Actually, I should have realised it from 5 years ago when trying to use some
bits of it for windows on my 16mm locomotive. Perhaps the answer would be
to drill some small hole in the hope that the Araldite will ooze through and
provide a locking mechanism, instead of an adhesive mechanism, when it sets.
You can get primers or promoters designed to make bonding to
polyolefins (polythene, polypropylene) and other hard-to-stick-to
plastics like silicones more effective, but they tend to be expensive.
It will say something like "activator for low surface energy plastics"
on the bottle.
It is a good idea to wear rubber gloves when using, some of them are a
There are also a few glues made for that sort of stuff, like Loctite
polyolefin bonder. Again, the good ones are expensive, and they tend to
be the sort of stuff with a six month shelf life.
I'm not up-to-date with the latest products, but regarding the cheaper
ones, the ones which come on a card don't seem to work as well as the
ones which come in separate bottles. YMMV here.
There are hot-melt glue sticks made specially for the low surface energy
plastics as well.
A cheaper way is to wipe with alcohol of some sort then flame treat -
pass the end of a butane or propane flame over the surface, moving quite
fast, back and forward overlapping strokes.
There should be no obvious change in the plastic, if there is you did it
Glue within a few minutes of flame treating, the effect doesn't last
long. You will probably need a few tries to get it right - the idea is
for the glue to wet the surface thoroughly and easily.
-- Peter Fairbrother
For RTV silicone, I had good results from using one of the proprietary
silicone rubber remover products to treat the surface of the cured rubber for
a few minutes, before wiping it off again. The paint has survived with no
problems on the silicone 'putty' of the window frames for three years now.
The reason for using RTV silicone on windows was because I was retrofitting
Crittal steel window frames with sealed unit double glazed panels.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.