The type of plastic often used to wrap cheese intrigues me - it is a devil
to start a tear but once a tear is started ot goes all over the place with
no effort.

What is going on with the material properties?

On Sat, 16 Apr 2016 16:12:15 GMT
DerbyBorn wrote:

The type of plastic often used to wrap cheese intrigues me - it is a
devil to start a tear but once a tear is started ot goes all over the
place with no effort.

What is going on with the material properties?

The same with the stuff that radishes are wrapped in. Almost impossible
to start an opening, but once you have, it's no use as a wrapper any
more.

It's all the responsibility of The Organisation, aka a TV series of many
years ago, in which Donald Sinden was the head of a company whose sole
purpose was to make life difficult for people. Examples we
Food Wrappers, as here, that drove people to distraction and even
murder; and a little old lady in a blue Mini driving continuously
around a roundabout with the left flashers on.

--
Davey.

On 16/04/16 17:12, DerbyBorn wrote:
The type of plastic often used to wrap cheese intrigues me - it is a devil
to start a tear but once a tear is started ot goes all over the place with
no effort.

What is going on with the material properties?


It's from the same lab as the bags used to contain frozen fruit!

The first attempt at confounding the public was to vacuum pack sliced meats
with a transparent piece over the top so you cannot tell how much water was
added to make the weight up, they used to leave a corner free to pull it off
with, but that was far too easy so now they glue it down firmly all the way
around the edges, and then when you pierce it, usually with a tip of a
fork, there is not enough to cover the meat up again so you need a bag or
clingfilm to do that. It seems to me that most food packaging is specially
designed to be convenient for the makers but inconvenient for the customer.
The tearing issue is because once the surface is broken it unzips so to
speak, but when complete and stretched it is very strong.
Brian

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On 16/04/16 17:12, DerbyBorn wrote:
The type of plastic often used to wrap cheese intrigues me - it is a
devil
to start a tear but once a tear is started ot goes all over the place
with
no effort.

What is going on with the material properties?


It's from the same lab as the bags used to contain frozen fruit!

On 17/04/16 08:36, Brian Gaff wrote:
The tearing issue is because once the surface is broken it unzips so to
speak, but when complete and stretched it is very strong.

That mode of tearing is when you have a material with relatively high
tensile strength, but relatively low elasticity.

Once a split starts, the low elasticity puts a huge stress concentration
at the tear.


--
How fortunate for governments that the people they administer don't think.

Adolf Hitler

On Sun, 17 Apr 2016 08:36:44 +0100
"Brian Gaff" wrote:

It seems to me that most food packaging is specially
designed to be convenient for the makers but inconvenient for the
customer.

See my post about The Organisation programme with Donald Sinden!

--
Davey.

The Natural Philosopher wrote in news:nevks3$f8g$1
@news.albasani.net:

On 17/04/16 08:36, Brian Gaff wrote:
The tearing issue is because once the surface is broken it unzips so to
speak, but when complete and stretched it is very strong.

That mode of tearing is when you have a material with relatively high
tensile strength, but relatively low elasticity.

Once a split starts, the low elasticity puts a huge stress concentration
at the tear.



Thanks - that is the sort of info I wanted.