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A 'satin' electropolish?

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 can sometimes be more economical than mechanical polishing, but the compelling attraction is the nature of the finish. Mechanical polishing, creates a finish resembling (under magnification) a farmer's plowed field; although the scale of the furrows and clods can be reduced it is always there. Electropolishing can produce a finish resembling (under magnification) gentle ocean swells.

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

Ed. note: This forum was founded as a gathering place for sharing anecdotes, tips, & opinions in a spirit of camaraderie.
        When names are withheld & free confidential consulting requested by a stranger, readers may be less likely to engage.225 people named Ashish have posted on this site.

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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