Gasket lube or not?

[northernone]

A thread post got me thinking.

Many of the shallow waterproof compact cameras use gaskets instead of orings to seal the battery/port/memory card doors.

They come with a sheen of lube when new but no mention of ongoing lubricant beyond the warning of removing sand and other debris. Also the suggested 130$ annual seal replacements on the tough series.

What is your experience with using the gaskets 'dry' or do you add inert lube?

Could lube reduce a gasket's sealing abilities?

Curious,
Cameron

P.s. Yes, the wrong lube can chemically react with rubber or silicone seal.

 

[snowdog61]

A gasket is used to compensate for the minor surface irregularities that exist between the mating surfaces, and with adequate compression, to provide the seal. A perfectly lapped/mated surface wont need a gasket as the fluids' (gas or liquid) viscosity typically will prevent flow. An o-ring needs a small amount of lubrication to allow it to move & compress as the parts are brought together rather than snag and possibly tear (for static o-rings). Obviously if it's dynamic, it has to continuously move/slide so it gets a little additional lube beyond what is needed for a static case. So for a true flange-to-flange gasket, you typically do not use a lube/sealant unless there is a concern over the surface finish or flatness of the parts.

 

[fmerkel]

If it is a clamshell type (2 halves on a hinge) you absolutely need some lube. My wife did not once and the force/friction of closing the shell extruded a loop of gasket. She did not notice. >>>flood!
If it is a static press fit, you could debate the necessity. Me, I'd lube.

 

[KeithG]

If it is a clamshell type (2 halves on a hinge) you absolutely need some lube. My wife did not once and the force/friction of closing the shell extruded a loop of gasket. She did not notice. >>>flood!
If it is a static press fit, you could debate the necessity. Me, I'd lube.

Was this a gasket or an oring?

 

[fmerkel]

How do you define that? It was a great big O-ring that sits in a groove. It is easily removable. This is pretty typical of these kind of housings for compacts. There is a shearing force with closing, and the clasp only holds it closed. It does not really contribute to water tightness, just keeping it closed.

Her prior Nikon p5000 had a similar O-ring but the back did not pivot in. It was held in with straight pressure by 4 clamps. The clamp pressure is absolutely critical. I guess I think of that more as a gasket, but it was a similar large O-ring. It was removable but with more difficulty being more captive in a groove. Lube was not critical.

 

[KeithG]

How do you define that? It was a great big O-ring that sits in a groove. It is easily removable. This is pretty typical of these kind of housings for compacts. There is a shearing force with closing, and the clasp only holds it closed. It does not really contribute to water tightness, just keeping it closed.

Her prior Nikon p5000 had a similar O-ring but the back did not pivot in. It was held in with straight pressure by 4 clamps. The clamp pressure is absolutely critical. I guess I think of that more as a gasket, but it was a similar large O-ring. It was removable but with more difficulty being more captive in a groove. Lube was not critical.

A gasket is used between 2 smooth (normally flat) mating surfaces. Hence gaskets are (normally) flat as well. Think of a head gasket for an engine.

An oring fits into a groove and requires the groove to form a seal. Technically an oring is a type of gasket.

But in common use the term gasket means the flat mechanical seal while an oring is an oring gasket. They work differently and need to be treated differently.

 

[KeithG]

as per snowdog, there is no need to lube a gasket. it will not help form a seal. it can only harm the seal by attracting stuff or causing the gasket material to breakdown.

To add to the confusion there are "liquid gasket" products out there. These do cure to form a gasket or can be used to try help fix up a damaged gasket.

 

[fmerkel]

What I was describing then is most clamshell type housings use an O-ring.
The Nikon p5000 Fantasea housing was using an O-ring as a gasket. It is not flat. The groove it's in can collect debris. Personally I think best practice is to remove it, clean the groove, clean the O-ring, lube it lightly, and re-install.
Now, if the sealing area was dead flat with nowhere to collect debris you could just wipe off the mating surfaces and use it.