DIY Electropolishing

We wanted to provide a simple informational post for electropolishing hobbyists who are interested in DIY Electropolishing. Please bare in mind that there are potentially environmental and health ramifications of electropolishing chemicals which you must consider. Please consult EPA literature on chemical usage and disposal before attempting to electro polish. Also if you plan to electro polish a product for market, make sure that you are adhering to ASTM standards for the industry you are in.

There are three main pieces of the puzzle you will need for your DIY electropolishing project: 1. Electrolyte formula 2. Container 3. Electricity

Electrolyte Formula

I personally started out using commercial formulas such as the one made by ESMA. Other DIY electropolishers like to make the formula themselves. Here are a couple of recipes I found on

The Metals Handbook, Vol 2,”Heat Treating, Cleaning and Finishing”, 8th
edition gives a couple of recipes:

#1 sulphuric acid 41%
phosphoric acid 45%
water 14%
operating temp: 170-230F
current density: 200-350 A/sq.ft.

#2 phosphoric acid 56%
chromic acid 12 %
water 32%
operating temp: 80-175F
current density 100-1000 A/sq.ft.

All percentages by weight. You might want to get a copy of the book. It
contains articles on electropolishing and every other finishing method you
could want. Copies are available on the used book sites.

Electropolishing Tank or Container

Use a stainless steel container as the cathode (negative electrode) double welded inside and out. Stainless steel can withstand high temperatures, which are needed if too much water enters the electrolyte. The container should be larger than the part you plan to electropolish. Most industrial containers used in electropolishing also have a heating system for the electrolytes. The correct temperature for the electrolyte formula is between 150 and 220F. 

Electricity

The electricity is connected to the part you plan to electropolish. For electricity you can use something as simple as a 12 volt battery. The amount of amps that you send to the work piece depends on the surface area of the work piece. Here is a link to a decent formula you can go off of. http://www.surfinetek.com/electropolishing/electropolishing.html

The commercial version of your electricity source looks more like this –

DIY Electropolishing

DIY Electropolishing

Connecting the Electricity

The “current connection” in the above picture is what you would connect to your part and then submerge in the electrolyte formula. Once you have gotten your DIY electropolishing system down, you can get a commercial rack system like this to crank out thousands of stainless  steel products at a time  – http://www.associatedrack.com/products_electro-polishing-tooling.html

Here are a few additional discussions on the topic:

  • http://www.practicalmachinist.com/vb/general/small-scale-electropolishing-diy-techniques-150006/
  • http://bbs.homeshopmachinist.net/archive/index.php/t-38026.html

We hope that this post on DIY electropolishing was helpful. This blog post was meant to be informational and provide a general roadmap to understanding electropolishing. Please consult additional resources or an expert before electropolishing. We take no responsibility for adverse outcomes resulting from DIY electropolishing attempts. Once you have mastered DIY electropolishing, you can also develop a process for pre and post cleaning of your work piece which all industrial electropolishers have.

If you are looking to take your project from the garage to the industrial don’t hesitate to reach out. We offer top of the line electropolishing services!