Chemical Components Of Silicone Grease

[DavyJones]

I recently took in a vintage MB piston filler to repair, and needed to apply some silicone grease. I started doing some research regarding what type of silicone grease to use, since this area seems to be somewhat gray, in the sense that many silicone grease products are not labelled with much detail beyond saying "SILICONE GREASE". I had some of the Danco branded product, which I picked up at Lowe's, and was curious if it had any fillers in it that I should be worried about. After doing some research I came up with the following... perhaps somebody can correct me if I'm wrong.

 

First of all the package is marked simply as "Silicone Grease", which, is a good start in my mind. It's also marked certified to ANSI/NSF-61, which apparently means its food grade (much like some of the other available products that are commonly used for this application). My final investigation was another marking on the package which reported CAS# 007631869. I did a quick google, and came up with a report from which I pulled the following information:

 

Material Safety Data Sheet Issue Date: 03/17/03

Section 1: Chemical Product and Company Identification

Cat#: 24298

Part Name: SILICA MICROSPHERES, 0.01 MICRON *(BROAD DISTRIBUTION)

Supplier: Polysciences, Inc.

400 Valley Road

Warrington, PA 18976

Telephone #215-343-6484

Section 2: Composition/ Information on Ingredients

Item# Name CAS# Fraction

1 Silicon oxide 007631869 0.4

2 Water 007732185 0.6

 

 

It seems the Danco product is widely distributed at some very large retail chains, and at around $3 for a little tub that will last a lifetime quite a bargain. I was at first skeptical because the product is labelled simply as "silicone grease" and not "100% silicone grease", but it would appear it is in fact 100%.

 

Likewise, I've seen many people touting the Dow Corning 111 product, which has the following reported makeup on its MSDS:

 

CAS Number / Wt % / Component Name

63148-62-9 / 70.0 - 90.0 / Polydimethylsiloxane

7631-86-9 / 7.0 - 13.0 / Silicon dioxide

Trade Secret / 5.0 - 10.0 / Silicone Metalloid Complex

 

 

So, obviously the Danco product is not petroleum based at all, but what is polydimethylsiloxane, and how are the two different? If the Danco product is so widely distributed, why not use it? Does the other product offer some sort of benefit? Is there a chemist in the house?

[Chi Town]

I'm waiting on an answer to this as well, as I have this product myself, Danco in it's unopened state......

[hedgehogmeister]

Disclaimer: I'm not a chemist, but I've taken a few lab classes in my time.

 

From http://en.wikipedia.org/wiki/Polydimethylsiloxane :

"Polydimethylsiloxane (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones.^[1] PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties."

 

You'll often encounter it in a 2-part mixture under a variety of tradenames (most common I've heard of is Dow Corning's "Sylgard"). One tub will contain relatively short (~200 monomer?) chains of PDMS monomer, the other some sort of catalyst which will encourage the oligo-DMS chains to make bigger ones, I guess.

 

From my experience, the short-chained PDMS product has about the consistency and lubricative properties of glycerin, although I imagine an unequal mixture of short+long chains could produce a viscosity similar to that of the silicone grease I've gotten from the hardware store. [short chain = more "fluid like"; long chains = "thicker fluid"; reaaaallly long chains = "hard jello"]

 

FWIW, PDMS is extremely inert, hence its use as a mold material for microchannels that cells get pushed down single file, or even small "bioreactors" where particular strains of bacteria can be grown with steady streams of fluid and nutrient to nourish the bacteria and flush away the waste products. That, and a quick look at the composition of a not-poly-DMS monomer (CH₃[si(CH₃)₂O]_nSi(CH₃)₃, a buncha Cs and Hs bonded to a Si) suggests that it's not gonna react with your pen parts at all.

 

tl;dr? go for it---if it's good enough for growing extremely valuable bacteria with rare mutations in biomedical research, it's good enough for your pen.

Edited June 15, 2014 by hedgehogmeister

[anideaweb]

I'm very interested in this topic as well. One thing to note though, possibly, is that the MSDS for the grease itself (I found it at http://www.homedepot.com/p/DANCO-0-5-oz-Silicone-Faucet-Grease-9D00088693/203193536) also lists silicone dioxide as one of the ingredients. I don't know if that would have any effect on the outcome of this discussion at all.

 

Amazon sells a tub of pure silicone grease for divers (http://www.amazon.com/Trident-Diving-Equipment-Silicone-Grease/dp/B001O768Z4/ref=sr_1_2?ie=UTF8&qid=1402835163&sr=8-2&keywords=trident+silicone+grease). And the MSDS sheet (http://www.tridentdive.com/aalp20.pdf) for this one lists DIMETHYLPOLYSILOXANE as the only ingredient.

Edited June 15, 2014 by anideaweb

[DavyJones]

So here's what I see as the big question... and this is totally based off of the wording. Wouldn't 100% pure silcon dioxide also be 100% pure silicone? I know there is a difference between silicon and silicone, but I'm not quite sure how that would apply to this situation.

See video below. The chemist that hosts this video series is hilarious... and quite educational.

[DavyJones]

I often find myself replying to my own posts the most

 

I re-watched the video and the professor says that a silicone is simply silicon atoms that share a bond with oxygen... therefore, wouldn't silicon dioxide in the Danco product be silicone?

[MarkTrain]

Dimethylpolysiloxane is a thick oil. Silca (SiO2) is added as a thickener to make it a grease.

 

Also, the refernece to CAS# 007631869 in the OP post is incorrect as it refers to colloidal silica not silicone grease. Colloidal silica is an aqueous suspension of silica, definitely not a grease.

 

Silca is not silicone. Silica is a hard mineral (quartz) present mainly in sand or glass. Silicone is an organosiloxane, ie it has hydrocarbon groups (methyl).

 

Mark

Edited June 15, 2014 by MarkTrain

[DavyJones]

 

Also, the refernece to CAS# 007631869 in the OP post is incorrect as it refers to colloidal silica not silicone grease. Colloidal silica is an aqueous suspension of silica, definitely not a grease.

 

...

 

Silicone is an organosiloxane, ie it has hydrocarbon groups (methyl).

 

 

I'm just stating what is marked on the packaging. The colloidal silica product is being sold as silicone grease, which, apparently may be misleading.

 

Also...

 

Would those hydrocarbon groups add a petroleum type element to the compound, therefore making it unsafe to use with plastics, o-rings, etc.?

Edited June 15, 2014 by DavyJones

[MarkTrain]

 

 

Would those hydrocarbon groups add a petroleum type element to the compound, therefore making it unsafe to use with plastics, o-rings, etc.?

No. The hydrocarbon groups make silicone what it is. Without them silicone would be hard as a rock. Silcones are quite diferent from petrochemicals because of the C-Si bond.

Edited June 15, 2014 by MarkTrain

[DavyJones]

So, my take away from this is:

 

The Danco product while labelled as Silicone Grease is not really grease, rather colloidal silicon, which does not have the same lubricating properties as true silicone grease.

i would feel confident in using it as a seal for converting a pen to an eyedropper, but would not use it as a true lubricant for a piston filling mechanism.

[MarkTrain]

So, my take away from this is:

 

The Danco product while labelled as Silicone Grease is not really grease, rather colloidal silicon, which does not have the same lubricating properties as true silicone grease.

i would feel confident in using it as a seal for converting a pen to an eyedropper, but would not use it as a true lubricant for a piston filling mechanism.

Actually, I checked in my workshop and I have some Danco silicone grease and it is definitely not colloidal silicon, which would wash off with water while the Danco stuff is waterproof. As far as I can tell the Danco silicone grease is identical in appearance and working properties to my Dow Corning high vacuum silicon grease. The ANSI/NSF-61 marking indicates it is food grade. The CAS#007631869 does not tell what this is made out of but rather just indicates that this stuff contains silca (used as a thickener), which is classified as an irritant and as such hazardous.

[DavyJones]

Actually, I checked in my workshop and I have some Danco silicone grease and it is definitely not colloidal silicon, which would wash off with water while the Danco stuff is waterproof. As far as I can tell the Danco silicone grease is identical in appearance and working properties to my Dow Corning high vacuum silicon grease. The ANSI/NSF-61 marking indicates it is food grade. The CAS#007631869 does not tell what this is made out of but rather just indicates that this stuff contains silca (used as a thickener), which is classified as an irritant and as such hazardous.

 

I'm very interested in this topic as well. One thing to note though, possibly, is that the MSDS for the grease itself (I found it at http://www.homedepot.com/p/DANCO-0-5-oz-Silicone-Faucet-Grease-9D00088693/203193536) also lists silicone dioxide as one of the ingredients. I don't know if that would have any effect on the outcome of this discussion at all.

 

tl;dr? go for it---if it's good enough for growing extremely valuable bacteria with rare mutations in biomedical research, it's good enough for your pen.

 

 

I'm waiting on an answer to this as well, as I have this product myself, Danco in it's unopened state......

 

I quoted all interested parties so they would get a flag to come back and check this post. I went and pulled the MSDS for the Danco product and have included it here. Apparently I need to learn how to read, because I totally missed anideaweb's post stating they did the exact same thing. It appears the Danco product is very similar to the Dow Corning product, minus the "trade secret", and therefor should be perfectly safe for use. The big plusses here are that it is WIDELY available without having to order from someone online, and is cost effective. Yay for research and pooled knowledge!

[DavyJones]

Also, I gather that 100% pure Polydimethylsiloxane would be an oily liquid, and that any of the silicone greases being sold have to have sme sort of thickening agent added.

[Sach]

I recently took in a vintage MB piston filler to repair, and needed to apply some silicone grease. I started doing some research regarding what type of silicone grease to use, since this area seems to be somewhat gray, in the sense that many silicone grease products are not labelled with much detail beyond saying "SILICONE GREASE". I had some of the Danco branded product, which I picked up at Lowe's, and was curious if it had any fillers in it that I should be worried about. After doing some research I came up with the following... perhaps somebody can correct me if I'm wrong.

 

First of all the package is marked simply as "Silicone Grease", which, is a good start in my mind. It's also marked certified to ANSI/NSF-61, which apparently means its food grade (much like some of the other available products that are commonly used for this application). My final investigation was another marking on the package which reported CAS# 007631869. I did a quick google, and came up with a report from which I pulled the following information:

 

Material Safety Data Sheet Issue Date: 03/17/03

Section 1: Chemical Product and Company Identification

Cat#: 24298

Part Name: SILICA MICROSPHERES, 0.01 MICRON *(BROAD DISTRIBUTION)

Supplier: Polysciences, Inc.

400 Valley Road

Warrington, PA 18976

Telephone #215-343-6484

Section 2: Composition/ Information on Ingredients

Item# Name CAS# Fraction

1 Silicon oxide 007631869 0.4

2 Water 007732185 0.6

 

 

It seems the Danco product is widely distributed at some very large retail chains, and at around $3 for a little tub that will last a lifetime quite a bargain. I was at first skeptical because the product is labelled simply as "silicone grease" and not "100% silicone grease", but it would appear it is in fact 100%.

 

Likewise, I've seen many people touting the Dow Corning 111 product, which has the following reported makeup on its MSDS:

 

CAS Number / Wt % / Component Name

63148-62-9 / 70.0 - 90.0 / Polydimethylsiloxane

7631-86-9 / 7.0 - 13.0 / Silicon dioxide

Trade Secret / 5.0 - 10.0 / Silicone Metalloid Complex

 

 

So, obviously the Danco product is not petroleum based at all, but what is polydimethylsiloxane, and how are the two different? If the Danco product is so widely distributed, why not use it? Does the other product offer some sort of benefit? Is there a chemist in the house?

I'm waiting on an answer to this as well, as I have this product myself, Danco in it's unopened state......

Disclaimer: I'm not a chemist, but I've taken a few lab classes in my time.

 

From http://en.wikipedia.org/wiki/Polydimethylsiloxane :

"Polydimethylsiloxane (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones.^[1] PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties."

 

You'll often encounter it in a 2-part mixture under a variety of tradenames (most common I've heard of is Dow Corning's "Sylgard"). One tub will contain relatively short (~200 monomer?) chains of PDMS monomer, the other some sort of catalyst which will encourage the oligo-DMS chains to make bigger ones, I guess.

 

From my experience, the short-chained PDMS product has about the consistency and lubricative properties of glycerin, although I imagine an unequal mixture of short+long chains could produce a viscosity similar to that of the silicone grease I've gotten from the hardware store. [short chain = more "fluid like"; long chains = "thicker fluid"; reaaaallly long chains = "hard jello"]

 

FWIW, PDMS is extremely inert, hence its use as a mold material for microchannels that cells get pushed down single file, or even small "bioreactors" where particular strains of bacteria can be grown with steady streams of fluid and nutrient to nourish the bacteria and flush away the waste products. That, and a quick look at the composition of a not-poly-DMS monomer (CH₃[si(CH₃)₂O]_nSi(CH₃)₃, a buncha Cs and Hs bonded to a Si) suggests that it's not gonna react with your pen parts at all.

 

tl;dr? go for it---if it's good enough for growing extremely valuable bacteria with rare mutations in biomedical research, it's good enough for your pen.

Dimethylpolysiloxane is a thick oil. Silca (SiO2) is added as a thickener to make it a grease.

 

Also, the refernece to CAS# 007631869 in the OP post is incorrect as it refers to colloidal silica not silicone grease. Colloidal silica is an aqueous suspension of silica, definitely not a grease.

 

Silca is not silicone. Silica is a hard mineral (quartz) present mainly in sand or glass. Silicone is an organosiloxane, ie it has hydrocarbon groups (methyl).

 

Mark

Silicone is a polymer of alternating silicon and carbon atoms..

 

------C-Si-C-Si-----

 

There are also two other bonds on each of the silicon or carbon atoms, since both have a valence of four, but that's the basic structure.

 

Mustn't confuse element silicon with polymer Silicone...!

Edited June 16, 2014 by Sach

[MarkTrain]

 

Silicone is a polymer of alternating silicon and carbon atoms..

 

------C-Si-C-Si-----

 

There are also two other bonds on each of the silicon or carbon atoms, since both have a valence of four, but that's the basic structure.

 

Mustn't confuse element silicon with polymer Silicone...!

This is incorrect. Organosiloxanes have a Si-O-Si-O backbone with the alkyl groups hanging off the Si's. The general formula for organosiloxanes is (R2SiO)n where R is a methyl group for polydimethylsiloxane.

Edited June 16, 2014 by MarkTrain

[Sach]

This is incorrect. Organosiloxanes have a Si-O-Si-O backbone with the alkyl groups hanging off the Si's. The general formula for organosiloxanes is (R2SiO)n where R is a methyl group for polydimethylsiloxane.

Yes you are correct. My mistake, thanks for the correction!

Edited June 16, 2014 by Sach

[GG917]

ploydimethylsiloxane can either be a thick oil or grease-like in appearance, it just depends on the length of the chains. Same as for butane and candle wax: same stuf (polyalkanes), the one in candle wax is longer.

 

Silica (a form of silicon oxide) is more like an abrasive than a lubricant. Colloidal silica can maybe do the job (not really my field in chemistry).

[OcalaFlGuy]

All of this whole thread for something that costs a whole $2 from Anderson pens?

 

Really?

 

You're kidding me, right?

 

Bruce in Ocala, Fl

[Mr.Rene]

Good point Bruce...

Collectors world is a bit freaky...

[pen2paper]

it is a little freaky.. but, as a person who likes old and some new pens, the word silica, (abrasive) was worrying me..

ok, back to my quiet place ; )