath … makes sense to me. A more aggressive bead blasting also strikes me as appropriate. Before I burden my blaster and my electropolisher (both incredibly nice and trying to be as helpful as they can) with more experiments, I thoughtIi would solicit advice from a wider audience. Any experience, advice, or theoretical musings will be greatly appreciated, but bear in mind that I am not now nor have I ever been a professional electropolisher. Any highly specific technical details on the setup he’s running will largely be lost on me.
Or are we just attempting the impossible?
Many thanks,
Carson Maddox
furniture design – Chicago, IL, US of A
2004
A. An electropolishing operation seems to be a contradiction of a satin finish. It is primarily used for brightening. Satin, to me, means a dull, flat finish. Electropolishing will not give you that appearance. You must either blast the parts and leave it like that or try a mass finishing operation. One will give you a dull dimpled texture using glass beads and the other a flat brushed look using an abrasive dry organic media.
AF Kenton
retired business owner – Hatboro, Pennsylvania