Lava not rising

[Matthew]

Hey guys,

I recently got my first lamp out of storage, a mathmos jet. 

The top cap was broken years ago, hence why it went away.  I recently made a replacement for it, but have a weird problem.  I stole it’s light/lamp/bulb  a while ago to put in an Astro. 

Astro and Jet both have everyday 40watt SES 240v bulbs (230 volts here). Currently drawing 34 watts. 

I made a new top for it. However the lava just sort of hangs about like the picture. It has its usual start up spurt and melt back, but then does this shape with the odd rise and fall to max 1/2 way up. Taking the cap off yesterday seemed to allow lava to rise more but didn’t watch for more than 10 minutes, so thought perhaps getting too hot?  Stuck a dimmer on it today just in case bulb was too high watts (base says 40w max). However can’t get the lava to flow all the way to the top on max power with or without lid today. 

have I got some kind of lazy lava or are there any tricks anyone suggest (without resorting to refilling or replacing the bottle?)

thanks so much lovely people. 

[Lava_Head_UK]

I only use 25w spotlight bulbs in my Astrobaby’s, Telstars and Jets and the 30 w equivalent in all my Astro’s they don’t get as hot and still flow beautifully. 

[Matthew]

Thanks, let me dial the dimmer down to 25watts for a few hours and see what happens.

[Matthew]

ok, so dialling down the power it got even less active...  so thought I'd go back the other way, its now @35 watts according to the power meter, and have made a tin foil reflector to go in the base to see if it will help..  Room its in is currently about 19.4degrees C.

Am about ready to give up with this one though..     So went out and bought a couple of s/h astro babies.  £45 for both, one an orange on clear and one a very dark blue on clear dated 98 and 02 according to stamp on base (I recognise I've mixed base and lids).. Just need some more bulbs now.

[Mark]

It's past it's sell by date unfortunately, like the majority you see on ebay now.

You can tinker with the contents, but personally I never manage to get them looking 100% again.

You could replace with another bottle via ebay, but you'd have to look for a good one, and the price of Jets has really jumped this year!   

Message me though if you do look for a replacement, as I'm selling most of my lamps off, and probably have a good one tucked away. 

[Matthew]

Cheers Mark, will drop you a message about the ones you are selling. Now I have 4 + space projector, I’m not sure I’m going to stop. 

I’m pretty sure it’s something to do with the replacement lid I made. When I say made, it’s the end of a Pringles tube sprayed black. Now I would expect the metal end to conduct heat, however I made a stabiliser out of wood, I wonder if it’s insulating the bottle and keeping the top too hot.   With the original broken lid on tonight it’s doing it’s thing. I’ll make another lid without the wood insert and see how that goes, or if i get really keen I’ll make a metal lid from some stainless.

 

[Mark]

That's odd.

The lid shouldn't make any difference tbh. Should run the same with the lid on/off.

Regardless, looks like it's flowing well now. Perhaps it was just a little sleepy after being in storage so long!

[Modulo '70]

I agree with Mark, in my experience I don’t think the lid has any bearing on the flow and that the globe is just a bit ‘sleepy’ after the time in storage. I must test my blue/green Jet bottle which has been stored in the garden summer house since 2011. Funnily, Ive another Jet with a very similar break to the cap.

[Matthew]

ok so bit more playing (I really can't leave this one alone), and I found that it is working with both caps now, but only with the heat shield under the bulb - I do wonder perhaps if its simply waking up like Mark mentioned, or if the heat shield is doing anything, certainly with lower wattage it did even less which fits with the heat shield idea to send more heat up.

[Mark]

Heat shield? Is that something you've added?

There shouldn't be any shield in there.

Have you tried it with a 30w R39 spot/reflector bulb?

[Matthew]

heat shield - yup I made it, its thick aluminium foil (aka a cut up takeaway tray).  My theory went like this,  with the normal bulb in, the wax rose up and stuck about 5cm up just like in the first pic, occasionally moving down then back to there, but never rising more than half way.  Dropping the wattage and it did the same, but lower.  40 watt bulb (measured @ 35 watts) was the maximum I had, so I wondered about if I could shift some of the heat that otherwise conducts through the sides up, and sure enough this now seems to work.  Yesterday I had it running with the old broken lid as that seemed to work better (not sure enough to say now for certain though), today I ran it up then swapped with the lid you see above "Pringles mark 1".  If only my non contact thermometer hadn't broken I could have done a little bit of proper thermal modelling rather than just guessing my way along!

Bulb - yep, before I aded the heat shield/reflector I tried 2 different 30W R39 reflectors, one swapped over from another lamp, one new (both read 25watts on my power meter), and it was pretty much the same as the golf ball lamp tuning at 25 watts.

[john]

all you need are proplene gycol add abit with masterfluid and it with flow use 30w bulb which be better but i had this alot with the old mathmos jets easy to fix.

[Mark]

If you've got any tips for the glycol it would be good to hear them.

I've never had much luck.

Did get a Crestworth lantern flowing beautifully after a filter and some glycol, but after not using it for a couple of weeks it was flat again, and wouldn't recover properly.

I know other people have better luck, so probably just my technique, but now sure how I'm going wrong!