I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Cheers

On 27 Nov, 17:20, GMM wrote:
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. *Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Clingfilm?

Bolted
wibbled on Friday 27 November 2009 17:22

On 27 Nov, 17:20, GMM wrote:
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. *Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Clingfilm?

Grease the pipe. Vaseline should be good enough.

Or rather than cling film (which will stick in its own peculiar way) just
wrap a piece of plastic sheet round and tape it in place.

--
Tim Watts

This space intentionally left blank...

On Fri, 27 Nov 2009 17:49:09 +0000, Tim W wrote:
Bolted
wibbled on Friday 27 November 2009 17:22

On 27 Nov, 17:20, GMM wrote:
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. *Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Clingfilm?

Grease the pipe. Vaseline should be good enough.

Or rather than cling film (which will stick in its own peculiar way) just
wrap a piece of plastic sheet round and tape it in place.


Teflon baking sheet from Morrisons?

GMM wrote:
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Cheers
wrap it in clingfilm

In article ,
Owain writes:
On 27 Nov, 17:20, GMM wrote:
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. *Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?
Sleeve the pipe in plastic sheet first?

Probably worth padding out with several turns, to increase the
effective diameter a little so you don't end up with an impossibly
tight fit. I would lightly oil the outer surface of the plastic.
My recollection is that cling film stuck quite well to expanding
foam, when I did some 10 years ago (although cling film isn't
the same stuff nowadays).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

The Natural Philosopher
wibbled on Friday 27 November 2009 18:59

wrap it in clingfilm

The Croydon Condom?

--
Tim Watts

This space intentionally left blank...

On Nov 27, 5:20*pm, GMM wrote:
I'd like to use some foam around a plastic downpipe, where
it goes through a flat roof, but don't want to stick it in place.

I'm puzzled...
- You are probably using lead/aluminium flashing around it?
- The hole can be made to a suitable oversize within limits?
- Expanding foam cuts with a padsaw as easy as pie?

By padsaw I mean a handle with coarse blade on it.

Go buy a padsaw.
Make the hole sufficiently oversize.
Fill in with expanding foam.

If you really must have a future-removeable slip joint:
- Find another pipe which is oversize, expand foam that one in place
- Use a non-setting mastic between that pipe and the downpipe

An example would be 3M 08509 which is a non-setting butyl good (used
on car windscreen seals, never sets, just forms a skin which is
waterproof - comes in a sealant-gun style cartridge).

On Nov 27, 10:04*pm, "js.b1" wrote:
An example would be 3M 08509 which is a non-setting butyl goo

goo not good.

Use it between the outer tube and the inner tube, expanding foam the
outer tube to the roof.

On Fri, 27 Nov 2009 09:20:22 -0800 (PST), GMM
wrote:

Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Silicone oil, or wrap it baking parchment which is usually paper with
a silicone oil coating. http://www.lakeland.co.uk/F/product/5511_5510

On Fri, 27 Nov 2009 14:04:43 -0800 (PST), "js.b1"
wrote:

On Nov 27, 5:20*pm, GMM wrote:
I'd like to use some foam around a plastic downpipe, where
it goes through a flat roof, but don't want to stick it in place.

I'm puzzled...
- You are probably using lead/aluminium flashing around it?
- The hole can be made to a suitable oversize within limits?
- Expanding foam cuts with a padsaw as easy as pie?

By padsaw I mean a handle with coarse blade on it.

Go buy a padsaw.
Make the hole sufficiently oversize.
Fill in with expanding foam.

And expanding foam is degradable in daylight is it not?

In message
, GMM
writes
I'd like to use some foam around a plastic downpipe, where it goes
through a flat roof, but don't want to stick it in place. Can anyone
recommend a suitable release agent to coat a piece of pipe with and
mould the whole through the foam while it sets?

Someone post ... the link
--
geoff

On Fri, 27 Nov 2009 23:21:56 +0000, geoff wrote:

Someone post ... the link
--
geoff

What you talking about ..What link?

In message , Usenet Nutter
writes
On Fri, 27 Nov 2009 23:21:56 +0000, geoff wrote:

Someone post ... the link
--
geoff

What you talking about ..What link?


Aah - you'll have to wait until someone who knows cottons on to what I
mean

--
geoff

On Nov 27, 10:53*pm, Usenet Nutter
wrote:

And expanding foam is degradable in daylight is it not?

Correct, hence I also said...

Fri, 27 Nov 09 14:04:43 -0800 (PST), "js.b1" wrote:

You are probably using lead/aluminium flashing around it?

Around the top outside.
Around the bottom inside I assume he will have a ceiling. :-)

The problem is most pipes are not perfectly round, so anything that
acts as a "release agent" needs to also provide sufficient clearance
for the withdrawal of the pipe - not just prevent adhesion. Several
layers of clingfilm would do it, but an issue is its longevity.

Using an outer pipe as a sleeve with non-setting butyl sealant in
between seems to provide a workable solution. The flashing on the roof
providing the waterproofing. It's about £8.59 a tube plus postage -
last I bought was 2007.


An alternative would be to use a "marine grommet", or "plastic roof
flashing":
- Basically a cone of plastic or rubber with a square baseplate
- The cone is ridged at different circumferences allowing it to be cut
to size
- It seals against the pipe via mastic or if rubber simply compression

They might exist on Ebay at a sensible price.

In article ,
geoff writes:
In message , Usenet Nutter
writes
On Fri, 27 Nov 2009 23:21:56 +0000, geoff wrote:

Someone post ... the link
--
geoff

What you talking about ..What link?


Aah - you'll have to wait until someone who knows cottons on to what I
mean

http://www.diyfaq.org.uk/humour.html#foam

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

js.b1 wrote:
On Nov 27, 10:53 pm, Usenet Nutter
wrote:
And expanding foam is degradable in daylight is it not?

Correct, hence I also said...

Fri, 27 Nov 09 14:04:43 -0800 (PST), "js.b1" wrote:

You are probably using lead/aluminium flashing around it?

Around the top outside.
Around the bottom inside I assume he will have a ceiling. :-)

The problem is most pipes are not perfectly round, so anything that
acts as a "release agent" needs to also provide sufficient clearance
for the withdrawal of the pipe - not just prevent adhesion. Several
layers of clingfilm would do it, but an issue is its longevity.

Using an outer pipe as a sleeve with non-setting butyl sealant in
between seems to provide a workable solution. The flashing on the roof
providing the waterproofing. It's about £8.59 a tube plus postage -
last I bought was 2007.



Look., maybe I am being obtuse, but if you want a removable pipe with a
watertight seal, why not simply lay down a ring of silicone rubber round
it BEFORE foaming in place?

But I must say 'removeable' and 'watertight' don't belong in quite the
same sentence.

Another option if its waste pipe size, is to cut down a loo coupler with
a rubber ring seal and welly that in place with the foam.

BUT it seems stupid to me. Make a big hole, foam in place and slip
flashing over the lot. Then if the pipe needs to come out, remove
flashing and use padsaw in foam to remove pipe, which goes in the skip.
Its cheap enough.

My first time back here since I posted and this seems to have caused a
disproportionate amount of consternation! So much for trying to be
brief and not explaining the whole job....

The situation is pretty straighforward: A hopper set into the top
surface of the roof, which covers the carport. Everything newly
sealed etc etc. The downpipe makes a sliding fit around the tapered
base of this, like all good downpipes should. The underside of the
roof (carport ceiling you might call it) is plasterboard and skim.
With various leaks, changes of downpipes etc over the years, the 'ole
in this 'ceiling' has become a lot bigger than is right, and I'm
looking to tidy the whole lot up. There are two things I could do:
Fill up the 'ole (with a bit of squirty foam, allowing for the issues
described in 'the link'), or fix a plate (a square of ply) on the
ceiling with the right size 'ole in it. Either way, it would be a
good plan to allow for the downpipe to be removed etc (if only to make
it easier to paint behind). Clearly, either hole (in ply or foam)
needs to be a bit bigger than the pipe to allow it to be slid out:
Still haven't got a firm plan on how to do this for the foam (probably
something a bit thick wrapped around it a few turns), but clearly it
would defeat the purpose if it was stuck to the foam (and we all know
how sticky foam can be!), so I need to find a release agent. My first
thought was anything oily/greasy, but I thought I'd tap the wealth of
experience here to see if there was a simple one-liner!