There's various types of brushed finishes. For my stuff I don't think I do anything special. However, I came up with a long list of things I do to get "my" look. Note that I mostly use ACS. Back when I was doing the ammonite piece for Saul Bell I switched from PMC3 to PMC+ to get the result I wanted. The PMC3 formula has since changed.
It helps to know what you want your finished piece to look like before you start. I rarely go for a mirror finish since I like a more mat or satin, steely look. Also, I think how my pieces are finished begins with how they are started or how I go about my work. No real secrets here. OK here's my long list of tips. Ignore if you are not interested:
- Perhaps, this is the key - never handle the clay more than it needs to be handled to achieve your desired effect. The more you handle your clay, the more you'll have to refine. That may seem counter-intuitive for a "clay" but it is true. I.e. choose the most efficient way to get to your destination by planning your steps. Have everything ready when you start.
- I don't know if there is anything more fundamental than learning how to knead your clay, BUT knead your clay only when necessary (if there are bumps or if it's too dry) and make sure to compress your lump by pushing it together after kneading so there are less fold lines. Of course, the more pristine your clay is the less you'll have to refine.
- Do your work before the clay dries, less cracks equal less refinement. Cracks can be interesting texture but try to control when it happens. The clay will dry whether you want to work fast or not. You should always be aware of this.
- For a uniform shape, use a template or stencil.
- If you need to pick up your piece, place it on a non-stick surface before texturing or cutting it out. Then, turn over the surface and gently let the clay fall into your hand rather than trying to grab it with your fingers or scraping it off the surface. Gently place it on to your prepared drying shape.
- Gently pat down the rough edges with your finger while the piece is still moist (less to sand later).
- After drying completely, refining for me typically starts with an Emory board or needle files and then progresses to 400 and 600-grit sandpaper. Some surfaces, if they are uniform, I'll go straight to 600-grit and just go over it lightly or maybe even not at all (remember, I'm not going for a mirror finish). A tool that removes more material, will leave larger marks. Don't move on to the finer grits until you have done enough work with the coarser materials. I usually try to sand in circular motions and use sandpaper either folded or rolled for more control.
- When using files, choose a file edge that matches the surface you are refining. E.g. round file edge for the inside of a hole. Flat edges are usually OK for broadly curved convex outside edges.
- I almost always fire at 1472F or higher.
- Use a good quality scratch brush. I brush only in one direction - gently, not like I'm scrubbing a dirty tire. I don't ever use water and soap. Not to say you can't, just that I don't. Brush thoroughly. While brushing normally results in a mat finish, it shouldn't look dull. Make sure to get at all the white areas. If you aren't sure, concentrate on one area and then compare it with the rest of the piece. It should look even when you are done.
- After brushing, then I apply a Liver of Sulfur patina (fairly dark) and then I wash and dry my piece.
- I polish the entire piece well with a Sunshine polishing cloth. On the raised areas, I try to get as much of the darkness off as possible - I do this and brushing while watching TV. To get into the tight tiny areas I used a toothpick to push the cloth around.
Develop your own routine. Try different methods until you get the results you like. Let me know if you have any questions.