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sugar - acid Tuxedo agate

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deb193
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« on: July 26, 2010, 05:32:59 pm »

I have been trying to develop a good procedure for making sardonyx using the ancient sugar-acid methods. Mostly I'm relying on George Fisher's writeup in his book, and a similar account by Kurt Nassau. I have had some good to mixed results, but it is a work in progress.

I was inspired when I heard theGemShop had made a batch in 2005 which they marketed as Tuxedo Agate (http://thegemshop.com/osc/gal_cab_tux_05.php)

I bought a few slabs from them in 2007 at the World of Agate show (see below). On a recent visit to the shop, they only had one bag left. It had about 8-10 slabs and was priced at $150. I paid $29 for my 3 slabs. They are cut thin because there is a limit to how deep the treatment penetrates. I am working to understand how to get the deepest penetration. The thickest one is 5mm, but the thinest is only 2.8mm.




Here is some of what I cooked:








Some preforms:


I made some thick slabs and cut some high domes. I lost the color on the edges, so I soaked them in sugar again, and cooked them again. Here is some of the ones done twice shown at different stages. Currently this is 220g, and I need to sand and polish. From the top, dry, then wet, recooked on bottom)
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« Reply #1 on: July 26, 2010, 05:44:55 pm »

WOW!  What a difference between the original material and your cooked versions.  It really brought out the banding!
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thewrightthings
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« Reply #2 on: July 26, 2010, 05:58:09 pm »

What striking results you got.  How long at each temp, and what's the sugar acid part, if I may ask?
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deb193
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« Reply #3 on: July 26, 2010, 06:14:42 pm »

Prolonged soaking in a saturated sugar solution gets sugar molecules into the pore space of the agate. About 3 weeks at room temp. Some agates have more pore space than others. Moroccan and Brazilian work well. Sugar is a compound of Carbon Hydrogen and Oxygen. The acid strips off the hydrogen and oxygen (making water and other vapors). In ancient time it was acetic acid (vinegar). Today sulfuric acid is recommended, but it is more hazardous to handle. Simmer at about 350 F to 390 F for one to several hours. (Some recommend longer and/or hotter). Neutralize with water and soda after removing rock from acid.

More details are online in George Fisher's book. But things like exact concentration of acid and exact temperatures are a bit fuzzy.

Soaking in sugar at 120 F was a bust because it formed a syrup that did not seem able to penetrate as well as thinner mix at room temp.

I am going to try fructose instead of sucrose, because that is a smaller molecule. I am also experimenting with heat instead of acid to carbonize the sugar, and trying other types of agate. I tried to actually boil the acid, but as I passed 475F there was way too much caustic smoke - even for outdoor cooking. I may try a 24hr simmer at just under 300F.
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« Reply #4 on: July 26, 2010, 06:16:13 pm »

These agates are more beautiful up close. MOst of them are a delightful chocolate brown color:)
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thewrightthings
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« Reply #5 on: July 26, 2010, 09:52:48 pm »

Daniel, thanks for that info.  So, first you soak it in a sugar soln. , then simmer in vinegar? , and then neutralize and that beautiful stone results.......if you're lucky.  Is that the order?
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deb193
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« Reply #6 on: July 26, 2010, 10:00:19 pm »

well, the Corsicans and Romans used vinegar. I use concentrated sulfuric acid obtained from bio-diesel supplier. I understand vinegar does not get as black.
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theimage1
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« Reply #7 on: July 26, 2010, 10:05:30 pm »

A few recommendations form an old chemist.

1.) heat the agate to about 100C and hold it for a while to de-gas as much as possible and dehydrate making the pores open up as much as possible. A light vacuum will help here too.
2.) try pulling a vacuum on the agate and the sugar solution while in the soaking process. If there is any gas in the pores the vacuum will help remove it, and allow the liquid to penetrate.
3.) one of the most porous agates around is snake-skin agate, it's the one they used to use to make the  copper dendrites form by induction with an iron nail.

I would guess you can get a simple vacuum from a 5 gallon plastic pail with snap on top (Like the ones used in 5 gal paint cans), put a pipe fitting on top with a simple on/off valve. Use a shop-vac to pull the vacuum when filled. and then close the valve.

Anyway just some old tricks for degassing porous catalyst before we used them in some liquid chemical reactions. It improved the liquid contact in the porous structure of the catalyst.

ron
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« Reply #8 on: July 26, 2010, 10:09:39 pm »



More details are online in George Fisher's book. But things like exact concentration of acid and exact temperatures are a bit fuzzy.

Soaking in sugar at 120 F was a bust because it formed a syrup that did not seem able to penetrate as well as thinner mix at room temp.

I am going to try fructose instead of sucrose, because that is a smaller molecule. I am also experimenting with heat instead of acid to carbonize the sugar, and trying other types of agate. I tried to actually boil the acid, but as I passed 475F there was way too much caustic smoke - even for outdoor cooking. I may try a 24hr simmer at just under 300F.

This is really interesting Daniel.

When it comes to chemistry, I do not have any input or answers except to imagine it is like mixing any other chemicals for any number of applications. There is a pretty specific mix of each chemical, heat, and length cooking/mixing time that create the ideal chemical reactions for a perfect recipe.

These look really great. 5mm is certainly workable !

Black and white is beautiful !

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deb193
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« Reply #9 on: July 26, 2010, 10:13:10 pm »

the heating before soaking sounds useful, as well as the vacuum. Thanks. I was thinking about one of these canisters that you can pump out the air to keep coffee fresh longer. It is not high vacuum, but it might be enough.

The snakeskin is porous, and I have some to grow dendrites. But, no white bands. It would make an all black stone.
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MrsWTownsend
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« Reply #10 on: July 26, 2010, 10:41:29 pm »

I had no idea there was even such a process...  The results are spectacular!  I need to get me that book.  Thanks for posting this~ I am learning new things on this forum ALL OF THE TIME!!!!
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thewrightthings
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« Reply #11 on: July 27, 2010, 04:59:04 pm »

It's wonderful how much we all learn from this forum.
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« Reply #12 on: July 27, 2010, 07:47:16 pm »

Much of the Black Onyx slabs that you can buy (expensively!!) form various vendors has a strong chemical odor as you work it. I think they are treated in Germany with analine dyes.
Bob
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The Polished Pebble
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« Reply #13 on: July 27, 2010, 08:15:56 pm »

So, I have a stupid question....Why don't you do the grinding & forming BEFORE you cook the stone?

I get that it is nice to see the prefered finish color combos before you start....but if you waited - you would only have to do it once.

Connie
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deb193
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« Reply #14 on: July 27, 2010, 08:54:57 pm »

it is entirely my lack of imagination to "see" when looking at the plain stone. But, since I expect to have ongoing batches, throwing them back in is not a problem.
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The Polished Pebble
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« Reply #15 on: July 30, 2010, 01:11:50 pm »

Daniel, do you think these would work?



This is from a piece of Horse Canyon Waterline agate. They are not very big....the largest one is only a hair over 1" wide.

Connie
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stonesthatrock
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« Reply #16 on: July 30, 2010, 01:55:42 pm »

those are so pretty..........  you learn something new here everyday.  I don't know that was a cooked material.

ty danial.

mary ann
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deb193
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« Reply #17 on: July 30, 2010, 03:12:41 pm »

Connie -

It would depend on if the porosity of the clear and amber bits is more than the white bits. Usually when water beads more readily on the white part it is god. If you have water beading all over, it might not take any carbon. But, it might also just take a thin outline between layers, which might look neat.

I suspect some of the area around the rim would stay clear.
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« Reply #18 on: May 11, 2013, 09:13:32 am »

I bought some TA a few years ago at Quartzite.  I knew it was processed but I didn't know how. Thanks for enlightening us! And please update us on your fructose experiment.

Tim
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« Reply #19 on: May 11, 2013, 10:32:12 am »

My sugar solution sits empty. I need to get back to this project.
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- Daniel

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« Reply #20 on: May 14, 2013, 09:18:14 am »

Daniel,  I'm trying a deviation from your process at present.  I bought a pressurized storage container for racket balls at a yard sale, and decided to try to force the sugar water into the stone with the slight pressure that can be pumped into the container over the 3 week soak.  The stone I'm using is an agate but with very subtle shading difference making up an attractive "scene = pattern".   If the process enhances that pattern it will be a worthwhile process.  I realize that a negative pressure is likely to pull out air bubbles that preclude the entering of the sugar, but maybe a positive pressure can do something for penetration as well.  cheers,  Tom 
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« Reply #21 on: June 19, 2013, 05:12:25 pm »

Since I mouthed off and told us all that I was trying a deviation from the recipe, I must confess that my result was less than impressive.  Admitting that a lot of differences in contrast can result from exposure and or photshoping, I don't see the expected pattern any better in the processes versus the unprocessed.  Possible reasons are: 1. concentration of sugar; 2. type of stone; 3. using positive pressure versus negative. 4. timing of sugar and acid treatments. (I used muriatic acid but diluted it by 3:1).  Here are the before and after photos although not identical orientations (dah!  Next time.).

Before treatment:



 
After treatment: 


I hope this does not discourage anyone from trying this.  I'll try to show a cab from this piece once I work it up. Tom 
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Tom
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« Reply #22 on: June 19, 2013, 05:45:04 pm »


Fascinating!

And you have just caused me to do a 180 on some of my thinking. I used to have very unkind thoughts about people that altered agate, as well as the people who bought those fluorescent flamingo pink slabs in gift shops. Didn't like the turquoise or any other color either.

This stuff is gorgeous! So you have neutralized a lot of negative attitude I was projecting, I'm sure the world also thanks you.

Thanks for sharing.
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« Reply #23 on: June 20, 2013, 07:51:11 am »

Tom, it may have been the stone. If there are not variations in density that correspond to the variations in shade, then no joy.

I had not considered muriatic acid so I cannot comment. The question would be what gas is formed pulling the hydrogen and oxygen out of the sugar to bind with the chlorine in the hydrochloric acid?

You can tease apart sugar penetration problems from acid stripping issues by baking the stones at about 400F for an hour. Too much hoter and the stone would get unacceptably brittle. If you get espresso colors, then you did get sugar into the pore space.

I have also wondered if I could take 5lbs of slabs oven dried at 230F for 3 hours, weight them, then soak in saturated sugar solution for 3 to 12 weeks, then lightly rinse and weigh again to get some idea of porosity (i.e., sugar solution in pore space).

I have two types of stone in my sugar bath right now. I want to add a particularly pale/bland ocean jasper. Maybe a 4th type. Then I plan to try to use the Australian low heat (160F) over several weeks in the acid step.

I just need to rig some fume abatement.

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VegasJames
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« Reply #24 on: July 20, 2013, 09:51:22 pm »

well, the Corsicans and Romans used vinegar. I use concentrated sulfuric acid obtained from bio-diesel supplier. I understand vinegar does not get as black.

Sulfuric acid is a strongly hygroscopic acid.  It is used in the process of making nitroglycerine for this reason.  As the nitric acid reacts with the glycerine water is formed, which can dilute the nitric acid.  Sulfuric acid takes up the water to keep the nitric acid concentrated.

For those who have not worked with sulfuric acid though do your homework and be extremely careful with this stuff.  I work with quite a few acids and sulfuric is the one that worries me the most.  It can strip hydrogen and oxygen from organic substances forming water and leaving behind carbon.  This includes skin among other things.

I had a roommate once that I told to never touch my chemicals.  Of course my roommate did not listen and ended up spilling a container of sulfuric acid on the carpet, which immediately turned to a black, gooey mess.

Sulfuric acid does the same thing to sugar molecules.  This is actually a common science experiment for students.  When the sulfuric acid is added to the sugar the hydrogen and oxygen are stripped from the sugar leaving behind the carbon.

Anyway, be really careful when using it.

If someone wants to try this though another common source of sulfuric acid is in the plumbing supply of some stores where it is used as an alternative to potassium hydroxide (Drano) or sodium hydroxide (Red Devil Lye) as a drain cleaner.  Sulfuric acid is superior to the hydroxides for cleaning out drains.
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« Reply #25 on: August 14, 2013, 12:08:53 pm »

well thegemshop has made a new batch, and it can be yours for $150/lb (no picking your own slabs).

http://thegemshop.com/collections/slabs/products/tuxedo-agate-slabs-1-lb-lot

... I need to get back to cooking. turn $5/lb agate into $150/lb agate. wow.

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sealdaddy
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« Reply #26 on: August 15, 2013, 06:18:41 am »

Excellent, friend~!!!!
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« Reply #27 on: August 18, 2013, 09:27:55 am »

I used to cook Andamooka matrix opal in a crock pot of sugar solution. I'd have to add water when it got too thick and I cooked 8 to 10 chunks and slabs for maybe a week at a time set on simmer. I know the opal was more porous than agate so maybe the times have to be extended. When I figured it had cooked long enough I would wrap each chunk or slab in aluminum foil individually and place them in an iron fry pan. That pan went into a kiln that I used for lost wax casting burnout for several hours (approx. 3-4 hours at 500 deg.). The heat turned the sugar black. Too much heat burned off the carbon and the stone would come out the original color. I let it cool to room temperature in the kiln. It was lots of fun lightly sanding the black stone to reveal the colors, now with a black background. I never tried the acid as there were too many warnings and I could not have left it un attended.  I'm going to slab up some agate today and try it out. I'll let everyone know how it worked in about a week or so.

Fred
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sealdaddy
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« Reply #28 on: August 18, 2013, 11:26:09 am »

I'm going to slab up some agate today and try it out. I'll let everyone know how it worked in about a week or so.

Fred

Yes...Please Do~!!
Thank you~
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« Reply #29 on: August 18, 2013, 02:36:40 pm »

I don't understand how too much heat can cook off the carbon. I thought carbon does not cook off - especially to leave stone w/ original color. I will have to research this.

I have used 450 deg oven to get dark brown, but I could not get black in oven.
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« Reply #30 on: August 18, 2013, 03:03:58 pm »

I know that when I am burning out wax for casting, if I don't get the flask to approx. 1200 to 1300 degrees I am left with brown and black traces where the wax didn't burn out completely. This could possibly cause an incomplete casting. If I get the flask to 1300 and hold that temperature for a while it all burns out completely and I'm left with white plaster indicating a complete burn out. I know that if I got the Andamooka matrix opal too hot, I was left with a clean piece of opal with no traces of the sugar. I only have manual controls on the kiln that I use so I can't be sure of the exact temperature. Since I over heated that batch I have tried to keep it between 500 and 600 degrees and haven't had a problem since. When I couldn't get the level of black that I wanted I just put it in with the next batch to cook in the crock pot and eventually I did get the level of black that I wanted.  Unless you are using a kiln with the ability to reach 1000 to 1500 degrees I wouldn't worry about over heating.

Fred
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hardrockcafe
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« Reply #31 on: October 07, 2013, 11:17:57 am »

Daniel stopped by my house a year ago last summer and brought some of his sugared agate for us to cook.  Here are some photos of the results:

Uncooked, dry:


After cooking, dry:


After cooking, wet:


Some worked better than others; he'll have to help with the IDs.  I recall the lower right is Redline Agate, but I don't remember the others.

I'm finally getting set up to cab again after 2 years off due to a house remodel, so I'll be cabbing these before long and will post the results.
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deb193
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« Reply #32 on: October 07, 2013, 11:31:15 am »

Yes. Missouri Redline Agate. A lace agate that has one red lace line. It did seem a little too dense to take the treatment very well.

I think the top right was from a stalactite looking agate I cut. It was not cave onyx, but looks a bit like it.

The bottom left is a Moroccan agate, but so is the top left. The one on top was too dense to absorb much sugar, so it too did not change a lot.
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hardrockcafe
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« Reply #33 on: October 07, 2013, 11:36:58 am »

Yes, my favorite is the upper right, although I think the lower Moroccans turned out well, too.
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hardrockcafe
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« Reply #34 on: October 07, 2013, 11:53:08 am »

I thought I'd share a little story about cooking this agate.  When Daniel came with the agate, he thought he brought a bottle of sulfuric acid, but it turned out he grabbed the wrong bottle and it was sodium silicate (as I recall).  He also brought an industrial strength hotplate.

At any rate, I didn't have any sulfuric acid handy so we tried acetic acid.  It did nothing at all.

Daniel had to leave, so I saved the agate for another day.  Shortly thereafter I got a bottle of drain cleaner (sulfuric acid) and started cooking the agate in a pyrex dish on a hot plate placed on a piece of plywood in the backyard.  Daniel had been concerned that my cheap Walmart hotplate might not get hot enough to boil the acid.  He needn't have worried.

The acid boiled for about half an hour and it looked like the agate had turned as brown as it was going to get, so I shut off the hotplate.  As it was cooling, the pyrex dish cracked and I was really glad I had used the plywood.  Hot sulfuric acid leaked out of the dish, all over the hotplate and the plywood.  I grabbed my baking soda that I had out to neutralize the acid and started dumping it as fast as I could.  It would bubble for a while, I'd stir, add more baking soda, and it would bubble, etc. until I was finally satisfied that I had it sufficiently neutralized.  My hot plate still hasn't recovered---it's still got corrosion and baking soda coming off of it.

A couple of words of caution:  if you do this, keep baking soda handy and stay away from the boiling acid.  The fumes are extremely toxic and can be fatal in sufficient strength.  Stay upwind.  In addition, I had a tiny bit of acid splash my heavy cotton shirt and it promptly ate a hole in it.
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deb193
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« Reply #35 on: October 07, 2013, 12:06:43 pm »

I have been meaning to try lower temperature over a period of weeks. Some guys that darken the matrix of Adamoka opal use sugar acid method, but only heat at 160F, but for 3 weeks. One guy used a potpourri dish.

I got a bunch of rock that has soaked from 2 months to a year. just been throwing stuff in. I need to put a crock pot under a plastic hood out on my patio and let it go for 3 weeks and see what happens.
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hardrockcafe
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« Reply #36 on: October 07, 2013, 01:04:05 pm »

The electric bill would add up in a hurry.  I wonder if you could make a solar collector that would generate enough heat...
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hardrockcafe
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« Reply #37 on: October 09, 2013, 12:42:16 pm »

Daniel, have you tried clear Blackskin Agate or Montana Agate?

They may not be good candidates without obvious banding, but I'm thinking Montana Agate often shows banding on the rind, even if the agate is clear...
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« Reply #38 on: October 09, 2013, 07:09:32 pm »

those are both very heavy in the hand. I would be worried not enough pore space, but I have not tried. maybe blackskin.
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hardrockcafe
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« Reply #39 on: October 09, 2013, 09:15:17 pm »

Yes, they do seem dense.
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hardrockcafe
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« Reply #40 on: October 10, 2013, 06:52:50 am »

For a completely different look, I wonder if chevron amethyst would work giving brown/black and blue/purple...
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« Reply #41 on: October 10, 2013, 07:47:02 am »

it think you might have better luck with amy lace
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deb193
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« Reply #42 on: October 20, 2013, 07:32:40 pm »

The electric bill would add up in a hurry.  I wonder if you could make a solar collector that would generate enough heat...

actually, for a crockpot on low the cost may be modest.

http://www.cockeyed.com/science/power_use_database/crock_pot.html

Item:    Crock Pot: 312 Watts
Description:    A crock pot is a slow-cooking vessel which uses a heating element
Power:    Has two settings, Low (223 watts) and High (312 watts). Probably uses a thermostat to turn heater on and off.

Power Cost:
at 12 per kw/h    
Cost per Minute:    6 hundredths of one cent (0.06)
Cost per Hour:    3.7
per Day (8 hrs):    30
per Month (5hrs/day):    $5.69
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hardrockcafe
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« Reply #43 on: October 21, 2013, 06:23:51 pm »

You're right!  Much cheaper than I thought.  Give it a shot!
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