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Post by broseph82 on Oct 21, 2014 17:34:14 GMT -5
I have a few questions regarding using Opticon:
1) is it necessary to have heat on it or can I just leave it soaking for a day or so?
2) is the hardener necessary?
I had an older gentleman tell me he use to just soak his slabs/cabs in it and that's all he did for it to seal and harden the rock (but that was a long time ago for him).
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Tom
fully equipped rock polisher
My dad Tom suddenly passed away yesterday, Just wanted his "rock" family to know.
Member since January 2013
Posts: 1,557
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Post by Tom on Oct 23, 2014 8:05:27 GMT -5
Bobby can likely better answer this than me, but:) Your results will be much much better using heat. Heat not only thins the resin but it tends of open up the fracture line somewhat, that allows the opticon to fill the void. At the very least you should be somewhere warm to do the fix. Opticon tends to be pretty thick at room temps.
As for not using hardener I don't think you would be happy, the resin will NEVER harden and will most likely leach out from the fracture or get contaminated with dirt etc. The hardening step is the "seal" for the fracture. There is no doubt that the fracture dissapeers with just the resin but it will never be truly "sealed" without the hardener.
Others please chime in, this is in my limited experience.
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Post by bobby1 on Oct 25, 2014 23:44:26 GMT -5
Tom is correct on all points. I heat the stone to a point that it is too hot to grip with your bare hands. I slip Tygon tubing over the ends of a pair of long needle nosed plier to grip it with. Heating the stone more widens the fracture so the Opticon can penetrate deeper. The final step is to mix the hardener and apply it over the fracture gap while the stone is still hot.
Bob
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on Sept 14, 2015 21:26:04 GMT -5
Resurrecting this old, but excellent thread... I have a cab that I have taken up thru the 600 wheel and noticed a small fracture in the top end of the cab. Historically I have just reshaped the cab to get rid of the flaw but I am inclined to try to save this one if possible and plan to use bobby1 's recipe/process at the start of this thread. My question is should I stop and try to use the Opticon to seal it now before I finish it off or complete my sanding and polishing then seal the finished cab. In advance, many thanks for your input. Cheers |
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Post by bobby1 on Sept 23, 2015 0:51:23 GMT -5
I finish the cab and then do the fracture sealing process. This keeps me from having to do any cabbing work over the sealed fracture line and possibly from having the polishing wheel undercut the fracture sealing material and showing the fracture blemish.
Bob
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Post by broseph82 on Oct 8, 2015 7:43:25 GMT -5
I finish the cab and then do the fracture sealing process. This keeps me from having to do any cabbing work over the sealed fracture line and possibly from having the polishing wheel undercut the fracture sealing material and showing the fracture blemish. Bob So would this not be good for slabs? I have a bunch of silvery moonstone and this stuff is so brittle. I've got some shaped out, but it likes to chip off in layers when I'm least expecting it. I'd hate to trash this stuff because I have so much, but would rather seal it to be able to work with it. If you're saying it may undercut on the wheels then that's no bueno. Ugh....... |
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micellular
has rocks in the head
Rock fever is curable with more rocks.
Member since September 2015
Posts: 640
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Post by micellular on Dec 3, 2015 13:17:09 GMT -5
Bobby can likely better answer this than me, but:) Your results will be much much better using heat. Heat not only thins the resin but it tends of open up the fracture line somewhat, that allows the opticon to fill the void. At the very least you should be somewhere warm to do the fix. Opticon tends to be pretty thick at room temps. As for not using hardener I don't think you would be happy, the resin will NEVER harden and will most likely leach out from the fracture or get contaminated with dirt etc. The hardening step is the "seal" for the fracture. There is no doubt that the fracture dissapeers with just the resin but it will never be truly "sealed" without the hardener. Others please chime in, this is in my limited experience. I absolutely agree with this. I tried doing bobby1's method last week and it worked like a charm. However, I don't think that heating the stone to fairly low temperatures causes the fractures to widen significantly. Wouldn't heavily fractured stones just fall apart? Anyone got some crappy Morgan Hill poppy jasper to experiment on? The linear thermal expansion coefficient (TCE) of quartz is pretty small at ~0.77 x 10^-6 m/mK (for a sense of scale, it's around 4 for borosilicate glass, 5.3 for sapphire, 9 for plate glass, 14 for concrete, and 17 for copper). Source
Back of the envelope calculation for the math-inclined, assuming 1/2" cab (1 cm) on either side of fracture and coefficient of quartz. The following is in metric. When I heated my stone, it was initially at room temp (20C) and I measured the temperature at ~ 140F (~60C). change in length = initial length x TCE x (change in temperature) change in length = 0.01m x 0.00000077 m/mK x 40K change in length = 3.08 x 10^-7 m change in length = 0.308 microns (0.012 thou for you imperialists) While this doesn't affect the final outcome in any way, I think the reason Opticon works better with a hot stone is, as Tom pointed out, because its viscosity greatly decreases with increased temperature, and thus it is able to better penetrate fractures via improved capillary action. Michelle |
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diamondust
off to a rocking start
Member since January 2014
Posts: 20 
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Post by diamondust on Dec 3, 2015 22:07:23 GMT -5
HI, I have been using Bobs process for a while now with great success, Sometimes I use it before I polish, to stabilize a stone then again after its polished. I heat my stones with a halogen bulb in a gooseneck. The stone gets very hot. I leave them overnight sometimes. I am in the process of carving a Christmas gift for a coworkers wife. It a Jade Sea horse on coral carved from ( I think it is white and lavender marble) with a jasper base, the base was difficult because It is Brecciated and full of flaws. Anyway, I carved out as many fractures and flaws as possible, then I polished it, and finally I coated it with unhardened Epoxy resin and heated it under my halogen bulb for a few hours, then I rubbed the epoxy into it by hand( wearing rubber gloves) and let it bake a few more hours. then I wiped the unhardened resin from the stone, mixed a small amount with hardener and rubbed it all over and let it set 30 minutes( to catalyze the resin in the fractures), finally I wiped all of the remaining resin from the stone, which brought the polished surface back, but with a greatly improved finish, because now all of the small little pits and flaws are filled. I have been able to save many otherwise lost causes with this method. and I tell others about it whenever I see a beautiful stone with a fracture.
Thanks Bob!
David
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rabbit
off to a rocking start
Member since March 2017
Posts: 1
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Post by rabbit on Mar 13, 2017 19:52:40 GMT -5
Thanks for the great info, I was wondering if you have ever used it on an Opal? I'm worried about the heat and i was wondering whether the natural porosity of that stone, it being hydrophilic, would aid in the absorption process? Any tips would be more than welcomed!
Rabbit
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Tommy
Administrator 
Member since January 2013
Posts: 12,981
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Post by Tommy on Sept 16, 2022 7:27:49 GMT -5
*~ bump ~* restored the photos.
I love this tutorial and had really good success with it when I was just getting started.
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