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Author Topic: Epoxy letting go  (Read 708 times)

Dihusky

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Epoxy letting go
« on: November 30, 2020, 10:13:50 PM »
I was wondering if anyone else has experienced problems with epoxies  letting go.

I ran out of Tite-on so changed to JB-Quik, its been working well and just bought some more, now it's a different story, been cutting a pair of Sapphires for earrings, both stones have fallen off at different stages creating no end of problems as I am sure you can imagine. What was weird is when they let go there was no stress on the stone, they just fell off!

I used superglue on the epoxy to remount so now I've transferred using Dextone on the first stone, all looked good until I wanted to remove the first dop, bit of heat on the dop and the transfer dop fell off, the pre transfer dop stayed put thankfully. Reset the transfer using bigger dops to improve the bond area and keeping fingers crossed for the next trial.

Has anyone else experienced similar problems?

Faceting Frank

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Re: Epoxy letting go
« Reply #1 on: November 30, 2020, 11:18:16 PM »
Never used anything but 5 minute Araldite for years and it’s as solid as a rock. Only disadvantage is doping the stone, unlike wax you can’t move the stone.
I have two stops on the bottom and side of the transfer jig and work out where they need to be when doping the stone.
 After transfer doping I hold the stone with a wet tissue and put a weight on the dop to be removed and use a BBQ lighter to heat the dop. It easily removes the dop and I put the stone in water to prevent an issue with the other glue.
« Last Edit: December 01, 2020, 07:29:12 AM by Faceting Frank »

MakkyBrown

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Re: Epoxy letting go
« Reply #2 on: November 30, 2020, 11:56:08 PM »
Make sure you clean your stone with fresh acetone not the acetone you've been soaking dops in. I cook my transfer jig in the oven for 15-20 minutes at 50degreesC. Sets the dextone hard, never had a stone come off since doing the above.

Faceting Frank

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Re: Epoxy letting go
« Reply #3 on: December 01, 2020, 07:42:00 AM »
Bit more to add to that. Glue the stone to the other dop in the transfer jig with Blu-Tack and set that up with the stops. Leave a 3mm gap between the dop to be glued and stone, so the glue can get in there. Slide the dop up to the stone and finish off.

Dihusky

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Re: Epoxy letting go
« Reply #4 on: December 01, 2020, 10:19:35 PM »
Makky, Are you using the 5 min Dextone or the slow set, 5 min grabs quickly but quotes 16hrs to full strength. I haven't tried cooking the glue as yet, certainly worth a try, might use the drying oven as I can control the heat and time accurately. Cleaning I use Isopropyl on used lens cleaning cloths as they're lint free.

Frank, I use Blu-Tack a fair bit, particularly for accurate doping of rough and setting up stones for repair work, an invaluable tool. I used it for holding the dropped stones whilst aligning and the alignment was pretty good as there were some impressions in the epoxy to help, then superglue and accelerator, fortunately didn't lose too much in the re-cut, the stones are only 4 x 6 pears so didn't have much to play with anyway, think I spent about half an hour on each before I was happy enough to apply the superglue.

Client hasn't got any spare material for a start over, a lot of the rough he provided had been sorted by his Father so was pretty useless, then there was the jar of better material but all too small, 2ct or less, the two I selected were the best of the bunch, one a messy 12ct and the other 6ct.

tinker

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Re: Epoxy letting go
« Reply #5 on: December 02, 2020, 10:15:51 AM »
I have used 2 Pak Epoxy for ten years now, no problem with the stones falling off the dop, when it comes time to remove the stone, I soak it in Acetone, no heat needed, the stone just falls off after about two hours or you can remove after an hour with a stanley knife if in a hurry, the Acetone softens the glue.


MakkyBrown

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Re: Epoxy letting go
« Reply #6 on: December 02, 2020, 11:45:39 PM »
I'm using the 5minute dextone. If I get the ratios slightly wrong, cooking helps. Put it in the oven, have a cupper then ready to go. Perhaps being colder in Tassie is also a factor why I use the oven.

Bucket

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Re: Epoxy letting go
« Reply #7 on: December 03, 2020, 10:03:00 PM »
Make sure you clean your stone with fresh acetone not the acetone you've been soaking dops in.

I've never used acetone to clean my stones prior to dopping, just metho and a lint free cloth. I use the ones that you get for cleaning glasses. I've rarely had one drop off, just one or two very small stones and I've used either too much pressure on them or haven't used a big enough dop so very little surface to attach to. I'm using what will be my last tubes of Tite On, I've also used JB Quik before and found it OK. I have another pack of it in my drawer for future use.
Common sense isn't exactly common

Moth

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Re: Epoxy letting go
« Reply #8 on: December 07, 2020, 01:05:08 PM »
I used tite-on but am down to my last half tube so using JB Weld. I was taught to clean with metho first, which I still do today but I now 'flat dop' with wax so I can move the stone around to maximise yield. I sometimes transfer with wax but prefer the epoxy for the second stage. If initially dopping with epoxy I have a small jig (made for me by Graham Young) I simply mark a spot on the stone where I would like the dop to be centered, then position the stone on blue tack so the dop drops straight down at 180 onto the pre-marked dot - simply just apply glue to the dop face and drop it down.

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