Using Inland Flat Lap Machines for Glass Polishing and Shaping
Glass Surfaces: General Guidelines

Shaping and polishing glass will be either a 4 or 5 step process depending on how much material removal is required. The process is broken down into initial Roughing and Shaping, Smoothing, Pre-Polishing, and finally Polishing Use the instruction guide included with your SwapTop™ Flat Lap Machine for product assembly and lap changing instructions. We highly recommend working through the process with practice pieces first.

STEP 0: ROUGHING
This step is required only if you need to remove a large amount of material, e.g. flattening the bottom of a paperweight or removing glass left from the punty. Install the 170 grit lap and spin to make sure it and the master lap are centered. Remove material until you have created the general shape, size, or depth of your finished surface. If you have less than a millimeter or so to remove you can probably skip this step and start at Step 1

STEP 1: SHAPING
This step will either create your initial shape or if you started at Step 0 remove the deeper scratches left by the 170 grit lap and attain the final shape. Install the 325 grit lap, spin to make sure it and the master lap are centered. Remove material until you have a look similar to the surface having been roughly sandblasted.

STEP 2: SMOOTHING
This step will remove the scratches left by the shaping process. Install the 600 grit lap, spin to make sure it and the master lap are centered. Proceed to grind until you have a finely frosted surface. A properly shaped surface is perfectly smooth and satiny in appearance. Rinsed and dried you should not see any scales (aka dimples, facets, flats, etc) or scratches. Hold it up to a bright light and look for sparkles or deep lines. Scales are most easily observed by watching the piece dry. Because the “scales” will have deeper puddles of water, they will evaporate more slowly. Wet your piece and watch for this phenomenon. If you see any scratches or scales, you may not have smoothed long enough. If after additional smoothing you can still see scratches or scales, they are too deep to remove. You must return to Step 1 (325 grit) and take an additional cut off the piece to remove them and then return to this smoothing step. Your piece is ready to move to pre-polishing when you have a uniform, finely frosted surface.

STEP 3: PRE-POLISHING
Here you remove the satin-like finish left from the previous step. Install the 1200 grit diamond lap, spin to make sure it and the master lap are centered. Your goal is a very smooth, hazy surface. There should be no visible scratches or scales at this point. If you can see scratches you need to go back to Step 1 and remove them proceeding through Step 2 and 3.

STEP 4: POLISHING
This is where the hazy surface is polished to a high sheen. There are many different polishes, pads, and combinations of the two that can be used for a final polish. Those commonly used for glass include diamond compound (graded diamond particles mixed evenly in a water soluble carrier) or cerium oxide slurry and a felt polishing pad.

• Setting Up with Diamond Compound: Apply the felt pad (or your preferred substrate) to the master and install on your machine. Wet the pad and then briefly turn the machine on and off to spin off excess water. Squeeze the syringe plunger to apply the diamond compound in a series of small dots around the pad surface; about a dozen on a 6” pad, and 16 or so on an 8” pad to start. Once charged you only need to apply addition diamond compound occasionally when you notice that the pad is no longer polishing.
• Setting up with Inland Polishing Compound (Cerium Oxide): Apply the felt pad (or your preferred substrate) to the master and install on your machine. Wet the pad and then briefly turn the machine on and off to spin off excess water. Make a slurry of the cerium oxide according to its directions. Apply a small amount to the pad; using a brush to paint radial lines that divide the pad into thirds or quarters (like a small pizza!) should be sufficient. A new felt pad may need additional cerium oxide applied until the pad becomes "charged". Once charged you only need to apply addition cerium oxide occasionally when you notice that the pad is no longer polishing. Using excess cerium oxide can cause balls to form under the surface being polished and make scratches. After your pad is installed and charged you can begin polishing.

Do not use the water drip during step four or you will quickly rinse away your polishing medium from the pad. Turn on the machine and adjust the speed. Polishing is generally done at higher speeds than grinding steps and is something you just need to develop a feel for. You don’t want to press so hard that you stall the wheel or create so much friction you cause heat fractures. On the other hand you do need to apply some pressure for the polishing process to occur. If the polish starts to cake up on your glass or dry out, add water to the glass piece by rinsing the piece under water. You will also want to periodically rinse and dry your piece to check your progress and look for scales and scratches. If you see them you must return to Step 1 (325 grit) and follow through the steps, always using the complete order of grits as they won’t be polished out.

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