Acrylic and IPA - Do not mix!

[Simeon]

I have read previously that you should never use IPA to clean acrylic crystals and I filed that knowledge internally, to avoid it. 

 

While pre-cleaning some movement parts with IPA, I managed to get a healthy splash of it on clear part of a cheap mainspring barrel press. I wiped it off quickly and didn't think any more about it. About 10 minutes later I picked it up to put it away and there was a massive crack running right across its diameter and down the sides. When prodded it cleanly split into two halves. 

 

Lesson: be cautious as to where the IPA ends up. You might think it is one of the more benign chemicals that we may use but it can obviously do damage. 

[Kalanag]

Strange! To be sure about the IPA as the cause of the crack I would treat one of the broken halfs with IPA again and see what happens.

[tomh207]

I would see acetone being a problem but IPA, not so sure. That looks more like a stress fracture, chemical incompatibility I would expect “melting “ of the material rather than this.

 

Tom

[Neverenoughwatches]

1 hour ago, tomh207 said:

I would see acetone being a problem but IPA, not so sure. That looks more like a stress fracture, chemical incompatibility I would expect “melting “ of the material rather than this.

 

Tom

May have had an unnoticed fracture/ flaw in its structure waiting to be further stressed. Glass has manufacturing flaws that can suddenly rupture with temperature random stress changes. Toughened glass can do it spectacularly for no apparent reason.

No reason i can think of to use any solvent when restoring an acrylic crystal when diminishing grades of wet and dry and a final polishing paste makes a good job. Maybe a good reminder to safely store away the crystal when ipa is being used.

[HectorLooi]

We were taught in dental school that alcohol can cause crazing of the acrylic used for dentures. But I've never seen a crazed denture in my 38 years of practice. Crazed patients... yes.

From my own personal experience, I once cleaned the acrylic lens of an LED torch with IPA and almost immediately a crack line started to form.

[rjenkinsgb]

I know for a fact that using "Locktite" on any screws or nuts in contact with acrylic causes the plastic to start cracking in that area. I've seem it on machines that have acrylic door windows & guarding.

There are definitely some solvents that affect it, though I've never noticed anything with IPA; it possibly depends on how long it's on contact?

 

[mikepilk]

On 7/28/2024 at 6:59 AM, Simeon said:

I have read previously that you should never use IPA to clean acrylic crystals and I filed that knowledge internally, to avoid it. 

As an experiment I once tried 99% IPA on an old acrylic crystal. It first went cloudy, then cracks developed.

I assume that all optical lenses are not any form of acrylic, as don't lens wipes contain IPA ?

[Jon]

1 hour ago, mikepilk said:

As an experiment I once tried 99% IPA on an old acrylic crystal. It first went cloudy, then cracks developed.

How long did it take until it went cloudy and cracked?

interesting, as I tend to give a mucky acrylic crystal a splash of IPA and wipe off to clean it. i've never had one crack or go weird on me.

[Geotex]

Medical and research apparatus is often fabricated from thick sheet acrylic, and since there is usually a spray bottle of one type of alcohol or another on most lab benches, inadvertent damage often occurs.  Woe be to the undergraduate helper that compromises an expensive piece of equipment by innocently wiping it down! I've even seen "No alcohol" decals on newly-purchased items as a reminder from the manufacturer. 

Product info often states that concentrations below 30% are moderately compatible and can be used for brief cleaning exposures, but most people stock concentrations above 60% on the bench because that is where you need to be for disinfecting activity as a surface treatment. 

[mikepilk]

1 hour ago, Jon said:

How long did it take until it went cloudy and cracked?

interesting, as I tend to give a mucky acrylic crystal a splash of IPA and wipe off to clean it. i've never had one crack or go weird on me.

I think I left it for several minutes.  Like you, I will still give a swift wipe of an acrylic with a splash of IPA.

[gpraceman]

On 7/28/2024 at 4:05 AM, Neverenoughwatches said:

May have had an unnoticed fracture/ flaw in its structure waiting to be further stressed. Glass has manufacturing flaws that can suddenly rupture with temperature random stress changes. Toughened glass can do it spectacularly for no apparent reason.

One night, we were bringing a pot of water to boil on our cooktop and the tempered glass portion of our vent hood shattered rather spectacularly.  Threw glass shards up to 20 ft away. Dinner was ruined and we had quite a mess to clean up.  Luckily none of us were at cooktop at the time.

I am rather surprised that IPA would have that affect on acrylic.

[Neverenoughwatches]

43 minutes ago, gpraceman said:

One night, we were bringing a pot of water to boil on our cooktop and the tempered glass portion of our vent hood shattered rather spectacularly.  Threw glass shards up to 20 ft away. Dinner was ruined and we had quite a mess to clean up.  Luckily none of us were at cooktop at the time.

I am rather surprised that IPA would have that affect on acrylic.

Couldn't say regarding acrylic but if has an external flaw somewhere that is affected and the piece has internal stressed going on then i suppose its structure could be compromised.  Toughened glass is renowned for this, i once remember picking up a double glazed unit , grabbed each side  it shattered and left 2 imprints of missing glass were my hands were. The explosion can send glass hurtling everywhere, fortunately the pieces are too small to cause serious wounding but they can still cut and the glass dust can be a problem. 

[RichardHarris123]

I can't find any information in why IPA could shatter acrylic.  Crazing is caused by the top layer being dissolved and resetting at a non uniform rate.  I can only take an educated guess that the acrylic was already stressed. 

[Simeon]

14 hours ago, RichardHarris123 said:

I can't find any information in why IPA could shatter acrylic.  Crazing is caused by the top layer being dissolved and resetting at a non uniform rate.  I can only take an educated guess that the acrylic was already stressed. 

Almost certainly it would have been because the part was under stress to begin with. It looks like it is machined from a solid piece and it is ultimately used for pressing components together. The IPA would have just have worked on the stresses already present.