Lava Lamp Scientists

Comment by Jennifer on March 30, 2010 at 12:23pm

Hey Magic Lamp-post pics! Is your blue/white one you did? Looks great! What kind of wax did you use?

Comment by Jennifer on March 30, 2010 at 12:26pm

Nevermind-I see them on your profile. I love "black beauty". You must share some of your techniques. Your wax looks more opaque than I get mine, I'm always looking for ways to make it more opaque!

I love that you are naming them, like works of art! I do feel like this is such a neat creative outlet! Screw sculpting and painting!

Comment by MagicLamp on March 31, 2010 at 2:34am

Ah yeah.."Casper" was my first homemade lava lamp, made to replace the wax and fluid of a defective chinese one. I initially intended it to be blue on blue, so I got some tealights from LIDL which were blue...only to discover they were mostly white with just a flake of blue on the visible side. So yeah, in the end it turned out blue/white. The wax is just tealight wax, mostly white with a speck of blue and a solid pink one mixed in.

Comment by MagicLamp on April 4, 2010 at 1:43pm

Just a tip I felt like sharing with fellow lava lamp scientists: when making my homemade lamps: while the chinese one had its own coil, one of the challenges I faced was finding a way to provide the other two with their own coils....and hardware stores don't sell ready-made springs, apparently. I tried with electrical copper wire and metallic dish scrubbing brushes, but they didn't work well (too soft?).

Some pages on the internet suggested twisting your own coils from iron/inox steel, but I found an acceptable solution with materials I had at home: I just daisy chained some inox paper clips together (use your imaginarion, you can just make a girdle or form a flower-like structure, just threw them in the lamp and twisted it around so they "open up" on the lamp's bottom. They work great and break the wax just fine.

Comment by MagicLamp on April 4, 2010 at 1:46pm

About the wax I used: I found it best to use high-quality candles with all-solid color wax. They cost more, but they are worth it, for they have great opaqueness and color consistency compared to white waxes with just external color coatings. The black wax comes from such candles. It occasionally shows bubbles or some blobs get too transparent, but otherwise it has a near pro-grade opaqueness. I will post the candle brand if I find it. They were quite expensive though, like 3 Euro for just two candles, enough for 1 lamp.

Comment by Jennifer on April 4, 2010 at 1:47pm

Wow, great idea! I have found springs at my local Ace hardware, but they are so stiff and thick that I have to get my husband to fix them for me and then still, he usually scrapes up his fingers.
Thanks!

Comment by João Roberto Gabbardo on April 4, 2010 at 3:44pm

I was looking again the coil from my damaged (and disassembled) lava lamp and it is made by 0.4mm diameter stainless steel. The coil serves to distribute the heat in the bottom of the bottle and stainless steel is far to be the best material to do so. The heat conductivity of stainless steel is less than copper (best) and aluminum and the main reason of use stainless steel is by its greater mechanical strength compared to the other two later materials. Copper and aluminum are too much soft and is easy to deform them permanently. On the other hand a coil made by a thin stainless steel wire is sufficient hard to be squeezed and inserted in the bottle opening and returns to the previous shape. Here in Brazil we can found thin stainless steel wire in crafts material store and I bet you can found it easily there. Make a coil using a thin stainless is very easy and you don’t need any kind of special tool: just wrap firmly the wire in a rod with the diameter you want make the coil. You can use a Philips screw driver, for example. But why a Philips screw driver? Well, if you use a regular screw driver surely you will not be able to remove the coil from it due to the flared extremity!

Best regards,

João Roberto Gabbardo

Comment by MagicLamp on April 4, 2010 at 4:32pm

I don't know if the coil has -or even if it's supposed to have- any serious effect on spreading the heat: after all, it has too small a mass, too little surface area and total thermal capacity compared to the fluid, wax and even the glass surrounding it.

I know it has an important role in breaking up the surface tension of the blobs though: the soft copper and dish-scrubbing wire mesh just let the wax "flow" through them without breaking it, and the wax kept itself in one big blob. The hard steel paper clip OTOH resulted in the wax breaking up almost immediately on contact.

Then again....it might be that due to its being metallic and closest to the lamp's filament, it might have a localized high temperature gradient (although the surrounding fluid and wax would cool it almost immediately). I wonder how a lamp where the coil was a direct heating element would perform....

Comment by João Roberto Gabbardo on April 4, 2010 at 5:31pm

I must admit that my experience with lava lamps is very little; after all I only had one lava lamp! In spite of it worked well, the clear liquid was clouded. Probably the lamp was packaged warm and immediately shipped. I made several experiences intending to repair the lamp (but letting the original ooze) and discovered that if you shake the lamp when it is warm the ooze mix with the water at some extent clouding it. In my thoughts the coil seems to spread the heat in ooze like the heatsinks used in electronic components.
If you consider a lava lamp operating in such way like ever having enough quantity of ooze in the bottom to let the coil completely covered, how it will act to break the ooze surface tension? In this situation the blobs will emerge due to the heating from the top of the accumulated ooze or a quantity of ooze is splashed forming a blob when one cool blob falls in the accumulated ooze.
Anyway the metallic coil is better to transfer the heat to the ooze than the glass but as you pointed, due to its low size and mass how much it takes part in the working of the lamp?
I think that if the ooze was heated directly by the coil it would be work in the same way but with a increasing of the energy efficiency. In the actual lamps the incandescent light bulb serves to furnish heat and light with low efficiency since the heating happens mainly by radiated heat. Using an element like the coil to directly heat the fluids will save energy and would allows use LEDs as light sources that are much more efficient than incandescent lamps.

Best regards,

João Roberto Gabbardo

Comment by MagicLamp on April 5, 2010 at 11:26am

Well, the ooze is much softer than the coil and touching it disrupts the blobs' surface. If there was just enough wax for one blob in the whole lamp, then yeah, a coil wouldn't be necessary: the same blob would keep going up and down due to heat gradients. If you have multiple blobs though, when you have a malfunctioning coil (e.g. too thick, too porous, too dirty) then they tend to stay separated, like many baloons, and don't recombine.

Consider e.g. what happens at the top of the lamp, where blobs touch for long times but very seldom break up and mix (only if the lamp overheats they connect away from the coil) or what happens to "in flight" blobs that touch: they just bounce off each other.

By the time the lamp heats up enough as a whole to start the cycle, the coil can't make any difference (and for that matter, it can't be hotter than its surroundings: its temperature will be dominated by the fluid and wax around it). Now, if you had a charcoal black disk directly facing the lightbulb, even several centimeters inside the bottle...then yeah, that would localize some extra heat due to irradiation, but still no big deal.

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