Sciencemadness Discussion Board

Rain-X water repellent & properties of glass - is it a coating or just cleaning effect?

RogueRose - 16-8-2018 at 05:59

Some time ago I had a major fog problem inside my windshield and researched some options and looked at Rain-X and other water repellents for glass and found that they were mainly solvents or alcohols like Acetone, MEK, methanol, ethanol, Iso-propanol and sometimes water - one product adds a little HCl and H2SO4.

The Rain-X water repellent wipes were ethanol (30-60%), acetone (10-30%) and isopropanol (10-30%) as per MSDS and the 2-in-1 cleaner/repellent lists water (60-100%) and acetone (3-7%) as ingredients. Most other products are very similar in their composition.

I had anhydrous acetone, methanol, ethanol & isopropanol and mixed some different combinations and cleaned areas of the windshield and got different results for each, the individual compounds alone didn't do a whole lot, but together they seemed to work better.

I watched a video about restoring windshields and the guy used 0000 steel wool (the finest) and scrubbed the entire windshield - then applied rain-x.

Looking at how fresh "virgin" glass acts with water, it beads much like rain-x, I'm wondering if these products and procedures are not just cleaning the surface of contaminates. I can't think how any of the solvents could make a coating on the glass, and I would think the steel wool would just restore it to the "virgin" surface.

Maybe some of you have had experience with cleaning your glassware that will translate to this process and give insight into it.


The bottom PDF is the one with the acids but it also has a fair amount of Triethoxyoctylsilane which I'm wondering if this acts as a coating (filling in very small cracks, pours, crevices, etc) or possibly an abrasive.

Anyway, I looked to see if there were other ingredients in the Rain-X original liquid and didn't see anything about "trade secret - not listed" other than the exact quantites listed, so it seems it is acting as a cleaner. So that might also mean that getting the effect can be had by scrubbing with steel wool?


Attachment: 630021-630061-Rain-X-Original-Glass-Water-Repellent-Wipes-06212018.pdf (81kB)
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Attachment: 630023-Rain-X-Shower-Door-Water-Repellent-06232018.pdf (81kB)
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Attachment: Rustoleum NEVERWET Spray - 287337.pdf (132kB)
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Texium - 16-8-2018 at 06:04

Rain-X does deposit some kind of water-repellent material. I applied some to my windshield recently. If you look at the instructions, you have to smooth it over the surface of the windshield, and a hazy residue appears as it dries. Once it's fully dried, you take a dry cloth to it and wipe off the excess residue. It's probably a very small percent of some ethanol soluble non-polar compound that will stick well to glass. Maybe some kind of silicone? I have also heard that getting it back off of the windshield if you don't want to use Rain-X anymore can be a pain.

Metacelsus - 16-8-2018 at 06:06

Quote: Originally posted by RogueRose  

The bottom PDF is the one with the acids but it also has a fair amount of Triethoxyoctylsilane which I'm wondering if this acts as a coating (filling in very small cracks, pours, crevices, etc) or possibly an abrasive.


The silane reagent will chemically bond with the glass, making it hydrophobic (due to the octyl chain).

[Edited on 8-16-2018 by Metacelsus]

Texium - 16-8-2018 at 06:32

Quote: Originally posted by Metacelsus  
Quote: Originally posted by RogueRose  

The bottom PDF is the one with the acids but it also has a fair amount of Triethoxyoctylsilane which I'm wondering if this acts as a coating (filling in very small cracks, pours, crevices, etc) or possibly an abrasive.


The silane reagent will chemically bond with the glass, making it hydrophobic (due to the octyl chain).

[Edited on 8-16-2018 by Metacelsus]
Aha, I brushed over that when reading the OP. My random conjecture was surprisingly close. That would also explain why it's a pain to remove if you no longer want it. You'd probably have to use a strong base...

RogueRose - 16-8-2018 at 06:37

Look at the first two PDF's and you will see that there isn't anything other than solvents in the Rain-X. I looked at about 10 others (rain-x brand) and they were very similar, one had a propelyene glycol in a small percent, and I think it was a water repellent for fabrics or leather.

The silane, is for the Rustoleum product, which touts "nano" magic in their commercials. This still doesn't explain anything about the rain-x thing and I looked up the rules for MSDS and SDS and it has to list all ingredients, even if trade secret, but it only has to disclose % and pertinent medical info for trade secrets. None of that is listed with Rain-X.

DavidJR - 16-8-2018 at 14:56

Quote: Originally posted by RogueRose  
Look at the first two PDF's and you will see that there isn't anything other than solvents in the Rain-X. I looked at about 10 others (rain-x brand) and they were very similar, one had a propelyene glycol in a small percent, and I think it was a water repellent for fabrics or leather.

The silane, is for the Rustoleum product, which touts "nano" magic in their commercials. This still doesn't explain anything about the rain-x thing and I looked up the rules for MSDS and SDS and it has to list all ingredients, even if trade secret, but it only has to disclose % and pertinent medical info for trade secrets. None of that is listed with Rain-X.


That's not correct, safety data sheets frequently neglect to list ingredients which are not considered to be hazardous at the concentration at which they are present in the product.
Quote: Originally posted by RogueRose  

Looking at how fresh "virgin" glass acts with water, it beads much like rain-x, I'm wondering if these products and procedures are not just cleaning the surface of contaminates. I can't think how any of the solvents could make a coating on the glass, and I would think the steel wool would just restore it to the "virgin" surface.

Maybe some of you have had experience with cleaning your glassware that will translate to this process and give insight into it.


Actually, very clean glass is hydrophilic. Water will sheet over it and not bead up at all. This is because the surface of the glass is covered in silanol groups which are polar.

Try soaking your glassware in a strong base bath overnight and you'll see what I mean.

The long octyl chains on the silane derivative mentioned will of course render the surface non-polar and thus hydrophobic. Similarly stationary phases for reverse-phase chromatography often consist of silica gel powder which has been treated with a similar silane derivative to produce a surface with chemically bonded stationary phase molecules- often C18 chains.

[Edited on 16-8-2018 by DavidJR]

diddi - 16-8-2018 at 15:45

rain-X is brilliant stuff. i can drive in pelting rain with no windshield wipers on. even at lowish speeds.

Deathunter88 - 16-8-2018 at 20:39

DavidJR is correct, MSDS's and the newer SDS's only usually list hazardous materials in concentrations above 0.1% (if I remember correctly). You can easily verify this for yourself by looking at the data sheets for paints and varnishes. Most will only list the solvents in them, but it's obvious they contain other materials too.

AJKOER - 17-8-2018 at 07:06

Quote: Originally posted by Deathunter88  
DavidJR is correct, MSDS's and the newer SDS's only usually list hazardous materials in concentrations above 0.1% (if I remember correctly). You can easily verify this for yourself by looking at the data sheets for paints and varnishes. Most will only list the solvents in them, but it's obvious they contain other materials too.


My further understanding based on a thread I did on percarbonate and commercial additivies (like TAED, see comments at http://www.sciencemadness.org/talk/viewthread.php?tid=74533#... ), which in themselves may not be hazardous items, is that the latter are not mentioned in the contents.

The warning labels, however, suggest toxic issues are possible based on further reactions with water and other items possibly added by the consumer (like bleach).

A bit confusing unless you have a full understanding of the legal disclosure rules and subsequent aqueous chemistry involved.

My suspicion in the case of the product war between H2O2 vs NaOCl based bleaches, was the need for the benign H2O2 camp to accelerate its power by a chemical conversion to a nasty organic peroxide which does, in fairness, eventually breakdown into harmless products. However, the persistent misconception of the safety of their H2O2 based percarbonate product may have led to injuries (and lawsuits) that now obviously requires some very pronounced changes in warning labels.

Bottom line, read the ingredients and all warning labels to surmise the true nature of the product you are buying!

[Edited on 17-8-2018 by AJKOER]

Dr.Bob - 17-8-2018 at 10:40

Rain x works by chemically bonding an octyl group to the Silicons in the glass, via

Triethoxyoctylsilane reacts with glass to form EtOH + glass--O-Si-O-Si(OEt)2-Octyl

This effectively leaves a chemically bonded "wax" on the surface of the glass, made of millions of octyl groups on the surface. Only it does not come off as easily as real wax, which is just a film on the glass, not chemically bonded. But the chemically bonded layer is only essentially one molecule think at each point, so it eventually comes off as base, fluoride or acid from the air/rain reacts with the glass.

RogueRose - 18-8-2018 at 02:21

After I looked at the various MDSD/SDS's for rain-x products I looked up the international agreement requiring SDS's and what was required to be listed for the products. It stated that all ingredients must be listed, concentrations/percentages could be given in ranges and if there is a unique "trade secret" ingredient which is not used by another company (IDK how this is determined) or is not public knowledge of what it is it has to be listed (as "trade secret or proprietary) and the actual percentage must be given. If the substance is toxic (as per the TSCA) then they must list the relevant medical information for the secret ingredient in a general way and must be willing to disclose the ingredient to a medical professional in an emergency.

What I read was pretty clear, I know I have seen a lot of SDS's that seem lacking in their component make-up but that doesn't mean that the SDS is "legit", meaning official or following the rules of the agreement. It is also very possible that there are many versions of the SDS, one that is submitted and one that is made much more public, which may omit some data. IDK, it seems one of those things where requirements don't match with what is happening and that could be some legal loophole or whatnot.

DavidJR - 18-8-2018 at 02:31

Would you be able to link your source for that?

RogueRose - 18-8-2018 at 03:28

These are some of the sites I looked over when I was researching it that are in my browser history. There were a couple others but IDK where they are.


http://www.ilpi.com/msds/ref/tradesecret.html

http://www.ilpi.com/msds/osha/1910_1200.html#1910.1200

http://www.msds-europe.com/safety-data-sheet-knowledge-base/

https://en.wikipedia.org/wiki/Safety_data_sheet

https://en.wikipedia.org/wiki/Toxic_Substances_Control_Act_o...

Deathunter88 - 18-8-2018 at 03:40

Quote: Originally posted by RogueRose  
After I looked at the various MDSD/SDS's for rain-x products I looked up the international agreement requiring SDS's and what was required to be listed for the products. It stated that all ingredients must be listed, concentrations/percentages could be given in ranges and if there is a unique "trade secret" ingredient which is not used by another company (IDK how this is determined) or is not public knowledge of what it is it has to be listed (as "trade secret or proprietary) and the actual percentage must be given. If the substance is toxic (as per the TSCA) then they must list the relevant medical information for the secret ingredient in a general way and must be willing to disclose the ingredient to a medical professional in an emergency.

What I read was pretty clear, I know I have seen a lot of SDS's that seem lacking in their component make-up but that doesn't mean that the SDS is "legit", meaning official or following the rules of the agreement. It is also very possible that there are many versions of the SDS, one that is submitted and one that is made much more public, which may omit some data. IDK, it seems one of those things where requirements don't match with what is happening and that could be some legal loophole or whatnot.


Your research seems to be incorrect or completely outdated. As per the recently adopted GHS system:

DISCLOSURE OF INGREDIENT NAMES
The chemical identity of an ingredient must be disclosed on an SDS in accordance with
Schedule 8 of the WHS Regulations (Disclosure of ingredients). In some cases, a generic
name may be used.
Ingredients that are not classified as hazardous but have an exposure standard and which are present above 1% should be mentioned in the SDS if it is likely that they might be released under standard storage and application conditions.
Disclosure of ingredient names is not required by the WHS Regulations for those ingredients that meet only physicochemical and/or environmental hazard classifications, or for nonhazardous
ingredients.
There is no requirement to disclose the identity of ingredients for the following GHS health hazard categories because they fall outside the scope of the WHS Regulations:
„ Acute toxicity – Category 5 (oral, dermal and inhalation)
„ Skin corrosion/irritation – Category 3
„ Serious eye damage/eye irritation – Category 2B
„ Aspiration hazard – Category 2
„ Aquatic toxicity (all categories)
„ Flammable gas – Category 2
„ Ozone depletion.

Source: https://www.safeworkaustralia.gov.au/system/files/documents/1705/mcop-preparation-of-safety-data-sheets-for-hazardous-chemicals-v1.pdf

For more information if you still insist otherwise:
https://www.chemsafetypro.com/Topics/GHS/GHS_cut_off_value_GHS_concentration_limit.html

EDIT: Ah yes, any site that still uses MSDS instead of SDS is outdated (as seen in your sources).

[Edited on 18-8-2018 by Deathunter88]

RogueRose - 18-8-2018 at 03:55

IDK what a GHS is but from what I have seen in the US the MSDS is the standard and is often called an SDS.

If you need to find what is in a product, what do you search for? If you need to find what is in "Windex" or some other product, what would you do a search for?

wildfyr - 21-8-2018 at 05:08

Rogue, you can argue about the SDS compliance but the fact remains the Rain-X products work by using alkoxy silanes. I've rotovapped it down and taken NMR before. Its there. Furthermore its a dead obvious way to do what their product does.

You can (gently) evaporate some down yourself and attempt to examine it. If it was only solvents, then there shouldn't be any residue.

GHS=Globally harmonized system. Its how SDS sheets are being standardized worldwide.

If you need to find out whats in a product you often have to use instruments yourself. Companies don't want to give away their secrets if at all possible, they spent big bucks having chemists work on those formulations. If any jackass could copy it, they would lose money.

This is a good site for household product ingredients from the US gov't, but it doesn't always have full info

https://hpd.nlm.nih.gov/cgi-bin/household/list?tbl=TblBrands...

you can also search by products containing a certain ingredient.


[Edited on 21-8-2018 by wildfyr]

DrP - 22-8-2018 at 00:53
Quote: Originally posted by RogueRose  
IDK what a GHS is but from what I have seen in the US the MSDS is the standard and is often called an SDS.

If you need to find what is in a product, what do you search for? If you need to find what is in "Windex" or some other product, what would you do a search for?


We called them MSDS's as the convention for many years. This was changed a few years back by REACH and the EU to simply, SDS to try to standardise things globally. The GHS is the 'Global Harmonised Standard' I think...

It standardises the hazard labelling used for transport, labelling and SDSs. Much better than 100s of different countries using their own individual labelling systems - it will avoid confusion in the long run. It is much safer that all of us use the same pictorials and statements for hazard identification.
Quote: Originally posted by wildfyr  
Rain-X products work by using alkoxy silanes. I've rotovapped it down and taken NMR before. Its there.
[Edited on 21-8-2018 by wildfyr]


Hi Wildfyr! :-) Good to see you here. I guess the silane sets up Si-H bonds on the surface of the glass to repel H2O? Is that how it works? (rather than being covered in surface hydroxyls which hydrogen bond to the water).

[Edited on 22-8-2018 by DrP]

wildfyr - 22-8-2018 at 06:53

Hey P! Ah, I should be more clear. No Si-H bonds involved, rather (RO)XSi-((CH2)XCH3)Y

The active ingredient in Rain-X is either a simple alkyl functionalized alkoxysilane like octyltriethoxysilane, or some oligomeric polyalklysiloxane-based derivative. Since Rain-X contains some water this distinction is pretty grey, alkoxysilanes will freely oligomerize and dissociate in a water containing solution. The nature and ratio of alkoxys is that of the alcoholic solvents. Methoxy silanes are most reactive, and longer chains are less reactive.

In such systems a catalytic amount of acid or base will cause condensation of the alkoxy silloxane with the surface silanols of glass. This is the reaction https://ars.els-cdn.com/content/image/1-s2.0-S1359835X100008...

In the case of Rain-X the R group is an alkane, which is the source of the hydrophobicity.

[Edited on 22-8-2018 by wildfyr]

DrP - 22-8-2018 at 07:12
Quote: Originally posted by wildfyr  
In the case of Rain-X the R group is an alkane, which is the source of the hydrophobicity.

[Edited on 22-8-2018 by wildfyr]


Ah - that makes sense, thanks - I though it might be a siloxane or something. If R is an alkane then it would repel water for sure.



Quote: Originally posted by wildfyr  
Hey P!


I did wonder if you would work out where I know you from :D lol. You did.

RogueRose - 22-8-2018 at 14:01

Quote: Originally posted by wildfyr  
Rogue, you can argue about the SDS compliance but the fact remains the Rain-X products work by using alkoxy silanes. I've rotovapped it down and taken NMR before. Its there. Furthermore its a dead obvious way to do what their product does.

You can (gently) evaporate some down yourself and attempt to examine it. If it was only solvents, then there shouldn't be any residue.

GHS=Globally harmonized system. Its how SDS sheets are being standardized worldwide.

If you need to find out whats in a product you often have to use instruments yourself. Companies don't want to give away their secrets if at all possible, they spent big bucks having chemists work on those formulations. If any jackass could copy it, they would lose money.

This is a good site for household product ingredients from the US gov't, but it doesn't always have full info

https://hpd.nlm.nih.gov/cgi-bin/household/list?tbl=TblBrands...

you can also search by products containing a certain ingredient.


[Edited on 21-8-2018 by wildfyr]


I wasn't trying to argue that there wasn't something else in it, I thought there was as well, but from looking at the rules for the MSDS/SDS (current to the time of the publication of the company provided MSDS - so they should have been compliant with THOSE rules at the time) there should't have been any other product in the solution besides the solvents - at minimum there should have been a listing of "trade secret" ingredient.

This is kind of frustrating when looking at MSDS even when the ingredients add to 100%, there could be somethign that isn't there, even in large percentages of 1-15%! I think companies do this because they know no one is going to check each product MSDS but I am assuming that they would be liable if that unlisted ingredient cause harm in some way, especially if it wasn't even listed as a trade secret and totally omitted!

There is one solvent/glue I was looking at that had Toluene, acetone, MEK and 15% of "trade secret" and listed all the medical precautions for all the others but nothing for the other ingredient. This stuff smells like super glue but with a much stronger punch (burns nose for hours) and I think it has to be the secret ingredient Now if something happened b/c the company didn't list the medical issues pertaining to the "trade secret" how can they be not liable? That is kind of rhetorical, but I'm just showing that there seems to be some seriously harmful stuff that isn't being listed in products data sheets.

Deathunter88 - 22-8-2018 at 16:15

Quote: Originally posted by RogueRose  
Quote: Originally posted by wildfyr  
Rogue, you can argue about the SDS compliance but the fact remains the Rain-X products work by using alkoxy silanes. I've rotovapped it down and taken NMR before. Its there. Furthermore its a dead obvious way to do what their product does.

You can (gently) evaporate some down yourself and attempt to examine it. If it was only solvents, then there shouldn't be any residue.

GHS=Globally harmonized system. Its how SDS sheets are being standardized worldwide.

If you need to find out whats in a product you often have to use instruments yourself. Companies don't want to give away their secrets if at all possible, they spent big bucks having chemists work on those formulations. If any jackass could copy it, they would lose money.

This is a good site for household product ingredients from the US gov't, but it doesn't always have full info

https://hpd.nlm.nih.gov/cgi-bin/household/list?tbl=TblBrands...

you can also search by products containing a certain ingredient.


[Edited on 21-8-2018 by wildfyr]


I wasn't trying to argue that there wasn't something else in it, I thought there was as well, but from looking at the rules for the MSDS/SDS (current to the time of the publication of the company provided MSDS - so they should have been compliant with THOSE rules at the time) there should't have been any other product in the solution besides the solvents - at minimum there should have been a listing of "trade secret" ingredient.

This is kind of frustrating when looking at MSDS even when the ingredients add to 100%, there could be somethign that isn't there, even in large percentages of 1-15%! I think companies do this because they know no one is going to check each product MSDS but I am assuming that they would be liable if that unlisted ingredient cause harm in some way, especially if it wasn't even listed as a trade secret and totally omitted!

There is one solvent/glue I was looking at that had Toluene, acetone, MEK and 15% of "trade secret" and listed all the medical precautions for all the others but nothing for the other ingredient. This stuff smells like super glue but with a much stronger punch (burns nose for hours) and I think it has to be the secret ingredient Now if something happened b/c the company didn't list the medical issues pertaining to the "trade secret" how can they be not liable? That is kind of rhetorical, but I'm just showing that there seems to be some seriously harmful stuff that isn't being listed in products data sheets.


Stop being so paranoid about everything. If anything, it makes no sense for companies to lie in their SDS's as some are no doubt citing it during legal disputes.

DrP - 23-8-2018 at 00:22

Quote: Originally posted by RogueRose  

I thought there was as well, but from looking at the rules for the MSDS/SDS (current to the time of the publication of the company provided MSDS - so they should have been compliant with THOSE rules at the time) there should't have been any other product in the solution besides the solvents - at minimum there should have been a listing of "trade secret" ingredient.


They only have to list what is hazardous on the SDS though... you do not need to give a complete ingredients list on a SDS, only a list of those chemicals that have a hazard classification with their percentages and the associated warnings. So they could well list all of the solvents on the SDS and not say what the polymer is if it isn't hazardous. Even if it IS hazardous, it still doesn't need to be listed on the SDS if it is under a certain percentage for its hazard classification.

It's just SDS now. MSDS is old terminology, although I do not know what the convention is in the USA - they are sometimes a century behind when it comes to global harmonization standards... look at SI units. SI units were globalized last century to avoid confusion and problems for collaborative work around the globe. There are only 3 countries not using SI units - Burma, Liberia and the USA. We still use pints and miles for shopping and travel here, but you have to get in line with international standards when collaborating on research and use SI units. A Globally Harmonised System for hazard labels is a no brainer also.