Plate has been replaced in the main by float glass - much more uniform, and most importantly, much fewer bubbles for the unwary. Add in that its easily cut, and available upto 3/4 thick, and you have a recipe for much atm use...

As a result, skills and techniques have improved, and shared to reduce the issues experienced by previous groups suh as astigmatism, to make the process laborious, but relatively straight forward...

The quality of the result will be determined by the skill of the mirror maker - and to really push the boat out in terms of performance, you have to be pretty good at making mirrors

Your mirror is probably fine - just add a fan or two to assist with cool down, and you should be good to go.

Owen