Re: gEDA-user: Isopropyl alcohol vs. ethanol

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Mon, Apr 24, 2006 at 01:13:43AM +0200, Bill Sloman wrote:
> At 23:54 23-4-2006, you wrote:
> >On 4/23/06, Karel Kulhavy <clock@xxxxxxxxxxxxx> wrote:
> 
> >> >Is it true that PCB's should be washed by isopropyl alcohol and 
> >not > ethanol because ethanol has small molecules that creep into 
> >the part > cases and wreak havoc >>there?
> 
> 
> 
> >>I've never personally heard this, but it is feasible I suppose. 
> >Ethanol is only C2H3OH, which is a much smaller molecule than isopropanol.
> 
> Ethanol is CH3.CH2.OH . Iso-propanol  is CH3.CH(OH).CH3, which is one 
> CH3 group larger - not a vast difference. Both are much larger than 
> water  - HOH - and nobody seems to worry about water creeping into 
> the parts, or a least not since they perfect the plastic package some 
> thirty-odd years ago.
> 
> Iso-propanol is a less polar solvent than ethanol, and more effective 
> at dissolving grease and oil, and it is somewhat less volatile, which 
> means you can wipe it off the surface you are cleaning before it evaporates.
> 
> >>In California supermarkets, isopropanol is vastly more popular (in 
> >fact, you cannot even purchase a bottle of ethanol at most 
> >supermarkets; the closest you get is >Vodka), so I honestly cannot 
> >remember a time when I actually possessed a bottle of actual ethanol.
> 
> 
> >>> Is it OK to use denaturated ethanol (burning spirit) to clean PCB's?
> 
> > Probably not, because the "denatured" part simply means infused 
> with *methanol*, which is an even smaller molecule yet.  BTW, 
> methanol is used specifically because > it acts as a poison, thus 
> hoping to deter would-be drunkies from ingesting otherwise 200-proof 
> alcohol.
> 
> Denatured alcohol is mostly ethanol, plus additives that make it 
> unpleasant to drink. In England it is called "methylated spirits" but 
> methanol is rarely used these days - see 
> http://en.wikipedia.org/wiki/Methylated_spirits
> 
> >>What's maximum safe time to leave a PCB inside the bath?
> 
> >I always spot-wash individual solder joints.  I personally never 
> bathe a whole PCB.
> 
> Me too - more because you seem to need to scrub the surface to get 
> rid of the excess flux
> 
> >> Is it allowed to pour isopropyl alcohol into the sink? Is the 
> same allowed with denatured ethanol?
> 
> >It depends on your locality, of course, but in the US, it is legal. 
> Both are not only biodegradable, but also evaporate quickly (contrary 
> to popular belief, ethanol [at least] >dissolves water, not the other 
> way around, so after it evaporates, all that's left is water). You 
> *probably* don't want to make a habit of it though, as I'm unaware of 
> any long->term environmental effects.  What follows is 100% pure 
> hypothesis. Alcohol vapors in the sewer system may allow easier 
> ignition of the methane gas (it's like adding fuel >additive to 
> petrol), thus somewhat increasing the hazard of explosion.  If vapors 
> come into regular contact with PVC or other plastic pipes, it may 
> also contribute to their >dissolving, thus prematurely aging the 
> pipe, or causing leaks. -- Samuel A. Falvo II

If I drink half liter of Vodka and then puke into the toilet, the
result is basically almost like pouring methylated spirit there, isn't?

Looks like I'll use meth spirit because (heh meth spirit that's like
double meaning - a spirit for meths ;-) ) it's cheaper and they have
it every grocery :)

CL<
> 
> Small quantities of ethanol and iso-propanol aren't going to damage 
> the sewers or the sewage treatment plants - there is going to be 
> ethanol and iso-propanol in waste water from time to time from 
> natural fermentation. Nobody working on an industrial scale could get 
> away with flushing either solvent into the sewers, nor should they, 
> but hobbyists don't work with big enough volumes of solvent to 
> produce detectable levels of contamination.
> 
> -- 
> Bill Sloman, Nijmegen
> 
>