1-1/8" X 21" Cork Sanding Belt – 20 Pack | For Premium Glass Fabrication Finishing

Hinge cutouts, notches, handle holes and the inside of a radius are the places a 4 inch wet belt sander cannot reach, so glass shops finish them on a Makita 9031-type file sander with a 1-1/8 x 21 belt. This is the polishing belt for that sander: plain, ungritted natural cork on a cloth backing, charged with cerium oxide slurry to take a 400 to 800 grit silicon carbide finish to a clear polish in the spots the big machines miss.

We convert these in Anaheim, California and pack them 20 to a box, because a file belt is narrow, works hard and gets changed more often than a wide belt. Shower door and frameless hardware shops buy them for polishing cutouts; stained glass and art glass studios use them for small bevels and edges on pieces too small for a floor machine.

• Ungritted cork on cloth: a carrier for cerium oxide or pumice, no abrasive grain of its own
• 1-1/8 x 21 size for the Makita 9031 and CR Laurence LD118 file sanders
• Polishes hinge cutouts, notches, holes and small bevels a 4 inch belt cannot reach
• Follows the 1-1/8 x 21 silicon carbide belt on the same sander after 400–800 grit
• 20 belts per pack for a station that polishes cutouts all day
• Converted in Anaheim, California; free shipping on orders over $200

Why is a cork belt the last belt on a file sander?

A 1-1/8 x 21 silicon carbide belt grinds the notch or cutout, stepping from 50 or 60 grit up through 400 or 800. Every one of those grits leaves a scratch pattern, and the finest still reads as a grey matte against the polished face of the lite. The ungritted cork belt carries loose polishing compound in its pores and rubs it against the glass with enough firmness to remove that last matte and leave the cutout clear.

Cork has no cutting action of its own. Run dry with no compound it heats the edge and does nothing useful; charged with cerium oxide slurry it gives an optical polish; charged with pumice it gives a quicker, cheaper bright pre-polish that many shops accept on cutouts that will be covered by hardware. The same cork belt polishes small stone, solid-surface and acrylic features after a 400 grit pass, and knife makers use cork with a green stainless compound on bevels after 600 to 800 grit.

Which compound should you use on a 1-1/8 x 21 cork belt?

• Cerium oxide: for a fully polished notch or exposed cutout on shower doors, frameless enclosures and mirrors. Mix with water to a thin cream and apply to the running belt. Best after 600 or 800 grit.
• Pumice: for hardware cutouts and hinge notches that will be hidden under a clamp or hinge plate, where a bright pre-polish after 400 grit is enough. Faster and cheaper than cerium.
• Fine polishing paste or green stainless compound: for plastics, stone and steel work on the same file sander. Low to medium speed, sparing application.

Compound is sold separately. Keep one cork belt per compound; a file belt is cheap enough that there is no reason to risk a grain of pumice scratching a cerium-polished edge.

Grit guide: what the cutout should look like before cork

The cork belt only removes the scratch left by the last silicon carbide belt. On a file sander, where the belt is narrow and the operator is working freehand, it is tempting to jump grits; do not.

If the polished notch still shows grey lines in the corners, the previous grit did not reach the corners. Go back one belt and work the corners, then polish again.

Which sanders take a 1-1/8 x 21 cork belt?

• Makita 9031 belt sander: the file sander most glass shops run this size on, usually with a water drip for the silicon carbide belts. Verified fit.
• CR Laurence LD118 sander: the same 1-1/8 x 21 belt, named on our matching silicon carbide listing.
• Other file and finger belt sanders built around a 1-1/8 inch by 21 inch belt. Confirm the size in the manual; the 3/8 x 21 and 1/2 x 18 file belts look similar in the box.

This belt is the polishing partner to our 1-1/8 x 21 silicon carbide glass belt and mounts the same way: retract the arm, slide the belt on, check the inside of the belt for a direction arrow, release the arm and set tracking so the belt runs centred on the nose wheel. Cork is thicker than a coated belt, so it will feel tighter on the arm; that is normal. Turn the water drip off, or well down, before charging the cork belt.

How to charge and run a cork file belt

1. Finish the silicon carbide sequence to 400 grit at minimum, 600 or 800 for the quickest cerium polish. Rinse the cutout and wipe it so no grinding swarf is carried onto the cork.
2. Mix cerium oxide or pumice with water to a thin cream. Keep it in a squeeze bottle; on a narrow belt a brush wastes most of it.
3. Charge the running belt at low to moderate speed. Apply slurry to the moving cork until the whole face is damp and evenly coated. The belt is only 1-1/8 inch wide, so it takes little compound and needs re-charging more often than a wide belt.
4. Polish with light pressure. Let the arm and the belt do the work; sweep the belt around the cutout the way you did with the silicon carbide belt. Pressure heats the corners of a notch and does not speed the polish.
5. Keep the cork damp, not wet. Turn the water drip off. Flooding washes the compound out of a narrow belt in seconds. Add a drop of slurry as the face dries and the polish slows, and never let the belt run dry with compound caked on it.
6. Check against a light before moving to the next cutout. Grey in the corners means one grit back, not more time on cork.
7. Store spare belts flat or hanging in the box; do not fold a cork belt.

Use it for / don't use it for

Use it for

• Polishing hinge cutouts, notches, handle holes and clamp reliefs on shower doors and frameless enclosures
• Polishing small bevels, inside radii and edges on stained glass, art glass and small mirror pieces
• Touching up a polished edge where the floor machine left a dull spot
• Small stone, solid-surface and acrylic features after a 400 grit belt
• Knife bevel pre-polish with a green compound on a file sander

Don't use it for

• Grinding, seaming or removing chips; that is the silicon carbide file belt's job
• Running dry with no compound, or under the water drip
• Anything coarser than a 400 grit scratch
• Long exposed edges; use a 3 or 4 inch cork belt on a wider machine for those

Specifications

Frequently asked questions

Related products and guides

• 1-1/8" x 21" Silicon Carbide Glass Fabrication Belts, 40 pack (grinding stages before cork)
• All glass fabrication abrasives (silicon carbide belts, cork belts and discs)
• 3" x 21" Cork Sanding Belt, 8 pack, for portable belt sanders
• 1-1/8" x 21" Surface Conditioning Belts for the same file sanders
• Custom belt sizes, including cork, made to order in about 3 days