The Art Clay Club: Working With Abrasives

Art Clay, dried or fired, is easy to shape, smooth, and polish using a range of abrasives. The right abrasives make it easy: the wrong abrasives make it difficult to refine the shape and leave hard-to-remove scratches.

You can buy most of these abrasives in the high street or from a catalogue: if you've got the right shops and free time. So, to make things simple, Kitiki tested hundreds of tools from around the world to make sure that you get the best. None of them is expensive.

You'll enjoy using good tools rather than continually improvising. They'll help you manage a creative and efficient work environment. And they'll last a long time.

There's no universal all-purpose abrasive. Some do some jobs better than others, so you need a selection to get a good finish and optimise your time.

ABRASIVE PAPERS

WET+DRY: UP TO SCRATCH

Abrasive wet+dry papers usually have a coating of aluminium oxide or silicon carbide grit bonded to water-resistant paper.

When Art Clay has been dried, but not fired, don't wet the abrasive paper as it softens the clay and pulls up the surface. For fired Art Clay, soak the papers for 10 minutes before starting: they last longer and give a better finish when they're wet.

The abrasiveness is measured by the size of the particles, or grit. Industry measures the size in microns, whereas grades are determined by the mesh size used in manufacture. However, 400 grit particles are not half the size of 200 grit particles.

MICRONS	MESH	ROUGH GUIDE
4	5000	ultra fine
7	2500	super fine
15	1200	micro fine
18	1000	fine
25	800	medium-fine
30	600	medium

A selection of grades, such as 600, 1000, 1200, and 2500, allow you to shape, clean up, and semi-polish surfaces. Until you know how effective they are, start with 1200, to minimise the risk of scratches.

Art Clay, dried and fired, is easy to work with. Use a soft brush to make sure that no grit particles are left on your work before starting the next phase and use a hand-held battery-powered mini-vac to clean up the grit and dust around your work area. Don't blow the dust, especially as some will inevitably go in your eyes.

At Kitiki, we use and sell a set of sheet abrasives, including wet+dry papers, ready-cut to a handy 100mm x 120mm. They're cut from industrial sheets on a heavy-duty guillotine. Abrasive wet+dry paper doesn't tear very well and, if you cut it, it will soon blunt your scissors or modelling knife.

Decorators' sandpaper is made from glass particles: all the grit sizes, 16 to 200, are far too coarse and will leave deep scratches. Garnet paper is generally used in woodworking. Aluminium oxide grit is used in tumblers. Oilstones and waterstones would only be appropriate for a flat mirror-finish.

Whilst testing wet+dry papers, I bought one of those special offer packs: 10 sheets for Ł2. Some of them were not graded, many were too coarse for fine metal, and they all fell apart when wet. However, the worst thing was that the grit came off and got everywhere, contaminating the work area, abrasive papers, and polishing cloths.

ABRASIVE CLOTH

Art Clay, after firing, is matte-white, but the powdery coating is easily brushed off to reveal bright metal. Depending on the shape, you can use an abrasive cloth, a flass-fibre brush, or a wire brush. Afterwards, use a soft brush to make sure that no grit particles are left on your work before starting the next phase. It can be washed in luke-warm detergent, rinsed, and dried.

Abrasive cloth is good for cleaning up rings or other smooth shapes as it just folds around the contours. However, it won't get into corners or recesses.

At Kitiki, we use and sell a set of sheet abrasives, including fine abrasive cloths, ready-cut to a handy 100mm x 120mm. They're cut from industrial sheets on a heavy-duty guillotine. Abrasive cloths don't tear and, if you cut it, it will soon blunt your scissors or modelling knife.

ABRASIVE GLASS-FIBRE BRUSHES

GLASS-FIBRE BRUSH

A glass-fibre brush is made from abrasive-grade fibres. It's harder than a brass brush and, because of its shape, better for fragile or highly-shaped pieces. It'll get into corners or recesses.

At Kitiki, we use and sell glass fibre brushes. Turning the handle pushes the glass fibres out. Retract them after use so you don't accidently scratch any polished work.

ABRASIVE WIRE BRUSHES

BRASS BRUSH

A brass brush is softer than a steel brush, so better for fragile or highly-shaped pieces. However, it won't get into corners or recesses.

Although some people use a steel brush, steel is a lot harder than silver and you may end up with scratches that are hard ro remove.

At Kitiki, we use and sell brass-wire brushes. brass wire brush. Put it away after use so you don't accidently scratch any polished work.

MINI DRILL

One of the most useful mini-drill accessories is a rotary wire brush. It's the quickest easiest tool for cleaning up dried Art Clay and getting a good even finish on fired Art Clay. However, like all the other abrasives, it doesn't do everything.

Most mini-drills come with a selection of rotary accessories, so you probably won't need to buy any more for a while, unless you need replacements, run a full-time workshop, or obsessively like to collect.

Abrasive discs come in different grits and are cheap to buy. It's not worth cutting your own discs and blunting your knife blade, especially as the drill will vibrate if they're even slightly irregular.

Polishing pads are made from a close-weave felt. If you want to cut your own, a thinner or looser felt will soon come off the spindle. The international standard size is 21mm in diameter.

And, with all abrasive discs, don't press too hard, particularly with the edge, or you'll make a crescent-shaped groove. Remember with Art Clay that most of the shaping is done before firing, whilst it's still easy to work with.

If you're working with drills and rotary accessories, you need to be aware of the risks, however slight. It's unlikely, but ginding grit, brush wire, drilling scraps, and polish can fly off. Given a chance, they head straight for your face, so it's important to wear safety glasses: you've only got one pair of eyes.

The Kitiki Drill Kit 1 consists of a low-voltage drill, a mains adapter, chuck collets, abrasive discs, grinding wheels, grinding tips, rotary cutters, brushes, engraving tips, polishing pads, and small-size drill bits.

LINT-FREE CLOTHS

Always use soft lint-free clothes for cleaning, drying, and polishing. For each task, use a new one, so that you don't polish with one that's previously picked up grit or filings.

Domestic cleaning cloths shed fibres which will get into your clay. The Kitiki lint-free cloths are in a pack of 100, and measure 80mm x 80mm.

POLISH

POLISH IT OFF

Most domestic polishes are too coarse. At Kitiki we use 15gm pots of aluminium oxide paste. In use, the tiny particles fracture into smaller angular particles which lead to a highly polished surface.

The polish medium is petroleum-based, so should be rinsed off with warm water and a little detergent. Always wash your hands afterwards, as tiny abrasive particles left on your skin will mark the surface.

POLISHING CLOTHS

TAKE A SHINE TO THEM

Polishing is done with a little polish on a cloth. At Kitiki, we use 160mm x 160mm fibre cloths. They're machine washable, but we usually rinse them out in warm water with some washing-up liquid. Unlike some polishing cloths, they don't go hard after washing.

BURNISHERS

SHINE ON

Silver and gold are fairly soft metals that can be shaped, smoothed, and polished easily with abrasive papers, abrasive cloths, wire brushes, and polishing compounds.

However, rubbing the surface with a burnisher compresses, smoothes, and shines it in a way that normal polishing doesn't. You need to be careful to you use the edge of the tip, until you feel confident: using the point may scrath your work.

It seemed impossible to buy a burnisher in the high street. The Kitiki burnishers are imported from Japan: although they're hardened metal they need polishing to keep them at their best.

COLOURING

Immersing the finished silver piece in liver of sulphur produces a range of colours: gold to amber to blue to magenta to black, depending on the dilution, the temperature, and the time. Liver of sulphur, chemically potassium sulphide, has a strong smell and is poisonous.