Foams (?)...

[Don Y]

There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\"). They are similar to
styrofoam in that way -- but *not* styrofoam.

The first is white. Has the appearance of being \"wet\"
(shiney). Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

Anyone have names for either/both of these? (it\'s hard to tell
from web photos if the items are as I expect)

 

[Don Y]

On 6/18/2023 1:55 PM, Don Y wrote:

There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\").  They are similar to
styrofoam in that way -- but *not* styrofoam.

The first is white.  Has the appearance of being \"wet\"
(shiney).  Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

This is, apparently, polyethylene foam. And, the rigidity
likely is enhanced by sheets being bonded together instead
of thicker sheets.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

 

[Jasen Betts]

On 2023-06-18, Don Y <blockedofcourse@foo.invalid> wrote:

There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\"). They are similar to
styrofoam in that way -- but *not* styrofoam.

The first is white. Has the appearance of being \"wet\"
(shiney). Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

Anyone have names for either/both of these? (it\'s hard to tell
from web photos if the items are as I expect)

I think shiny is PE look for recycling hints.

--
Jasen.
🇺🇦 Слава Україні

 

[Martin Brown]

On 18/06/2023 21:55, Don Y wrote:

There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\").  They are similar to
styrofoam in that way -- but *not* styrofoam.

There are some rigid PU foams too.

A rough rule of thumb is that the rigid foams tend to use MDI whereas
the fleximble soft foams tend to use TDI as the active isocyanate
component. There are various other rigid foam families with related
chemistry like the polyisocyanurates.

https://en.wikipedia.org/wiki/Polyisocyanurate

The first is white.  Has the appearance of being \"wet\"
(shiney).  Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

That is foamed polyethylene. Waxy ones tend to be poly olefeins.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be
such a nuisance for holding static charge.

Most pure plastics are white or clear if they are pure enough but some
random pale shade or dirty brown if they aren\'t. Araldite for instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it
outside and don\'t try it on flexible PU foams. Some of the fire
retardants in them can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

--
Martin Brown

 

[Don Y]

On 6/19/2023 2:27 AM, Martin Brown wrote:

On 18/06/2023 21:55, Don Y wrote:
There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\").  They are similar to
styrofoam in that way -- but *not* styrofoam.

There are some rigid PU foams too.

A rough rule of thumb is that the rigid foams tend to use MDI whereas the
fleximble soft foams tend to use TDI as the active isocyanate component. There
are various other rigid foam families with related chemistry like the
polyisocyanurates.

What drives the (retail) price? Are the ingredients that much
more/less expensive? Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

https://en.wikipedia.org/wiki/Polyisocyanurate

The first is white.  Has the appearance of being \"wet\"
(shiney).  Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

That is foamed polyethylene. Waxy ones tend to be poly olefeins.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such a
nuisance for holding static charge.

Dunno. It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Most pure plastics are white or clear if they are pure enough but some random
pale shade or dirty brown if they aren\'t. Araldite for instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it outside and
don\'t try it on flexible PU foams. Some of the fire retardants in them can
generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos! :>

 

[Martin Brown]

On 19/06/2023 18:05, Don Y wrote:

On 6/19/2023 2:27 AM, Martin Brown wrote:
On 18/06/2023 21:55, Don Y wrote:
There are two types of \"foam\" that are pretty rigid (unlike
urethane foam that is \"cushiony\").  They are similar to
styrofoam in that way -- but *not* styrofoam.

There are some rigid PU foams too.

A rough rule of thumb is that the rigid foams tend to use MDI whereas
the fleximble soft foams tend to use TDI as the active isocyanate
component. There are various other rigid foam families with related
chemistry like the polyisocyanurates.

What drives the (retail) price?  Are the ingredients that much
more/less expensive?  Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI
Toluene di-isocyantate which is volatile and really rather nasty to
handle. It is a skin and lung sensitiser anyone who works with it should
have respiratory protection. MDI is quite tame by comparison.

https://en.wikipedia.org/wiki/Polyisocyanurate

The first is white.  Has the appearance of being \"wet\"
(shiney).  Often used like styrofoam in shipping large items.
But, unlike styrofoam, it usually isn\'t *molded* to the
contour of the item packaged but, rather, squarely cut
(or, built up of layers of different shapes glued together).

That is foamed polyethylene. Waxy ones tend to be poly olefeins.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be
such a nuisance for holding static charge.

Dunno.  It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?

Most pure plastics are white or clear if they are pure enough but some
random pale shade or dirty brown if they aren\'t. Araldite for instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it
outside and don\'t try it on flexible PU foams. Some of the fire
retardants in them can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos!  :

Most packaging manufacturers will send you a sample if you ask them.

Here is a really good example of how not to do a plastic burn test 24
mins and 30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire


--
Martin Brown

 

[Don Y]

On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI whereas the
fleximble soft foams tend to use TDI as the active isocyanate component.
There are various other rigid foam families with related chemistry like the
polyisocyanurates.

What drives the (retail) price?  Are the ingredients that much
more/less expensive?  Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI Toluene
di-isocyantate which is volatile and really rather nasty to handle. It is a
skin and lung sensitiser anyone who works with it should have respiratory
protection. MDI is quite tame by comparison.

No, by \"ease of handling\" I meant after manufacture. I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state. But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such a
nuisance for holding static charge.

Dunno.  It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?

No, this appears to be somethign else. Or, perhaps because of the resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process. You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.

Most pure plastics are white or clear if they are pure enough but some
random pale shade or dirty brown if they aren\'t. Araldite for instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it outside
and don\'t try it on flexible PU foams. Some of the fire retardants in them
can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos!  :

Most packaging manufacturers will send you a sample if you ask them.

I\'ve made attempts in the past with no real success. They want to deal
with ongoing customers, not \"one-offs\".

And, most of the local \"foam stores\" are in the practice of selling
foam for \"furnishings* -- cushions, etc.

Here is a really good example of how not to do a plastic burn test 24 mins and
30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire

\"BBC iPlayer only works in the UK. Sorry, it’s due to rights issues\"

 

[Lasse Langwadt Christensen]

tirsdag den 20. juni 2023 kl. 16.33.02 UTC+2 skrev Don Y:

On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI whereas the
fleximble soft foams tend to use TDI as the active isocyanate component.
There are various other rigid foam families with related chemistry like the
polyisocyanurates.

What drives the (retail) price? Are the ingredients that much
more/less expensive? Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI Toluene
di-isocyantate which is volatile and really rather nasty to handle. It is a
skin and lung sensitiser anyone who works with it should have respiratory
protection. MDI is quite tame by comparison.
No, by \"ease of handling\" I meant after manufacture. I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state. But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.
The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such a
nuisance for holding static charge.

Dunno. It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?
No, this appears to be somethign else. Or, perhaps because of the resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process. You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

https://ecpplastictrays.com/wp-content/uploads/2023/02/EPE-Small-Cavity-Foam-Tray-Black.jpg ?

afaiu foams like that is made by putting tiny pellets in a form and steaming them to to expand (like popcorn)

 

[Don Y]

On 6/20/2023 8:34 AM, Lasse Langwadt Christensen wrote:

tirsdag den 20. juni 2023 kl. 16.33.02 UTC+2 skrev Don Y:
On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI whereas the
fleximble soft foams tend to use TDI as the active isocyanate component.
There are various other rigid foam families with related chemistry like the
polyisocyanurates.

What drives the (retail) price? Are the ingredients that much
more/less expensive? Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI Toluene
di-isocyantate which is volatile and really rather nasty to handle. It is a
skin and lung sensitiser anyone who works with it should have respiratory
protection. MDI is quite tame by comparison.
No, by \"ease of handling\" I meant after manufacture. I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state. But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.
The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such a
nuisance for holding static charge.

Dunno. It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?
No, this appears to be somethign else. Or, perhaps because of the resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process. You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

https://ecpplastictrays.com/wp-content/uploads/2023/02/EPE-Small-Cavity-Foam-Tray-Black.jpg ?

Yes!!!! Note the (visual) texture at the exposed surfaces! You feel like
you can \"pluck\" a chunk out of it and know exactly what the boundaries of that
chunk will be before you remove it!

> afaiu foams like that is made by putting tiny pellets in a form and steaming them to to expand (like popcorn)

This suggests it can\'t be done \"at home\" (unlike some of the \"foam in a can\"
products available).

But, at least, now, I can search for a local vendor/disti.

Thanks!

 

[Martin Brown]

On 20/06/2023 15:32, Don Y wrote:

On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI
whereas the fleximble soft foams tend to use TDI as the active
isocyanate component. There are various other rigid foam families
with related chemistry like the polyisocyanurates.

What drives the (retail) price?  Are the ingredients that much
more/less expensive?  Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI
Toluene di-isocyantate which is volatile and really rather nasty to
handle. It is a skin and lung sensitiser anyone who works with it
should have respiratory protection. MDI is quite tame by comparison.

No, by \"ease of handling\" I meant after manufacture.  I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state.  But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.

Depending on how much you want and what it is for you might be able to
utilise one of the grades nominally sold for home insulation. That
should be relatively common. The other option is to have it precut at
source to the sizes you want and shipped to you as a parcel. Beware that
the dust from it can be nasty and allergenic (very bad for eyes).

A fairly common trick is to have corner supports for you delicate kit
and/or put it in a bag and fill with loose blown polystyrene or these
days starch based cheesy wotsits.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to
be such a nuisance for holding static charge.

Dunno.  It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?

No, this appears to be somethign else.  Or, perhaps because of the
resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process.  You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.

I don\'t think I\'ve ever seen it then.

Most pure plastics are white or clear if they are pure enough but
some random pale shade or dirty brown if they aren\'t. Araldite for
instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it
outside and don\'t try it on flexible PU foams. Some of the fire
retardants in them can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos!  :

Most packaging manufacturers will send you a sample if you ask them.

I\'ve made attempts in the past with no real success.  They want to deal
with ongoing customers, not \"one-offs\".

Your best bet might be find a source of the foamed polyethene/propylene.
You can easily cut it to size and hot glue.

The other bespoke option if it is still available was the one we used
which was to wrap the instrument in thin polythene and inject a semi
rigid PU foam mix into the void in dabs to hold it in position. The kit
with the mixer gun was expensive but since we shipped a lot of stuff it
was worth it. Not especially eco friendly since it is a one time use.

And, most of the local \"foam stores\" are in the practice of selling
foam for \"furnishings* -- cushions, etc.

Here is a really good example of how not to do a plastic burn test 24
mins and 30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire

\"BBC iPlayer only works in the UK. Sorry, it’s due to rights issues\"

Spoof a UK IP address and it should work. It is on Youtube

https://www.youtube.com/watch?v=pP8p3I_6Uns

Google search terms \"forensics the real csi birmingham bbc youtube\"


--
Martin Brown

 

[Lasse Langwadt Christensen]

tirsdag den 20. juni 2023 kl. 23.07.59 UTC+2 skrev Martin Brown:

On 20/06/2023 15:32, Don Y wrote:
On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI
whereas the fleximble soft foams tend to use TDI as the active
isocyanate component. There are various other rigid foam families
with related chemistry like the polyisocyanurates.

What drives the (retail) price? Are the ingredients that much
more/less expensive? Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI
Toluene di-isocyantate which is volatile and really rather nasty to
handle. It is a skin and lung sensitiser anyone who works with it
should have respiratory protection. MDI is quite tame by comparison.

No, by \"ease of handling\" I meant after manufacture. I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state. But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.
Depending on how much you want and what it is for you might be able to
utilise one of the grades nominally sold for home insulation. That
should be relatively common. The other option is to have it precut at
source to the sizes you want and shipped to you as a parcel. Beware that
the dust from it can be nasty and allergenic (very bad for eyes).

A fairly common trick is to have corner supports for you delicate kit
and/or put it in a bag and fill with loose blown polystyrene or these
days starch based cheesy wotsits.
The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to
be such a nuisance for holding static charge.

Dunno. It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?

No, this appears to be somethign else. Or, perhaps because of the
resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process. You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.
I don\'t think I\'ve ever seen it then.
Most pure plastics are white or clear if they are pure enough but
some random pale shade or dirty brown if they aren\'t. Araldite for
instance.

Anyone have names for either/both of these? (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it
outside and don\'t try it on flexible PU foams. Some of the fire
retardants in them can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos! :

Most packaging manufacturers will send you a sample if you ask them.

I\'ve made attempts in the past with no real success. They want to deal
with ongoing customers, not \"one-offs\".
Your best bet might be find a source of the foamed polyethene/propylene.
You can easily cut it to size and hot glue.

The other bespoke option if it is still available was the one we used
which was to wrap the instrument in thin polythene and inject a semi
rigid PU foam mix into the void in dabs to hold it in position. The kit
with the mixer gun was expensive but since we shipped a lot of stuff it
was worth it. Not especially eco friendly since it is a one time use.

you can also get these, https://www.amazon.com/Instapak-Quick-IQRT80-Expandable-Foam/dp/B00KFK5IIE

 

[Don Y]

On 6/20/2023 2:07 PM, Martin Brown wrote:

On 20/06/2023 15:32, Don Y wrote:
On 6/20/2023 3:41 AM, Martin Brown wrote:

No, by \"ease of handling\" I meant after manufacture.  I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state.  But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.

Depending on how much you want and what it is for you might be able to utilise
one of the grades nominally sold for home insulation. That should be relatively

I looked at that option, already. They are aluminum faced.

common. The other option is to have it precut at source to the sizes you want
and shipped to you as a parcel. Beware that the dust from it can be nasty and
allergenic (very bad for eyes).

Yeah, but it would still be oversized -- maybe 2x3 (by many layers \"deep\")

A fairly common trick is to have corner supports for you delicate kit and/or
put it in a bag and fill with loose blown polystyrene or these days starch
based cheesy wotsits.

I\'m looking to be able to readily remove -- and replace -- items, not
ship them.

The second is black (VERY dark grey?).  It also has the cellular
structure of styrofoam, if examined closely.  Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such
a nuisance for holding static charge.

Dunno.  It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?

No, this appears to be somethign else.  Or, perhaps because of the resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process.  You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.

I don\'t think I\'ve ever seen it then.

ISTR it being used in every \"projector\" carrying case that I\'ve had.
But, they tend to be boxy (with a snout) so can easily be accommodated
by foam that isn\'t \"form fitted\" (like styrofoam normally would be)

Most pure plastics are white or clear if they are pure enough but some
random pale shade or dirty brown if they aren\'t. Araldite for instance.

Anyone have names for either/both of these?  (it\'s hard to tell
from web photos if the items are as I expect)

You can take a fair guess at some with a melt/burn test but do it outside
and don\'t try it on flexible PU foams. Some of the fire retardants in them
can generate nerve agents in the smoke.

The smell of burning polystyrene is very distinctive.

Even harder to tell *smell* from web photos!  :

Most packaging manufacturers will send you a sample if you ask them.

I\'ve made attempts in the past with no real success.  They want to deal
with ongoing customers, not \"one-offs\".

Your best bet might be find a source of the foamed polyethene/propylene.
You can easily cut it to size and hot glue.

That was my original hope. The \"source\" being the sticking point.

The other bespoke option if it is still available was the one we used which was
to wrap the instrument in thin polythene and inject a semi rigid PU foam mix
into the void in dabs to hold it in position. The kit with the mixer gun was
expensive but since we shipped a lot of stuff it was worth it. Not especially
eco friendly since it is a one time use.

There are some foams sold in aerosol (disposable) cans but the foam seems
not to be very robust (I think they are intended for use sealing around
windows and doors... things that aren\'t \"disturbed\" regularly. THEY are
\"one time use\" as once you push the button to start dispensing foam,
you\'d best not stop until done (as the foam hardens in the dispensing
nozzle once you stop)

And, most of the local \"foam stores\" are in the practice of selling
foam for \"furnishings* -- cushions, etc.

Here is a really good example of how not to do a plastic burn test 24 mins
and 30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire

\"BBC iPlayer only works in the UK. Sorry, it’s due to rights issues\"

Spoof a UK IP address and it should work. It is on Youtube

https://www.youtube.com/watch?v=pP8p3I_6Uns

Wow! Interesting. Some of the storage containers we use are
likely made of the same material. And, accessible (after hours)
by urchins.

I\'ll have to relay this to the powers that be and arrange for
them to, at least, be isolated away from other materials
and the building itself!

Google search terms \"forensics the real csi birmingham bbc youtube\"

 

[Jasen Betts]

On 2023-06-20, Don Y <blockedofcourse@foo.invalid> wrote:

On 6/20/2023 8:34 AM, Lasse Langwadt Christensen wrote:
tirsdag den 20. juni 2023 kl. 16.33.02 UTC+2 skrev Don Y:
On 6/20/2023 3:41 AM, Martin Brown wrote:

A rough rule of thumb is that the rigid foams tend to use MDI whereas the
fleximble soft foams tend to use TDI as the active isocyanate component.
There are various other rigid foam families with related chemistry like the
polyisocyanurates.

What drives the (retail) price? Are the ingredients that much
more/less expensive? Or, is it ease of handling (softer foams
can be rolled and compressed to occupy less volume)

Softer flexible foams are a less crosslinked polymer and require TDI Toluene
di-isocyantate which is volatile and really rather nasty to handle. It is a
skin and lung sensitiser anyone who works with it should have respiratory
protection. MDI is quite tame by comparison.
No, by \"ease of handling\" I meant after manufacture. I.e., twine is
easier to handle than sheets of plywood -- because it can be folded back
(rolled up) on itself whereas plywood has a largely immutable shape.
And so soft vs. hard/rigid foam.

I can buy a 2x8\' sheet of SOFT foam and have it shipped to me in
a compressed/rolled state. But, that same 2x8\' sheet of rigid
foam would have to be trucked or shipped via special carrier.
So, my only hopes for purchasing it are to find someone with
it \"in stock\" that I can pick up locally.
The second is black (VERY dark grey?). It also has the cellular
structure of styrofoam, if examined closely. Often used in
instrument/tool cases.

That might well be carbon black loaded polystyrene intended not to be such a
nuisance for holding static charge.

Dunno. It\'s kind of rubbery and -- if you look at it closely -- looks
like styrofoam in that you can see the borders of the various \"bubbles\"
in the foam.

Do you mean the stuff that CMOS chips are shipped on or something else?
No, this appears to be somethign else. Or, perhaps because of the resulting
dimensions, is manufactured in a different way.

Imagine pea-sized black pellets that have been heated until soft/tacky
and then thrown together into a molding process. You can almost *see*
the boundaries of each pellet (\"cell\") as you examine the surface of the
foam.

https://ecpplastictrays.com/wp-content/uploads/2023/02/EPE-Small-Cavity-Foam-Tray-Black.jpg ?

Yes!!!! Note the (visual) texture at the exposed surfaces! You feel like
you can \"pluck\" a chunk out of it and know exactly what the boundaries of that
chunk will be before you remove it!

afaiu foams like that is made by putting tiny pellets in a form and steaming them to to expand (like popcorn)

This suggests it can\'t be done \"at home\" (unlike some of the \"foam in a can\"
products available).

Yes, the steam pressures involved far exceed the capabilites of
a typical kitchen

--
Jasen.
🇺🇦 Слава Україні

 

[Martin Brown]

On 21/06/2023 07:11, Don Y wrote:

On 6/20/2023 2:07 PM, Martin Brown wrote:
On 20/06/2023 15:32, Don Y wrote:

A fairly common trick is to have corner supports for you delicate kit
and/or put it in a bag and fill with loose blown polystyrene or these
days starch based cheesy wotsits.

I\'m looking to be able to readily remove -- and replace -- items, not
ship them.

Ah! In which case the polyethylene foam is probably what you want.
Is there no equivalent of these guys (not the cheapest) in the US?

https://www.efoam.co.uk/closed-cell-polyethylene-foam.php

You might even be able to buy it in rolls at 6mm thick (if you don\'t
mind having to uncurl it for use).

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.

I don\'t think I\'ve ever seen it then.

ISTR it being used in every \"projector\" carrying case that I\'ve had.
But, they tend to be boxy (with a snout) so can easily be accommodated
by foam that isn\'t \"form fitted\" (like styrofoam normally would be)

Projector carrying cases in the UK tend to be soft cloth based things
with the lens assembly held facing upwards with a bit more protection.

Your best bet might be find a source of the foamed polyethene/propylene.
You can easily cut it to size and hot glue.

That was my original hope.  The \"source\" being the sticking point.

Search \"polyethylene packaging foam\" or see if you can find a local
friendly company that actually uses the stuff in bulk.

The other bespoke option if it is still available was the one we used
which was to wrap the instrument in thin polythene and inject a semi
rigid PU foam mix into the void in dabs to hold it in position. The
kit with the mixer gun was expensive but since we shipped a lot of
stuff it was worth it. Not especially eco friendly since it is a one
time use.

There are some foams sold in aerosol (disposable) cans but the foam seems
not to be very robust (I think they are intended for use sealing around
windows and doors... things that aren\'t \"disturbed\" regularly.  THEY are
\"one time use\" as once you push the button to start dispensing foam,
you\'d best not stop until done (as the foam hardens in the dispensing
nozzle once you stop)

The thing about the professional mixer guns is that they self purge the
dispensing head and take a tank of resin and a tank of isocyanate.

And, most of the local \"foam stores\" are in the practice of selling
foam for \"furnishings* -- cushions, etc.

If you don\'t care what it looks like. You might be able to find a
tougher grade of PU upholstry foam made from recycled material and
usually intended for the base layer to spread the load. It has a softer
(more expensive) grade put on top to act as a cushion.

Here is a really good example of how not to do a plastic burn test
24 mins and 30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire

\"BBC iPlayer only works in the UK. Sorry, it’s due to rights issues\"

Spoof a UK IP address and it should work. It is on Youtube

https://www.youtube.com/watch?v=pP8p3I_6Uns

Wow!  Interesting.  Some of the storage containers we use are
likely made of the same material.  And, accessible (after hours)
by urchins.

I don\'t think the storage containers themselves should be all that
flammable. Warehouse grade plastic containers should have some level of
(nasty) fire inhibitor in them. The problem was that they were storing
loose plastic waste in all of them and in small pieces for recycling.
Almost a perfect fuel air mix and once it is going it drips liquid fire!

Worth burn testing a small piece taken off your oldest one(s) though
(well away from anything flammable and don\'t breathe the fumes) because
if any are lacking flame inhibitors it will be the oldest ones.

I\'ll have to relay this to the powers that be and arrange for
them to, at least, be isolated away from other materials
and the building itself!

It might be worth doing the test on the plastic they are made from first
- but if their contents are flammable then you do have to beware. The
most impressive fire barrier I have ever seen is an MgO based material.

Something like this one (but not this particuloar one).

https://www.laver.co.uk/sheet-materials-information/alton-mgo-board

It saved most of a warehouse in a similar catastrophic fire.

--
Martin Brown

 

[Don Y]

On 6/21/2023 12:58 AM, Martin Brown wrote:

On 21/06/2023 07:11, Don Y wrote:
On 6/20/2023 2:07 PM, Martin Brown wrote:
On 20/06/2023 15:32, Don Y wrote:

A fairly common trick is to have corner supports for you delicate kit and/or
put it in a bag and fill with loose blown polystyrene or these days starch
based cheesy wotsits.

I\'m looking to be able to readily remove -- and replace -- items, not
ship them.

Ah! In which case the polyethylene foam is probably what you want.

The black stuff seems classier... :>

Is there no equivalent of these guys (not the cheapest) in the US?

https://www.efoam.co.uk/closed-cell-polyethylene-foam.php

There are plenty of foam sellers. But, not \"down the street\".
So, it has to be shipped. Which adds to the already high price
(relative to urethane foam that I can pick up at any craft store)

You might even be able to buy it in rolls at 6mm thick (if you don\'t mind
having to uncurl it for use).

Oh, that would be painful! I need total thicknesses in the 10+ inch
range. Building up from 6mm sheets would leave me with a block of
ADHESIVE, not FOAM!

It is very firm -- you would have to be VERY determined to mar
it with a hammer as it would just bounce off in any casual strikes.

I don\'t think I\'ve ever seen it then.

ISTR it being used in every \"projector\" carrying case that I\'ve had.
But, they tend to be boxy (with a snout) so can easily be accommodated
by foam that isn\'t \"form fitted\" (like styrofoam normally would be)

Projector carrying cases in the UK tend to be soft cloth based things with the
lens assembly held facing upwards with a bit more protection.

They tend to be hard cases, here. Open it up and there are \"pockets\"
for the projector, remote, cables, etc. Easy out, easy back in.

My (commercial) video cameras are similarly packed in shipping cases.

I think the point with all of these is that you can drop the case and
not sweat the contents.

Your best bet might be find a source of the foamed polyethene/propylene.
You can easily cut it to size and hot glue.

That was my original hope.  The \"source\" being the sticking point.

Search \"polyethylene packaging foam\" or see if you can find a local friendly
company that actually uses the stuff in bulk.

I tried asking the manufacturers for names of THEIR customers with a similar
goal. They weren\'t real keen on telling me! (understandably so, in hindsight)

The other bespoke option if it is still available was the one we used which
was to wrap the instrument in thin polythene and inject a semi rigid PU foam
mix into the void in dabs to hold it in position. The kit with the mixer gun
was expensive but since we shipped a lot of stuff it was worth it. Not
especially eco friendly since it is a one time use.

There are some foams sold in aerosol (disposable) cans but the foam seems
not to be very robust (I think they are intended for use sealing around
windows and doors... things that aren\'t \"disturbed\" regularly.  THEY are
\"one time use\" as once you push the button to start dispensing foam,
you\'d best not stop until done (as the foam hardens in the dispensing
nozzle once you stop)

The thing about the professional mixer guns is that they self purge the
dispensing head and take a tank of resin and a tank of isocyanate.

Ah. No, these mix the foam in a dispensing tube that you can target
to the area of application. But, once you stop, the foam in the
tube starts to set. You can replace the tube and start up again...
IF you have a spare tube!

The same is true of some of the industrial epoxies that I use
(e.g., to set bolts in concrete). They usually provide two or
three \"mixing nozzles\" for this reason.

[If you need a fourth, you have to buy another tube of epoxy and
set of three nozzles. So, you plan very carefully before starting!]

And, most of the local \"foam stores\" are in the practice of selling
foam for \"furnishings* -- cushions, etc.

If you don\'t care what it looks like. You might be able to find a tougher grade
of PU upholstry foam made from recycled material and usually intended for the
base layer to spread the load. It has a softer (more expensive) grade put on
top to act as a cushion.

Yes, that\'s how cushions for chairs, couches, etc. are made, here. But, even
the densest of those foams wouldn;t hold up to a persistent load without
deforming, over time. (for the same reason furniture cushions loose
their shape)

Here is a really good example of how not to do a plastic burn test 24 mins
and 30.5m in on the real CSI. Destroyed the entire facility...

https://www.bbc.co.uk/iplayer/episode/m001mg1l/forensics-the-real-csi-series-3-3-playing-with-fire

\"BBC iPlayer only works in the UK. Sorry, it’s due to rights issues\"

Spoof a UK IP address and it should work. It is on Youtube

https://www.youtube.com/watch?v=pP8p3I_6Uns

Wow!  Interesting.  Some of the storage containers we use are
likely made of the same material.  And, accessible (after hours)
by urchins.

I don\'t think the storage containers themselves should be all that flammable.
Warehouse grade plastic containers should have some level of (nasty) fire
inhibitor in them. The problem was that they were storing loose plastic waste
in all of them and in small pieces for recycling. Almost a perfect fuel air mix
and once it is going it drips liquid fire!

Oh. I thought they (in their testing) were using bits of the container
that hadn\'t burned...

Worth burn testing a small piece taken off your oldest one(s) though (well away
from anything flammable and don\'t breathe the fumes) because if any are lacking
flame inhibitors it will be the oldest ones.

Most of this stuff is lacking in provenance. It\'s more of a \"we\'ll take
whatever you are willing to give us\" arrangement. (And, you have to wonder
why they\'ve chosen to give you THOSE things!)

And, the folks who are \"filling\" those containers are typically developmentally
disabled. Or, \"begrudgingly participating\" (e.g., in lieu of jail time). So,
they either can\'t -- or aren\'t motivated to -- notice hazards in the making.

[They are barely capable of noticing hazards to their own health/welfare!
E.g., I refuse to drive the forklift if any are around. It\'s hard enough
managing the load on the forks, worrying about slipping in the gravel (or,
getting STUCK!) and trying to navigate to your destination without
worrying that some cretin will come rushing out to drop a piece of tin in
the gaylord I\'ve got on the forks. Or, to cheerfully greet me as he may not
have seen me earlier]

We often receive items that are prototypes or \"internal use only\" so you
can\'t always GUESS what the risk factors might be with them. And, if you
don\'t have anyone skilled to make those assessments (\"triage\") on site,
you never know what problems are lurking.

\"No, don\'t throw 70AHr batteries in with the scrap metal. That\'s a
short just waiting to happen!\"

\"No, don\'t accept items that have unknown solvents/reagents in them!\"

\"No, don\'t accept that large box of /sharps/ of dubious heritage!\"

[A few of us used to handle triage so these sorts of problems were caught
before they became problems. But, I\'ve stepped away in favor of activities
that I can perform at home (save travel time, nicer work environment,
less physically challenging, etc.) and others have moved away due to covid]

I\'ll have to relay this to the powers that be and arrange for
them to, at least, be isolated away from other materials
and the building itself!

It might be worth doing the test on the plastic they are made from first - but
if their contents are flammable then you do have to beware. The most impressive
fire barrier I have ever seen is an MgO based material.

Something like this one (but not this particuloar one).

https://www.laver.co.uk/sheet-materials-information/alton-mgo-board

It saved most of a warehouse in a similar catastrophic fire.

I suspect the more practical risk factor is the propane tank on the
fork lift. I once asked what the procedure was for handling a
fire (cuz you are sitting *on* the engine with the propane tank
immediately behind you). Most of it made sense. But the
\"off-the-record\" warnings were more telling. E.g., \"when you call
the fire department, be sure to tell them that you have a fire
in a PROPANE forklift. They will park DOWN THE STREET and walk
up to the property -- to keep their equipment out of harm\'s way.\"
(so, doesn\'t that mean I should get the hell away from here???)

[You likely have other tanks on hand that can also become involved]