70's Lava Lamp - Lava stops flowing

[A]

Hello,

I recently found 70's Lava lamp at a thrift store, one with red lava and in beautiful condition. I was thrilled because this lamp is a lot nicer looking than my other 70's lamp with green lava that I found at an estate sale many months ago. The green lamp was cloudy when I got it but has cleared up with regular use, the lava is just faded, full of bubbles, and doesn't flow as nice as others, but it still works okay and I have enjoyed using it.

After plugging in my new lamp I was amazed at how much better the lava is on this lamp, I keep having the same issue every time I run it. The lava flows fine for a while and then after about 4 hours of use the lava all of a sudden stays at the bottom of the globe and stops flowing. I believe the lamp is somehow overheating. There's a sticker on the base that says to use a 40 watt appliance bulb only. It did have the correct bulb, and I even swapped the bulb from my green lamp that we know works fine, and had the same issue.

What can I do?

[Claude J]

it's an aristocrat

The wax should not stay at the bottom when overheated, it should all be floating at the top.

I do see the photo that your coil is flipped.

It may help to:  VERY CAREFULLY and SLOWLY tilt the bottle to the side to try to get the coil flat on the bottom of the bottle

The coil is responsible for transferring the heat from the light bulb to the lava.

Another option is to change the fluid, but that's a whole other story and commitment

[Keith]

This is what to look for regarding overheating.  If your lamp is overheating and you have the proper bulb you may need to use a dimmer to adjust the flow.  Also your room temperature could be to warm, Lava lamps do best in rooms between 70 to 74 degrees F.  

[Claude J]

Good to know Keith

I guess I always caught it before i hit a critical stage
Keith said:

This is what to look for regarding overheating.  If your lamp is overheating and you have the proper bulb you may need to use a dimmer to adjust the flow.  Also your room temperature could be to warm, Lava lamps do best in rooms between 70 to 74 degrees F.  

[Johnny]

wow 10 hours thats a long time to have one going and lot more than mathmos lamps, mine never on more than 6 hours 

[Keith]

or "continuous action (perhaps days)" according to this 1967 instruction page.  NOT RECOMMENDED!!!

Johnny said:

wow 10 hours thats a long time to have one going and lot more than mathmos lamps, mine never on more than 6 hours 

[kero48]

It is also possible the lava could be reaching the end of it's life.

[Cate Smith]

I don’t get the difference between the getting to warm and the just right the seem pretty much the same to me 

[bob]

When a lot of wax is at the top and stays there vs moves up and down

[Autumn]

Can you take a time lapse or pictures every 30 minutes from startup of the lamp running? What could be happening is the liquids in the lamp expand as they heat up. When liquids expand they become less dense. If they become light enough the wax may be unable to overcome that reduction of density which would cause it to sit at the bottom. It's hard to know just from a single picture though. It could also be the wax not sticking to the coil. That will also interrupt the flow.