Old Silicone...

[Steve Firth]

Jersey is one of the Channel Islands.

You see I can post something that's "right" amd also irrelevant.

I'll spell it out. Diesel is perfectly capable of softening silicone. I mentioned this in a previous post.

So rattling on that naptha is a general name for petroleum spirity (true) and that it isn't the active ingredient (false) shows a remarkable talent for ignoring that which went before.

And everything you posted was largely irrelevant and another example of the sort of comment that I referred to.

[Cicero]

==============================================================================

I think that 'O' ring refers to the cross section of the ring rather than the fact that it is circular. If this is the case you might make a

*gasket* but I doubt if you could make a true 'O' ring which usually fits slightly proud into a concave groove.

Cic.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Spamlet" saying something like:

Hmm. First time I discovered the incompatibility of silicone sealant (proper gasket stuff) and petrol was approx 1977 on a VW Beetle carb.

[Spamlet]

Don't know what you are getting your sealers in, but most of mine come with nozzles that can be cut to produce any width of round section bead up to about 5 or 6mm. Quite worth experimenting with seals - as the poster described. And as I already noted, using this stuff wet, as gasket can be dodgy, s you don't know how much is being squeezed into the device you are sealing and some of it can easily end up blocking jets, and air or oilways. Indeed, I often used to find it in the bottom of bike carb float chambers.

S

[Spamlet]

Your observation of diesel's solvent properties was not in dispute, and I was pleased that this led me to rediscover solvent principles that I had forgotten. I found it all relevant, but am sorry if you found it unhelpful.

S

[Cicero]

==============================================================================

==============================================================================

There is a big difference in the way that 'O' rings and gaskets work. Gaskets, either solid (paper etc.) or liquid (squeezed from tube - e.g. Hermetite) are compressed between two flat faces.

'O' rings are circular solid rubber rings with circular cross section and are usually fitted into a concave groove in a part which is then pushed into another part to make a seal. There is no mechanical flattening of the 'O' ring except by the difference in diameters of the two parts.

Cic.

[Spamlet]

I think we all rather took that a read before making our various remarks on the topic. Rather difficult to do any mechanics without finding this out for one's self don't you think? ;-)

S

[Cicero]

==============================================================================

==============================================================================

==============================================================================

Not really, since you said,

"... the 'o' ring seals in our 25 litre drums of iso propyl alcohol looked exactly as if they were indeed made by just a circle of blue RTV bead: and I will now think of making o rings like that in future."

That comment suggests a lack of knowledge of 'O' rings, how they're made and their uses. I merely offered a bit of helpful information to clarify, which is the purpose of this group.

Cic.

[Spamlet]

Sorry if I gave that impression. In the STC labs where I first worked, we even made our own silicon rubber on occasion. And the soft blue o-ring 'like' if you prefer, seals in the caps of our IPA drums did look as if they had simply been made by squirting a bead into a former much as I had envisaged must be being done by the poster (I actually kept quite a few of them for this purpose and have even cut them down to size for other uses, sticking the ends with superglue.). I would have no hesitation in trying to make seals for non critical uses in this manner, though one has to be careful of air bubbles (at STC we used to degas samples under vacuum before pouring). And also, while the term 'ring' might usually be met with the round things we have in our garden hoses, in vehicle alternatives to gaskets, as being discussed, the 'o ring' in question is often a very long and winding bead that loops up and down between all the convolutions of a say rocker box cover, and can be a right pain to keep in place without pinching - so much so that it itself often gets stuck in with 'gasket' goo...

And we have covered the subject in more detail recently too.

S