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Isopropanol vs Ethanol for Flux cleaning

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langwadt:

--- Quote from: Nusa on December 12, 2017, 11:51:05 am ---
--- Quote from: langwadt on December 12, 2017, 10:31:54 am ---
--- 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,)

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.

--- End quote ---

there's an EU standard for denatured alcohol:

100 L of absolute ethanol: 3 litres of isopropyl alcohol, 3 litres of methyl ethyl ketone and 1 gram denatonium benzoate.
 
does that minute amount of denatonium benzoate really matter?

--- End quote ---

Yes. Denatonium benzoate isn't considered toxic, but it's called the most bitter substance known to man. Even that low dose is detectable and highly objectionable to most humans. It's added to all sorts of poisonous products to discourage ingestion. There are even nail polish products designed to stop nail-biting or thumb-sucking.

--- End quote ---

I know it is enough that no one want to drink it, but when used for cleaning is it really enough to leave a residue that makes a difference?

JacquesBBB:
You can find isopropanol from reputable source at low price on amazon.

https://www.amazon.fr/ISOPROPANOL-alcool-isopropylique-99-9/dp/B01HJOCKEI/ref=sr_1_5?s=hpc&ie=UTF8&qid=1513151772&sr=1-5&keywords=Isopropanol

https://www.amazon.fr/H%C3%B6fer-Chemie-GmbH-6-l-disopropanol/dp/B005J4B4LG/ref=pd_sbs_328_1?_encoding=UTF8&psc=1&refRID=EMFSZ3M9DRHHWK0B8QEJ

IanMacdonald:
Isopropanol is probably the better choice for PCBs but be aware that it causes rubber to swell up so keep it off grommets or the like.

TheUnnamedNewbie:
Depending on the flux I've found that ethanol doesn't do all that well in regards to cleaning things. Isopropyl works better (I actually like to use disinfecting swabs, I can get 100 or such for a few euros, and use cotton swabs to clean up after wetting the board with the swab).

janoc:

--- Quote from: TheUnnamedNewbie on December 13, 2017, 11:42:58 am ---Depending on the flux I've found that ethanol doesn't do all that well in regards to cleaning things. Isopropyl works better (I actually like to use disinfecting swabs, I can get 100 or such for a few euros, and use cotton swabs to clean up after wetting the board with the swab).

--- End quote ---

Yep, ethanol tends to leave a white residue if cleaning some gel and rosin-based fluxes and you don't use enough of it to wash it off. IPA doesn't do that. However, for normal water-based fluxes it is not a problem.

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