|Use around one heaped tablespoon of 220 or 400 (depending where you are upto) grit per one pound of rock. Tumble the barrel for around 5 to 7 days using 220 and then repeat this page using 400 grade grit.
Looking at the specimins after each completed 220 or 400 stage will reveal virtually no difference in the rocks to the naked eye – so don’t worry – everything is going fine! However at an almost microscopic level, changes have occured on the surface of the stones and you can try to imagine what these would look like if magnified.
After 80 – the surface is scoured with thousands of scratches which dig into the rock to a depth of however large a piece of 80 grit is. After 220, these scratches aren’t as deep, they are only as deep as however large a piece of 220 grit is. After 400, they are less deep again, as deep as however large a piece of 400 grit is.
Because grit particles get smaller with each increase in value of the grade number, the scratches are smaller. Also, the grit breaks up during the process, so the final scratches are actually less deep than the size of the grit particles of a given grade.
Very basically – this is how it works. Once we have rocks which are completely scoured with tiny tiny scratches, so small that the rock is smooth, we can move onto the final polishing stage – which is step 3.