I recently had to replace the bulb in my Mathmos Astro Baby. It takes a 30 watt reflector bulb. The original bulb from Mathmos was frosted, and I got a new one from ASDA but it is clear.
I didn't think this should make any difference to the flow of the lamp, but I have noticed that after about 5 hours of operation there starts to be dozens and dozens of tiny pea-sized blobs of lava floating around, so it seems to be getting a bit too warm.
Do you think this could be due to the bulb being clear rather than frosted? Has anyone experienced the same problem with clear bulbs?
It could also be down to your frosted bulb being a filament bulb and the replacement being halogen?
I usually buy slightly lower power halogens for my lamps as they are more efficient and create more heat and light despite using the same amount of power.
The boxes for them sometimes have a wattage on them as well as a wattage which it is equivalent to in filament form.
E.g. a 28w halogen bulb might be equivelent to a 35w filament bulb.
Thanks for the replies guys. The temperature in my room has been pretty constant before and after the change of bulb (I actually have a digital thermometer in my room for the precise purpose of knowing whether it's too hot/cold for my lamps to run properly ). As far as I can tell both the frosted and clear bulbs I've used are ordinary filament bulbs - not halogens.
I have ordered some frosted bulbs from eBay - we'll see how they compare!