What doesn't Expanding Foam stick to ?

[Andrew Mawson]

What DOESN'T expanding foam stick to? I want to bridge a gap in the apex of
a roof, that foam would droop away from, so need to install a temporary
'shelf' until it has hardened.

Picture here:

https://www.dropbox.com/s/o7czysxiile30p7/Apex-Gap.jpg?dl=0


(Background: this is a barn with fibre cement roof that I had sprayed with
foam insulation some years ago, but they failed to seal the apex properly
despite claiming that they had. Access is extremely difficult as the barn is
full of immovable objects (large lathes, milling machines etc) and the apex
is about 15 foot up so it will have to be done in short sections - its about
40 foot long)

Andrew

[Robin]

On 09/04/2016 09:11, Andrew Mawson wrote:
> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex
> of a roof, that foam would droop away from, so need to install a
> temporary 'shelf' until it has hardened.
>

Idiot boy question: why not accept that expanding foam sticks to most
stuff and use as a "shelf" something that you are happy to leave there
which won't do any damage if they do fall off in time? Eg lengths cut
from polystyrene sheet?

--
Robin
reply-to address is (intended to be) valid

[michael adams]

"Andrew Mawson" <andrew@please_remove_me.mawson.org.uk> wrote in message
news:nead87$2h8$1...@dont-email.me...

> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex of a roof,
> that foam would droop away from, so need to install a temporary 'shelf' until it has
> hardened.

Just cover whatever you use for "shelving" with polythene or
any other thin transparent sheeting as a barrier. Fixed on the
underside with drawing pins etc. To save the pins tearing the
plastic first reinforce the site of the pins with squares of duck
tape or similar.

The worst that can happen is that the barrier doesn't work
and it sticks but after pulling out the pins taking down the board
and trimming all you're left with are strips of transparent
polythene on the foam.

Or it might separate with no problems at all.

As was pointed out in a previous thread all plastics are
different, as in plastic sheeting and knowing the precise chemical
composition of what you have available, and so it may just be a
case of try it and see. ( I could go up in the loft right now and maybe
check out some old carrier bags which had been subject to
"foam abuse" but there would be little point)

Or maybe treating the polythene with a further barrier.


michael adams


...

[Unknown]

On 09/04/2016 09:11, Andrew Mawson wrote:

The classic GRP mould release system is to polish the mould with
silicone polish, over which you paint white PVA. The resin sticks to the
PVA, but that separates easily from the polish.


--
Colin Bignell

[alan_m]

On 09/04/2016 09:11, Andrew Mawson wrote:

> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex
> of a roof, that foam would droop away from, so need to install a
> temporary 'shelf' until it has hardened.

Cover the shelf in (cooking) cling film.





--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

[Tim Watts]

Cling film wrap the shelf - the cling film may or may not stick to the
foam, but that would not matter if it stayed up there presumably?

I used the cling film trick around door threshold oak strips when I
needed to embed the wood onto 3-4 big blobs of isopon to get a level
surface to mount the oak onto.

The oak lifted straight out and the cling film peeled off the isopon
leaving a perfectly moulded set of pads :)

[Tim Watts]

The trick with concrete shuttering is a mixture of sump oil and diesel
(at least in the USA - probably would frowned upon here!)

[jim]

"Andrew Mawson" <andrew@please_remove_me.mawson.org.uk> Wrote in
message:

> What DOESN'T expanding foam stick to?

A greased surface?

--
Jim K


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[The Natural Philosopher]

why not use something covered with a sacrficial polythene sheet.
Clingflim or similar.


--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

[Andrew Mawson]

"The Natural Philosopher" wrote in message
news:neaod0$nfs$2...@news.albasani.net...

>
>On 09/04/16 09:11, Andrew Mawson wrote:
>> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex
>> of a roof, that foam would droop away from, so need to install a
>> temporary 'shelf' until it has hardened.
>>
>> Picture here:
>>
>> https://www.dropbox.com/s/o7czysxiile30p7/Apex-Gap.jpg?dl=0
>>
>>
>> (Background: this is a barn with fibre cement roof that I had sprayed
>> with foam insulation some years ago, but they failed to seal the apex
>> properly despite claiming that they had. Access is extremely difficult
>> as the barn is full of immovable objects (large lathes, milling machines
>> etc) and the apex is about 15 foot up so it will have to be done in
>> short sections - its about 40 foot long)
>>
>> Andrew
>
>why not use something covered with a sacrficial polythene sheet. Clingflim
>or similar.
>
>

Thanks for all the suggestions :)

Andrew

I've just worked out roughly that it would take 13 750 mL cans of foam, so
maybe not a practical solution. :(

What I need is something like the foam pipe insulation you can get - ie a
sausage like shape - that I can push into the gap to seal it. But it needs
to be about 6 inch diameter and stiff enough to be poked in and stay with
it's own 'gription'

So where can I get 6" diameter stiff foam - 1 metre lengths would be
convenient, and i'd need a total of 13 metres of them !

Andrew

[Brian Gaff]

Candle wax, oils and greases generally?
Brian

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"Andrew Mawson" <andrew@please_remove_me.mawson.org.uk> wrote in message
news:nead87$2h8$1...@dont-email.me...

[harry]

Cling film.

[damdu...@yahoo.co.uk]

On Sat, 9 Apr 2016 15:04:25 +0100, "Andrew Mawson"
<andrew@please_remove_me.mawson.org.uk> wrote:


>>
>
>Thanks for all the suggestions :)
>
>Andrew
>
>I've just worked out roughly that it would take 13 750 mL cans of foam, so
>maybe not a practical solution. :(
>
>What I need is something like the foam pipe insulation you can get - ie a
>sausage like shape - that I can push into the gap to seal it. But it needs
>to be about 6 inch diameter and stiff enough to be poked in and stay with
>it's own 'gription'
>
>So where can I get 6" diameter stiff foam - 1 metre lengths would be
>convenient, and i'd need a total of 13 metres of them !
>
>Andrew
>

Armaflex who make a lot of the pipe insulation also supply the same
material in sheet form .
https://www.pipelagging.com/product/371/25mm-Class-O-Armaflex-Flat-Plain-Insulation-Sheet-2m-x-0.5m

You could cut sections out of that roll it up and push it in , they
also make a jointing tape and on a clean dry surface that sticks like
shit to blanket.

A tightwads option would be to cut up foam camping mats.

G.Harman

[Adam Aglionby]

On Saturday, April 9, 2016 at 3:04:21 PM UTC+1, Andrew Mawson wrote:
> "The Natural Philosopher" wrote in message
> news:neaod0$nfs$2...@news.albasani.net...
> >
> >On 09/04/16 09:11, Andrew Mawson wrote:
> >> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex
> >> of a roof, that foam would droop away from, so need to install a
> >> temporary 'shelf' until it has hardened.
> >>
> >> Picture here:
> >>
> >> https://www.dropbox.com/s/o7czysxiile30p7/Apex-Gap.jpg?dl=0
> >>
> >>
> >> (Background: this is a barn with fibre cement roof that I had sprayed
> >> with foam insulation some years ago, but they failed to seal the apex
> >> properly despite claiming that they had. Access is extremely difficult
> >> as the barn is full of immovable objects (large lathes, milling machines
> >> etc) and the apex is about 15 foot up so it will have to be done in
> >> short sections - its about 40 foot long)
> >>
> >> Andrew
> >
> >why not use something covered with a sacrficial polythene sheet. Clingflim
> >or similar.
> >
> >
>
> Thanks for all the suggestions :)
>
> Andrew
>
> I've just worked out roughly that it would take 13 750 mL cans of foam, so
> maybe not a practical solution. :(

Dozen cans of foam is under 50 quid

>
> What I need is something like the foam pipe insulation you can get - ie a
> sausage like shape - that I can push into the gap to seal it. But it needs
> to be about 6 inch diameter and stiff enough to be poked in and stay with
> it's own 'gription'
>
> So where can I get 6" diameter stiff foam - 1 metre lengths would be
> convenient, and i'd need a total of 13 metres of them !

If you can find it, its the postage that will be a killer ;-)

Above can foam and poly layflat tubing usually used for packaging, foam fill in situ..
>
> Andrew

[harry]

On Saturday, 9 April 2016 09:10:55 UTC+1, Andrew Mawson wrote:

You have another problem too.
Expanding foam turns into one huge hollow bubble if too thick.
ie you can't fill voluminous spaces with it.

It needs moisture to go off too. So wet down slightly in the place you out it in.

[polygonum]

Maybe an appropriate form of silicone?

http://www.wacker.com/cms/en/industries/chemical/polyurethane/polyurethane.jsp?country=GB&language=en

--
Rod

[Muddymike]

On 09/04/2016 10:10, alan_m wrote:
> On 09/04/2016 09:11, Andrew Mawson wrote:
>> What DOESN'T expanding foam stick to? I want to bridge a gap in the apex
>> of a roof, that foam would droop away from, so need to install a
>> temporary 'shelf' until it has hardened.
>
> Cover the shelf in (cooking) cling film.
>
>
>
>
>

+1

Mike

[DICEGEORGE]

cut kingspan with a blunt woodwork saw ,
jam it in the gap,
use a foam gun to seal the gaps

[g]

[www.GymRatZ.co.uk]

On 09/04/2016 15:04, Andrew Mawson wrote:

> I've just worked out roughly that it would take 13 750 mL cans of foam,
> so maybe not a practical solution. :(

Quite bizarrely I was just about to post a question as to the "quality"
of ToolStation expanding foam as I have 6 new windows to fit this weekend.

http://www.toolstation.com/shop/Adhesives+%26+Sealants/d180/Expanding+Foam/sd2857/Contractors+Foam+12+Pack/p36594

12 cans of gun grade or hand held for £44 (£3.60 a tin)

Bought a gun the other day but ToolStation also do a good price for one.

[DICEGEORGE]

OR IS THE GAP AT THE RIDGE FOR VENTILATION?

[Andrew Mawson]

"DICEGEORGE" wrote in message
news:80bd5a8d-1887-4db8...@googlegroups.com...

>
>OR IS THE GAP AT THE RIDGE FOR VENTILATION?

George,

Yes it was for ventilation originally when it was a cow barn, but my CNC
machines don't fart as much as cows :)

Andrew

[Bob Eager]

I have this vision of a farmer having a cowshed like this, with the
ventilation led to a vertical pipe in the corner and a permanent 'flare'
as on an oil rig.

[dec]

so expansion foam does NOT stick to cling film?

so is that the best way to stop it stic king to the mold framework?

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[dec]

would a silicon spray work do you think?

[dec]

https://www.google.com/search?as_q=silicone+mold+release&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=&as_occt=any&safe=images&as_filetype=&tbs=

[dec]

here is a link to a home-made solution from previous Google link. this solution (pun intended) was mentioned elsewhere too.

[Brian Gaff]

Are you sure it sticks to anything? I thought the whole idea was to expand
into voids, and seal up the hole.
Brian

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[SteveW]

On 31/10/2022 09:14, Brian Gaff wrote:
> Are you sure it sticks to anything? I thought the whole idea was to expand
> into voids, and seal up the hole.

It is horribly sticky and sticks to almost anything. The low-expansion
version is used as an adhesive - bonding plasterboard to walls and the
like. Get it on your jeans and you'll forever have a pair of jeans with
a patch of hardended foam on. Get it on your skin and, unless you use a
solvent, it'll take days to get it off.

[alan_m]

The solvent doesn't work once the foam is cured.

[Animal]

I believe it only comes off as the skin's surface is shed with it.
Polythene is one of the least stickable materials on the planet, might be worth trying.