Newsgroup: it.scienza.chimica
Titolo: costruire una "lava lamp"

Ciao a tutti
conoscete le "lava lamp" o "motion lamp" ??
Sono quelle lampade che assomigliano a dei missili, composte da un
recipiente di vetro con dentro un liquido, una volta accese si staccano dal
fondo del recipiente delle bolle di una sostanza semisolida (di solito
colorata) ad effetto lava che arrivano in cima e poi ridiscendono per unirsi
nuovamente alla massa da cui si sono staccate.
Mi sto dannando da giorni ma non riesco a capire quali sono gli ingradienti
per potersela costruire.
Ci sono diversi siti in inglese ma io proprio non capisco......qualcuno ha
delle informazioni più chiare ????????
grazie
andrea

..se lo fai per divertirti ok, ma dal punto di vista economico conviene
comprarla:-)
http://pigseye.kennesaw.edu/%7Ebwhyte/make.htm
http://www.oozinggoo.com/howto.html
ciao!

 wrote in message
EqBW7.368947$sq5.17...@news.infostrada.it...
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Alcol isopropilico (in tutti i supermercati)
olio minerale (in tutte le automobili)
Così complicato?
-- 
Best regards, Jack.
Beauty x Brain x Availability = Constant

Scusa ma dove lo trovo l'alcool isopropilico in tutti i supermercati?

Ho inviato  questo messaggio qualche giorno fa ma ancora non ho risolto il
mio problema quindi scusate se lo ripeto .
grazie e ciao
andrea




 ha scritto nel messaggio
news:a0n35j$4hm$1...@pegasus.tiscalinet.it...


 ciao
Si trova dal ferramenta e costa pochissimo, un appunto, è ottimo per
sgrassare tutto ciò che è di plastica e non la rende opaca, al contario
dell'acetone
ciao!

 ha scritto nel messaggio
news:UmhZ7.24877$s04.1...@news.infostrada.it...


in the water.
Sure. You are in the wrong group.
In addition if you don't understand any of this or have no knowledge
of the chemicals suggested DON'T DO IT.
Some can cause problems if spilled on the rug or on your hands.
look at  
http://hyperreal.com/drugs/misc/lava.lamp.plans
It's in the sci.chem FAQ:
<start paste>
Contributed by: Jim Webb 
A container filled with clear or dyed liquid contains a
non-water-soluble substance (the "lava") that's just a little bit
denser (heavier), and has a greater thermal coefficient of expansion,
than the liquid around it. Thus, it settles to the bottom of the
container. A heat source at the bottom of the container warms the
substance, making it expand and become less dense than the liquid
around it. Thus, it rises. As it moves away from the heat source, it
cools, contracts a bit, and becomes (once again) heavier than the
medium. Thus, it falls. Heavy, light, heavy, light. Sounds like a
Milan Kundera novel. (Actually, to be more precise: dense, less dense,
dense, less dense.)
31.3 How do I make a Lava Lamp?
Contributed by: Jim Webb 
Method #1. A new, easy, simple, cheap lava lamp recipe
Use mineral oil as the lava. Use 90% isopropyl alcohol (which most
drugstores can easily order) and 70% isopropyl alcohol (grocery-store
rubbing alcohol) for the other ingredient. In 90% alcohol the mineral
oil will sink to the bottom; slowly add the 70% alcohol (gently mixing
all the while; take your time) until the oil seems lighter and is
about to "jump" off the bottom. Use the two alcohols to adjust the
responsiveness of the "lava." 
This mixture is placed in a closed container (the "lava lamp shape" is
not required, although something fairly tall is good) and situated
over a 40-watt bulb. If the "lava" tends to collect at the top, try
putting a dimmer on the bulb, or a fan at the top of the container.
To dye the lava, use an oil-based dye like artists' oil paints or a
chopped-up sharpie marker. To dye the liquid around it, use food
coloring. 
Two suggestions for better performance: 1) Agitation will tend to make
the mineral oil form small bubbles unlike the large blobs we're all
used to. The addition of a hydrophobic solvent to the mixture will
help the lava coalesce. Turpentine and other paint solvents work well.
To make sure what you use is hydrophobic, put some on your hand (if
it's so toxic you can't put it on your hand, do you want to put it in
a container that could break all over your room/desk/office?) and run
a little water on it. If the water beads, it should work fine. 2) For
faster warm-up time, add some antifreeze or (I've not tried it) liquid
soap. Too much will cloud the alcohol. Keep in mind that the addition
of these chemicals may necessitate your readjusting the 90% to 70%
alcohol mixture.
Method #2. The official way. (from US Patent # 3,570,156 March 16,
1971)
The patent itself is not very specific as to proportions of
ingredients. The solid component (i.e., the waxy-looking stuff that
bubbles) is said to consist of "a mineral oil such as Ondina 17
(R.T.M.) with a light paraffin, carbon tetrachloride, a dye and
paraffin wax." 
The medium this waxy stuff moves in is roughly 70/30% (by volume)
water and a liquid which will raise the coefficient of cubic thermal
expansion, and generally make the whole thing work better. The patent
recommends propylene glycol for this; however, glycerol, ethylene
glycol, and polyethylene glycol (aka PEG) are also mentioned as being
sufficient.
This mixture is placed in a closed container (the "lava lamp shape" is
not required, although something fairly tall is good) and situated
over a 40-watt bulb. If the "lava" tends to collect at the top, try
putting a dimmer on the bulb, or a fan at the top of the container.
Method #3. The "less official" way (from Popular Electronics,[3] )How
to make a Lava Lamp, by Ralph Hubscher, _Popular Electronics_
magazine, March 1991, p. 31 (4). Gernsback Publications.)
Several non-water-soluble chemicals fall under the category of being
"just a little bit heavier" than water, and are still viscous enough
to form bubbles, not be terribly poisonous, and have a great enough
coefficient of expansion. Among them: Benzyl alcohol (Specific Gravity
1.043 g/cm3), Cinnamyl Alcohol (SG 1.04), Diethyl phthalate (SG 1.121)
and Ethyl Salicylate (SG 1.13). [The specific gravity of distilled
water is 1.000.]
Hubscher recommends using Benzyl Alcohol, which is used in the
manufacture of perfume and (in one of its forms) as a food additive.
It can be obtained from chemical or laboratory supply houses (check
your yellow pages); the cheapest I could find it for was $25 for 500
ml (probably 2, maybe 3 regular-sized lava lamps' worth). An
oil-soluble dye is nice to color the "lava"; Hubscher soaked the
benzyl in a chopped up red felt-tip pen and said it worked great.
[Benzyl alcohol is "relatively harmless", but don't drink it, and
avoid touching & breathing it.] 
Hubscher found that the benzyl and the water alone didn't do much, so
he raised the specific gravity of the water a little bit by adding
table salt. A 4.8% salt solution (put 48 grams of salt in a container
and fill it up to one liter with water) has a specific gravity of
about 1.032, closer to benzyl's 1.043. I find that the salt tends to
cloud the water a bit.. you might want to experiment with other
additives. (Antifreeze? Vinegar?)
This is put into a closed container and placed above a 40-watt bulb,
as above. Either way, I would suggest using distilled water and
consider sterilizing the container by immersing it in boiling water
for a few minutes.. algae growing in lava lamps is not very hip.
Caveat: Some of these chemicals are not good for you. Caveat 2: Some
of these companies are not good for you if they find you've been
infringing on their patent rights and trying to sell your new line of
"magma lights." Be careful.
 
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