Opal glue.

[dom105]

Does anyone know what type of glue to use when making an opal doublet etc.
Also what is the thinnest piece of opal you can use.

[Bucket]

Dom, the ones I have done, the backing started thicker than I wanted so i could get a grip on the stone better, after completing the top, I ground away the excess backing.  I found that easier than trying to slice the backing thin enough. To glue them I used a two part epoxy, clear one if you have it. Let them dry for at least 24 hours before starting. Opal again should at least start as thick as you can, depending on where the colour sits in the opal, but the thinnest I've ended up with would be 1-2 mm.

[Rusted]

Epoxy 330 is great glue for this, strong, dries clear and doesn't yellow over time. It's the stuff conservators use for mending valuable antiques.
It's not cheap but is really good.

[MakkyBrown]

Other options would be UV glues, opticon and maybe Selleys All-Clear(which you can get from Bunnings), but not sure how well it holds up long term. I think Aussiesapphire sells the 330.
MB

[dom105]

That's interesting, I've actually been throwing away anything less than 3mm thick. I wasn't aware that you could do anything with it. Thank you all for the information.

[Bucket]

Dom if it's got decent colour, it's well worth thinking about doublets, I much prefer solids myself but can't bare to throw away good opal!

[dan1000]

Off the back of this, what materials is best for the backing of a doublet?

Black spinel?

Cheers!

[Bucket]

Dan1000, any black good quality material is OK. I've used a local jet black jasper that takes a good polish. Black glass is also something I've heard used but black spinel would work quite well. I've also used other materials for non opal doublets, I've backed cabs of clear quartz with golden rutile with lapis lazuli and malachite. The lapis worked better, malachite was too busy.

[dan1000]

Thanks for that, Bucket! I've got plenty of black spinel and a few bits of black potch so I'll have a crack with them when the clubs open back up!

[Bucket]

Technically speaking, I think the purists use black potch from Lightning Ridge, but any black solid stone is OK by me.