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| Isopropanol vs Ethanol for Flux cleaning |
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| danny_d:
Hey guys! So, I'm in need of purchasing new alcohol for flux cleaning, and I was wondering which one of the the above types would be best. I can get either Isopropanol or Ethanol (both 95%) for the same amount of money, however the Isopropanol bottle only comes in 100ml, and the Ethanol in 1 Liter. Even a 100ml would last me for quite a while, still, I'd prefer going with the Ethanol (unless it's considered unsafe for my intended purpose of course). In terms of safety (PCB plastic dissolving) and leaving residue, which one would be better? I've read somewhere that Ethanol often contains Methanol as well (which can be unsafe to some types of plastic, but whether that's relevant to PCB type plastic, or when the Methanol is in very small quantities I wasn't able to find an answer for) |
| Ian.M:
It depends what the Ethanol is denatured with. If its denatured with Bitrex (denatonium benzoate), that will leave behind an undesirable persistent ionic residue. If its denatured with other solvents and volatiles its probably acceptable (and it cant have more than 5% and still meet 95% purity spec,) Its unlikely to be un-denatured at the same price as Isopropanol as the tax on potable alcohol in most countries is prohibitively high for most technical uses. e.g. in the Netherlands, as of 2016, the duty on 1l of potable 95% Ethanol was 16 Euro, applied before other taxes. |
| ogden:
--- Quote from: Ian.M on December 10, 2017, 02:04:05 pm ---It depends what the Ethanol is denatured with. If its denatured with Bitrex (denatonium benzoate), that will leave behind an undesirable persistent ionic residue. If its denatured with other solvents and volatiles its probably acceptable (and it cant have more than 5% and still meet 95% purity spec,) --- End quote --- Right. Worst choice would be gambling with denaturated Ethanol. Anyway base of all PCB cleaning solutions is isopropanol which obviously shall be tried first. If do not like how it works, then get clean ethanol from chem store, mix isopropanol:ethanol 2:1. Thou Ethanol is more aggressive to some plastics than isopropanol. |
| danny_d:
Thanks guys, and yeah, it's denatured ethanol. However, after more searching, I've found a source of pure (medical grade) 95% ethanol (which is not denatured), this would be perfectly fine, correct? |
| janoc:
--- Quote from: danny_d on December 11, 2017, 11:26:45 pm ---Thanks guys, and yeah, it's denatured ethanol. However, after more searching, I've found a source of pure (medical grade) 95% ethanol (which is not denatured), this would be perfectly fine, correct? --- End quote --- Yes, but expensive overkill. Isopropanol is completely fine. Denatured ethanol is fine as well if you have one that doesn't leave a residue. I have encountered this only once. It is also a lot easier to obtain than isopropanol - any drugstore carries it, isopropanol not so much. Not impossible to find but you will likely need to order it online. |
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