Shellac...

Shellac is a natural coating used by furniture types for centuries... it doesn't fade much over centuries, is very hard, gives a very warm feel and look and is easy to work with... comes from the substance secreted by a south asian beetle in protecting its eggs... beetle spit... kinda...

sanding back the first fill coats of shellac on the foot end... head end nearest camera...

putting together the frame for the first time to accurately determine foot and head board lengths...

... then back to shellacing and sanding... you can see in the bottom right the head end top surface is starting to glisten well after just a few coats...

all the mattress tub boards are held by jigs off the floor so it is easier to coat the routed edges as well...
... using a shellac 'rubber' is the best way to apply shellac over a large flat surface... it holds a good 'charge' of shellac and by using pressure you can very finely control the amount of shellac deposited...