Is acetone more greasy now?

I use a fair bit of acetone. I have always accepted that it leaves a bit of an oily residue. Recently I have been finding a *lot* of oily residue. Is it just a rogue bottle or has anyone else noticed this? If so is the likely cause cutting costs during production?

Michael Koblic, Campbell River, BC

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I haven't noticed any change lately, but commercial grades of acetone contain a lot of reprocessed material from large commercial recovery operations. It's notoriously oily and is avoided by boat manufacturers, for example, who use acetone to clean the wax off of surfacing-grade polyester resin before applying furniture laminations and so on. I don't know what they call the virgin grade but that's what you need, if the oil causes a problem for you.

This has been true for decades. I learned it when I worked in a molding plant for Ranger Yachts, back in 1973.

Residue is more critical for certain purposes.

I generally use lacquer thinner as a final cleaner for many things, although naptha solvents are generally good enough for most purposes such as painting. Denatured alcohol is my secondary solvent.

There is a grade of acetone that that can be purchased from a pharmacy.. a friend operating a electronic repair shop used to use it for cleaning video heads and the various mechanical parts in the tape path.

You might try MEK if the residue you're seeing is interfering with what you need as far as clean surfaces. I haven't used it in quite a long time, and recently noticed it's not as readily available as it was a few years ago, but it generally gets metal very clean.

And then there's brake cleaners and other nasty formulas for certain cleaning purposes.

Acetone evaporates almost instantly, and leaves *no* residue. If you're seeing any oily residue at all from acetone, it's not pure. Bitch at the supplier.

What specific product are you using, so I know what to avoid? :-)

You probably want to ask your supplier, and perhaps your supplier's competitors if your supplier does not bring you joy. My ever-dimmer memory has the phrases "technician (or technical) grade" and "reagent grade".

Basically, if you just need it for cleaning tools then a bit of gunk in there isn't a terrible thing. If you need it to be _really clean_ then you want reagent grade -- and you need to expect to pay for it.

In article , snipped-for-privacy@gmail.com writes

I have a bottle of 'nail varnish remover' -mainly acetone but it contains a small amount of lanolin which makes it useless for degreasing etc. Similar problem with 'rubbing alcohol' (called 'surgical spirit' over here) -this has a small amount of castor oil in it.

You answered a longstanding question I have.

I mix denatured alcohol/acetone 4:1 to make a soldering flux solvent. Works great. But over the last 2 years, the mixture has turned milky and sticky as soon as I make it.

I'll try it with virgin acetone and see if it works better.

This can came from HD. It is not a problem really as I have been using a two-stage procedure for degreasing for some time now (that is if I need a *really* clean item - has to pass a waterbreak test).

It's just that the amount of grease in this last can was more than I remember previously.

BTW I find proper degreasing another one of those Black Magic procedures: You have to do it right before the next process, you cannot do it a day in advance. You also cannot do Stage 1 one day and the Stage 2 the next day. Why? Lord knows...

Michael Koblic, Campbell River, BC

A really clean metal or glass surface has a great affinity to attract hydrocarbons out of the air. I used to design optics for instruments that measured film thickness on silicon wafers. These were sensitive enough to detect a average thickness change of less than 0.1 angstrom (yes, this is less then the width of an atom, but that much of a change would just mean that a few extra molecules are sprinkled over the measurement spot). In any case, you could take a freshly cleaned silicon wafer, put it in the machine, and watch over the next hour or so as a monolayer or two of hydrocarbon attached itself to the surface. You could then heat the wafer on a hot plate and drive off the hydrocarbons again. High vacuum equipment is usually baked at low pressure before installing to get rid of hydrocarbons and water.

The high vacuum people have it down to a science. Don't have time to look it up, but a google of cleaning vacuum equipment will probably get you some useful info.