Lava Lamp Thread

[Phauss]

Lava lamps! Why? You'd know why if you had one. Here I plan to have my "think out loud" area for making a lamp of my own. Eventually, you can make requests or build one yourself.

Needed materials:

• A brick of candle wax from a craft store
• Beeswax, also from a craft store
• Oil pastels (to color wax)
• 70% alcohol
• 91% alcohol
• Glass container
• Source of light/heat (25 watt bulb, I believe)
• Food coloring (to color "water")(optional)

[Phauss]

Firstly, I'm worried about pressure building in the lamp from the expanding liquids in the glass. A remedy to take a load off is to leave air at the top so it can compress while the liquids expand. We don't want our container exploding because the stuff in the jar has nowhere else to go.

Then I'm worried about the integrity of the glass itself under pressure. I'm not sure if the lava lamp people do anything special with their glass globes, but I thought a good way to relieve the load would be to release the pressure when the lamp was hot, then reseal the opening. This would create a negative pressure (a vacuum) inside when things were cool, something I'm not too worried about.

I realize that alcohol (which will make up the "water" that the liquid wax floats in) evaporates easily even at room temperature at ambient pressure. If I were to release the pressure while the lamp was hot, alcohol vapor may escape the glass container and possibly bubble and/or boil off. The pressure within the sealed container might be needed to prevent alcohol evaporation and bubbling. The glass might just have to contain the pressure. I don't think it would be anything phenomenal, anyways.

[Phauss]

You can't tell me that this jar isn't exactly perfect for what I'm trying to do. It cost only half as much as the jar I was eventually going to get, too. $5 at TJ-Maxx.

The way I've seen this done is with a Sobe bottle, which is 20oz, or 591mL. This jar is either 2L (2000mL) or 2qt (64oz) (the tag on the jar didn't say), so I'll make some appropriate calculations later on. It's roughly 3.5x the size of the Sobe bottle.



Prices so far:

Jar	$5
Wax
---1lb	$7
---1.5lb	$8
---4lb	$20
1lb Beeswax	$18
48 pc. Oil Pastel Set	$6
16oz (~475mL) Rubbing Alcohol
---70%	$1
---91% (x4 to fill jar)	$4

I'll adjust the totals on a per-lamp basis once I figure things out.

[Phauss]

I noticed the rubber gasket didn't seal so well on this jar when I bought it. I'll head over to Lowe's or Home Depot to look for some rubber O-rings for a better seal. I'll also add the price per O-ring to the overall cost.

About the light/heat source: I believe that since the stock 20oz lamp I have uses a 25W bulb, it would be safe to assume at least 40W is needed due to the increased volume of the jar.

To-Do:

• Determine per-lamp values and amounts for a 2L container.
• Find beeswax (stores I've been to have sold out of it)
• Buy waxes, alcohols, O-ring, and bulb.
• Figure out some sort of stand.

[Phauss]

I was writing the To-Do when it dawned on me to see if a coffee can would work well as a stand. Lo and behold, I present this:



It's a very nice coincidence that the can is the exact diameter of the jar. I have two more cans which could be used as mounts for future lamps.

The jar sits on the lip just below the top edge of the can. For pure function I would just leave the can as-is, but I'd like to wrap the can with some sheet metal or something. That would raise the stand's top edge further above the bottom of the jar to cover excess "lava" that would sit at the bottom and to make more of a pocket for the jar itself to sit in. I like the look of the wire top lid, so I probably won't make a cap for the jar.

A light bulb will fit very nicely and I can mount a bulb socket inside with a few screws. Drilling a hole in the can for a chord won't be a problem either.

[Forb]

Holy crap, that is a huge jar. I was picturing something much shorter and wider.

[Phauss]

I bought a couple of bulbs, a socket, some wire, and a switch at Lowe's today. The setup works beautifully and fits very well in the can. I'll think of a way to mount the socket in the can, maybe with a small block of wood or something.



I also bought a rubber O-ring for the jar, but I bought the wrong size by accident. I'll return it for a different one. It was around $1 for the O-ring.

I'll make a list of parts I'm using for the lamp itself, since I only had a list for the "lava" ingredients inside the lamp. I'm making the actual lamp on the fly right now and I'm having a lot of fun doing it.

Lamp parts:

Coffee Can
2L Jar	$5
2-pack 40W Bulbs	$2.50
Chord/Switch/Socket	$5
Sheet Metal (12"x24") -or- Snap Aluminum Ducting (4"x24")	$5 $3
Total	~$15-20

Instead of flat sheet metal, I decided to use snap aluminum ducting going for around $3 per 2 foot section. It was thinner than the available 26 gauge sheet metal and already curled, so it would be easier to wrap around the can. My sheet metal snips would also have an easier time cutting it (although 26 gauge metal is pretty thin, too.) I didn't buy any metal this time around because it's not an essential part of the lamp yet. I want to keep my options open until things are put together. (To clarify the above chart, 4" is the diameter of the ducting.)

I found a roughly 4 foot chord with the socket, plug, and switch already put together for cheaper than it would've been for the individual parts. The bulb socket is a candelabra base, so I went with round 40W bulbs. Good information to know if I ever make you a lamp and the bulb goes out. (Or you could just look at the bulb.)

The lamp itself is cheap to make and can even be made for free if you cannibalize another lamp or scavenge for parts. The pricey parts of the whole project are the things inside the jar.

[Phauss]

I solved the O-ring issue by just buying a 6" square of packing rubber and cutting a ring from the square. There's enough material to make two gaskets for these jars. The overall price of the rubber was $1.50, so $.75 per lamp.

Now the lid of the jar sits evenly and makes a good seal.

[Loktarr]

Can't wait to see it complete!
Any idea on what colors it's going to be?

[Phauss]

I want to make it an olive-green or greyish-blue colored wax in a clear liquid, but I still have to make sure the thing works first. There won't be any color during preliminary testing, just the waxes an alcohols in the jar to get the densities right.