Lab Procedure-Fine Grinding
"The sample MUST be washed thoroughly before proceeding from one
fine grinding stage to the next!!!"
1. Manual Fine Grinding is performed by drawing the specimens in one direction across the surface of the
water lubricated abrasive paper. (Back to front is recommended) Use of backward and forward motion is
less desirable because there is a tendency to rock the sample, producing a curved rather than a flat
surface.
2. Begin with the lowest grade abrasive paper (240 grit) and proceed to the highest (600 grit).
3. To monitor progress, each fine grinding step should be performed in a direction off-angle with respect to
the previous step.
4. Fine Grinding should be continued until the previous stage's scratches are gone, using a few extra
strokes to assure complete scratch removal.
5. Sufficient water must be applied to provide lubrication and flush away the removal products. Too much
water will result in a hydroplaning action where the sample rides on a film of water, thereby reducing the
effectiveness of the abrasive. Use the valve at the top of the roll-grinder to increase and decrease the
quantity of water needed or desired.
6. The specimen should be carefully rinsed after each step of Fine Grinding; debris from one step must not
contaminate the next step! Rinse the specimen very thoroughly before proceeding to polishing.