"David Peters" wrote in message
...
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Thanks for any info.

David

------



FOOTNOTE:

I can add that here in the UK the main type of denatured alcohol we
can buy for home use is "methylated spirits" and in the UK this is
made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol. This can lead to confusion about what someone is
referring to, so for clarity I can repeat that I am referring to UK
meths/ethanol. ]


Because you cannot safely drink 2-propanol.

--
Dr. Dickie
Skepticult member in good standing #394-00596-438
Poking kooks with a pointy stick.
"The most exciting phrase to hear in science, the one that heralds new
discoveries,
is not 'Eureka!' ('I found it!'), but rather 'hmm....that's funny...'"
- Isaac Asimov

David Peters wrote:
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

So, given the choice between ethanol and isopropanol, I'd choose
ethanol. But given the choice between meths and isopropanol, I'd choose
the latter any day.


--
Grunff

David Peters wrote:
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?


Hmm dunno if it is, is it? It may depend on the relative concentrations
of each when compared to each other.

For example 0.02M propan-2-ol (isopropyl alcohol) will be stronger than
0.002M ethanol. Assuming the same concentrations (water to pure chemical
ratio), then the only two reasons I can see are that:

1. Propan-2-ol has a longer hydrocarbon chain than ethanol (dunno how
much difference this can make apart from making the chemical more
viscous)...

H H H H H
| | | | |
H-C-C-C-H H-C-C-H
| | | | |
H O H O H
| |
H H
(propan-2-ol) (ethanol)

2. The functional alcohol (O-H) group is on the second chain in
propan-2-ol and therefore is joined to a carbon with only one
hydrogen atom connected to it... Therefore propan-2-ol is a secondary
alcohol. As to why this would make too much of a difference I am not
sure, look up the chemistry of primary and secondary alcohols. Since
I don't think you are fully oxidising them I can't see how this would
make too much difference.

Another thing apart from concentrations, is that you mention meths...
It is only valid really comparison if the two chemicals are in their
pure form.. Not apart of a cleaning agent such as meths of window
cleaner etc.

Good luck, maybe you could feed us some more background information.

P.S. Clever people this is only what I remember from my A level
chemistry.. Please correct me if I've made a mistake :P.

--
Regards,
Aaron.

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:

David Peters wrote:
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

So, given the choice between ethanol and isopropanol, I'd choose
ethanol. But given the choice between meths and isopropanol, I'd choose
the latter any day.

On Fri, 03 Jun 2005 15:17:55 +0100, Custos Custodum
wrote:

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Why does it do that? is it the methanol or the pyridine ?

"David Peters" wrote in message
...
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Thanks for any info.

David

------



FOOTNOTE:

I can add that here in the UK the main type of denatured alcohol we
can buy for home use is "methylated spirits" and in the UK this is
made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol. This can lead to confusion about what someone is
referring to, so for clarity I can repeat that I am referring to UK
meths/ethanol. ]

I strongly suspect that the cleaning power of ethanol vs. propanol depends
on the nature of the dirt being removed.
While it is an oversimplification, think of dirt as being either water
soluble or oil soluble. Ethanol (two carbons and one hydroxyl group) will
be more effective in removing water soluble dirt, while propanol (three
carbons and one hydroxyl) will be more effective at removing grease (oil
like substances). Lighter fuel is very effective at removing grease, but is
even is more fire hazard than the alcohols.

Ernie

In article , David Peters wrote:

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol.

That is not correct. In the US, "denatured alcohol" is specifically ethanol
with small amounts of poisonous additives (usually, but not always, methanol)
to render it unfit for beverage use.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

According to Custos Custodum :
On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:

David Peters wrote:
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Um, I think someone's confused. Methanol (which does eat rubber)
is _not_ denatured ethanol - it's methyl alcohol, aka methyl hydrate
aka CH3OH, aka "wood alcohol". Ethanol is C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

David Peters wrote:

Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Thanks for any info.

David

------

FOOTNOTE:

I can add that here in the UK the main type of denatured alcohol we
can buy for home use is "methylated spirits" and in the UK this is
made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol. This can lead to confusion about what someone is
referring to, so for clarity I can repeat that I am referring to UK
meths/ethanol. ]

The denaturants for ethanol to render it non-drinkable (short of Kitty
Dukakis) are crud. Ethanol is rather volatile.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

"David Peters" wrote in message
...
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

The additives in household meths seem to affect its value as a cleaner,
which, as it is sold as a fuel, is not unreasonable. If you want to use
meths as a cleaner, you need to get hold of industrial meths.

Colin Bignell

Chris Lewis wrote:

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.


In the UK, you can purchase something called 'methylated spirit' or
'meths' for short. This is typically 97% ethanol, 3% methanol, and a
touch of pyridine + purple dye (to stop people drinking it).


--
Grunff

Grunff wrote:
Chris Lewis wrote:

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.


In the UK, you can purchase something called 'methylated spirit' or
'meths' for short. This is typically 97% ethanol, 3% methanol, and a
touch of pyridine + purple dye (to stop people drinking it).

I doubt if the purple dye (IIRC methyl violet) would stop anybody ;-) It's
the pyridine that really gives it a nose!
I wouldn't use meths for cleaning alone, as there's always the likelyhood of
leaving some dye residue. Properly denatured ethanol would be better, but I
think the Exercise men would take a dim view of retail sales - although one
can buy "duty-paid" pure ethanol (at about 75GBP per Winchester), and the
C&E probably won't bother so much (but you will be very, very much
poorer...)

--
--
Ron Jones

Don't repeat history, see unreported near misses in chemical lab/plant
at http://www.crhf.org.uk

Chris Lewis wrote:

According to Custos Custodum :

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:



David Peters wrote:

Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?


It isn't.


Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.


It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.


Um, I think someone's confused. Methanol (which does eat rubber)
is _not_ denatured ethanol - it's methyl alcohol, aka methyl hydrate
aka CH3OH, aka "wood alcohol". Ethanol is C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.

David Peters wrote:

Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Probably because it's a little less volatile and so doesn't evaporate before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.

On Fri, 3 Jun 2005 11:32:03 -0400, "Ernie"
wrote:


"David Peters" wrote in message
...
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Thanks for any info.

David

------



FOOTNOTE:

I can add that here in the UK the main type of denatured alcohol we
can buy for home use is "methylated spirits" and in the UK this is
made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol. This can lead to confusion about what someone is
referring to, so for clarity I can repeat that I am referring to UK
meths/ethanol. ]

I strongly suspect that the cleaning power of ethanol vs. propanol depends
on the nature of the dirt being removed.
While it is an oversimplification, think of dirt as being either water
soluble or oil soluble. Ethanol (two carbons and one hydroxyl group) will
be more effective in removing water soluble dirt, while propanol (three
carbons and one hydroxyl) will be more effective at removing grease (oil
like substances). Lighter fuel is very effective at removing grease, but is
even is more fire hazard than the alcohols.

Ernie


Ernie is essentially correct. There are other nuances of chemistry
that enter into consideration such as the relative acidity of ethyl
alcohol versus iso-propanol and the molecular shape, but the "grease"
solubilizing idea is a simple way of representing the why you might
use 2-propanol over ethanol.
Gary Dyrkacz

Radio Control Aircraft/Paintball Physics/Paintball for 40+
http://home.comcast.net/~dyrgcmn/

On Fri, 3 Jun 2005 19:29:12 +0100, "Ron Jones"
wrote:

I wouldn't use meths for cleaning alone, as there's always the likelyhood of
leaving some dye residue.

It's not too hard to find uncoloured meths. Try a real hardware shop, or
a painters' supplier.

OTOH I still haven't found a source for it without the pyridine.

On Fri, 03 Jun 2005 16:04:06 +0100, Andy Dingley
wrote:

On Fri, 03 Jun 2005 15:17:55 +0100, Custos Custodum
wrote:

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Why does it do that? is it the methanol or the pyridine ?

Not sure about the methanol, but pyridine is certainly used in
industry as a solvent for rubber.

On Sat, 04 Jun 2005 04:05:59 +0100, David Peters
wrote:

On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:

Chris Lewis wrote:

According to Custos Custodum :

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff
wrote:

David Peters wrote:

Why is isopropyl alcohol (propanol) reckoned by many people
to be a better general cleaner around the house than the
ethyl alcohol (ethanol) which is found in methylated spirits?


It isn't.


Ethanol has a lower toxicity. However, denatured ethanol
(meths) has pyridine added to it. Apart from being one of the
most vile smelling compounds, pyridine is relativly toxic.


It also rots rubber, which is why you should never use meths
for cleaning tape recorder pinch rollers.


Um, I think someone's confused. Methanol (which does eat
rubber) is _not_ denatured ethanol - it's methyl alcohol, aka
methyl hydrate aka CH3OH, aka "wood alcohol". Ethanol is
C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says
"meths". if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.


I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

These are simply the additives for the different classes of methylated
spirits. What constitutes the basic 'spirits' is presumably defined
elsewhere.

David Peters wrote:

On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:


Chris Lewis wrote:


According to Custos Custodum :


On Fri, 03 Jun 2005 13:59:36 +0100, Grunff
wrote:

David Peters wrote:


Why is isopropyl alcohol (propanol) reckoned by many people
to be a better general cleaner around the house than the
ethyl alcohol (ethanol) which is found in methylated spirits?


It isn't.


Ethanol has a lower toxicity. However, denatured ethanol
(meths) has pyridine added to it. Apart from being one of the
most vile smelling compounds, pyridine is relativly toxic.


It also rots rubber, which is why you should never use meths
for cleaning tape recorder pinch rollers.


Um, I think someone's confused. Methanol (which does eat
rubber) is _not_ denatured ethanol - it's methyl alcohol, aka
methyl hydrate aka CH3OH, aka "wood alcohol". Ethanol is
C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says
"meths". if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.



I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha

I think that IS methanol^^^^

and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

David Peters wrote:
On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:

Chris Lewis wrote:

According to Custos Custodum :

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff
wrote:

David Peters wrote:

Why is isopropyl alcohol (propanol) reckoned by many people
to be a better general cleaner around the house than the
ethyl alcohol (ethanol) which is found in methylated spirits?


It isn't.


Ethanol has a lower toxicity. However, denatured ethanol
(meths) has pyridine added to it. Apart from being one of the
most vile smelling compounds, pyridine is relativly toxic.


It also rots rubber, which is why you should never use meths
for cleaning tape recorder pinch rollers.


Um, I think someone's confused. Methanol (which does eat
rubber) is _not_ denatured ethanol - it's methyl alcohol, aka
methyl hydrate aka CH3OH, aka "wood alcohol". Ethanol is
C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says
"meths". if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.


I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

IIRC wood naphtha = wood alcohol = methanol

--
--
Ron Jones

Don't repeat history, see unreported near misses in chemical lab/plant
at http://www.crhf.org.uk

I wouldn't use meths for cleaning alone, as there's always the
likelyhood of leaving some dye residue.


On Sat 04 Jun 2005 11:26:47, Andy Dingley wrote:

It's not too hard to find uncoloured meths. Try a real hardware
shop, or a painters' supplier.

OTOH I still haven't found a source for it without the pyridine.


That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

If it helps, the contents page is at at:
http://www.opsi.gov.uk/si/si1987/Uks..._en_1.htm#tcon

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

If it has colouring then my reading says it would be UK
"Mineralised Methylated Spirits" which has colouring and also
pyridine. This has twice the wood naptha at 10%.

I wouldn't think that the last class "Denatured Ethanol" is
something which is commonly sold to the public.

"David Peters" wrote in message

Why is isopropyl alcohol (propanol) reckoned by many people to
be a better general cleaner around the house than the ethyl
alcohol (ethanol) which is found in methylated spirits?

FOOTNOTE:
I can add that here in the UK the main type of denatured
alcohol we can buy for home use is "methylated spirits" and in
the UK this is made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made
of ethyl alcohol. This can lead to confusion about what
someone is referring to, so for clarity I can repeat that I am
referring to UK meths/ethanol. ]


On Fri 03 Jun 2005 16:32:03, Ernie wrote:

I strongly suspect that the cleaning power of ethanol vs.
propanol depends on the nature of the dirt being removed.
While it is an oversimplification, think of dirt as being either
water soluble or oil soluble. Ethanol (two carbons and one
hydroxyl group) will be more effective in removing water soluble
dirt, while propanol (three carbons and one hydroxyl) will be
more effective at removing grease (oil like substances).


Thanks for the info. Can I ask about what you have written in
that paragraph.

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?

In article , David Peters wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?

Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot of
things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely to
dissolve plastic than a shorter one). I've also successfully used paint
thinner (mineral spirits) to clean various plastics without damage. And I've
not observed gasoline to be particularly harmful to plastics either. OTOH,
acetone (2-propanone) and MEK (2-butanone) are terribly destructive to many
common plastics. IOW, it ain't the length of the chain, but what's attached to
it, that does the damage.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

On Sun, 05 Jun 2005 15:33:25 +0100, David Peters
wrote:

That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

This is "Mineralised Methylated Spirits" made by Barrettine. Exactly the
same label as for their purple product and the same smell of pyridine,
but no colour.

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

There's a spec for it, but I haven't found a supplier in less than 40
gallon drums.

David Peters wrote:
I wouldn't use meths for cleaning alone, as there's always the
likelyhood of leaving some dye residue.


On Sat 04 Jun 2005 11:26:47, Andy Dingley wrote:

It's not too hard to find uncoloured meths. Try a real hardware
shop, or a painters' supplier.

OTOH I still haven't found a source for it without the pyridine.


That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

If it helps, the contents page is at at:
http://www.opsi.gov.uk/si/si1987/Uks..._en_1.htm#tcon

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

If it has colouring then my reading says it would be UK
"Mineralised Methylated Spirits" which has colouring and also
pyridine. This has twice the wood naptha at 10%.

I wouldn't think that the last class "Denatured Ethanol" is
something which is commonly sold to the public.

Quite right. If fact there there tends to be 2 main grades of IMS:
74op = colourless dry ethanol/methanol, now usually called 99% IMS
66op = same but damp with water (made from ethanol/water azeotrope IIRC) now
usually called 95% IMS

[op means "over proof", that means 74op = 174 UK proof. 100 proof =
ethanol:water mix which when wetted with gunpowder will flash when lit
(about 56.5% IIRC)]

There are also a few other grades of denatured ethanol, for use when the
methanaol would give rise to unwanted impurities - cyclohexane, toluene,
pyridine are all known. I would guess all grades of ethanol are unavailable
to the general public - except the purple one and "duty paid". (unless you
brew it yourself... hic..)

--
--
Ron Jones

Don't repeat history, see unreported near misses in chemical lab/plant
at http://www.crhf.org.uk

On Sun, 05 Jun 2005 15:48:45 +0000, Doug Miller wrote:

In article , David Peters wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?

Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot of
things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely to
dissolve plastic than a shorter one). I've also successfully used paint
thinner (mineral spirits) to clean various plastics without damage. And I've
not observed gasoline to be particularly harmful to plastics either. OTOH,
acetone (2-propanone) and MEK (2-butanone) are terribly destructive to many
common plastics. IOW, it ain't the length of the chain, but what's attached to
it, that does the damage.

It really depends on the plastic and the solvent. Some plastics like
polypropylene are almost totaly inert and aren't really attacked by
anything. Polystyrene on the other hand is attacked by practically
everything (it seems). Essentially this is because there are very few
points of attack in polypropylene. It is basically just a long chain of
carbons. Polystyrene however has plenty of places to attack. There are
other factors that come into play though such as how much cross-linking
there is in the polymer.

--

.¸¸.·´¯`·.¸¸.·´¯`· Shallow Sea Aquatics .¸¸.·´¯`·.¸¸.·´¯`·
.¸¸.·´¯`·.¸¸.·´¯ http://www.shallowsea.com ¸.·´¯`·.¸¸.·´¯`

On Sat, 04 Jun 2005 11:26:47 +0100, Andy Dingley wrote:

On Fri, 3 Jun 2005 19:29:12 +0100, "Ron Jones"
wrote:

I wouldn't use meths for cleaning alone, as there's always the likelyhood of
leaving some dye residue.

It's not too hard to find uncoloured meths. Try a real hardware shop, or
a painters' supplier.

OTOH I still haven't found a source for it without the pyridine.

Pyridine IIRC has been implicated in male fertility problems which gives
you another good reason to use propanol rather than meths. You can get
drunk by drinking propanol. I wouldn't recommend it though the hangover is
apparently much worse than with alchohol.

--

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On Fri, 03 Jun 2005 16:04:06 +0100, Andy Dingley wrote:

On Fri, 03 Jun 2005 15:17:55 +0100, Custos Custodum
wrote:

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Why does it do that? is it the methanol or the pyridine ?

Possibly a combination of factors. The "rotting" could well be the solvent
drawing out some of the components of the rubber which would leave it
brittle. It may also be the case that the pyridine or methanol actually
chemically attacks the rubber which could certainly happen in the precense
of UV.

--

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On Mon, 06 Jun 2005 08:16:32 +0100, doozer
wrote:

another good reason to use propanol rather than meths.

Unfortunately I'm not cleaning with this stuff, I'm using it as a
solvent for shellac to finish furniture. Isopropanol behaves quite
differently to ethanol and isn't usable for French polishing.

According to Ron Jones :
David Peters wrote:
On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:
Chris Lewis wrote:
I don't know what the Grunff is referring to when he says
"meths". if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.

I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

IIRC wood naphtha = wood alcohol = methanol

Yeah. Methanol is one of the main ingredients of the gas given off when
you heat wood to high temperatures. Principle component that
causes the "flame" in burning wood. It used to be called wood alcohol,
because the primary source was charcoaling ovens - capture the gasses,
let it condense, and voila, wood alcohol.

[Naptha is an old fashioned name. Used because it approximates the
same thing as petrochemical naptha - which is pretty much a "heavy
gasoline". Wood alcohol produced by classic means isn't very pure.]

Books describe it as "destructive distillation of wood".

Nowadays, most of it is a petrochemical industry product, and much
purer.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

On Fri, 3 Jun 2005 23:39:26 +0100, "Mike" wrote:

Probably because it's a little less volatile and so doesn't evaporate before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.



That would be my guesstimate although I can't give a good explanation
why this should be so. I'm no chemist. It is only one carbon atom
higher and that shouldn't affect the evaporation that much. Home use
solvent alcohols are mainly ethyl alcohol because they are cheap to
manufacture from fermentation or from raw stock (CO, H2).

The adulteration by methyl alcohol is from historical times when wood
alcohol was used to make grain alcohol undrinkable. Grain alcohol was
too useful a solvent to use for just drinks alone. But drinks alcohol
was one of the few staples the lord could depend on for taxes (salt
and grain harvests being some of the others.) By adding wood alcohol
(from charcoal manufacturing distillates?) even the dumbest village
yokel knew that adulterated alcohol would make him blind, make him
lose his bodily functions or more likely kill him.

Wood alcohol in the test tube oxidizes into formaldehyde, then to
formic acid and finally CO2 and water. In the body oxidation stops
at formaldehyde the stuff used in biology class to preserve
specimens. Nerves being the most sensitive get "preserved" first,
thus blindness and ataxia. By the time there is enough to kill you
the result will be a well pre-preserved corpse. Ethyl alcohol on the
other hand oxidizes to acetaldehyde, acetic acid then to CO2 and
water.

On Mon, 06 Jun 2005 17:44:57 GMT, PaPaPeng wrote:

On Fri, 3 Jun 2005 23:39:26 +0100, "Mike" wrote:

Probably because it's a little less volatile and so doesn't evaporate before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.



That would be my guesstimate although I can't give a good explanation
why this should be so. I'm no chemist. It is only one carbon atom
higher and that shouldn't affect the evaporation that much. Home use
solvent alcohols are mainly ethyl alcohol because they are cheap to
manufacture from fermentation or from raw stock (CO, H2).

Its not just the molecular weight that changes and effects the
evaporatoin, especially in small chain alcohols. There are both
molecular shape factors and hydrogen bonding changes that also
influence the evaporation/heat capacity.

The adulteration by methyl alcohol is from historical times when wood
alcohol was used to make grain alcohol undrinkable. Grain alcohol was
too useful a solvent to use for just drinks alone. But drinks alcohol
was one of the few staples the lord could depend on for taxes (salt
and grain harvests being some of the others.) By adding wood alcohol
(from charcoal manufacturing distillates?) even the dumbest village
yokel knew that adulterated alcohol would make him blind, make him
lose his bodily functions or more likely kill him.

Wood alcohol in the test tube oxidizes into formaldehyde, then to
formic acid and finally CO2 and water. In the body oxidation stops
at formaldehyde the stuff used in biology class to preserve
specimens. Nerves being the most sensitive get "preserved" first,
thus blindness and ataxia. By the time there is enough to kill you
the result will be a well pre-preserved corpse. Ethyl alcohol on the
other hand oxidizes to acetaldehyde, acetic acid then to CO2 and
water.

Gary Dyrkacz

Radio Control Aircraft/Paintball Physics/Paintball for 40+
http://home.comcast.net/~dyrgcmn/

"Gary Dyrkacz" wrote in message
...
Probably because it's a little less volatile and so doesn't evaporate
before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.


That would be my guesstimate although I can't give a good explanation
why this should be so. I'm no chemist. It is only one carbon atom
higher and that shouldn't affect the evaporation that much. Home use
solvent alcohols are mainly ethyl alcohol because they are cheap to
manufacture from fermentation or from raw stock (CO, H2).

Its not just the molecular weight that changes and effects the
evaporatoin, especially in small chain alcohols. There are both
molecular shape factors and hydrogen bonding changes that also
influence the evaporation/heat capacity.

I believe that in most short chain hydrates in the liquid form (water,
methane, alcohols, etc) it is the weak hydrogen bonds between molecules that
affect the evaporation most. Water would be wholly gaseous at room
temperature/standard pressure without this.

Doug Miller wrote:
In article , David Peters wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?


Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot of
things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely to
dissolve plastic than a shorter one). I've also successfully used paint
thinner (mineral spirits) to clean various plastics without damage. And I've
not observed gasoline to be particularly harmful to plastics either. OTOH,
acetone (2-propanone) and MEK (2-butanone) are terribly destructive to many
common plastics. IOW, it ain't the length of the chain, but what's attached to
it, that does the damage.


Actually, what he stated is generally correct, but
ethanol and propanol are very close, so one would
probably never see any significant difference.

Of course, what you said is correct also, what is
on the end is important, but when comparing two
alcohols, the same thing is on the end.

As for plastics, oil has some fairly long chains
and it is sold in plastic bottles and oil/gas
mixtures certainly don't bother the oil bottle
plastics. And then of course, there are plastic
gas containers. It would be a pretty lousy
plastic that would be bothered by methanol,
ethanol, or propanol.

George E. Cawthon wrote:

Doug Miller wrote:

In article , David Peters
wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is more
likely than ethanol (with only two carbons and one hydroxyl) to
actually DISSOLVE some types of plastics which I am might be trying
to clean?



Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot
of things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely
to dissolve plastic than a shorter one). I've also successfully used
paint thinner (mineral spirits) to clean various plastics without
damage. And I've not observed gasoline to be particularly harmful to
plastics either. OTOH, acetone (2-propanone) and MEK (2-butanone) are
terribly destructive to many common plastics. IOW, it ain't the length
of the chain, but what's attached to it, that does the damage.


Actually, what he stated is generally correct, but ethanol and propanol
are very close, so one would probably never see any significant difference.

Of course, what you said is correct also, what is on the end is
important, but when comparing two alcohols, the same thing is on the end.

As for plastics, oil has some fairly long chains and it is sold in
plastic bottles and oil/gas mixtures certainly don't bother the oil
bottle plastics. And then of course, there are plastic gas containers.
It would be a pretty lousy plastic that would be bothered by methanol,
ethanol, or propanol.

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which plastic.

According to The Natural Philosopher :

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which plastic.

That's for sure. First, there are "polar" and "non-polar" solvents. Alcohols
are an example of the former (OH bond), and gasoline/kerosene etc are
an example of the latter. What they dissolve _tends_ to be fairly
mutually exclusive.

And of course, "curing type" plastics (ie: epoxy resin, polyethylene)
are immune to most solvents of either kind.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

George E. Cawthon wrote:
It would be a pretty lousy
plastic that would be bothered by methanol,
ethanol, or propanol.

Styrofoam cups seem to melt with booze in them.

--
I miss my .signature.

"Chris Lewis" wrote in message
...
According to The Natural Philosopher :

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which
plastic.

That's for sure. First, there are "polar" and "non-polar" solvents.
Alcohols
are an example of the former (OH bond), and gasoline/kerosene etc are
an example of the latter. What they dissolve _tends_ to be fairly
mutually exclusive.

And of course, "curing type" plastics (ie: epoxy resin, polyethylene)
are immune to most solvents of either kind.

Except that methanol will dissolve many epoxies. It is rather slow
though.....

William...

--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.