Hydrocarbon solvents - 9n3 for the chemists

We use acetone on lab glassware if we want to get rid of all traces of water so maybe that's the reason? But I'd imagine that IPA will do perfectly fine for bike bits. And even then I'd still use both, IPA then acetone.

My immediate concern with acetone is how it impacts any plastics, like pvc or polycarbonate. 

Anecdotally, I used IPA to clean a plastic tick remover card that I carry in my wallet. It instantly crazed and became brittle.

With any of the 'somewhere in between water and petrol' solvents it can be surprisingly difficult to predict how they'll act on different solutes. For example IPA can damage some ploycarbonartes but not all (the same being true for acetone I suspect). I'm not sure what the effect is with IPA and your component but I wouldn't be surprised if there are certain additives in, say anodising, that IPA can interact with and Acetone can't.

as others have said, the fact they all will remove grease is irrelevant, they have different effects on other substances too, and without knowing what solvent and surface it's contacting, it's impossible to say what the effect will be. There's labs that just do compatibility testing to resolve this so I'd go with the manufacturer recommendation.

The component being cleaned hasn't been damaged by the IPA. 5 parts are being replaced but the bit being cleaned is small steel parts in a soft flexible plastic retainer. I appreciate that we don't know what the plastic is and therefore don't know the affect the solvents have. However, the comments from the manufacturer were about cleaning, not damage to the plastic. Acetone isn't expensive and I feel like they've been good to me so I have no qualms about using their suggested solvent

Just thought it was an interesting topic for discussion. Possible more interested in the advice from ZFC about chain cleaning.

Does this really made a difference? I assume they both degrease and flash off to leave no residue.

Just be mindful that a lot of publicly available solvents like that are not pure, they can contain oils and other solvents.

Same with methylated spirits, that almost always has oil base to it (as well as Bitrex or some other vile tasting compound to stop you drinking it).

Just be cautious if using on disc brakes on particular and as mentioned, they can react to some plastics and rubber compounds too.

And what do I need to know about hydrogen embrittement?

Are you welding or electroplating? If neither, then I think ignorance is fine.

Acetone is much more likely to damage plastics than IPA (it's death-in-a-bottle for polycarbonate as even the vapour causes stress cracking). It's also bad for de-fatting your skin.

Meths is a decent cleaning solvent (better than IPA) that will also remove small amounts of water. You can buy IMS (that doesn't have the colouring, etc.) for about the same price as IPA or acetone.

[As a side note: Quite why people feel the need to wash all of the oil and grease out of their chains defeats me - Clean the muck off the outside, apply lube of choice to the rollers, and give them a wipe with something oily to stop the plates rusting.]

The plan with the chain is to get them fully degreased so the hot immersive wax can get a proper bond.

https://www.plasticsintl.com/chemical-resistance-chart

We generally use IPA to clean surfaces and remove grease. Acetone is more aggressive and with most plastics will attack it even in the time it takes to wipe.

Will look at polycarbonate and IPA. Didn't know that but can see why.

There are non solvent based degreasing methods that work (pretty much soap and hot water). If you were going to go down a multiple step approach I'd do that. Maybe follow with a quick solvent rinse. I would have thought that immersion in hot wax was enough to displace any residual solvent or trace amounts of grease?

I would have thought that immersion in hot wax was enough to displace any residual solvent or trace amounts of grease?

It usually works the other way round - any residual grease stops the wax adhering to the chain.

Same way that any residual degreaser on a chain will instantly turn new fresh lube into a black gunky mess.

Avoid IMS if you can, it's toxic, even the clear stuff.

IPA is a good general solvent for cleaning as it's generally miscible with everything, so you can use it as a bridge between polar and non-polar liquids. It's also fairly benign and you can get very pure versions quite easily.

Acetone is an excellent solvent, fairly benign and less flammable/volatile than IPA, it's also able to be used as a bridge solvent but it's harder to get clean versions as it's so good at attacking everything and keeping hold of it (why it's avoided in chromatography).

IPA is a common hydrogen source in metal-catalysed transfer hydrogenations, so that will be the source for hydrogen embrittlement. However, for IPA on bare metal surfaces that is surely a trace process that is relevant for large scale industry considerations - wiping a metal bike component down doesn't sound like it's in that category tbh but I could be wrong. Maybe someone out there has an embrittled chain from reckless IPA use.

Solvent effects are hard to predict and understand from just general chemical reactivity - a bare ketone like acetone is very reactive from a chemistry pov but stuff like methylene chloride or dimethylsulfoxide would be considered much stronger solvents in layman's terms. Paint-strippers and brick-dust dissolvers. The polarity is critical.

Maybe someone out there has an embrittled chain from reckless IPA use.

Yeah, I'm sure that's why my last chain broke.

If anyone wants to learn about hydrogen embrittlement (and why wiping bike parts with solvent won't cause it):

NTRS.NASA.GOV "https://ntrs.nasa.gov/api/citations/20160005654/downloads/20160005654.pdf"

I think the hydrogen embrittement theory is more related to soaking chains in degreasers or other chemicals for 3xtended periods.

The recommendation for the mineral turps and methylated spirits is to avoid the problem.

At the risk of revealing how limited my knowledge of chemistry is, am I right in thinking that this hydrogen embrittement shouldn't be a concern if something is pH neutral?

taken me ages to work out what 9n3 refers too. Not sure now if clever or dumb.

No, I just have large fingers and a small screen. The 9 is over the O and the 3 over the e.

I'm a bugger and tend to just use automotive brakes cleaner....

Bring back ICI 'Trike'.

Best at degreasing metals after machining,......but keep away from plastics and skin.

Anyway, the Montreal protocol put paid to any more of that...as a serious ozone depleter.

I think the aerospace industry still use it.

It’s also bad for de-fatting your skin.

Acetone will also carry anything dissolved in it through the skin. For removing traces of oil/grease I’d use isopropyl alcohol over acetone as it’s a little bit better at dissolving hydrophobic materials.

Edit: if I really wanted to degrease at home I’d use white spirits. At work, diethyl ether or petrol (40-60).