Problems with lava flow

[Reed]

I am having problems with two of my lava lamps. The first is a vintage 70s Aristocrat. I am currently using a "Reveal" brand 40 watt bulb for better color. The color is very nice, but the lava stops flowing after awhile. The lava will heat up and begind to flow well. however, the lava on flows well for 45 minutes to one hour, then it stops flowing and collects in one blob that floats at the bottom of the globe. No lava is left remaining on the coil. It appears as if the fluid around the lava has become heated to the point that the fluid is flowing around the lava, keeping it suspended, and preventing the lava from heating up enough to flow properly. But the odd thing is that the lava does flow correctly (and quite nicely) before it reverts to this bad behavior. The lava has done this both the the Reveal bulb and with a regular 40 watt appliance bulb.

My other lamp is a late 90s vintage Carlisle /Wizard lamp. It is currently running a 40 watt hgh intensity bulb, as called for on the sticker in the base. It also exhibits the same flow characteristics/problems as the Aristocrat described above. Flow starts out fine, but after a bit of time the lava collects into a floating blob at the bottom of the globe with no lava touching the coil.

Gently turning the lamps does not cure the problem.

Help! Anyone have any suggestions?

Thanks.

P.S. I will post pictures tonight once I get the lamps turned on and flowing.

[LampHead]

Both lamps are showing classic signs of overheating, try running them on a dimmer.

LampHead

[Reed]

Thanks! I'll try it. I thought it might be overheating, but figured that since I am using the correct wattage bulbs, that wasn't the problem. I guess I was wrong!