Cheapest way to make up to 99% pure isopropanol - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: June 28, 2019, 02:45:21 am
content: Normally buying isoprop. there is a rip off because its 50%, too low to be usp and won't disinfect things, and too watery to act as a good solvent. But 50% in a large botles fits their margins. Also the cheapest source even though 50% is water. Buy a bunch of bottles. Next you turn it into 99% by adding a large amount of salt until you see two cm thick layer on the bottom. Shake vigously. settle, an aquous layer will form, decant.this is making the aqueous fraction super saturated. Once it's super saturated it will pull the water in all the way out of the prop. up to 99%. The fractions will separate like oil and water. You can add more salt to be sure but dont have to. Add molecular seives or another drying agent like Ca salts, and you have a very easy way to get to complete dryness, with no heat or still. Although compleate dryness is not neccisarry for most things. All for 1/2 the price of buying 91%. You can make the 99% down into 70% for cuts and first aide, or 85% for a good universal solvent/ cleaner/ screen cleaner. Just keep the bottles capped tight as water/humidity will get to them or leave on molecular seives. You could do this with other alcohols too.

author: JackJones
author_rank: Regular Contributor
timestamp: June 28, 2019, 04:41:33 am
content: Gasoline de-icers are usually isopropanol. Some of them do have additives in them so you have to check that. The one I use is pure isopropanol with nothing added. 4€/L, can't really beat that.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 28, 2019, 06:13:46 am
content: 1 L of 99.85% IPA is €6.15 at the cleaning specialist. And it's not even a product that can be sold freely. (something drugs related)It must have better availability in countries that don't restrict the substance, right?

author: ogden
author_rank: Super Contributor
timestamp: June 28, 2019, 06:14:13 am
content: Worst thing for cleaning electronics and screens is IPA contaminated with saltwater.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: June 28, 2019, 08:17:32 am
content: Thanks BeaminI find it expensive to get hi quality IPA locally.Sent using iPhone

author: mariush
author_rank: Super Contributor
timestamp: June 28, 2019, 09:17:21 am
content: Go to a veterinarian, they'll have 90% and higher alcohol. Another option that's often available is the 70% variety.See for examplehttps://pipevet.com/alcohol-isopropyl-99-galIn Australia, (random Google search) ... here's 5L 99% for 30$ :https://www.sydneysolvents.com.au/isopropyl-alcohol-ipa-isopropanol-99-5-litre20 liters for 80$ (and other quantities):https://www.sydneysolvents.com.au/?rf=kw&kw=IsoPropyl+Alcohol+

author: Zero999
author_rank: Super Contributor
timestamp: June 28, 2019, 09:40:40 am
content: You don't want pure isopropanol. Some water is a good thing because it dissolves some salts, which alcohol can't. I don't know what percentage of water is best, but 50% seems reasonable.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 28, 2019, 09:49:33 am
content: Quote from: Zero999 on June 28, 2019, 09:40:40 amThis is why flux cleaners are not one solvent.

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 28, 2019, 11:00:01 am
content: Quote from: Zero999 on June 28, 2019, 09:40:40 amHmm, as individual solvents this is true, but when you add water to IPA all you've really done is make it a worse solvent for both organic substances and salts. If you want to cover all your ionic bases [rimshot!] then it's best to wash first with deionized (not distilled) water then with 99% IPA. The water removes the salts and the 99% IPA removes both the water and any organic residues. Drying over 4a molecular sieves is actually good practice routinely used in clean rooms, fabs or if you live in Florida, where just leaving your bottle of 99% IPA open for a few minutes will suck up enough water to take it to the 91% azeotrope.

author: GreyWoolfe
author_rank: Unknown
timestamp: June 28, 2019, 11:42:19 am
content: If you want a little water in you IPA, CVS sells 91% IPA for just a couple of bucks a bottle. I keep that and the MG Chemicals 99.9%. I can't be bothered to try to make my own. However, thanks for posting that.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: June 28, 2019, 12:13:20 pm
content: Yeah I use around 10% distilled water added to IPA for PCB wash. It’s just doesn’t dry or wash properly with straight IPA. But I’d rather be adding to than buying diluted

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 28, 2019, 09:54:38 pm
content: Whats the white residue leftover on PCBs after I use mine which is from a drug store and probably %70 or so ?

author: Shock
author_rank: Super Contributor
timestamp: June 28, 2019, 10:16:57 pm
content: Quote from: lordvader88 on June 28, 2019, 09:54:38 pmThe salt that Beamin added.

author: Ian.M
author_rank: Super Contributor
timestamp: June 29, 2019, 12:04:43 am
content: Easy enough to check for. Evaporate a ml or so to dryness on a watch glass, then, if there is significant residue, do a flame test on the residue. Sodium yellow in a flame test is *SO* obvious - you don't need a fancy platinum wire and high purity hydrochloric acid to clean it - a piece of Nichrome wire cleaned in the flame is plenty good enough.However the white residue on the board is quite likely to be ionic compounds from the flux, and in that case, you'll have next to nothing on the watch glass to test.Properly preparing pure dry alcohols is not a good 'kitchen sink' chemistry project - without the correct apparatus with well-fitted joints there's too much risk of fire or explosion and a high probability you'll re-contaminate your product, so if you do have salt (or other sodium compounds) in your IPA change suppliers!

author: Electro Detective
author_rank: Super Contributor
timestamp: June 29, 2019, 12:11:08 am
content: I sort of gave up on that stuff, due to the sometimes 'mystery residue' milky stain thing, which members here state is saltand the sometimes longish drying times.My current fav is non residue electronic contact spray cleaner, either directly sprayed on, or into a container for use with Q-tips, brushes etc.I buy any decent stuff that's apparently 'safe to use on -most- plastics' in bulk or on sale.It gets the job done and obliterates gunk, oils and flux etc, dries super fast, and no residue afaictI use it before and after a large intermittent PCB soldering adventure (prep and post clean) and have had no comebacks or issues ever.I use it sparingly/wisely because it ain't cheapbut won't be going back to salty watered down suss isohol any time soon

author: Beamin
author_rank: Super Contributor
timestamp: July 02, 2019, 10:46:38 pm
content: My point was here in the US we have "dollar stores" that sell big bottles of 50% IPA which is useless but cheap: 50% doesn't disinfect 70% is best for germs, and 91 is better for cleaning but if you need drier you can use the salt method.If you decant right and throw away a little product because its so cheap the salt residue is almost non existent as nacl isn't really soluble in isoprl.

author: ogden
author_rank: Super Contributor
timestamp: July 03, 2019, 12:50:46 am
content: Quote from: Beamin on July 02, 2019, 10:46:38 pmEven if you get unrealistic 99% IPA in result, remaining 1% of impurities is exactly that: nacl solution in water. I would not say it is "almost non existent". Sure you can use such for disinfection, but you better do not use it for cleaning electronics of optics/screens.

author: Nerull
author_rank: Frequent Contributor
timestamp: July 03, 2019, 01:10:09 am
content: Quote from: Beamin on July 02, 2019, 10:46:38 pmQuoteIn general if you're depending on effective sterilization you shouldn't be using alcohol. Multiple outbreaks of bloodstream infections have been attributed to use of alcohol as a disinfectant.

author: radiolistener
author_rank: Super Contributor
timestamp: July 03, 2019, 01:24:52 am
content: Buying 99% ethanol also is restricted, because it can be used to produce alcohol which needs license and certificates.But I found that some medical liquids actually consists clean ethanol (it consists of 95.2% C2H6O and the rest is water). These liquids have strange and different names. But actually this is clean ethanolSo, I'm buy it to clean pcb from flux

author: mariush
author_rank: Super Contributor
timestamp: July 03, 2019, 03:05:32 pm
content: Here, a common "sanitary alcohol" is 70% ethanol . The rest is water,Sodium salicylateandmethylene blue, to make the alcohol unusable for drinks.Still some of the very poor people use bread or other techniques to filter the alcohol and drink it.It's about 1$ for 0.5 liter... regular 90% or better IPA can be bought for less.

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 03, 2019, 03:09:20 pm
content: A cheap source of clean ethanol (96-97%) is bioethanol fuel for lamps.

author: ov_darkness
author_rank: Contributor
timestamp: July 03, 2019, 03:45:29 pm
content: I pay about 7.5EUR for 5 liters of 99% IPA. For sth like 12EUR I can buy analytical grade one.

author: VE2UM
author_rank: Contributor
timestamp: July 03, 2019, 04:24:59 pm
content: IPA = India Pale Ale?Sorry, it's hot here today.... Couldn't resist !!!!

author: westfw
author_rank: Super Contributor
timestamp: July 03, 2019, 11:54:15 pm
content: The geographical dependencies are ... interesting.QuoteIn the US, the standard seems to be 70% IPA. I don't know why.QuoteI've never seen 50% isopropyl for sale. The common stuff is 70% ("Rubbing Alcohol"), which sometimes goes on sale for about $1/16oz.QuoteReally? I though whiskey was moderately effective as a disinfectant (at 80 proof or 40%)QuoteBe careful; in the US, many de-icers are methanol, which is substantially more toxic that IPA.QuoteI've heard that. But it's also available at the local grocery store. I was behind a woman who was buying 4+ bottles once. She mentioned to the cashier that she worked at a Stanford Bio lab, and it was less of a hassle to get at the grocery than it was to order from their technical suppliers...

author: tooki
author_rank: Super Contributor
timestamp: July 04, 2019, 02:46:18 pm
content: Quote from: westfw on July 03, 2019, 11:54:15 pmBecause 70% is the concentration for optimal effectiveness as a disinfectant. Above this, the alcohol actually coagulates the cell walls of bacteria instead of dissolving them, causingreduceddisinfecting action.Additionally, the water slows down evaporation, which can be useful in disinfecting to make sure there's enough time to dissolve the germs. (Whereas in technical applications, this can be a distinct disadvantage.)

author: tooki
author_rank: Super Contributor
timestamp: July 04, 2019, 02:53:37 pm
content: 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

author: magic
author_rank: Super Contributor
timestamp: July 04, 2019, 05:23:21 pm
content: 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 pmGood 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.

author: Ian.M
author_rank: Super Contributor
timestamp: July 04, 2019, 05:56:39 pm
content: Quote from: magic on July 04, 2019, 05:23:21 pmIn the other recent IPA topic:https://www.eevblog.com/forum/projects/drying-ipa-with-silica-gel-will-this-work/msg2522505/#msg2522505I 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.

author: Brumby
author_rank: Unknown
timestamp: July 05, 2019, 01:27:10 am
content: 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 Ihaverecently 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.

author: westfw
author_rank: Super Contributor
timestamp: July 05, 2019, 07:14:13 am
content: QuoteI meant "why Isopropyl in the US and Ethanol elsewhere."

author: tooki
author_rank: Super Contributor
timestamp: July 05, 2019, 08:50:56 am
content: Oh, gotcha. Probably because it's legally so much easier to deal with, since it's not drinkable.That said, here in Switzerland, for example, both seem to get used (medically) about equally often (purely by my own observation, no hard stats).What I have discovered, for cleaning purposes, is that high-proof ethanol is available at the grocery store, sold as fondue pot fuel, which is very cheap, and whatever it's denatured with is not Bitrex, which can't be allowed anywhere near food for obvious reasons. It does leave some residue when dry, so it's not ideal as a final rinse, but it works eminently well enough for the bulk. (So I just use technical IPA or bona fide flux remover for that.)

author: vealmike
author_rank: Regular Contributor
timestamp: July 08, 2019, 12:39:15 pm
content: Ah, now I understand the whole Tequila thing. Well, OK 2/3rds of it. What does the lime wedge do?

author: fixit7
author_rank: Regular Contributor
timestamp: July 08, 2019, 01:20:04 pm
content: Quote from: Beamin on June 28, 2019, 02:45:21 amAs an experienced chemist, I can offer you some tips on IPA.Your post is not clear about what you are looking for.I can tell you that 91% IPA is an excellent disinfectant.The reason is behind the mode of action of 70% IPA. Bacterial cells have proteins in their cell wall and when this protein comes in contact with the 70% IPA during disinfectant application, coagulation of proteins takes places in which denaturation of proteins occurred and after that IPA penetrate in the interior of the cell which cause lysis or death of the cell. Protein coagulation also happens in case of 100% IPA but with very fast rate and because of this very fast protein coagulation process denatured protein forms protective layer out side of the cell. When this happens, 100% can not penetrate inside the cell and not able to kill the microbe. Microorganisms become dormant in that conditions. In case of 70% IPA protein coagulation takes place with a slow rate and due to this 70% IPA get enough time to penetrate in the cell and kill the microorganism. Another factor is contact time, 70% IPA takes longer time to evaporate from any surface hence get enough contact time and in this mean time it show its efficacy but in case of 100% IPA, evaporation will be very fast, contact time will be less and it will not be so effective against microbes. That's why 70% IPA solution is used as disinfectant in pharmaceuticals industries.Good luck in your quest.

author: Beamin
author_rank: Super Contributor
timestamp: July 08, 2019, 04:22:49 pm
content: Quote from: VE2UM on July 03, 2019, 04:24:59 pmI always think that. Harpoon IPA out of new England is the best for cleaning off flux so is their hefeweizen UFO "unfiltered offering" is the best bear ever.I guess this varies wildly depending on the way your country taxes ethyl alcohol or converts crude oil into alcohol like in the case of IPA. I'm also surprised that so many people here just think of using it for cleaning flux. I always leave the flux for the most part and use alcohol for cleaning and disinfecting. You can also use it to make hash oil as I did as a kid. Funniest use is taking a 5 gal water jug, rising with IPA then touch a match to the top as it makes a huge roaring sound and huge flame and scares the hell out of people then makes a pop sound(either the bottle self extinguishing or the sound from people pants)Mmmm filtering blue denatured alcohol through a slice of bread so you can drink it. That's what the most classy of wine snobs do, after they go blind and get cirrhosis and/or wet brain.The denatured ethanol around here smells like they put acetone in it.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 08, 2019, 05:37:38 pm
content: Denatured alcohol usually includes 2-butanone nowadays. The butanone causes the acetone-y smell.

author: macboy
author_rank: Super Contributor
timestamp: July 16, 2019, 04:39:26 pm
content: Here in Canada, I buy 99% IPA at Costco. Last time it was $9.99 for four 500 mL bottles ($10 / 2 liters), but I think the price is up to around $12 now. Still super cheap and super easy.

author: Cliff Matthews
author_rank: Unknown
timestamp: July 16, 2019, 05:55:18 pm
content: Quote from: macboy on July 16, 2019, 04:39:26 pmThanks, my friend is a member. Walmart wants 6.99 CDN / 500ml and it must be ordered (18+ 'over the counter').

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 16, 2019, 06:17:46 pm
content: I buy 32 oz 91% Isopropyl Alcohol at Wally World for $2.50. I buy it for disinfectant purposes but also use it for cleaning PCBs.

author: Beamin
author_rank: Super Contributor
timestamp: July 20, 2019, 02:47:34 am
content: Quote from: rcbuck on July 16, 2019, 06:17:46 pm91% isn't nearly as good as 70% which kills 99.99% of germs vs about 70% killed, for the 91%. The alcohol has to get into the cells so that's why less is better. The peptoglycan wall of the bacteria is not oil or alcohol soluble so only that 9% alcohol with 5% water gets in. Also remember the bacteria doesn't die until full dryness.

author: Smoky
author_rank: Frequent Contributor
timestamp: July 20, 2019, 03:26:16 am
content: This stuff works very well. I bought it on Ebay. It's $8 for one gallon, you get four quarts. $12 to shipIt works very well and leaves no residue.But most of the cleaning I do when soldering is Dupont 105 lacquer thinner. I have a five gallon can in the garage!

author: Nusa
author_rank: Super Contributor
timestamp: July 20, 2019, 05:09:11 am
content: Quote from: Smoky on July 20, 2019, 03:26:16 amI agree, it's both easier AND cheaper to buy better qualtiy iso in the first place than to concentrate it yourself.I looked it up, and Dupont 105 is hazardous stuff. You don't want to be touching or breathing it. So pay attention to protection and ventilation if you use it.CAS-No. Chemical name Concentration67-56-1 Methyl alcohol 50%108-88-3 Toluene 19%67-64-1 Acetone 15 - 26%1330-20-7 Xylene 8%100-41-4 Ethylbenzene 2.0%8032-32-4 Vm&p naphtha 1 - 4%

author: Beamin
author_rank: Super Contributor
timestamp: July 20, 2019, 07:30:31 pm
content: Quote from: Smoky on July 20, 2019, 03:26:16 amIs that really dry alcohol? Most is 98% because as soon as you open it the humidity gets into it. Dupont 105: is the 105 for all the different kinds of cancer it gives you?I just leave the flux on it adds character to my boards.

author: Smoky
author_rank: Frequent Contributor
timestamp: July 20, 2019, 08:31:48 pm
content: I pour a small amount of I-Max in a PPG mixing cup and use a trimmed China bristle brush to clean.I do the same with the lacquer thinner but I keep that in a squirt bottle.I've sprayed, Dupont, PPG, Standox, and Sikkens auto refinish products for about 38 years.While in the Marines, we went through barrels of dry cleaning fluid to clean rifles and machine guns. Why don't you go check that stuff out?I know what to use in my new electronics hobby.