TOOLS Buffing polymer clay basics

              

There are several options to finish the surface polymer clay objects. You can:

  • leave the surface as is after baking, usually a matte (non-shiny) finish
  • create a glossy or semi-glossy finish by sanding then coating / sealing the surface with an acrylic liquid
    • Future, Golden, Varathane are some popular liquid brands
  • create a glossy or semi-glossy finish by sanding then buffing with a wheel of soft fabric like cotton or acrylic polyester.

Buffing is defined as polishing the surface using a soft cloth.

There are certain situations when I prefer buffing to using an acrylic liquid. I make a lot of mixed media pieces where I do an antique effect. Materials, such as metal, will have a different reflective quality than polymer clay. Also, for an aged look, nooks and crannies should appear dark and matte. If the entire piece were coated, the entire thing would be consistently shiny and look fake. Variations in how a mixed media or complex piece reflects light can make it look more realistic.

On this page I'll discuss the various ways one can buff polymer clay surfaces.


  Buffing tools

Tools can be simple to complex. They range from:

 
  a comfy pair of denim jeans ;-) tumble buffing with a rock tumbler auto wax buffer
       
 
  mini rotary tool (e.g. Dremel) with a buffing attachment jeweler's bench lathe and flex shaft tools (e.g. Foredom, Grobet) standard workshop bench grinder / buffer

  Manual and Low Speed Buffing Tools

Low speed buffing, either by hand or using a rock tumbler (e.g. for beads) will, at best, produce a low or semi-gloss shine. Not that that's a bad thing. In fact, it's a great look, as is a matte finish. Which of the three finishes you choose is strictly a matter of taste.

Manual buffing is pretty self-explanatory and not a bad way to pass the time if you're just sitting.

Tumble buffing involves throwing small squares of a soft material and sanded beads into a rock tumbler; then tumbling for several hours. To learn more details on how to tumble buff, click How I tumble buff polymer clay.

You should note polymer clay is a soft material, so in the long run, high shine buffed beads worn against clothing will get rubbed by fabrics of various softness and may gradually lose a buffed high shine. However, it's easy to rebuff to regain that high shine.

Conversely, nicely sanded non-buffed beads feel very scrumptious and can eventually develop a semi-gloss shine if in a necklace where they might be rubbing against shirt fabric.


  High Speed Buffing Tools

To achieve a high glossy shine on a polymer clay surface, it must first be sanded well. The minimum recommended 'finishing' grit is 600 (CAMI) or P1200. Though many like to take things up a notch or two, going up to 1000 - 2000 (CAMI) grits.

After sanding, powered buffing machines can be used create a glass-like finish. I especially prefer buffed effects when dealing with translucent and pearlescent pieces. It really brings out the depth and sparkle.

Basic buffing steps (also see buffing safety recommendations)

  • Position your piece in the safety zone; the place where if the the wheel grabs your piece it will safely fly away from you.
  • When buffing, remember this phrase, "butterfly kisses". Make your motions delicate and light.
  • Move your piece towards the spinning wheel gently, slowly, smoothly, as in slow motion. Slowly, gently reposition your piece, turning, rotating.... Slowly, gently, smoothly pull your piece away when you are done.
  • Keep the piece slowly moving underneath the wheel. Don't allow the wheel to buff on one spot for too long. A high speed buffer can quickly heat up a small spot on a polymer clay piece causing a dull smear instead of a high shine.
  • Don't, under any circumstances, make quick, jerky motions. The wheel will scratch, grab and fling your piece when you do.

Mini-rotary tool: Since most of the things I make are small, I usually use one of those versatile mini rotary tools (with a buffing attachment). It's the most portable; doesn't require a dedicated space. I can sit at the table, pick up my Dremel and buff. It's great for small, quick jobs, like a few beads.

One important disadvantage is these mini tools may have high speed but not a great deal of power/torque. If they have to deal with too much resistance, you will here the motor complain and you may burnout the motor.

Dremel sells a stingy little muslin buffing wheel, but I much prefer the ones I make, using a wood screw as the mandrel (spindle) and polyester felt. Click these links to read how:

Jeweler's bench lathe/buffer: These machines have more powerful motors than the mini rotary tools. Designed for jeweler's, so they are a bit smaller than standard workshop machines.

I use the discontinued Foredom bench lathe B&G. It's a fine little machine, but now that I have a standard bench grinder, I don't know if I'll use this as much as I used to.

Because of their power, bench grinders/buffers might "walk" when running. If that happens, you need to either rest the base on one of those grippy liners or bolt it to a board that can be clamped to a work table.

  

Standard workshop bench grinder / buffer: Aahhh, the big guy. I call him Fred. Well, not really, but he does deserve a name. He's very photogenic. :)

Ok. Foredom and the like make wonderful appliances. But as you may have discovered in your polymer clay shopping adventures, there are certain craft or jewelers' appliances that have ordinary workshop equivalents that are much cheaper.

Foredom's famous bench lathe can cost a couple hundred dollars. A standard bench grinder plus buffing accessories can cost half as much. If you already have a bench grinder, it's definitely cheaper to purchase the buffing accessories than to go buy a whole new machine and all the needed parts.

For buffing plastics like polymer clay, there are special compounds you could use to improve the finish and the speed of achieving that finish. Caswell sells them here.

Mounting buffing wheels: standard workshop grinders usually come with couple few grinding wheels, but they may not include buffing wheels. Which isn't a bad thing, because the type of buffing wheels that would likely be included would be stiff thus wouldn't be well suited for polymer clay.

Buffing polymer clay takes a little special consideration because the friction from the spinning buffing wheels can easily overheat and soften the clay. You need to take steps to keep things cool. One of the steps is to use loose cotton wheels (instead of the stiffer fully stitched wheels).

The challenge is while many cotton buffing wheels, like the one shown here have the properly sized holes to match the machine's arbor (e.g. 1/2"), you might not be able to directly mount the wheels onto the bench grinder, unless it has a special holder. That's because the wheel's center is just fabric - there's nothing for the grinder to hold. The cotton wheel could just sit there idle, while the machine arbor spins madly.

   

To make this work, you may need a special part called an arbor adaptor.

An arbor is the spindle that sticks out from the motor; it's the part that spins. In the bench grinder, you may see reference to 1/2" or 5/8" arbor. That means the machine's spindle (or arbor) is 1/2" or 5/8" in diameter. Any grinding or buffing wheel you mount on the machine should have, say, a 1/2" or 5/8" diameter hole in the middle so the wheel will match the machine's 1/2" or 5/8" arbor. It's critical that the arbor and holes match for the whole thing to work.

The left hand side of the arbor adaptor slides onto the bench grinder's arbor. The silver discs in the middle are two cupped washers. The buffing wheels have to be sandwiched between those two washers. The big nut holds the cupped washers so the washers can keep a tight hold on the cotton wheels.

If your bench grinder doesn't already come with one, you can buy the adaptor. The challenge is not everyone that sells bench grinders has additional arbor adapters or even when they do, they may not know what they're for!

I bought my bench grinder ($40) at Home Depot, but they didn't sell the adaptors. Orchard Supply Hardware sold the adaptors but I couldn't find anyone who knew what they were. I had to hunt for it myself. I got my loose cotton buffing wheels at Caswellplating.com. However, you could try removing the outer stitched rings on standard buffing wheels.



  Buffing Safety

Regardless of which powered buffing machine you use, they all rotate at a speeds high enough to warrant respect and safety practices.

  • In relation to the wheel and the direction of its rotation, hold your piece below the wheel and in the area shown in the diagram (the safe polishing zone).

  • Make sure to get these out of the way: long hair, necklaces, scarves, cords, strings, or ties or anything that could get grabbed and wrapped around a rotating spindle.

  • Only buff with powered tools when you are alert and able to fully concentrate. If you're tired or distracted, you will have many project flings, damage and extra work to repair the damage..

  • Wear safety goggles. Buffing with a high-speed disc can produce a fine particle spray as the wheel's surface slowly wears away. Those particles can get in your eyes.

  • Don't bob the piece toward and away from the disc. That is a good way to cause the buffing wheel to grab and snatch the piece from your hands.

  • If the wheel tries to grab your piece:
    • if you sense it happening let it go. If flung, it will fling safely away from you, if you've held your piece in the safe polishing zone. You can build a simple catch box, lined with towels or pillows and place it behind the benched motor to catch the flung piece
    • more than likely the disc will leave a dull scrape mark on your piece. You may need to sand and buff that spot again.

  • Try not to touch any freshly buffed areas with your fingers. Those areas will be warm and soft and will easily take fingerprints.

There's nothing better than having a great tool when you need it.

Enjoy,
Desiree

Last update to this page: 18 Nov 07. Send comments, questions or suggestions to Desiree McCrorey.