Does Dyneema suffer from grease exposure?

[Franziska]

Hi,



got a bit of a special question.


We have a blank/raw Dyneema line running inside a polished stainless tube. It's used to control our large,pivoting wooden center board from deck.



I am wondering if lubing the Dyneema line with some grease inside the tube would allow the line move even easier inside the tube.



The line portion to be greased inside the tube is above the waterline and very far from the end splices.



Does anyone know if the Dyneema would somehow suffer from the grease exposure?

[hlev00]

You could ask at https://www.dyneema.com, but I imagine that something like a PTFE based grease should be fine. Also, Dyneema and similar materials are so slippery though that lube doesn't seem too beneficial and likely making more of a mess.

[s/v Jedi]

I agree that it shouldn’t be needed. If the Dyneema doesn’t feel slick as an eel, it’s time to replace it. The coating makes a lot of difference too. For now, my experience tells me to trust Samson Amsteel Blue with their Samthane coating. I simply don’t have enough experience with other brands but do know there’s bad ones out there.

[Franziska]

Originally Posted by hlev00

You could ask at https://www.dyneema.com, but I imagine that something like a PTFE based grease should be fine. Also, Dyneema and similar materials are so slippery though that lube doesn't seem too beneficial and likely making more of a mess.

Thanks.



I know it's very slippery :-) but, more slippery is better in this application.
The greasy portion will not see daylight for years (at least that is the plan) so messiness would not be an issue.

[s/v Jedi]

Originally Posted by Franziska

Thanks.

I know it's very slippery :-) but, more slippery is better in this application.
The greasy portion will not see daylight for years (at least that is the plan) so messiness would not be an issue.

But grease attracts dirt. I really think a clean Dyneema line will perform better.

[Franziska]

Originally Posted by s/v Jedi

But grease attracts dirt. I really think a clean Dyneema line will perform better.

Thanks, we will see how it works after relaunching in about 4 weeks time.


Will not apply grease before that. In the worst case I can do a little dive and grease it later...

[Benz]

Diesel oil will degrade Dyneema, so any grease related to diesel might be dangerous.
Marlow makes a silicone coating that I've used for Gunboat daggerboard lines, just to grease it through a lifting ferrule. I'd stick with silicone if anything was needed.

[Kd9truck]

[QUOTE=Benz;3849227]Diesel oil will degrade Dyneema, so any grease related to diesel might be dangerous.

I agree with Benz on this, I would not add any lubricant to dyneema as it has a very low friction rating. Avoid any solvent based lubricant and keep it away from everything as it will be the strongest hardest anything on your vessel, 316 SS not withstanding.

[ggray]

303 feels slippery to my fingers and puts a slippery finish on my inflatable.

I've lubricated plastics with it.

I'd use that before I would a grease.

[Franziska]

Originally Posted by ggray

303 feels slippery to my fingers and puts a slippery finish on my inflatable.

I've lubricated plastics with it.

I'd use that before I would a grease.

What iis 303?

[thinwater]

Originally Posted by Franziska

What iis 303?

Google 303 Products. A spray wax, sort of. At that rate, I wonder why no one mentioned Sailkote.

[thinwater]

Re. diesel or grease having an affect on Dyneema, what is the source of that information? DSM says no affect.



https://assets.ctfassets.net/q6qgec8...Resistance.pdf


I agree with the attraction of grit and wear from that source.

[Benz]

Originally Posted by thinwater

Re. diesel or grease having an affect on Dyneema, what is the source of that information? DSM says no affect.



https://assets.ctfassets.net/q6qgec8...Resistance.pdf


I agree with the attraction of grit and wear from that source.

My own experience is the source: a portion of Dyneema trampoline net frayed and essentially rotted, not from high traffic or long use, but because it was right next to the diesel fill that always dripped a few drops on it when filling up. I mended the spot with a patch of new netting, which also began to degrade. The rest of the original netting remained in good condition, despite traffic and abuse: the only difference was the diesel.

This is the only example I have, so not super-scientific, but to me it's telling. Perhaps it's a combo of diesel and sunshine? It'd be good to know how DSM tested theirs.

[thinwater]

Originally Posted by Benz

My own experience is the source: a portion of Dyneema trampoline net frayed and essentially rotted, not from high traffic or long use, but because it was right next to the diesel fill that always dripped a few drops on it when filling up. I mended the spot with a patch of new netting, which also began to degrade. The rest of the original netting remained in good condition, despite traffic and abuse: the only difference was the diesel.

This is the only example I have, so not super-scientific, but to me it's telling. Perhaps it's a combo of diesel and sunshine? It'd be good to know how DSM tested theirs.

That's good info. The problem is UHMPE (Dyneema) is made from polyethylene, the same stuff that every fuel tank is made from.


I think you hit on something, suggesting it might be the combination of diesel and sun. Dyneema is NOT invulnerable to UV, not even close. It is much better than PP, but on a rough par with polyester, for example. We know that polyethylene gas cans, for example, are not affected by fuel, but they are degraded by the sun. One of the reasons Amsteel can endure reasonably well in the sun is the polyurethane coating (Samthane). It also helps with abrasion. If the diesel degrades the coating, and polyurethane coatings have only limited diesel resistance, that combination would make the Dyneema more vulnerable to UV and abrasion.


So I think you have it. It is a combined effect. Good eye. As for any lubricant, with flexing they probably all degrade the coating to some extent, which would increase vulnerability to chafe. As others have said, if everything is clean, that is about the best you can do with polyethylene.

[Tupaia]

I would go with Silicone spray.