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You do not need to heat the solution... in fact do NOT pour lye into heated solution because they will react vigorously. The salts will dissolve in cold water (lye will warm it up a bit).Also the eggs will float since you just made the solution denser by adding salt and lye to it..
Century egg is pickled, meaning they are soaked in a strong brine solution that kills bacteria. I do not think bacteria can live in an extremely high ph environment, not to mention how salty it is. I have seen century egg sold in stores here in the states refrigerated and I do not think it's necessary since those eggs are preserved, so it will not spoil unless the shell broke.It's a bit like pickled eggs.
You can always buy a cheap K40 laser for around 400 dollars shipped. It won't be nearly as nice as Epilog but it will do everything an Epilog will do. It has no DSP control however... and it does lack on safety (for example NO laser off if the cover were opened), and I'm having a little bit of trouble locating the starting point of the engraving (it led to some mispositioned stuff... Will need to add a laser pointer to help me with this...)