Detail sanding
Detail sanding polymer clay is sanding a very specific area with any method while not touching the surrounding areas, or try not to anyways. Many cases when you want to detail sand is to remove spots, inclusions, tough areas and bring out special effects.
Normalizing (sanding) to smooth
Once an adequate base layer of CA is down on the polymer clay pen blank and cured we need to sand it off and make it smooth. At this point our shape comes out and we start to see for the first time the level of detail.
Banding
Banding is specific to lathe turning in this article. Radial rings that form from the lathe an if you hold the blank up to a light source and look from bushing to bushing it quickly becomes obvious where those ripples are. By stopping the lathe and sanding bushing to bushing (lathe OFF and with VERY light finger tip pressure) after EVERY grit you will achieve four things:
- A reduced amount of sandpaper needed.
- An increase in the visual details.
- Less time sanding at future grits.
- Elimination of banding.
Banding WILL happen so get use to it. Add enough CA to overcome this because if the low spots are to low then no matter what you do it will always form craters and you will never get them off correctly.
Inspection
Remove the clay pen blank from the lathe and hold it up to a light. You want to angle it so the blank material vanishes and all you see is the coating surface. You are looking for several things:
- Banding (Under coating or under sanding), this is corrected by more sanding. Very low spots that was not correctly filled needs to be redone.
- Thin spots (borderline excessive sanding). This is not ‘bad’ but can become a problem if you have to sand more
- Bald spots (under sanding or under coating) Sanding thru the finish is more often than not excessive sanding.
- Pits in the finish (under coating)
All of these can be easily corrected by going back to the filler coat and redoing that. Pay note of the areas that are thin, bald or pits and use a gentler finger pressure in that area and apply a thicker filler coat.
How to Polish your Polymer Clay Pen Blank.
There are a good hefty number of polishing products on the market today. There are a good number of classes that can be used, these classes generaly should NOT be overlapped but sadly they ARE by many. when you overlap schools you are adding MORE work to the job and that becomes a major problem and very ripe for failures. The generic classes are as following:
- Buffing
- Sheet Micro Abrasives
- Liquid abrasives
Buffing is normally done with a dry paste or liquid that is put on the spinning wheel then applied to the finished surface. The problems with buffing is it can grab the object and throw it across the room or at you and create a very dangerous situation. Many accidents happen because of feed failures into a buffer and the object has sharp corners. Sharp corners with high rate of speed on your skin does not make for a happy ending. Buffing WILL generate surface heat on the product and this can be a very bad thing.
Sheet microabrasives, such as micromesh is very very fine particles on paper, sponge or similar that can be used wet or dry. Generally these are made for plastics and most notably automotive headlight restoration. The down side is that many I have seen does not use the product properly, in most cases under used. Since it is in sheet form there is heat build up that can occur and when dealing with CA you want to keep heat down to a minimum for the first day or two.
Liquid abrasives. This is products such as Novus (which we recomend and use) They contain liquid abrasives in water. Water discipates heat 4 times faster than air so as long as it is wet and the surface is not gummed up or clogged you should not have a heat problem. The down side to liquid abrasives is they can be messy. If to much is applied the lathe will sling off the excess and that is wasteful.
Your goal is to polish the polymer clay pen blank to a point where the finish will MAGNIFY the detailed art work. If your CA application was good you will have a glowing 3D effect with the polymer clay millefiori cane slices. This can be very holographic under the proper lighting levels. Again all 3 schools can get this result and each does vary greatly by the product used. The key is to keep the surface heat down to a minimum and the more you go down the sanding / polishing chain the more surface heat you will generate because the partical size becomes smaller.
For a good starter on sanding polymer clay see this link.