Does anyone know where to get dental resin or similar fine, hard,
I've found a few items on eBay such as number 160736912918, which I'll
happily buy but wondered if there was anything better/cheaper/larger
quantity as the eBay items only give you about 4g for a tenner.
I have no particular job that needs it at the moment but quite often
want something harder and finer than trying to fill a hole or repair a
profile with Araldite, wood filler. An example might be repairing the
plastic sides to a friend's spectacles.
Do you really mean hard. or strong? I'll assume strong, which is what
you want for mending glasses.
Dental resins are usually bisphenol methacrylates with a lot of filler.
They are designed for teeth, and aren't really that suitable for other uses.
What I think you want is a structural methacrylate / polyurethane
adhesive, or else a really good epoxy. The structural glues can be
(meth)acrylates, or urethanes or quite often both at once. They'll
usually have -acrylate in the name somewhere though.
Typing "structural adhesive" into ebay gives several options. Note
however that you need fresh glue - for these glues the use-by date can
really mean exactly that. Keeping them in the bottom drawer of the
fridge can extend their shelf life.
Or, quite possibly a good epoxy is what you need. Not all epoxies are
the same! There is a huge difference between a fresh first-class epoxy
and cheap araldite in tubes which has been kicking around for years.
Epoxies are also a darn sight easier to use than the structural
acrylates/urethanes, which can have very short setting time, which
necessitate the use of mixing tubes which mix and dispense the resin all
at once, and which have to be thrown out after each use.
I (used to) use NHP 30 minute epoxy glue for mending-spectacles type
stuff, but I don't think it's available any more - however I'm told
Devcon and X-poxy are about the same. The 30 minute versions are
considerably stronger than the 5 minute versions, which I'd avoid.
I use West systems epoxies for non-gluing purposes.
I personally wouldn't bother with the structural urethanes/methacrylates
unless I need to glue very demanding stuff - I have some, but very
seldom use them.
Note that not all cyanoacrylates (superglues) are the same either. Cheap
ones can be used to tack things together temporarily for later
seperation, but if you use a good one, properly, on eg steel you will
not be able to mechanically seperate the joint. Ever. The steel will
-- Peter Fairbrother
I've just been asking round a few rocket people, who used to use the
no-longer-available NHP expoxy, and the general conclusion is that
Devcon Two Ton is a more than acceptable substitute.
-- Peter F
I used to use Super Steel Epoxy. Don't know if it's still available,
but used it for things like gluing rear view mirrors back on to the
screen in the old Audi 100. Never fell off again and the stuff sets
hard enough to work after a few minutes, then rock hard the next day.
Quite a few of the b&q offerings, araldite and devcon included were
rubbish in comparison.
Specialist (aerospace etc) companies like Silmid in Birmingham have a
vast range of adhesives for just about every application. Worth using
their site as a catalog to see what's available...