The Old Chunky Wax Problem

[Marc Berman]

I've recently inherited a 1975 Century with clear liquid and a gorgeously rich red wax. Initially I hadn't given much thought to the possibility of issues, but here we are. The lamp sat unused (stored in a box in a basement) for at least 20 years before my efforts to revive it.

So far I've run the lamp for a few days of 10-12 hour cycles, including most recently for 24-hours straight right before taking the attached image/video.

While after several hours it will start to flow somewhat, the chunkier fraction of wax always seems to wad-up in the top half of the globe, with more fluid wax rising to join it, then separating and dripping back down. Some of the chunks do seem to make the trip up and down the globe, but despite the churning never seem to fully melt or reincorporate.

While there's no shortage of people with this sort of issue (chunky wax), the methods people are using to fix it and the path they take to get there seem to vary wildly. On the surface of it, I've seen plenty of suggestions that cycling will help (run until it starts to soften, then cool completely, repeat several times). Admittedly I have a hard time wrapping my head around the physics of how this would work, since it would seem that if 24+ hours of constant uptime/heat can't completely melt the wax, nothing will. The two methods I'm considering (and could use some feedback on) are as follows:

1) Using a timer or smart switch to "set and forget" a pattern of cycling for a few days. Given the condition of the wax, what would be a good on/off duty cycle for the timer to achieve the best results? Since it can take upwards of 4-6 hours just to get the wax flowing, I'm not sure how long constitutes "until starting to soften."

2) I'd like to try a heating/superheating method, but rather than boil it in water on the stove which seems dangerous, I'd much rather submerge the globe in an immersion circulator (sous vide bath) set to an appropriate temperature. Does anyone think this will help? The idea being to heat all the liquid and wax to an even temperature simultaneously, reducing convection and cool spots. What would be a good temperature to use for this, being mindful of the normal operating temp of the lamp, trying to make it high enough that the wax fully melts and reincorporates, but low enough that it doesn't cause issues with pressure in the globe. If at all possible, I'd prefer to not have to pop the top, though I imagine this is easier with a Century lamp since they have the original style screw cap vs crimped-on closure.