"Mike Lyle" wrote in message
...



Perfect logic, but the fact remains that there isn't a glue for
poly[ethyl]ene, which isn't a million miles different from ptfe, the
non-stick frying-pan stuff. It's always joined by welding. The
problem is, I think, that the adhesives on gaffer tape and such-like,
while they will stick well to polythene till they dry out a few years
later, can't be applied in amateur conditions.

--
Mike.

Yup -but we are talking about repair -not construction.
A repair using the proper tape will outlast the useful life of the poly
sheet.
imho !
pete

"Howard Neil" wrote in message
...
Mary Fisher wrote:

You didn't specify "poking plastic" originally. Is that what you'd do?

Yes. I use the same principle in my veg patch. I cover it with old silage
sheet and make holes with a blow lamp. The sheet melts back to produce a
hard ring and a nice clean hole to plant the veg through.

Actually that's not a bad idea - for a veg patch. I might (albeit
reluctantly) follow your example :-)

However, I think that such holes might be too large for a polytunnel lacing
repair.

Mary

Peter Stockdale wrote:
"Mike Lyle" wrote in message
...



Perfect logic, but the fact remains that there isn't a glue for
poly[ethyl]ene, which isn't a million miles different from ptfe,
the
non-stick frying-pan stuff. It's always joined by welding. The
problem is, I think, that the adhesives on gaffer tape and
such-like,
while they will stick well to polythene till they dry out a few
years
later, can't be applied in amateur conditions.

--
Mike.

Yup -but we are talking about repair -not construction.
A repair using the proper tape will outlast the useful life of the
poly sheet.
imho !

Yes, that's quite right; but I was only answering the question about
why we can't get an adhesive which would work for polythene.

Mary Fisher wrote:
"Howard Neil" wrote in message
...

Mary Fisher wrote:


You didn't specify "poking plastic" originally. Is that what you'd do?

Yes. I use the same principle in my veg patch. I cover it with old silage
sheet and make holes with a blow lamp. The sheet melts back to produce a
hard ring and a nice clean hole to plant the veg through.


Actually that's not a bad idea - for a veg patch. I might (albeit
reluctantly) follow your example :-)

This may be a good time to ask local farmers for their used sheets. They
should now have cleared their silage and they will have to pay to have
the sheets removed. Someone offering to take a sheet off their hands for
nothing will be welcomed.


However, I think that such holes might be too large for a polytunnel lacing
repair.

You haven't seen the size of the laces. :-)

I'll post the result if my experiments tomorrow.


--
Howard Neil

In uk.d-i-y Peter Stockdale wrote:

"Mike Lyle" wrote in message
...



Perfect logic, but the fact remains that there isn't a glue for
poly[ethyl]ene, which isn't a million miles different from ptfe, the
non-stick frying-pan stuff. It's always joined by welding. The
problem is, I think, that the adhesives on gaffer tape and such-like,
while they will stick well to polythene till they dry out a few years
later, can't be applied in amateur conditions.

Yup -but we are talking about repair -not construction.
A repair using the proper tape will outlast the useful life of the poly
sheet.

But would have been impossible.

Given two edges 12" apart, taping it up just isn't going to work.
Lacing it up, and drawing the edges together worked well.
However, the proper tape does well with intermittent loads, but will creep
off the joint if it's under constant tension.

Mike Lyle wrote or quoted:

Perfect logic, but the fact remains that there isn't a glue for
poly[ethyl]ene, which isn't a million miles different from ptfe, the
non-stick frying-pan stuff. It's always joined by welding. [...]

``Polyethylene and polypropylene and nylon are pretty difficult,
because they do not have any pores, and almost no solvents can dissolve
them. Only soft, rubbery solvent-drying glues can work, because glues
can only hang onto the plastic by wetting its surface.''

- http://www.newton.dep.anl.gov/askasc.../chem03271.htm

``8005 - Scotch-Weld? Structural Plastic Adhesive
Two-part structural acrylic-based adhesive (10:1 mix ratio by volume),
that can structurally bond many grades of polyethylene, polypropylene,
and thermoplastic elastomers (TPE's) without any surface preparation at
room temperature.''

- http://www.tapecase.com/tc/prodASP/S...Structural.asp
--
__________
|im |yler http://timtyler.org/ Remove lock to reply.

"Howard Neil" wrote in message
news:4272a654$0$581
Mary Fisher wrote:



This may be a good time to ask local farmers for their used sheets.

I don't know farmers who use them and my garden plots are measured in low
single numbers of square yards, not hectares. And I only have four plots.

They should now have cleared their silage and they will have to pay to
have the sheets removed. Someone offering to take a sheet off their hands
for nothing will be welcomed.


However, I think that such holes might be too large for a polytunnel
lacing repair.

You haven't seen the size of the laces. :-)

Nor have you. He said "thick twine", not "ships' cable".

Mary



I'll post the result if my experiments tomorrow.


--
Howard Neil

Ian Stirling wrote:

I used baler twine, which is a 3mm or so plastic string, which can easily
be melted into a nice point.

....with the aid of a welding torch. Thereby fulfilling the LAW, which
requires ALL agricultural repairs to be made using baler twine and a
welder...

"Stefek Zaba" wrote in message
...
Ian Stirling wrote:

I used baler twine, which is a 3mm or so plastic string, which can easily
be melted into a nice point.

...with the aid of a welding torch. Thereby fulfilling the LAW, which
requires ALL agricultural repairs to be made using baler twine and a
welder...

Sssssssh! If They (spelt defra) hears that they'll devise forms to apply for
its use.

Mary

Tim Tyler wrote:
Mike Lyle wrote or quoted:

Perfect logic, but the fact remains that there isn't a glue for
poly[ethyl]ene, which isn't a million miles different from ptfe,
the
non-stick frying-pan stuff. It's always joined by welding. [...]

``Polyethylene and polypropylene and nylon are pretty difficult,
because they do not have any pores, and almost no solvents can
dissolve them. Only soft, rubbery solvent-drying glues can work,
because glues can only hang onto the plastic by wetting its
surface.''

- http://www.newton.dep.anl.gov/askasc.../chem03271.htm

``8005 - Scotch-Weld? Structural Plastic Adhesive
Two-part structural acrylic-based adhesive (10:1 mix ratio by
volume), that can structurally bond many grades of polyethylene,
polypropylene, and thermoplastic elastomers (TPE's) without any
surface preparation at room temperature.''

- http://www.tapecase.com/tc/prodASP/S...Structural.asp

Good news! (Note that I did mention things which work by wetting will
stick to pe in the part you cut for space.) I wonder what the
smallest available quantity is.

Of course, using it to mend a torn sheet would need you to cut strips
from another sheet, apply the adhesive, and apply them. Ready-made
mending tape still sounds quite attractive!

--
Mike.

Mary Fisher wrote:
"Howard Neil" wrote in message
news:4272a654$0$581

Mary Fisher wrote:



This may be a good time to ask local farmers for their used sheets.


I don't know farmers who use them and my garden plots are measured in low
single numbers of square yards, not hectares. And I only have four plots.


Ask your daughter to obtain some and collect it when you next visit?


I'll post the result if my experiments tomorrow.

I have now experimented and the results were excellent. No skill was
required, even the first hole was perfect.

I used a gas soldering iron (so it could be easily used outside) with a
pointed bit. By poking the poly, a round hole about 5mm across was
formed. The melted poly then formed a ring on the outside of this hole
and I believe that this ring would be strong enough to prevent tear-out
(I did not try putting it under tension). Simple, neat, and the join,
once under tension, could be covered with the poly joining tape if a
belt and braces solution is required.

If/when my polytunnel next tears, I will definitely give this a try.


--
Howard Neil

Stefek Zaba wrote:
I used baler twine, which is a 3mm or so plastic string, which can easily
be melted into a nice point.
....with the aid of a welding torch. Thereby fulfilling the LAW, which
requires ALL agricultural repairs to be made using baler twine and a
welder...

I think I'll stick to baler twine only thank you, especially for when my
trousers fall down.

Owain

"Howard Neil" wrote in message
...



This may be a good time to ask local farmers for their used sheets.


I don't know farmers who use them and my garden plots are measured in low
single numbers of square yards, not hectares. And I only have four plots.


Ask your daughter to obtain some and collect it when you next visit?

She's, er, otherwise engaged at the moment. Pregnant.


I'll post the result if my experiments tomorrow.

How about you picking up a bit for me, I'll collect it in July?

Mary

Mary Fisher wrote:
"Howard Neil" wrote in message
...


This may be a good time to ask local farmers for their used sheets.


I don't know farmers who use them and my garden plots are measured in low
single numbers of square yards, not hectares. And I only have four plots.


Ask your daughter to obtain some and collect it when you next visit?


She's, er, otherwise engaged at the moment. Pregnant.

Congratulations, Granny. :-)


I'll post the result if my experiments tomorrow.


How about you picking up a bit for me, I'll collect it in July?

I've already had my neighbour's plastic (the only one I know who has a
silage clamp). The others all use silage bales. :-(

--
Howard Neil

In uk.d-i-y Howard Neil wrote:
Mary Fisher wrote:
"Howard Neil" wrote in message
...

Mary Fisher wrote:


You didn't specify "poking plastic" originally. Is that what you'd do?

Yes. I use the same principle in my veg patch. I cover it with old silage
sheet and make holes with a blow lamp. The sheet melts back to produce a
hard ring and a nice clean hole to plant the veg through.


Actually that's not a bad idea - for a veg patch. I might (albeit
reluctantly) follow your example :-)

This may be a good time to ask local farmers for their used sheets. They
should now have cleared their silage and they will have to pay to have
the sheets removed. Someone offering to take a sheet off their hands for
nothing will be welcomed.


However, I think that such holes might be too large for a polytunnel lacing
repair.

You haven't seen the size of the laces. :-)

The plastic in some areas is quite degraded.
The south-east corner has perhaps 1/3 the pull-through strength of
the north-west one.