silicone paste vs silicone grease vs silicone spray lube
October 9, 2019 4:26 PM   Subscribe

What are the differences? What are the pros and cons ,and suited uses, of each? Hopefully someone here can sort this out for me. Also, where possible, can you please cite reputable sources for the info because I have seen many people claim personal knowledge that contradicts other people's personal knowledge. Such is the internet, I know. Thanks!
posted by atm to Home & Garden (8 answers total) 2 users marked this as a favorite
There are lots of formulations of silicone lubricants. Each have specific use cases. Silicone oil has the following properties which can be useful under certain circumstances:
  • temperature stability;
  • vacuum tolerance;
  • electrical insulation;
  • compatibility with many rubber and plastic compounds.
So if you have a lubrication situation where there are rubber o-rings involved, or if you need electrical insulation, or you're working in crazy hard vacuum situations and you don't want the lubricant to vaporize, it's likely to be a silicone-based compound you use. But it'll likely be a different formulation for each one of those.

Maybe if you have a specific need you can tell us about, rather than expecting all of the specs for all of the silicone compounds to flow into this thread, it might cut down on the anecdata.
posted by scruss at 8:18 AM on October 10, 2019 [1 favorite]

Sorry for the over-broadness, scruss.

I am really trying to find when, and when not, to use these options in home/auto and maybe common light industrial situations that I, as a diy-er, might find myself in. No crazy hard vacuum situations, haha. ANd no need for tons of specs...

posted by atm at 9:16 AM on October 10, 2019

Okay, so if you can find the Technical Data Sheet for each product, they'll usually cover it. F'rinstance, here's the one for 3M 08946 Silicone Paste (the tub of goop you can buy almost anywhere). The product uses list on p.2 is incredibly diverse. The only application they don't mention is metal-to-metal lubrication, which is maybe why 3M call it paste rather than grease.

(if I remember my tribology lectures from decades ago, grease is a very specific thing: something like lubricant suspended in a metal-salt soap. I suspect most silicone "greases" are actually pastes, as you wouldn't want all the great things that only silicone can do to be messed up by a fluid that can melt, catch fire, separate, emulsify, ...)
posted by scruss at 12:39 PM on October 10, 2019 [1 favorite]

I understand what you're saying, and (I probably should have said originally) I have read 3m's descriptions of their products, but the reason I'm here is that there seems to be a lot of overlap in the descriptions.

What my question is asking is for a direct compare/contrast of silicone paste vs grease vs spray lube as they would apply to situations I might encounter (described above). I'm hoping there will be someone who is familiar with the differences.
posted by atm at 1:34 PM on October 10, 2019

Maybe it would be more helpful to frame this as a general question about what type of lubricant to use when.

For a home DIYer who isn't concerned about vacuum tolerance, I think the main reasons you might want silicone over a petroleum-based lubricant are flame-retardance and non-reactivity with rubber and plastics. Beyond that sort of thing, the form of lubrication is mostly going to be determined by the application, regardless of the ingredients.

For instance, sewing machine oil is very low viscosity, so that all the tiny moving parts don't get gunked up with greasy fabric dust. On the other hand, if you're lubricating o-rings, you'd use a thicker grease because it will stay in place better and make for a tighter seal. I'm no expert but apparently this is hotly debated topic (also this).
posted by yeahlikethat at 3:23 PM on October 10, 2019

Silicone won't harm rubber so I use it when rubber is involved. For lubrication and/or protection. My question was about the differences between those forms of silicone products.

I have read that the spray lube may also contain petroleum products (which makes it inappropriate for rubber), but maybe the difference between the grease and the paste is too subtle for anyone except industry experts to know.
posted by atm at 7:49 PM on October 10, 2019

So I went ahead and bought some silicone paste. Compared with the silicone grease I already had, the paste is much thicker.

For future searchers, maybe the difference between the paste and the grease is just in the thickness.

Before marking this questions as resolved, I'll wait a little bit longer to see if anyone who really knows comes along.
posted by atm at 3:08 PM on October 11, 2019

If you want specifics from my 10+ years as a field service person and 25+ years of repairing bikes:

Silicone grease (two specific applications using different formulations):
  1. water displacement/lubricant between an O-ring and a Delrin clutch in a gear shifter (regular grease would cause the mechanism to swell and jam)
  2. packing a bike hub brake mechanism for heat dissipation.
Silicone paste (essentially the same stuff in all cases):
  1. packing for a switch box to suppress sparking, prevent water ingress and improve heat dissipation
  2. o-ring, gasket and gland prep for remote weather-tight instrumentation boxes(only as specified by manufacturer)
  3. stuffing material between o-ring seals between the case and shaft of a small slow-speed metering pump
  4. coating terminals of bike lighting systems to prevent corrosion.
Silicone spray:
  1. better-than-nothing water displacer for bike chains
  2. water displacer in bike lighting terminal boxes
  3. tyre wall shining (a different spray, but basically silicone oil).

posted by scruss at 6:43 PM on October 11, 2019 [1 favorite]

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