<p>Obscure alchemical recipes aside, the easiest way to &quot;turn&quot; steel into cast iron is by painting it.</p>
<p>The steel probably needs to be degreased (using thinner) and primed (with a metal primer). After that you can simply apply acrylic paint to the sphere.</p>
<p>You can mix in dirt or sand with the acrylics to get that textured look.</p>
<p>I would also suggest finding real-life reference for the look you're going for: your reference images look off and somewhat fake, especially too blue. Using real-life reference you could easily see the size of the particles you can mix in with the paint, and even get the sheen and reflectivity right, if so you prefer.</p>

CC BY-SA 4.0
2023-05-31T05:48:04.380Z
There are also [tutorials](http://craftthyme.com/faux-cast-iron-finish/) available that use a mixture of stone effect spray paint (for texture), bronze spray paint (for color) sanding (more texture) and matte varnish. Or [another tutorial](https://rogueengineer.com/faux-corroded-iron/) that uses chalkboard paint mixed with sand (pretty much what you suggest in your answer, but it creates a different look).
Elmy
CC BY-SA 4.0
2023-05-30T17:18:34.623Z
2023-05-30T17:18:34.623Z
Joachim
<p>I am working on a project building speaker enclosures using hollow carbon steel spheres like the kind listed here:</p>
<p><a href="https://i.sstatic.net/dA1dm.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/dA1dm.png" alt="enter image description here" /></a><br />
<sup><a href="https://www.kingmetals.com/Catalog/ItemContent.aspx?ItemNumber=1349" rel="nofollow noreferrer">Source</a></sup></p>
<p>I am looking to produce these enclosures with a variety of looks / finishes, but with a consistent form factor and fabrication process, so I want to use the same sphere component as a starting point.</p>
<p>For one of the looks / finishes, I was thinking a blackened cast / raw iron look would be really cool, something like in these reference images:</p>
<div class="s-table-container">
<table class="s-table">
<thead>
<tr>
<th><img src="https://i.sstatic.net/8pQk5.png" width="350"></th>
<th><img src="https://i.sstatic.net/umB8h.jpg" width="450"></th>
</tr>
</thead>
</table>
</div>
<p>Is there any treatment I could do to the outside of the steel sphere that would achieve this kind of look + texture?</p>

<material-selection><metalworking><metal><technique-selection><finishing>
Surface Treatment to Make Carbon Steel Look Like Cast Iron
Emmett Palaima
# Surface Treatment to Make Carbon Steel Look Like Cast Iron

(Asked by: username_0 on 2023-05-30)

I am working on a project building speaker enclosures using hollow carbon steel spheres like the kind listed here:

[![enter image description here](https://i.sstatic.net/dA1dm.png)](https://i.sstatic.net/dA1dm.png)  
[Source](https://www.kingmetals.com/Catalog/ItemContent.aspx?ItemNumber=1349)

I am looking to produce these enclosures with a variety of looks / finishes, but with a consistent form factor and fabrication process, so I want to use the same sphere component as a starting point.

For one of the looks / finishes, I was thinking a blackened cast / raw iron look would be really cool, something like in these reference images:

|  |  |
| --- | --- |

Is there any treatment I could do to the outside of the steel sphere that would achieve this kind of look + texture?

**Tags:** material-selection, metalworking, metal, technique-selection, finishing


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## 1 answers

### Answer by username_1 on 2023-05-30. Score: 3

Obscure alchemical recipes aside, the easiest way to "turn" steel into cast iron is by painting it.

The steel probably needs to be degreased (using thinner) and primed (with a metal primer). After that you can simply apply acrylic paint to the sphere.

You can mix in dirt or sand with the acrylics to get that textured look.

I would also suggest finding real-life reference for the look you're going for: your reference images look off and somewhat fake, especially too blue. Using real-life reference you could easily see the size of the particles you can mix in with the paint, and even get the sheen and reflectivity right, if so you prefer.

> **Comments:**
> **username_2**: There are also [tutorials](http://craftthyme.com/faux-cast-iron-finish/) available that use a mixture of stone effect spray paint (for texture), bronze spray paint (for color) sanding (more texture) and matte varnish. Or [another tutorial](https://rogueengineer.com/faux-corroded-iron/) that uses chalkboard paint mixed with sand (pretty much what you suggest in your answer, but it creates a different look).  

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