Dyneema; difficult to cut?

[Cerebus]

I have read that some people think dyneema is difficult to cut or own special cutting devices.

I have been splicing and making soft shackles for a few years and use a normal knife. It cuts as easily as any other rope I have found (my knives are sharp and honed).

What if anything is going on?

Is there a disparity?

 

[ChromeDome]

Different grades could explain it

Grade Key Properties SK75 Original standard strength SK78 Same strength as SK75 but with improved creep resistance and elongation. SK90 10-15% stronger than SK75/78, but similar creep to SK75. Largely replaced by SK99. SK99 20% stronger than SK78 with equivalent creep resistance DM20 Lower strength than SK78 but near-zero creep. 3G12 Optimized for cut protection (Diamond Technology) Bio-based Sustainable variant with identical performance to fossil-based Dyneema.

 

[justanothersailboat]

Maybe the reputation comes from people trying to cut it with scissors. It seems difficult to cut with ordinary scissors for some reason. Tendency to slide out and maybe ordinary scissors' idea of sharp isn't sharp enough? Very sharp knife seems fine to the limited extent I have tried. With a slightly less good knife it seems very easy to break up the end into a mess that's a nuisance to tidy up. I bought "dyneema scissors", I am fairly sure these are not essential, but they have a very fine sharp serration and do work.

 

[Roberto]

Industrial scissors for technicians operating with optical fibers (which have hmpe or aramid textile cover) work very well and cost about 10-15e.

 

[Cerebus]

Different grades could explain it

Grade Key Properties SK75 Original standard strength SK78 Same strength as SK75 but with improved creep resistance and elongation. SK90 10-15% stronger than SK75/78, but similar creep to SK75. Largely replaced by SK99. SK99 20% stronger than SK78 with equivalent creep resistance DM20 Lower strength than SK78 but near-zero creep. 3G12 Optimized for cut protection (Diamond Technology) Bio-based Sustainable variant with identical performance to fossil-based Dyneema.

Perhaps this is the reason.

But I have never had any trouble cutting dyneema or Kevlar (admittedly no Kevlar over 5mm in diameter)

I have bought from various sources over many years, so not sure of grade of dyneema.

Some from a mountaineer had an excellent braid/ sleeve/ cover. It was only 10mm but cut very easily.

Thickest was 2.5 inches to make a soft shackle for towing vehicles / recovery and I could still cut it easily.

My knives are sharp (can shave with them) and cut paper very easily; I do sharpen and then hone the blades with leather strop.

Will search for 3G12 because I don’t think I have tried that.

 

[Cerebus]

Different grades could explain it

Grade Key Properties SK75 Original standard strength SK78 Same strength as SK75 but with improved creep resistance and elongation. SK90 10-15% stronger than SK75/78, but similar creep to SK75. Largely replaced by SK99. SK99 20% stronger than SK78 with equivalent creep resistance DM20 Lower strength than SK78 but near-zero creep. 3G12 Optimized for cut protection (Diamond Technology) Bio-based Sustainable variant with identical performance to fossil-based Dyneema.

Also an excellent piece of information in tabular form, thank you.

 

[stranded]

I’d be interested in any experience with 3G12 - I’ve a fancy to make a bike lock from dyneema on the basis that because it is so light I could have a long length to secure everyting: it would be risky for a bike thief to be caught (as if) carrying a very sharp knife and maybe the favourite tools of bolt cutter or angle grinder wouldn’t work.

As well as a shorter stout steel lock, not instead of. At least it might bamboozle and thus deter them a bit.

 

[Cerebus]

I’d be interested in any experience with 3G12 - I’ve a fancy to make a bike lock from dyneema on the basis that because it is so light I could have a long length to secure everyting: it would be risky for a bike thief to be caught (as if) carrying a very sharp knife and maybe the favourite tools of bolt cutter or angle grinder wouldn’t work.

As well as a shorter stout steel lock, not instead of. At least it might bamboozle and thus deter them a bit.

First to find a YouTube video wins.

I have never heard of it, so eager to search.

 

[Cerebus]

I can only find gloves made of the cut resistant dyneema.

I own Kevlar cut resistant gloves for working with non- sailing things.

Have not heard of dyneema gloves before. New day.

Dyneema®

Searching in general stated dyneema was difficult to cut.

Perhaps I have only owned the cheapest stuff or perhaps my knives were good? But I have found dyneema to cut as easily as any other line so far.

The search for the G-dyneema continues.

 

[stranded]

First to find a YouTube video wins.

I have never heard of it, so eager to search.

Sounds like it might be OK if they try to shoot my bike…

3G12 Dyneema is a high-performance composite armor material that leverages the exceptional properties of Dyneema, a brand of ultra-high molecular weight polyethylene (UHMWPE) fibers produced by DSM (now Avient). “3G12” typically refers to a lay-up configuration used in ballistic armor systems, especially in hard armor plates.

Here’s a detailed breakdown:

What Is 3G12 Dyneema?

3G12 is not a standalone material but rather a lay-up code referring to a specific composite layering configuration involving 12 plies of third-generation Dyneema unidirectional (UD) fabric. It’s a standardized format for certain ballistic and armor applications.

“3G”: Third-generation Dyneema
“12”: 12 plies (layers) of UD fabric

Each ply in a Dyneema composite is made of parallel, unidirectional fibers that are cross-laid at 0°/90° angles in pairs and bonded together with a low-density thermoplastic resin.

Properties of Dyneema (UHMWPE)

High Strength-to-Weight Ratio: Dyneema is up to 15 times stronger than steel (per weight).

Lightweight: Extremely low density (~0.97 g/cm³) – it floats on water.

High Energy Absorption: Excellent for ballistic impact and fragment protection.

Low Backface Deformation: Reduces trauma to the wearer.

UV and Moisture Resistance: Resists environmental degradation.


Ballistic Performance

3G12 Dyneema composites are used in:

• Level III/III+ rifle plates (NIJ 0101.06 or newer 0101.07 standards)
• Vehicle armor and composite applique panels
• Ballistic shields

Typical characteristics in ballistic plates

• Multi-hit performance
• Capable of stopping 7.62x39mm, 5.56x45mm, and even some armor-piercing rounds (with hybrid configurations)
• Often combined with ceramics (e.g., SiC, B4C) in hard armor plates

Advantages

• Lightweight protection vs. ceramic-only or steel plates
• Durability in extreme conditions
• Corrosion and moisture resistance
• Excellent energy dispersion during ballistic impacts

Limitations

• Thermal sensitivity: UHMWPE can deform at temperatures above ~80°C (176°F)
• Cost: Generally more expensive than aramid (e.g., Kevlar) or steel
• Edge performance: Needs proper sealing and handling during manufacturing

 

[Cerebus]

I’d be interested in any experience with 3G12 - I’ve a fancy to make a bike lock from dyneema on the basis that because it is so light I could have a long length to secure everyting: it would be risky for a bike thief to be caught (as if) carrying a very sharp knife and maybe the favourite tools of bolt cutter or angle grinder wouldn’t work.

As well as a shorter stout steel lock, not instead of. At least it might bamboozle and thus deter them a bit.

How would you use it along with the usual bike lock?

A soft shackle to bambozzle them? Some can be complicated to undo, so could work against the thieving what- nots.

 

[stranded]

Yeah, thought a soft shackle. Nothing will stop them if they’re determined enough - the aim is to make them think bugger this for a lark and move onto something else.

 

[stranded]

Possibly particularly suitable to my level of bike - expensive enough to seem like a fortune to me but way short of the bike bling around these day, so not worth the bother to a pro.

 

[Cerebus]

Yeah, thought a soft shackle. Nothing will stop them if they’re determined enough - the aim is to make them think bugger this for a lark and move onto something else.

Yes, one of the soft shackle designs is bound to confuse the small minded thieving miscreants.

Some of the designs confused me when they first came out and I was smarter when I was younger and used to rope work.