Shrink tube: are there different types?

Thread Starter

rambomhtri

Joined Nov 9, 2015
304
Hi, I've been using shrink tube to "professionally" repair cables, join them... but I've just been using one kind/brand from my local store. I bought different diameters, and still haven't run out of any of them. The other day I was repairing an audio cable, for headphones, and although the result was nice, my shrink tube gets so hard and rigid, so you have a nice flexible cable and suddenly a straight hard cable. In electric or electronic environments this is not a problem, but sometimes I need a shrink tube that is flexible once it's been heated.

I wonder if you can briefly explain to me the kind of different shrink tubes and its uses. If I search for shrink tube in Amazon or Aliexpress, I get thousands of results but I only see the 2:1 or 3:1 ratio information, that's all the information I get. For example, if I try to replace this headphone's transparent shrink tube (hope you can differentiate where it ends):


I end up with a rigid end, not flexible. So, useless since it can't fit your ear shape. Where do manufacturers get these tubes?
Is it better to have 3:1 ratio or 2:1? Or that's simply a different spec that one should use when required?
 

jpanhalt

Joined Jan 18, 2008
8,090
Oh, come on. There are many different types of shrink tubing -- from the common PVC today to Teflon to solvent expanded Tygon and similar prior to the 1970's. Be more specific. Here's a start: https://www.mcmaster.com/shrink-tubing

I particularly like the neoprene type for high durability on high current connections, like welding cables.

Edit: Almost any thermoplastic can be stretched and then re-shrunk with heat.
 
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Thread Starter

rambomhtri

Joined Nov 9, 2015
304
Oh, come on. There are many different types of shrink tubing -- from the common PVC today to Teflon to solvent expanded Tygon of the 1970's. Be more specific. Here's a start: https://www.mcmaster.com/shrink-tubing

I particularly like the neoprene type for high durability on high current connections, like welding cables.

Edit: Almost any thermoplastic can be stretched and then re-shrunk with heat.
Nice! That's a start!
Which one should I use for headphones?
It must be flexible and adapt and an ear shape.
 

jpanhalt

Joined Jan 18, 2008
8,090
I am not sure exactly where you intend to put the "heat-shrink." However, you seem to be asking for something with conflicting properties: 1) Rigid enough to keep an expanded shape until heat shrunk; and 2) Very soft and pliable.

I would start with something that met property #2 and then figure out how to apply it.
Examples:
1) You expand it, dip in liquid nitrogen so it keeps its shape, then apply and let warm.
2) Expand it in a vacuum (outer sleeve), place it over the wires, then release the vacuum and remove the outer sleeve.
3) Your very flexible rubber might come as a two-part RTV. Then you just mix, paint/dip wire, and let cure.
4) Many rubbers (e.g., foam rubber) expand and/or get really soft but do not dissolve in some solvents (e.g., carbon tetrachloride, chloroform). Expand in the solvent, apply, and let the solvent evaporate. That method was used long before heat-shrink became common and is mentioned in my post above.
 
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Thread Starter

rambomhtri

Joined Nov 9, 2015
304
I am not sure exactly where you intend to put the "heat-shrink." However, you seem to be asking for something with conflicting properties: 1) Rigid enough to keep an expanded shape until heat shrunk; and 2) Very soft and pliable.

I would start with something that met property #2 and then figure out how to apply it.
Examples:
1) You expand it, dip in liquid nitrogen so it keeps its shape, then apply and let warm.
2) Expand it in a vacuum (outer sleeve), place it over the wires, then release the vacuum and remove the outer sleeve.
3) Your very flexible rubber might come as a two-part RTV. Then you just mix, paint/dip wire, and let cure.
4) Many rubbers (e.g., foam rubber) expand and/or get really soft but do not dissolve in some solvents (e.g., carbon tetrachloride, chloroform). Expand in the solvent, apply, and let the solvent evaporate. That method was used long before heat-shrink became common and is mentioned in my post above.
Where?
Easy, a headphone cable got damaged and I want to put heatshrink tube to repair the cut/cover the joint. I want the repaired section to be flexible, not rigid, just like the headphone cable. Or, in these in-ear monitor headphones, that go around your ear, you put a piece of heatshrink there to cover and protect more the cable in that area, also makes it more comfy, and also it is used to hold a clip all along the heatshrink. The clip is used to make it a "memory" cable.

It has to be shrinkable because you introduce it by that end or a jack plug, which is bigger than the cable.
 

jpanhalt

Joined Jan 18, 2008
8,090
I would use a liquid that self-cures or thin-wall rubber (silicone or some other very soft rubber) tubing. I do not think a normal heat shrink will be soft enough.

Suggestions for the liquid would be any 2-part silicone or something like "Goop" (alternatively E6000 from Eclectic Products, http://eclecticproducts.com/downloads/tds-e6000-craft-english.pdf). E6000 cures very thin and is quite tenacious.

For a solid, I would consider a spaghetti/string balloon, e.g.:

upload_2019-10-16_7-0-14.png

or other thin wall, stretchy, soft rubber tubing.
 

Yaakov

Joined Jan 27, 2019
1,603
Where?
Easy, a headphone cable got damaged and I want to put heatshrink tube to repair the cut/cover the joint. I want the repaired section to be flexible, not rigid, just like the headphone cable. Or, in these in-ear monitor headphones, that go around your ear, you put a piece of heatshrink there to cover and protect more the cable in that area, also makes it more comfy, and also it is used to hold a clip all along the heatshrink. The clip is used to make it a "memory" cable.

It has to be shrinkable because you introduce it by that end or a jack plug, which is bigger than the cable.
Alpha Wire makes an irradiated silicone heatshrink tubing as well as many other materials. However the silicone is, if I recall correctly, only about 1:1.7 ratio. I would search for them online, though, since they offer a very good range.
 
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