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Cheapest way to make up to 99% pure isopropanol

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tooki:
By the way, this article from HP (copied from one of several recent flux cleaning threads) says on p.11 that the optimal concentration of IPA for flux removal is 80%, because some of the activators in flux are soluble in water, but not alcohol, and so ~100% solvent will not produce optimal cleaning. As such, this entire exercise in raising the concentration is likely completely in vain.

http://hparchive.com/Bench_Briefs/HP-Bench-Briefs-1982-07-10.pdf

magic:
It could probably be distilled without a trace of salt but why bother when 99% is available off the shelf.


--- Quote from: tooki on July 04, 2019, 02:53:37 pm ---By the way, this article from HP (copied from one of several recent flux cleaning threads) says on p.11 that the optimal concentration of IPA for flux removal is 80%, because some of the activators in flux are soluble in water, but not alcohol, and so ~100% solvent will not produce optimal cleaning. As such, this entire exercise in raising the concentration is likely completely in vain.

http://hparchive.com/Bench_Briefs/HP-Bench-Briefs-1982-07-10.pdf

--- End quote ---
Good to know. Cleaning rosin flux with pure IPA always leaves a bit of white residue. I'll try with some deionized water added next time.

Ian.M:

--- Quote from: magic on July 04, 2019, 05:23:21 pm ---
--- Quote from: tooki on July 04, 2019, 02:53:37 pm ---By the way, this article from HP (copied from one of several recent flux cleaning threads) says on p.11 that the optimal concentration of IPA for flux removal is 80%, because some of the activators in flux are soluble in water, but not alcohol, and so ~100% solvent will not produce optimal cleaning. As such, this entire exercise in raising the concentration is likely completely in vain.

http://hparchive.com/Bench_Briefs/HP-Bench-Briefs-1982-07-10.pdf

--- End quote ---
Good to know. Cleaning rosin flux with pure IPA always leaves a bit of white residue. I'll try with some deionized water added next time.

--- End quote ---
In the other recent IPA topic: https://www.eevblog.com/forum/projects/drying-ipa-with-silica-gel-will-this-work/msg2522505/#msg2522505
I posted a link to an IPA concentration vs density (specific gravity) table.    80% IPA by volume would be a density of 0.85 g/ml @20 deg C.   Due to IPA's tendency to adsorb atmospheric moisture, if your stock bottle is getting low, or you suspect it has been poorly sealed, I would strongly recommend weighing a known volume to check its density *before* dilution.

Brumby:
To date, I've been getting the 2 litre IPA from Altronics which costs $26.95 and I have to drive more than half an hour to get it or pay for shipping.  I've never been able to work out what % it is, but it seems to work OK for me.

What I have recently found is a supplier in Sydney who offers 5 litres of 100%, 99% or 70% IPA delivered to my door the next day for $29.50 - or I can go for a 25 minute drive and pick it up (for the same price).  They also have other sizes including a 200 litre drum of 100% (but that's a bit much for me to handle).

I haven't ordered any, so I don't know if there are any hoops to jump through, but I'm not expecting anything too onerous if there are.

westfw:

--- Quote ---
--- Quote ---I don't know why.
--- End quote ---
Because 70% is the concentration for optimal effectiveness
--- End quote ---
I meant "why Isopropyl in the US and Ethanol elsewhere."

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