8" Mirror Polishing, Part 3: First Strokes
After all that setup, actually polishing a mirror is surprisingly simple. First you put your mirror on your tool and apply pressure so the pitch flows and takes the shape of your mirror (which happens faster if it’s hot, so you can leave the pitch lap in hot water to heat it up and speed up pressing). Then you take your mirror, put it on your tool, and push it back and forth without applying any downwards pressure. Pressure is an advanced technique that makes the polishing go faster, but too much pressure can grind one part of a mirror slightly lower.
After a few minutes every time I rotated the mirror there was a ringing squeak noise like dragging your finger along the rim of a wine glass. Allegedly that’s a good thing, but it makes me nervous when I hear it.
It turns out grinding a mirror involves grinding. My arms got tired after 30 minutes. Well well well, if it isn’t the consequences of my own actions.