# Simple Question: Soap & Water **URL:** \ **Category:** Factual Questions\ **Created:** [September 24, 2008, 2:04am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928 "2008-09-24T02:04:05Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 24, 2008, 7:07pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/21 "2008-09-24T19:07:14Z")
> [@Napier](#): > > \>Sodium laurylsulphate is a detergent and is made by the “esterification”\* of the alcohol with sulfuric acid. > > Thank you, Warm. It sounds like you know what you are talking about and maybe even have studied chemistry. _snerk_ You could say that. WarmNPrickly is a chemist. IIRC he’s studied a whole lot of chemistry. > [@](#): > > BTW, I think small articles like parts and little electronic gadgets say that “soap and water” bit so they can blow off the legitimate need to be able to clean products. Soap and water isn’t effective on lots of the things that get on little parts and gadgets, like label adhesive. Worse, the big challenge becomes getting rid of the soap by diluting and washing. > > I like isopropanol - like in “rubbing alcohol” - for many of these situations. There is almost no little gadget that isopropanol will hurt, and it is very easy to apply in a limited way. You don’t have to clean it off; there is no residue from its drying. The premoistened felt squares packaged in foil, sold in drug stores for diabetics to sterilize injection sites, are great for this, and they are amazingly convenient. > > Admittedly, isopropanol sometimes has no effect on label adhesive, and for that and other situations I wind up with Goof Off on a Q-Tip, Goof Off in a cup, kerosene, a nice light petroleum naptha, various ketones, dichloromethane, a 55 gallon drum of halogenated solvents (I got pulled out of one of these, half full, as a teenager, while cleaning a vacuum pump). There are all sorts of options, each with some spectrum of surfaces it will ruin. Do please be careful with the organic solvents. Many things that specify being cleaned with “soap and water” or as I see more commonly “mild detergent and water” say this because they will be damaged by solvents (including isopropanol). Solvents and plastics are frequently a Very Bad Thing. You’ll be okay with metals, so long as they’re not painted. Paint and solvents don’t play nicely, either. And halogenated solvents are no one’s friend. (but they do make the most lovely paint strippers, mores the pity) Which is why I’ve spent over six months this year finding effective alternatives in various chemical production processes. You know what is frequenty good for removing label adhesive that I promise won’t harm the surface of the object? Baby oil. Or vegetable oil if you don’t have any oily babies handy. (yeah, I studied chemistry too) ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [September 24, 2008, 9:29pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/22 "2008-09-24T21:29:52Z")
\>Do please be careful with the organic solvents. Many things that specify being cleaned with “soap and water” or as I see more commonly “mild detergent and water” say this because they will be damaged by solvents (including isopropanol). Many solvents will hurt many items, but, what kinds of things does IPA hurt? Only problem I’ve had has been some kinds of inks used on permanent labels. Is there anything else? \>And halogenated solvents are no one’s friend Dunno about that. Anybody that has had a solvent job catch fire would be about ready to fall in love with one. \>You know what is frequenty good for removing label adhesive that I promise won’t harm the surface of the object? Baby oil. Or vegetable oil if you don’t have any oily babies handy. O yah. I had part of my neck fused last Thursday and was still finding these goddam little EKG pads hiding here and there as much as 3 days later. I am almost as furry as Robin Williams, and it’s been years since I grew my head hair as long as my chest hair. There’s all this rubbery crap on my skin, tangled in my fur, etc etc. I’ve been using Vaseline for things that want to be soaked for a while - I know, its diffusivity sucks, but it’s nonpolar like the rubbers. In a pinch, in the past, I have used peanut butter. It stays on the target, and it makes me hungry. Fortunately this week we have mineral oil in stock. I wouldn’t say no to a pint of hexane, tho… ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [September 24, 2008, 10:34pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/23 "2008-09-24T22:34:56Z")
[QUOTE=Napier] Many solvents will hurt many items, but, what kinds of things does IPA hurt? Only problem I’ve had has been some kinds of inks used on permanent labels. Is there anything else? [/QUOTE] No, you probably covered most things. It is still pretty harsh as far as solvents go and some of the damage it does may not be immediately obvious. [QUOTE=Napier] \>And halogenated solvents are no one’s friend Dunno about that. Anybody that has had a solvent job catch fire would be about ready to fall in love with one. [/QUOTE] Speaking as someone who had a skipping Flaming Lips CD then decided to fix it with dichloromethane, it’s not a good idea to mess with chlorinated solvents. While most polymers are probably resistant to IPA, the same cannot be said of chlorinated solvents. While organochlorines certainly have a higher ignition temperature, when organochlorines do ignite they have a tendency to produce phosgene and dioxin. Generaly, if an item suggests soap and water to clean it, I will use something like Palmolive dish soap. I would never use plain old soap. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [September 25, 2008, 12:08am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/24 "2008-09-25T00:08:48Z")
\>Speaking as someone who had a skipping Flaming Lips CD then decided to fix it with dichloromethane You tried to wash polycarbonate with methylene dichloride? Did you know Solfy thinks you’re a chemist? ---
**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\ **Post date:** [September 25, 2008, 1:09am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/25 "2008-09-25T01:09:16Z")
> [@Solfy](#): > > You know what is frequenty good for removing label adhesive that I promise won’t harm the surface of the object? Baby oil. Or vegetable oil if you don’t have any oily babies handy. But then you need isopropanol to remove the oil. 🙂 Seriously, most of the time I’d rather have label adhesive stuck on something than any kind of mineral or vegetable oil. There’s nothing quite as disconcerting to me as touching an oily piece of electronics. What does rubbing alcohol harm as a cleaner? I want to know so I can go home and toss all of those things. If I can’t clean it with my anhydrous isopropyl, it isn’t worth keeping. ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 25, 2008, 1:37am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/26 "2008-09-25T01:37:37Z")
> [@groman](#): > > But then you need isopropanol to remove the oil. 🙂 Seriously, most of the time I’d rather have label adhesive stuck on something than any kind of mineral or vegetable oil. There’s nothing quite as disconcerting to me as touching an oily piece of electronics. > > What does rubbing alcohol harm as a cleaner? I want to know so I can go home and toss all of those things. If I can’t clean it with my anhydrous isopropyl, it isn’t worth keeping. The OP referenced soap and water would be good for removing the oil. 🙂 I’d be leery of IPA’s compatability with inks, as \*\*Napier \*\*mentioned (in fact I’d recommend it as an ink stain remover, particularly from LCD monitors - I’ve got small children), and some paints. I’ve had it soften paints before, but I don’t know what kind of paint it was. > [@Napier](#): > > Dunno about that. Anybody that has had a solvent job catch fire would be about ready to fall in love with one. In that case you’d have to weigh the risk of death by fireball vs death by cancer, carbon monoxide poisoning, and/or central nervous system depression. Aren’t chemicals great?! ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [September 25, 2008, 1:37am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/27 "2008-09-25T01:37:55Z")
> [@Green\_Bean](#): > > First off, there is a difference between “soap” and “detergent.” I’ll let someone better-versed explain it. One has an OH (hydroxy) and one has a COOH (hydroxyl) on the end of the carbon chain. I can never remember which is which, but I promised to look it up (again). Soap is better for your skin; detergent is better for your hair. I THINK: Shampoos are detergents. Laundry detergents are detergents. Hand dish-washing liquid is a soap, but machine dish-washing … stuff is a detergent. I also THINK that which is better to use depends more on the material being cleaned than the contaminant being removed. (I trust WarmNPrickly to step in here if I am wrong.) I do know that good hand dish-washing … stuff really is better at removing grease, so it can be used to get olive oil stains out of clothes. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [September 25, 2008, 2:22am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/28 "2008-09-25T02:22:38Z")
Technically soap doesn’t have a COOH at the end it has a COO- at the end. Likewise your typical liquid soap\* (hand soap, shampoo …) has a S(O[sub]2[/sub])O- at the end. The S(O[sub]2[/sub])O- is less basic than your COO- is so often is less harsh. Also COO- forms insoluble products with hard water that can be a nuisance. But detergent goes way beyond S(O[sub]2[/sub])O-. You could have N(C[sub]3[/sub]H[sub]6[/sub]CH[sub]3[/sub])3(CH[sub]3[/sub])+ Cl- as a detergent, but that would be an entirely different beast from what you would use normally since it is cationic. Some shampoo’s use similar things though. If you ever see TEA sodium laurethsulfate they mean N(CH[sub]2[/sub]CH[sub]2[/sub]OH)[sub]3[/sub]H+ LaurethS(O[sub]2[/sub])O- . This is a mild detergent that is both cationic and anionic at the same time so you get the benefits of both (I guess). I make no pretense of being a detergent chemist. - lets face it, colloquially soap and detergent are not well distinguished. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [September 25, 2008, 2:58am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/29 "2008-09-25T02:58:42Z")
> [@groman](#): > > What does rubbing alcohol harm as a cleaner? I want to know so I can go home and toss all of those things. If I can’t clean it with my anhydrous isopropyl, it isn’t worth keeping. I saw a lab rat destroy a brand new polycarbonate\* widget we’d just had machined by cleaning it with ethanol, which I’d consider to be as generally benign as isopropanol. I think it had micro cracks on the surface from the machining operations which the alcohol caused to propagate… like a tempered glass window hit by a baseball bat. OTOH I’ve used MDPE and PET bottles for storing ethanol (denatured with methanol) regularly with no problems at all. \*I’m pretty sure it was Lexan, but it might have been acrylic or clear PVC…been about 9 years ago. Later versions were made of vespel, which was very solvent and heat resistant, and much more expensive. ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 25, 2008, 3:06am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/30 "2008-09-25T03:06:35Z")
> [@j666](#): > > One has an OH (hydroxy) and one has a COOH (hydroxyl) on the end of the carbon chain. I can never remember which is which, but I promised to look it up (again). > > Soap is better for your skin; detergent is better for your hair. > > I THINK: > Shampoos are detergents. > Laundry detergents are detergents. > Hand dish-washing liquid is a soap, but machine dish-washing … stuff is a detergent. > > I also THINK that which is better to use depends more on the material being cleaned than the contaminant being removed. > > (I trust WarmNPrickly to step in here if I am wrong.) > > I do know that good hand dish-washing … stuff really is better at removing grease, so it can be used to get olive oil stains out of clothes. Try [this](http://www.cleaning101.com/cleaning/chemistry/)link to see if it clears up anything for you. “Soap” isn’t necessarily better or worse for your skin. Chances are the hand dish washing liquid you have is a detergent. Actual soaps are pretty rare now in consumer products since detergents can be more specifically engineered for their intended task, as well as that pesky “soap scum” problem mentioned upthread. Both the contaminant being removed as well as the material being cleaned are important in your selection process. For instance, it wouldn’t do your hair much good to clean it with dishwashing liquid. The same detergents that make it fabulous for removing alfredo sauce from your dinner plates make it strip too much from your hair. This (coupled with the hot water) is why housewives used to complain of “dish pan hands.” It can also strip the oils from your skin. The oils removed from your skin while showering are not the same as the oils removed from your dishes. This is why body wash wouldn’t be as good at removing the olive oil stains you mention from your clothes. So what you are trying to remove is important to consider, as well as what you’re removing it from. The cleaning method you’re using also dictates your detergent choice. Hand dishwashing liquid is made to foam because people like bubbles. Do not make the mistake of putting it in an automated dishwasher. ---
**Author:** ![tygerbryght](https://avatars.discourse-cdn.com/v4/letter/t/a9a28c/32.png) [@tygerbryght](https://boards.straightdope.com/u/tygerbryght)\ **Post date:** [September 25, 2008, 3:55am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/31 "2008-09-25T03:55:03Z")
> [@Solfy](#): > > Could you give a specific example of such a fabric? I’m honestly curious as to what and why this might be. Yes. I have a pair of surgical compression hose - the kind used for various reasons (among them, swelling in the feet and legs). I was told that I should use Ivory soap, and only Ivory soap. That using anything else - even Woolite - would cause the elastic component (rubber, I think?) to degrade, and rapidly. The woman who fitted them operated a store where they sell that kind of thing, and had years of experience of people coming back to complain about how their hose didn’t last. Me having them is a joke. I tried to tell them that I couldn’t put them on by myself, and I live alone, so they’d never get used. But the doctor ordered them, and that was that. The woman (she had some sort of training about the use of such items) put them on me. When I got home, I dutifully got the Ivory soap, and the one time they were washed - after I got them off (with considerable difficulty), they were carefully washed with Ivory soap. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [September 25, 2008, 12:19pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/32 "2008-09-25T12:19:16Z")
\>If I can’t clean it with my anhydrous isopropyl, it isn’t worth keeping. How can you keep your IPA in anhydrous form while cleaning something? Do you have a dessicated glove box, or what? I’m gonna go soak a machined polycarbonate doohicky in 90% isopropanol and report back. Betcha it looks no different! ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 25, 2008, 1:52pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/33 "2008-09-25T13:52:28Z")
> [@Napier](#): > > \>If I can’t clean it with my anhydrous isopropyl, it isn’t worth keeping. > > How can you keep your IPA in anhydrous form while cleaning something? Do you have a dessicated glove box, or what? > > I’m gonna go soak a machined polycarbonate doohicky in 90% isopropanol and report back. Betcha it looks no different! It doesn’t have to remain anhydrous while cleaning. I believe he was differentiating it from the commonly available 70% aqueous solutions most people have, sold in the US as “rubbing alcohol”. Depends on your polycarbonate. From [here](http://www.gallinausa.com/pdfs/polycarb.chemical.resistance.pdf): “Polymers are more susceptible to solvent or chemical attack when under stress and/or strain. Stress can be internal, caused during the manufacturing of the product, or due to externally applied loads. • The nature and strength of the chemical will affect the amount of damage. While some dilute chemicals will not attack a polymer, more concentrated solutions can do considerable harm. • The extent of chemical attack on a certain polymer is mainly dependent on the chemical structure of the polymer. In addition, the severity of attack generally reduces with increase in polymer molecular weight, crystallinity, and level of chain branching. • The effects of chemical exposure are increased at higher temperatures and with longer periods of exposure.” And more info on isopropanol’s compatibility [here](http://engineering.tufts.edu/microfab/index_files/docs/ChemList.pdf) (PDF warning): “Isopropanol Highly Flammable Incompatible with ABS plastic. Compatible with most other containers including glass, high density polyethylene (HDPE), polypropylene (PP), nylon and Teflon (PTFE).” (ABS plastic being acrylonitrile butadiene styrene) ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 25, 2008, 2:01pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/34 "2008-09-25T14:01:04Z")
> [@tygerbryght](#): > > Yes. I have a pair of surgical compression hose - the kind used for various reasons (among them, swelling in the feet and legs). I was told that I should use Ivory soap, and only Ivory soap. That using anything else - even Woolite - would cause the elastic component (rubber, I think?) to degrade, and rapidly. The woman who fitted them operated a store where they sell that kind of thing, and had years of experience of people coming back to complain about how their hose didn’t last. > > Me having them is a joke. I tried to tell them that I couldn’t put them on by myself, and I live alone, so they’d never get used. But the doctor ordered them, and that was that. The woman (she had some sort of training about the use of such items) put them on me. When I got home, I dutifully got the Ivory soap, and the one time they were washed - after I got them off (with considerable difficulty), they were carefully washed with Ivory soap. Interesting, thanks. A quick check shows manufacturers of compression stockings recommend “gentle soaps” like Ivory or Dreft, or a cleaner specifically sold for washing compression garments. According to the company that makes Dreft, it’s a detergent. What they both have in common is a lack of additives that may leave residues behind. It seems that the lack of additives and the mildness of the cleaner is more important than the soap/detergent details. But knowing this, it gives me pause regarding the care and feeding of female foundation garments. . . ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [September 25, 2008, 2:07pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/35 "2008-09-25T14:07:34Z")
> [@Napier](#): > > I’m gonna go soak a machined polycarbonate doohicky in 90% isopropanol and report back. Betcha it looks no different! In adition to what **Solfy** said, it is possible to dissolve some of the plasticizers without doing damage that is immediately apparent. Soak some Tygon tubing in IPA and see what happens. ---
**Author:** ![Interconnected\_Series\_of\_Tubes](https://avatars.discourse-cdn.com/v4/letter/i/13edae/32.png) [@Interconnected\_Series\_of\_Tubes](https://boards.straightdope.com/u/Interconnected_Series_of_Tubes)\ **Post date:** [September 25, 2008, 5:00pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/36 "2008-09-25T17:00:02Z")
You guys are just all a bunch of pansies. Soaps? Detergents? Surfactants are for wimps! Real men use piranha solutions. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [September 25, 2008, 5:05pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/37 "2008-09-25T17:05:26Z")
In direct response to the OP, just yesterday I received a tinted plastic visor that clips onto my car visor–great for commuting into a rising or setting sun, which I do. The instructions say to wash in soap & water. I plan to use dishwashing detergent even though it’s not “soap.” Certain chemical solvents are bad for plastic; ammonia can fog plastic (don’t use it on a motorcycle windshield). But detergent is just as good as Ivory. ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [September 25, 2008, 11:13pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/38 "2008-09-25T23:13:01Z")
I knew my post would encourage more informed responses; thank you both. I care much less if the washing material is a soap or detergent than I do about dyes and perfumes. I hate dyes and perfumes. I particularly hate them in dish … stuff. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [September 26, 2008, 2:07am UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/39 "2008-09-26T02:07:20Z")
[http://www.sterlitech.com/products/membranes/compatibilitychart.htm](http://www.sterlitech.com/products/membranes/compatibilitychart.htm) is a reference saying polycarbonate filtration membranes are recommended for service in isopropanol. A filtration membrane is a fine porous film. Recommending such a delicate piece of a polymer for service in a chemical suggests larger pieces would also be fine. It is true, in polymers and other solids, that there are generally planes of high stress, whcih sometimes become cracks, which sometimes allow a solvent to wick into the crack and go to work at the leading edge of the crack where tensile stresses are highest and bonds most vulnerable. This is a more complicated point than a compatibility chart for one company’s products would reflect, so this does not tell us with confidence that ethanol couldn’t hurt polycarbonate. And polycarbonate is famous for turning from Superman into the entrails of Clark Kent because you touched it with any of half of the liquid products a hardware store carries. Funny that way, polycarbonate. None of which I have turned up lying around in the basement, by the way. Usually I am tripping over the damn stuff in the dark, but suddenly everything’s acrylic and PE and nylon. Hell, I even have a little vespel around, and viton and PFA, a chunk of solid gadolinium tacked to the bulletin board, and no less than solid rhodium foil rattling around on the bookcase, but for polycarbonate I think I have to head out to the shopping mall or something. ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [September 26, 2008, 2:05pm UTC](https://boards.straightdope.com/t/simple-question-soap-water/464928/40 "2008-09-26T14:05:00Z")
> [@Napier](#): > > [http://www.sterlitech.com/products/membranes/compatibilitychart.htm](http://www.sterlitech.com/products/membranes/compatibilitychart.htm) is a reference saying polycarbonate filtration membranes are recommended for service in isopropanol. A filtration membrane is a fine porous film. Recommending such a delicate piece of a polymer for service in a chemical suggests larger pieces would also be fine. > > It is true, in polymers and other solids, that there are generally planes of high stress, whcih sometimes become cracks, which sometimes allow a solvent to wick into the crack and go to work at the leading edge of the crack where tensile stresses are highest and bonds most vulnerable. This is a more complicated point than a compatibility chart for one company’s products would reflect, so this does not tell us with confidence that ethanol couldn’t hurt polycarbonate. And polycarbonate is famous for turning from Superman into the entrails of Clark Kent because you touched it with any of half of the liquid products a hardware store carries. Funny that way, polycarbonate. > > None of which I have turned up lying around in the basement, by the way. Usually I am tripping over the damn stuff in the dark, but suddenly everything’s acrylic and PE and nylon. Hell, I even have a little vespel around, and viton and PFA, a chunk of solid gadolinium tacked to the bulletin board, and no less than solid rhodium foil rattling around on the bookcase, but for polycarbonate I think I have to head out to the shopping mall or something. \*\*Kevbo \*\*did mention that he wasn’t entirely sure it was polycarbonate. Keep in mind that polycarbonates are a class of polymers, and they are not all created equal. While they are generally considered safe with alcohols, that doesn’t mean there aren’t some out there that don’t like isopropanol at all. [Previous page](https://boards.straightdope.com/t/simple-question-soap-water/464928.md?page=1)