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 Post subject: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 5:13 pm 
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Hi, I'm going to cab a few more pieces of my rough welo opal this weekend. I was reading Paul Downing's book and it talks about using white glue and then putting nail polish over the top. Are there any other options for opal? I want to try something other than the wax.

Thanks!

Laura


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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 6:12 pm 
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I cold dop opal with 5 minute epoxy and then remove the dop by placing the assembly in a dish of cold water with a piece of paper towel under it and heat it to boiling in the microwave. Leaving the opal in the hot water, I tilt the assembly vertical and hold the stone down on one side with a wooden popsicle stick and tilt the dop the opposite direction. Since the epoxy is rubbery it takes little pressure to pop the opal off the dop. Scrape off any epoxy with another wooden stick under water. Make sure to leave the opal in the water until it cools to where you can put your finger in the water. I haven't found opal to be particularly heat sensitive, (while in water), but it is sensitive to drying while hot, thus the reason for keeping it underwater until it cools a bit.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 7:50 pm 
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Thanks, Michael,

How long do you let the epoxy set before you start working with the opal?


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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 7:57 pm 
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Laura, the white glue is the woodworking glue (PVA?)and you just soak it in cold water to remove. Many commercial cutters here use this and don't use the nail polish. For BIG opals they do use something stronger tho.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 9:09 pm 
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The Elmer's glue method is probably the safest for a beginner cutting smaller stones. Be sure to let the glue set up overnight. Since the glue is water-soluble a coating of clear nail polish, applied after the glue is dry, waterproofs it during cutting. Just scrape the polish off with a knife blade before an overnight soak to remove the glue.

Wax dopping is probably the quickest but it requires some special tricks that are too involved to be explained briefly. Gradual heating and cooling is the key. Raising or lowering temperature quickly will crack the stone.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 9:15 pm 
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I have always used wax to dop opals. Just dissolve some orange flake shellac in alcohol and paint it on the opal. When dry there is no need to heat the opal. The wax will stick to the shellac just fine. Soak in alcohol to remove and clean up.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 9:24 pm 
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That's an interesting approach Allen. I've used something similar in faceting but never thought of it as a cold-dopping method. What kind of wax do you use on your dopstick? Plain shellac or commercial dop wax?

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 10:44 pm 
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I glued up two of the smaller pieces with white glue and have to make a flat area on the others in the morning so that I can dop them up, thanks for the info, it's been helpful. I bought some epoxy too and will give that a try tomorrow.

Laura


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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 10:50 pm 
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Largos Mom wrote:
Thanks, Michael,

How long do you let the epoxy set before you start working with the opal?


I use my faceting transfer jig to hold the parts and set it all on top of the ultrasound tank's cover, so it heats up to maybe 100°F and I leave it there 20 minutes to 1/2 hour.

I would never use wax to dop anything...mostly because Home Depot doesn't carry it and I don't have any. The other reason is that I burn myself enough with my jewelers torch and every time I use wax I get burned by either the wax or the oxy-acetylene torch that's needed to use it. WAY too dangerous for me. Now if I could just get my fingers apart, (that crazy glue is very sticky), I'd be doing much better. Just say NO to wax! :P

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sat Nov 20, 2010 11:18 pm 
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michael_e wrote:
I would never use wax to dop anything...I burn myself enough with my jewelers torch and every time I use wax I get burned by either the wax or the oxy-acetylene torch that's needed to use it. P

Some of us opal cutters use sneaky methods that avoid the use of open flame. I've been wax-dopping fine and expensive opals for 35 years and haven't burned my fingers once. The only time I lost a stone was when I was in a hurry and used an alcohol lamp for heating. Hint: electric coffee-warmer. I think they sell stick shellac at Home Depot.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sun Nov 21, 2010 12:26 am 
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I recommend Loctite Blue cap Gel. It is more water resistant. When faceting, I transfer to it too, then use a paring knife to weaken the first one and snap it off with care.

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Last edited by gsellis on Sun Nov 21, 2010 12:23 pm, edited 1 time in total.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sun Nov 21, 2010 12:51 am 
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Rom
I am not familiar with stick shellac. I was speaking of orange flake shellac that jewelers use to hold things with. I use a green dopping wax. Not even sure of the name but I have probably a lifetime supply.
I was not trying to create a wax vs. --- debate. Just offering up what has worked for me for years.

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 Post subject: Re: Need advice on dopping opal
PostPosted: Sun Nov 21, 2010 3:39 am 
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allen wrote:
Rom
I am not familiar with stick shellac.

That comment was not addressed to you.
Quote:
I was speaking of orange flake shellac that jewelers use to hold things with. I use a green dopping wax. Not even sure of the name but I have probably a lifetime supply.

That's what I was asking -- thanks. As a jeweler and lapidary I'm familiar with both orange shellac and dop wax and use both as appropriate.

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