On 20/05/2021 13:46, David wrote:
On Thu, 20 May 2021 12:12:55 +0100, newshound wrote:

On 20/05/2021 12:04, David wrote:
I posted on this some time back, perhaps nearly a year, but can't seem
to find the original at the moment.

I have some moulded plastic fitting in my caravan which have proved
flimsy.
I need to both repair and strengthen them.
As a first check, should a fibreglass repair kit - that is, two part
epoxy resin and some fibreglass matting - be suitable for this kind of
repair?

I am about to investigate in more detail once I've emptied out the
caravan so I can get to the area in question.


What type of plastic? It's difficult to glue things to polyethylene and
polypropylene (for example), even though "sticky tape" of various sorts
will stick well.

Such a lot also depends on the loadings and requirements.

Traditional fibreglass kits use polyester resin rather than epoxy. It's
cheaper, more brittle, and does not stick quite so well to many things.
Epoxy plus fibre glass is good, provided it has the basic adhesion.
"Mechanical keying" is also a big help.

I'm not sure how to tell what kind of plastic it is.

It is hard rather than soft+flexible.

A crude guide is if it feels waxy then it is probably HDPE which almost
nothing will stick to reliably. If you can shave a piece off and try it
with various solvents and gentle heat that will distinguish cured resin
one time cure plastics from thermoplastics after that it is guesswork.

If you don't know what it is then slow epoxy is the least likely to
cause adverse solvent effects and be reasonably strong. Thermoplastic
glue sticks can be effective in the right circumstances too.

If you need a bit of flexibility and the load isn't too high I have had
some luck mending torn door seals with black Sugru (sp?).

--
Regards,
Martin Brown