Well, according to your experiments the material of the coil (or the object) placed in the bottom of lava lamp plays important role to break the ooze surface tension. The 2 coils I have are stainless steel made and this material probably was chosen due to be corrosion resistant (by first?) and for the propriety of break the ooze surface tension. The metallic paper clips are mainly made by galvanized steel. I’ sure you know how that the proposal of galvanization process is protect steel from oxidation by means of covering it with a fine zinc layer. So an interesting question arises: is the zinc better than the stainless steel or even the steel to break the ooze surface tension? I know the problems involved to heating using induction coils and I was just thinking in an alternative way – not the most efficient – of heat the lamp. Too much difficulties (and high cost) are involved to use it in lava lamp and it was a simply crazy suggestion of me. On the other hand if one wants uses heating by resistance instead of incandescent lights the best way of provide the illumination is using LEDs. Today we can found high power LEDs with efficiency higher than fluorescent lights making them very attractive to make experiments. Of course I agree with you that the use of incandescent lamps offers a very good cost-benefit to regular experimentation.
Concerning to your second message the shape of the lava lamp recipient is very important. The short recipients don’t provide sufficient temperature gradient and not allowing the ooze circulates properly. The heating is also a problem and an adjusting heat source is mandatory. Here is one drawback of use incandescent lamps to heat and illuminate at same time: you only reduces the heating as expense of reducing the light intensity. So tacking this problem in account seems to be attractive use independent sources of heat/light.

Best regards,

João Roberto Gabbardo

It seems like quite some time has passed since the last posting in this list and I suspect quite a lot has moved on since then. With the advent of more modern technologies and easier access to complex components I can see we can have a lot of time experimenting here.

One question I have is: What is the approximate proportion of Wax (goo) to Master Fluid?

Realising now I'm sitting here that I have a) an empty AstroBaby bottle, b) a full AstroBaby bottle and c) a set of new, clean measuring jugs, I set about finding out by first marking the wax height from the full bottle to the empty one (this will probably also be useful when adding wax later) then filling the bottle with water to this line (Note: the spring was still present throughout this procedure), then pouring it out into the small measuring jug (using the small 250ml one as the measurements will be easier to get accurate). Result, about 125ml to the wax height. Next I filled up the bottle to it's 'Full' level with water, poured off into the small jug (which hasd since been emptied) to the line the water came to from the 'wax' line and the rest into the big jug. After some careful levelig of the surface it was sitting on (to get an even level in the jug), it measured out at 675ml, making the total volume 800ml.

Thus the ratio of wax to fluid is 125:675, or dividing down 5:27 (a bit over 1:5, I may have been generous with the water).

Following this if I want to fill a 700ml bottle, I should need (700/(5+27)) x 5 wax and (700/(5+27)) x 27 Master Fluid, working out at about 110ml of Wax and 590ml Fluid. Assuming 2:1 wax to Perc this gives me 73ml of Candle Wax and 37ml of Perc. Also following the vague rule of 1 teaspoon of 'salt' to 100ml water I'll probably need just under 6 teaspoons of 'salt'.

I'll probably make up the solution a bit weaker than this to start with to allow me to adjust later.

Tim

(Hereford, UK)

Next time: Mixing and filling

So, first attempt completed and a total failure. Lovely red wax, clear(ish) fluid to start with - heated it up and absolutely no movement.

Then I decided to revisit my assumptions and calculations. Turns out the amount of Perc I'm using is WAAAYYY too much (Folks, 2:1 ain't gonna work) - looking at the numbers in a more scientific manner it's closer to 5:1, possibly 4:1 to allow for evaporation while mixing (Perc's pretty volatile).

Second lesson is the fluid went pretty cloudy with Epson Salts - I tried doubling the concentration and still no movement in the wax, the fluid just got cloudier. Next attempt will be pure glycerine added to the distilled water (Hopefully this will stay clear and be stable). 

Other factors: 1) Using the liquid colouring for the wax I bought doesn't really work too well - I ended up with a large surplus of beeswax and the liquid colour just didn't want to stick (ended up wiping most of it out of the melting vessel), concentrated wax colour chips worked well though. 2) Liquid colouring for the master fluid worked well - food colouring seemed to take pretty well but I don't know how long it will last.

Next steps: Hydrometer and measuring beakers arriving tomorrow, I want to get my numbers refined a bit more so I need to be more accurate in how much I'm putting in of each component and I want to see exactly what density the fluids are.

Tim

(Hereford, UK)