Adhesive

[Ruedeleglise]

A very basic piece of advice please. The best adhesive to glue an amber cabochon of 8mm into an 8mm bezel set ear stud and any general words of wisdom.

[Dennis]

There is no need to glue cabochons. They are he easiest of all shapes to set if you make your own cup.
Bought cups of course do not fit most stones of the same nominal size unless the stones are man made.
Just watch some videos on the subject, or buy a simple book for beginners, such as Anastasia Young.

Amber being rubbery will not glue well, because glues tend to be rigid. If you are desperate to finish, try gel superglue. Dennis.

[Goldsmith]

I would suggest that you try Araldite Instant which sets quickly and is a clear glue, see; https://www.amazon.co.uk/Araldite-Instant-Syringe-Epoxy-24/dp/B006JYQ1I6 I have used this glue many times when required without any trouble, when set it is colourless and does not effect the colours of semi transparent stones.

James

[Ruedeleglise]

Thanks again for your advices.

[eekoh]

Ah, just the info I was looking for.
My design doesnt involve completely flat surfaces so if it’s going to work it needs a good adhesive. Do you think it would be secure enough for something like this?
11482
The sea glass doesn’t have a highly polished surface but the silver will obviously be smoother. Would I perhaps need to slightly roughen the surface on the metal at the point of attachment?

[Dennis]

It's not completely clear why you want to glue your sea glass Hazel, perhaps a picture of it would help.

In principal glues work better on roughened surfaces, because that increases the surface area. Both gel superglue and clear epoxi, such as Araldite help to fill small gaps where the fit is uneven.
That said, mechanical retention is more certain to work in the long term and less likely to yellow the colour as it ages. Dennis.

[pearlescence]

It's a common misapprehension that glue should be applied to roughened surfaces because it increases surface area. In fact the opposite is true. Glues work by making permanent a vacuum between the two surfaces. The thinner the adhesive layer the better the adhesion. You don't rough up a solder joint, do you? Solder will only flow across a close, smooth and tight joint.

[Paul Kay]

It's a common misapprehension that glue should be applied to roughened surfaces because it increases surface area. In fact the opposite is true. Glues work by making permanent a vacuum between the two surfaces.

Pearlescence, are you sure about that? It worried me but I'm no glue scientist myself; I found this in the Guardian's Notes and Queries:

'How does glue work, why is it sticky and how can it bond seemingly impervious substances like glass and metal?

MOST adhesives work by first flowing and spreading over the surfaces of the materials (e.g. the glass or metal) to be joined. This obviously requires the adhesive to be of a relatively low viscosity so it is often sticky to the touch. The flowing and spreading action needs to be extremely effective so that the atoms of the adhesive and the materials to be joined come into contact with each other. This allows the molecules of the adhesive to be attracted to those of the materials being joined and then 'intermolecular forces of attraction' (present in all materials) can now hold the adhesive to the surfaces of the materials being joined. Note that the adhesive does not have to react chemically with the glass or metal. Finally, to be able to resist separation of the joint, the adhesive must usually now harden. Some adhesives do this via loss (by evaporation) of the solvent or water into which the adhesive had been dissolved by the manufacturer of the glue. Others do this by chemical reactions occurring within the adhesive to form a (strong) polymeric adhesive.

A J Kinloch, Professor of Adhesion, Imperial College, London SW7'

Note: According to The Royal Society 'Anthony Kinloch is the acknowledged world leader in the science and technology of adhesion'

[eekoh]

Thanks for replies.
Dennis, I've glued because I couldn't think of a better way to fix it into the domed shell with my current skills. Neither the glass nor the metal are a flat regular shape so it would be really tricky to make and fit a soldered bezel and I'm just not that keen on wrapped wire designs. Plus if I wrap it in wire it loses the impact of the colour pattern in the glass.
How would you approach a design like this?

[Sheen]

Perhaps solder 4 prongs to the inside of the dome?

[Dennis]

This seems a good place to quote a sign on a shop door near me:
'Children under twelve must be accompanied by an adult. We hope our customers will adhere to this notice.' Dennis.

[eekoh]

ha, i've got visions of a bunch of small children with ice cream smeared on their faces and sticky fingers adhered to the notice like fly paper!

[pearlescence]

What he says and what I say are not mutually exclusive
But things will stick without glue - think of two identical glasses

[handmadeblanks]

If I glued two interlocking Lego bricks together surely that bond would be stronger than simply gluing two smooth plastic bricks together? The reason being there is more surface area...? Isn't this what is happening on a microscopic level when you roughen up two surfaces that are to be glued together? More surface area to create a vacuum...? Lots of stuck glasses...?

[mick]

Thanks for replies.
Dennis, I've glued because I couldn't think of a better way to fix it into the domed shell with my current skills. Neither the glass nor the metal are a flat regular shape so it would be really tricky to make and fit a soldered bezel and I'm just not that keen on wrapped wire designs. Plus if I wrap it in wire it loses the impact of the colour pattern in the glass.
How would you approach a design like this?

Hey EEkoh

I have used some loctite glass glue on some top drilled glass and it seems to work well. It is clear setting and states in can bond just about anything to glass. Its £3 a tube so not to expensive to try :)

I always have some Iso alcohol handy too afterwards to catch any glue that leeches out.

If you are struggling to get a good hold you could also try using something porous as a bridge between the two surfaces. Fine fiberglass sheeting, cotton. Anything that isnt too thick and will absorb the glue well will work.




As regards the whole glue debate and surface area its not just about the surface area. Its ultimately about the glues ability to adhere to the surface. Roughing the surface up is the same as roughing a cars bodywork before painting. It does increase surface area but also allows the glue to form hooks as it sets in the rougher areas of the surface. Like velcro on a micro scale :)

Mick

[china]

Years ago I needed to fix a rear view mirror mount to a wind screen, first attempt it fell off< i rang the loctite technical dep. and the bloke said to polish the mount to a mirror polish.
I did this in 20 years ago, the car now belongs to a mate who is restoring it, the rear view mount is still in place

[Dennis]

That's torn it! I still religiously roughen or notch anything to be glued and probably shall continue to do so.

Certainly adhesion of epoxy is improved by roughening. Perhaps different situations need different treatments. Dennis.

[china]

Yes it is interesting, I would have gone the rough it up rout also, as Cabinet Maker by trade that was was always the way to go as you said the theory being more surface area, most likely different glues work in different ways