3 ms·

> I really don't like to see things like any sort of recommendation for use of n-propyl bromide. That shit's neurotoxic. I don't even like to see recommendatio

by bsder 2y ago

> I really don't like to see things like any sort of recommendation for use of n-propyl bromide. That shit's neurotoxic. I don't even like to see recommendations for IPA (isopropyl alcohol). In 95%+ of the cases ethanol (ethyl alcohol) is just as good and is way less toxic than IPA.

exmadscientist 2y ago
There are two problems with ethanol, one practical and one stupid. The stupid problem is that it's taxed heavily and thus is stupidly expensive. When not taxed it is probably denatured, but denatured with what? If you know the denaturant then you can use it with some degree of confidence. Methanol (methylated spirits) is acceptable in almost any technical application but is somewhat toxic, so for stupid reasons it is now rare. Denatonium benzoate is the other common denaturant, but it can leave annoying residues behind. Pick your poison (literally). At one point in my career we had ready access to untaxed, undenatured, 200-proof absolute ethanol. So I used it a lot! Turns out it's significantly more aggressive than isopropanol, and can strip coatings or generally even dissolve things that isopropanol cannot. I don't use ethanol any more, I have better things to do with my life than figure out what it is and isn't going to dissolve.
- qiqitori 2y ago
  I use 99.9% ethanol for electronics cleaning (not very frequently) and it leaves a white residue on some PCBs (e.g. JLCPCB ones?), but not all. It also seems more aggressive if I accidentally get it on my skin. Doesn't smell as bad as IPA though! I haven't heard that IPA is much worse than ethanol though, beyond what's stated on Wikipedia ("somewhat more toxic"; ethanol is obviously toxic as well). Should I be more concerned about using IPA?
  - alias_neo 2y ago
    > Should I be more concerned about using IPA? Not really. The entire planet was rubbing it on their hands for years during the pandemic. It'll dry your skin out, sure, if you're getting a lot of it on your skin, but you shouldn't be if you're not using it as hand sanitiser, and of course you're not drinking it.
    - kragen 2y ago
      Here in Argentina we never used isopropanol in our hand sanitizer, just ethanol. I suspect most other countries are the same.
  - exmadscientist 2y ago
    Personally I am not really concerned about any toxicity differences between ethanol and isopropanol. As the sibling comment says, they're both widely used in hand sanitizer. At the exposure levels present in electronics work, and compared to the other stuff that's going to be around, it doesn't seem worth worrying about to me. The white residue is a separate problem. Alcohols are not perfectly effective at dissolving all the components of flux residue, so you often get white crud left over. It's harmless, but ugly, and sometimes you just need a clean joint. I think it is possible to get this stuff off with alcohol and some skill, but who has time for that? Just buy proper flux remover. The best flux remover I know of is MicroCare SuprClean or PowerClean (they're very closely related, but definitely at least a little different; either way it's hard to tell them apart, so go for whatever's convenient). It is supposedly nontoxic (but remember they once said that about the last flux remover that got banned... and the one before that... and...), readily available from the usual places here in the US, and very, very powerful. Careful cleaning with it will not leave any white residue behind. (Careless cleaning will lead to the observation that flux remover solvents dissolve soils... which means the soils are right there to be redeposited should the solvents evaporate... so you have to actually manage to get the crud off the board if you want it clean. Dissolving alone is not enough!) I haven't done an exhaustive survey of flux removers, but this stuff certainly does the trick. I was originally looking for something that could dissolve Krytox residues (long story) and while I thankfully never had cause to test it, this stuff is based off some member of the Vertrel family, which is one of the few things in chemistry capable of that job. And anything that can even threaten Krytox is probably a tool worth having!
  - humanpotato 2y ago
    Occasionally I will "wash" dirty PCBs by spraying them with 50% ethanol, 50% water, then drying them with an air gun or the like to get the water off in a reasonable time. Nearly any properly designed board will not hold residual voltage for long when disconnected from power, so the slight conductivity of tap water is a non-issue.
jdietrich 2y ago
IPA is the main ingredient in many brands of hand sanitizer. I'm really not concerned about the risks involved with using a couple of millilitres of the stuff to remove some flux residue - I'd be more concerned about exposure to the flux.
thewanderer1983 2y ago
>I don't even like to see recommendations for IPA (isopropyl alcohol). Even worse, I've seen people recommend h2o. You can drown in that shit.
the__alchemist 2y ago
A: Getting ethanol is tricky. Lab Alley is the only supplier I've found that will sell it to individuals. Lab suppliers will sell if you have the right business paperwork in place, but will usually attach a huge hazardous shipping fee due to the flammabililty. You can get Isopronaol on Amazon. B: Isopropanol isn't that toxic. Much less so than methanol, for example.
- daniel_reetz 2y ago
  McMaster Carr now sells ethanol in large quantities.
  - the__alchemist 2y ago
    I just looked - only see denatured: https://www.mcmaster.com/products/ethanol/denatured-ethyl-alcohol-1~/ https://www.mcmaster.com/products/ethanol/denatured-ethyl-al...
- abeyer 2y ago
  You may pay more for it, but "culinary solvent" is what you want to buy if you are trying to get it as an individual. It's pure food grade ethanol. It's still tricky most places in the US -- you will likely have to jump through hoops to pay taxes and/or get the license to purchase, depending on your state's rules. I agree that IPA is not enough of a concern to actually justify it in my mind.
justin66 2y ago
Isopropyl alcohol... toxic?
sbierwagen 2y ago
Funny to see IPA called "toxic". In aircraft manufacturing it's considered the nice and friendly solvent in comparison to the stout stuff like MPK or MEK, and considerable effort is invested in convincing workers to use it when the big guns aren't needed. Or, natch, to get workers to wear gloves when working with solvents. (Much discourse on industrial safety casts corporations as the bad guys, with considerable evidence, but it is still the case that much safety equipment is bulky or unpleasant to use. Ketone-proof gloves are thicker and less pliable than latex gloves, which is no small consideration when doing fine work under time pressure. Easier to just wear two layers and change the outer glove when it starts to break down. When do you know it's breaking down? When you feel it leaking through. When you feel that, doesn't it mean you're already getting skin contact with the solvent. Well, yes, but....)
- kragen 2y ago
  MEK has the distinction of being the only material I know of that was simultaneously on both the FDA's "generally recognized as safe" food ingredients list and the EPA's "hazardous air pollutants" list, for which no safe emissions level is recognized. It did eventually get removed from the second. As far as I know, there has never been a fatality attributable to MEK exposure. https://en.wikipedia.org/wiki/Methyl_ethyl_ketone#Health_effects https://en.wikipedia.org/wiki/Methyl_ethyl_ketone#Health_eff...

by bsder 2y ago

exmadscientist 2y ago

There are two problems with ethanol, one practical and one stupid. The stupid problem is that it's taxed heavily and thus is stupidly expensive. When not taxed it is probably denatured, but denatured with what? If you know the denaturant then you can use it with some degree of confidence. Methanol (methylated spirits) is acceptable in almost any technical application but is somewhat toxic, so for stupid reasons it is now rare. Denatonium benzoate is the other common denaturant, but it can leave annoying residues behind. Pick your poison (literally). At one point in my career we had ready access to untaxed, undenatured, 200-proof absolute ethanol. So I used it a lot! Turns out it's significantly more aggressive than isopropanol, and can strip coatings or generally even dissolve things that isopropanol cannot. I don't use ethanol any more, I have better things to do with my life than figure out what it is and isn't going to dissolve.

qiqitori 2y ago
I use 99.9% ethanol for electronics cleaning (not very frequently) and it leaves a white residue on some PCBs (e.g. JLCPCB ones?), but not all. It also seems more aggressive if I accidentally get it on my skin. Doesn't smell as bad as IPA though! I haven't heard that IPA is much worse than ethanol though, beyond what's stated on Wikipedia ("somewhat more toxic"; ethanol is obviously toxic as well). Should I be more concerned about using IPA?
- alias_neo 2y ago
  > Should I be more concerned about using IPA? Not really. The entire planet was rubbing it on their hands for years during the pandemic. It'll dry your skin out, sure, if you're getting a lot of it on your skin, but you shouldn't be if you're not using it as hand sanitiser, and of course you're not drinking it.
  - kragen 2y ago
    Here in Argentina we never used isopropanol in our hand sanitizer, just ethanol. I suspect most other countries are the same.
- exmadscientist 2y ago
  Personally I am not really concerned about any toxicity differences between ethanol and isopropanol. As the sibling comment says, they're both widely used in hand sanitizer. At the exposure levels present in electronics work, and compared to the other stuff that's going to be around, it doesn't seem worth worrying about to me. The white residue is a separate problem. Alcohols are not perfectly effective at dissolving all the components of flux residue, so you often get white crud left over. It's harmless, but ugly, and sometimes you just need a clean joint. I think it is possible to get this stuff off with alcohol and some skill, but who has time for that? Just buy proper flux remover. The best flux remover I know of is MicroCare SuprClean or PowerClean (they're very closely related, but definitely at least a little different; either way it's hard to tell them apart, so go for whatever's convenient). It is supposedly nontoxic (but remember they once said that about the last flux remover that got banned... and the one before that... and...), readily available from the usual places here in the US, and very, very powerful. Careful cleaning with it will not leave any white residue behind. (Careless cleaning will lead to the observation that flux remover solvents dissolve soils... which means the soils are right there to be redeposited should the solvents evaporate... so you have to actually manage to get the crud off the board if you want it clean. Dissolving alone is not enough!) I haven't done an exhaustive survey of flux removers, but this stuff certainly does the trick. I was originally looking for something that could dissolve Krytox residues (long story) and while I thankfully never had cause to test it, this stuff is based off some member of the Vertrel family, which is one of the few things in chemistry capable of that job. And anything that can even threaten Krytox is probably a tool worth having!
- humanpotato 2y ago
  Occasionally I will "wash" dirty PCBs by spraying them with 50% ethanol, 50% water, then drying them with an air gun or the like to get the water off in a reasonable time. Nearly any properly designed board will not hold residual voltage for long when disconnected from power, so the slight conductivity of tap water is a non-issue.

jdietrich 2y ago

IPA is the main ingredient in many brands of hand sanitizer. I'm really not concerned about the risks involved with using a couple of millilitres of the stuff to remove some flux residue - I'd be more concerned about exposure to the flux.

thewanderer1983 2y ago

>I don't even like to see recommendations for IPA (isopropyl alcohol). Even worse, I've seen people recommend h2o. You can drown in that shit.

the__alchemist 2y ago

A: Getting ethanol is tricky. Lab Alley is the only supplier I've found that will sell it to individuals. Lab suppliers will sell if you have the right business paperwork in place, but will usually attach a huge hazardous shipping fee due to the flammabililty. You can get Isopronaol on Amazon. B: Isopropanol isn't that toxic. Much less so than methanol, for example.

daniel_reetz 2y ago
McMaster Carr now sells ethanol in large quantities.
- the__alchemist 2y ago
  I just looked - only see denatured: https://www.mcmaster.com/products/ethanol/denatured-ethyl-alcohol-1~/ https://www.mcmaster.com/products/ethanol/denatured-ethyl-al...
abeyer 2y ago
You may pay more for it, but "culinary solvent" is what you want to buy if you are trying to get it as an individual. It's pure food grade ethanol. It's still tricky most places in the US -- you will likely have to jump through hoops to pay taxes and/or get the license to purchase, depending on your state's rules. I agree that IPA is not enough of a concern to actually justify it in my mind.

justin66 2y ago

Isopropyl alcohol... toxic?

sbierwagen 2y ago

Funny to see IPA called "toxic". In aircraft manufacturing it's considered the nice and friendly solvent in comparison to the stout stuff like MPK or MEK, and considerable effort is invested in convincing workers to use it when the big guns aren't needed. Or, natch, to get workers to wear gloves when working with solvents. (Much discourse on industrial safety casts corporations as the bad guys, with considerable evidence, but it is still the case that much safety equipment is bulky or unpleasant to use. Ketone-proof gloves are thicker and less pliable than latex gloves, which is no small consideration when doing fine work under time pressure. Easier to just wear two layers and change the outer glove when it starts to break down. When do you know it's breaking down? When you feel it leaking through. When you feel that, doesn't it mean you're already getting skin contact with the solvent. Well, yes, but....)

kragen 2y ago
MEK has the distinction of being the only material I know of that was simultaneously on both the FDA's "generally recognized as safe" food ingredients list and the EPA's "hazardous air pollutants" list, for which no safe emissions level is recognized. It did eventually get removed from the second. As far as I know, there has never been a fatality attributable to MEK exposure. https://en.wikipedia.org/wiki/Methyl_ethyl_ketone#Health_effects https://en.wikipedia.org/wiki/Methyl_ethyl_ketone#Health_eff...