As I’ve probably mentioned in previous updates, I’ve given myself a schedule that compromises between the recommendations of the ATM class and the realities of my own busy life: I attend every second class. Today was to be a class day for me, except that my three year old daughter woke up with a fever, a sore throat, and no voice. The earliest doctor’s appointment we could arrange was bang in the middle of the class, so I couldn’t make it. I figure I’ll double up the next two weekends to make up for it.
Meanwhile, I’ve put in another two hours grinding with #120 grit, 1/3 diameter strokes working centre over centre. I’m assured that this will bring the surfaces of mirror and tool into closer and closer contact (perfect contact means that they are perfectly spherical), and I’m taking it on faith that this is what is happening. The other goal, that of smoothing the surface till no pits from the #80 grit are visible, is still a way off. The glass has a velvety smooth texture now, but a close examination with the naked eye reveals numerous tiny pits. These are the remains of the deepest scratches made by the previous level of grit. Each stage of grinding will have the same goal – to remove all evidence of the coarser grit used previously. I suspect that, as I progress, the pits will get harder and harder to spot. Logically, the only way to be sure is to grind until I cannot see any more large pits, then grind some more for another few hours to be absolutely certain.