Methylated spirit vs IPA

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Please educate me: why is it that some people 'believe' in IMS and others in IPA? What's the difference? When do you use one, when do you use the other?
Personally, I use IPA for everything, a friendly camera shop uses IMS only, but when I asked for an explanation all I got is a shocked stare. 

[Richard W.]

methylated spirit leaves a white residue, IPA doesn't.

[IanB]

They are different solvents with different dissolving properties. Methylated spirits is predominantly ethanol, whereas IPA is predominantly isopropyl alcohol. IPA is quite good at cleaning greasy marks, fingerprints, solder flux etc, from glass, circuit boards, tape heads and optics. It evaporates more slowly than meths. The IPA in my cleaning supplies is >99.9% pure and it should evaporate with no residue.

Pure anhydrous alcohol >99.9% would also be a clean solvent except you can't obtain it outside of a chemical laboratory and in any case it does not dissolve flux or grease very well. Methylated spirits is ethanol mixed with some methanol to make it poisonous, a bitter substance to make it undrinkable, and a purple dye to warn you what it is. It should be a fairly clean solvent but the dye and bitter substance could be left behind as a residue when it evaporates.

In the USA methylated spirits is rarely found. What you find instead is denatured alcohol, which is ethanol mixed with some gasoline and other adulterants to make it undrinkable. I really wouldn't want to use this as a high purity solvent, but in any case it doesn't dissolve solder flux so it's of little use for cleaning circuit boards.

For optics, methanol is often chosen as a cleaning fluid. This you may find from an optics supplier like a camera shop or a telescope shop. However methanol is poisonous so it should be used with care. Wear rubber gloves, use it in a ventilated area, don't get it on your skin and don't breathe the fumes. If you get 99.9% pure methanol it is a very clean solvent that will leave behind no residue at all and will evaporate quickly.

[RCMR]

For optics, methanol is often chosen as a solvent. This you may find from an optics supplier like a camera shop or a telescope shop. However methanol is very poisonous so it should be used with great care. Wear rubber gloves, use it in a ventilated area, don't get it on your skin and don't breathe the fumes. If you get 99.9% pure methanol it is a very clean solvent that will leave behind no residue at all and will evaporate quickly.

Don't tell this to the millions of RC model fliers who regularly find themselves bathed in methanol.

It is true that methanol is highly toxic but you've somewhat overstated the dangers.

The skin provides a good barrier against absorption and the fumes are more dangerous due to their wide stoichiometric ratio than because of any toxic effect on the body -- at least in the concentration levels you're likely to find when using a small bottle of the stuff in a room larger than your toilet.

[Kiriakos-GR]

Wow nice descriptions IanB 

In Greece we have isopropyl alcohol but is extremely expensive but very high quality.

The lesser expensive alcohol ( for general use )  it is painted blue, and it is alcohol mixed with water.

About cleaning lens I got one cleaning kit from Carl Zeiss,
it has a bottle with some fluid, but it does not evaporate that fast.
The set includes 10 moistened wipes, those does miracles,
but they are for one use only.   

https://photo-shop.zeiss.com/epages/cz.sf/en_GB/?ObjectPath=/Shops/CZ/Products/1216-071

[IanB]

Don't tell this to the millions of RC model fliers who regularly find themselves bathed in methanol.

It is true that methanol is highly toxic but you've somewhat overstated the dangers.

The skin provides a good barrier against absorption and the fumes are more dangerous due to their wide stoichiometric ratio than because of any toxic effect on the body -- at least in the concentration levels you're likely to find when using a small bottle of the stuff in a room larger than your toilet.

It never hurts to emphasize the dangers of something. On matters of fact I need to point out to you that skin is not a barrier to methanol absorption and this is one of the primary ways methanol can enter the body. Also note there are many toxic effects of methanol short of death to be wary of. Just because you haven't died doesn't mean you are not in danger of injury.

Honestly, splashing methanol over your skin with wild abandon is foolish. It's a risk you really don't need to take.

See, for instance: http://avogadro.chem.iastate.edu/MSDS/methanol.htm

[AntiProtonBoy]

I'm a fan of Acetone.  It has a much higher vapour pressure, so it vapourises quicker. And they are great for removing toner.

[IanB]

The trouble with acetone is it removes anything and everything. Often it will remove parts of the thing you are trying to clean. Acetone is the mutually assured destruction of cleaning solvents...nothing useful may be left after you use it.

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Thank you all for the explanations (IanB, you're my hero ).
I'll stick with my trusty IPA from now on.

[vk6zgo]

The "white residue" problem with Methylated Spirits tends to be overstated by many people,as a lot of the residue you see on PCBs is simply dissolved flux.

In the case of repaired PCBs,any residue does a lot less harm than the crud commonly found on the boards due to their operating environment.

"Metho" in Australia does not contain dye,& the amount of Methanol included is quite small,to the point that the only health warning on the label is "Do not drink".

Many commonly used domestic cleaners are much nastier,as is Unleaded Petrol (Gasoline).

In earlier times,we used such delightful substances as Carbon Tetrachloride! 

VK6ZGO

[AntiProtonBoy]

The trouble with acetone is it removes anything and everything. Often it will remove parts of the thing you are trying to clean. Acetone is the mutually assured destruction of cleaning solvents...nothing useful may be left after you use it.

And that's why it's awesome... but yeah, choose your surface carefully.

"Metho" in Australia does not contain dye,& the amount of Methanol included is quite small,to the point that the only health warning on the label is "Do not drink".

They are not too bad, the one I got from Bunnings is 95% pure.

[alm]

The trouble with acetone is it removes anything and everything. Often it will remove parts of the thing you are trying to clean. Acetone is the mutually assured destruction of cleaning solvents...nothing useful may be left after you use it.

It doesn't remove everything, but it dissolves many kinds of plastics. I used once it to clean some glue from a calculator. The glue was gone, but it also damaged the plastic case, so the end result was just as ugly. Metals, ceramics, glass and some types of plastics are just fine. In optics, some filters and mirrors are also cleaned with acetone, although you should check with the manufacturer whether the coating will tolerate it.

[vk6zgo]

The trouble with acetone is it removes anything and everything. Often it will remove parts of the thing you are trying to clean. Acetone is the mutually assured destruction of cleaning solvents...nothing useful may be left after you use it.

And that's why it's awesome... but yeah, choose your surface carefully.

"Metho" in Australia does not contain dye,& the amount of Methanol included is quite small,to the point that the only health warning on the label is "Do not drink".

They are not too bad, the one I got from Bunnings is 95% pure.

Yeah! that's where I got mine!

Nail polish remover is mostly acetone.

At my last work we had a big switchmode power supply blow up,& before we could replace the PCB we had to remove a lot of brown "scunge"from it.
We tried everything to no avail,so eventually I brought some of my wife's Nail polish remover to work.
A couple of drops on a rag,& the disgusting mess was gone.

It is also good for removing Polymer fallout from car windscreens---but be careful!

VK6ZGO

[FreeThinker]

The "white residue" problem with Methylated Spirits tends to be overstated by many people,as a lot of the residue you see on PCBs is simply dissolved flux.



In earlier times,we used such delightful substances as Carbon Tetrachloride! 

VK6ZGO

Whoa! Carbon Tet, I can still smell it now. We used to use it as a general degreaser for motors etc.  in the maintenance workshop and had degreasing pots in the heat treat department which were 5 to 6 metres deep, 1.5 metres diameter with heater coils in the bottom covered by 50 or so gallons of Carbon Tet. When heated you could see a white mist in the bottom of the tank as the vapour re condensed. Really healthy!!

[Mechatrommer]

However methanol is very poisonous so it should be used with great care. Wear rubber gloves, use it in a ventilated area, don't get it on your skin and don't breathe the fumes.

again, your teacher taught you well. the sound makes it the same class as viper sting. recommends youngs to stay at home. "dont open the unit, no user repairable inside". i bathed with spirit, thinner (what is thinner constitutes anyway?), and sometime... fiberglass resin.

[Gall]

In fact, methanol DOES absorb through the skin. It is unlikely to get poisoned by an occasional splash, just do not put your hands intentionally into methanol bath.

Methanol is not so toxic as some other organic solvents as long as it isn't ingested. The only thing that's really dangerous is that methanol's toxic effects are delayed (several hours after exposure) and can be permanent. So there's a chance to get poisoned without noticing it until it's too late.

A good antidote is ethanol. If you suspect you're in danger of methanol poisonong - just go to the bar and get drunk!

[Zero999]

Methylated spirit doesn't contain a massive concentration of methanol and is certainly not enough to cause poisoning by occasional skin contact. It's a good idea to wear gloves when using methylated sprint because it dissolves natural skin oils which can cause dermatitis, like any harsh organic solvent. It's a good idea to be in a well ventilated area whilst using methylated spirit because it smells horrible and can cause headaches, just like most other organic solvents.

I'm not saying you should wear thick rubber gloves and only use methylated spirit in a fume cupboard, just don't use it in confined spaces, keep the windows open (if possible and practical) and avoid getting it on your skin.

[IanB]

I'm not saying you should wear thick rubber gloves and only use methylated spirit in a fume cupboard, just don't use it in confined spaces, keep the windows open (if possible and practical) and avoid getting it on your skin.

No one is saying methylated spirit is particularly toxic (unless you drink it), but pure methanol as mentioned above is a different story. Pure methanol certainly merits caution in handling. It may not be "very" poisonous, but you certainly shouldn't splash it around like cologne.

Incidentally a danger not mentioned yet with both methylated spirits and methanol is flame and sources of ignition. Alcohol fumes will ignite quite readily and when alcohol does burn the flame can be almost invisible and therefore not noticed. People have been injured by pouring alcohol on or near a flame causing a big fireball, especially when topping up an alcohol burner that is still alight.

[Mechatrommer]

It's a good idea to be in a well ventilated area whilst using methylated spirit because it smells horrible and can cause headaches, just like most other organic solvents.

well tonight i just bought 1 new bottle with big "spirit" written on it. got no smell! , but evaporates quickly and i know its darn flammable. maybe an immitation or only contain <1% methanol?

[IanB]

well tonight i just bought 1 new bottle with big "spirit" written on it. got no smell! , but evaporates quickly and i know its darn flammable. maybe an immitation or only contain <1% methanol?

"spirit" is not sufficient to say what it is. It must surely say on the label at the back what the bottle contains?

Note that methylated spirits is alcohol and smells like, well, alcohol. If you don't know what alcohol smells like, open a bottle of vodka and have a sniff.

It is possible that what you have is this: http://en.wikipedia.org/wiki/Mineral_spirits

That stuff is a good cleaner and degreaser, but it might damage plastic parts or painted surfaces.

[Zero999]

Methylated spirits have a more bitter, altogether more noxious smell than vodka which could be due to the addition of methanol or possibly other chemicals to put people off drinking it.

[Mechatrommer]

no label on content at the back. i guess it read as "elcheapo". something that can damage plastic, painted surface, or permanent marker, i call it as "thinner", and it smells like you keep your urine for one week in a bottle and smell it. not exactly, but some element of smell is similar. i guess what i've used so far is consumer grade (diluted) spirit.

[Mechatrommer]

ok ok i got the content for "my thinner" toluene 60%, ketone 20%, other solvent 20%. this is the best pcb/flux cleaner i have so far from local, but it still leave slight residue, waterish like that difficult to evaporate, i need to use a blower to get rid of it. maybe i'm talking different vocabulary here, but hey its not my fault, its the manufacturer wrote on it.

[IanB]

ok ok i got the content for "my thinner" toluene 60%, ketone 20%, other solvent 20%

Perfect, what you have there is general purpose degreasing solvent. You might use it for cleaning bicycle chains, car engine parts, paint brushes, stuff like that. I wouldn't recommend it for circuit boards but you could use it if it is all you have.

[Mechatrommer]

why is it that some people 'believe' in IMS and others in IPA?

ok ok maybe i forgot the intro. IMS is "Methylated spirit" what is "I"? IPA, well, from wiki its...

International Phonetic Alphabet
International Phonetic Association
India Pale Ale
International Police Association

i dont think those fit the discussion here?