jamesp
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Post by jamesp on Dec 11, 2012 13:44:17 GMT -5
I have been getting whipped by gas expansion.Added 3 cups vinegar to 16 pound capacity tumbler.And 3 cups vinegar to it's twin plus 2 cups of sugar.Both have run 8 hours with a vacumn.The one with the sugar has a stronger vacumn.I like vacumn.What is happenning?
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Deleted
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Post by Deleted on Dec 11, 2012 14:06:37 GMT -5
well.... that is indeed strange.
Did you put vinegar directly onto the surface of the stones? The limestone rind should fizz. I'll test mine.
Did the temperature go down after you closed the barrel??
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jamesp
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Post by jamesp on Dec 11, 2012 15:58:11 GMT -5
Scott,i did put some stones in the straight vinegar and had little bubbles for not longer than 60 seconds. Filling pores i think.So the limestone rind must be kinda stable.It definately 'bleached, the stone though(inverse bleached).The tumbler is in a stable temp enviro.Great questions.The sugar/vinegar mix is doing best.I do not know why.I add sugar to all finish rotary tumbling operations and never have gas then.
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Deleted
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Post by Deleted on Dec 11, 2012 17:31:40 GMT -5
So the limestone rind must be kinda stable. Interestingly enough the rind is not limestone. At least not on the pieces you sent me! I put pool acid on the rind of all the pieces you send me and got ZERO reaction. That is a negative test for Calcium Carbonate in any form. Gosh I love this! Thanks!
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jamesp
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Post by jamesp on Dec 11, 2012 18:44:04 GMT -5
It looks like limestone,but rind may be more silicified than I thought.It is very hard.The water in this river is commonly at PH 5 and lower.If you don't believe it,look at the bizarre bluffs the acid water cut through the limestone.Maybe the acid bath for thousands of years dissolved all calciums.The bluffs are blinding white limestone with 1-12 inch round ball holes eat out of it with a wasp nest in every other hole.
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Deleted
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Post by Deleted on Dec 11, 2012 18:49:15 GMT -5
awesome description! The next query I have is this. What weathered out of those bluffs to make those "round ball holes"?
I would not expect limestone to survive eons long immersion in 5 pH water. That explains it.
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jamesp
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Post by jamesp on Dec 11, 2012 18:49:27 GMT -5
A section of low water Suwanee River about 8 miles down stream from I-75 with common coral shoals.Looking from above on google earth you can see numerous light brown areas in the river.These are the shallow areas due to coral.
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The Dad_Ohs
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Post by The Dad_Ohs on Dec 11, 2012 19:54:53 GMT -5
There's a very good chance that the vinegar you add and let sit for a few dissolved any remaining Limestone within the coral before you tumbled it.
If you want to test it, next time soak a batch in vinegar for a few, then rinse and tumble as usual, see if any pressure builds up after a couple hours or so. If no pressure, then the answer is you removed the last of the limestone from the coral, probably deeper within the recesses, which was being released by the tumbling action.
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jamesp
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Post by jamesp on Dec 11, 2012 21:18:28 GMT -5
I hear you Mario.I will say that i got dang lucky.The tumbling action grinds into deeper regions of the rock.Who knows what lies with in.
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Dora
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Post by Dora on Dec 12, 2012 2:15:51 GMT -5
Hello jamesp, One idea for the vacuum of the barrels is that some unknown chemical reactions inside are depleting the available oxygen. You are using vinegar so I’m assuming you are having a high pH problem. The idea of vinegar seems very interesting, the only thing with vinegar is that it turns water very acid fast, I think that 3 cups of vinegar is way too much. Perhaps just a little could have solved the problem. A simple test to observe this is to place some tap water in a cup and test the pH, then add some vinegar to it and re-test it, you will be surprised of how fast and low it gets. Baking soda and borax increase the water pH but I don’t think adding more things to the mix could be a good idea at all. Why don’t you try changing only one of the barrels and only add a minimal amount of vinegar (if the barrel is bulging) to see if it will get it close to neutral and solve the problem. If it does not perhaps the water is acid instead and borax, ivory soap or baking soda in small amounts could be tried. Just ideas, good intentioned ideas. I really hope you get to solve the problem.
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jamesp
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Post by jamesp on Dec 12, 2012 6:59:04 GMT -5
Dora,one cup of vinegar stopped the expansion for 2 hours,2 cups showed slight increase in pressure after 5 hours so i went with 3.I am running three 16 pound barrels so i am running out of my gallon of vinegar.But have plenty of barrels running same mix of rocks,so three to experiment with!For 6 days i have had these 3 and one larger barrel pop off.A MESS.Loss a lot of grit(15 cups) and chipped 20 percent of rocks.The 3 cups of vinegar barrel became nuetral pressure after 10 hours so I added 2 cups of sugar-a normal dose i use on the 16 pound barrels for cutting lubricant during 500 SC grit and AO polish.Instant vacumn!!Now running all 3 barrels w/3 cups vinegar and 2 cups sugar.All 3 pulling a nice vacumn this morning. So in my mind i have a solution-but i can not explain, you said-probably a "unknown chemical reaction" and i think you are accurate Dora.I buy sugar in 25 pound bag at Costco. Also lowered water level to 1-2 inches below rock level.I have always had higher pressures when the water level is higher than the rocks.More bubbles too.And i usually pour the constantly growing water level down to below the rocks every day or two.Especially on problem loads.This time i did not do this maintenance and i believe it stirred up the all 4 barrels,the slurry went to metallic colored foam and the it turned brown.Brown is always bad. The grit salesman gets on to me about running the slurry pasty.He says i am breaking down the grit too fast.I tell him when it's watery it does not coarse grind the rocks.I will stick to pasty.
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Minnesota Daniel
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Post by Minnesota Daniel on Dec 12, 2012 21:07:20 GMT -5
James,
Changing the pH of your slurry with vinegar, or baking soda or Borax will knock back the yeast or bacteria that are producing the CO2 in your barrels, but the culture will adapt eventually. I know it's the baking season, and we're all thinking of our favorite recipes, but if you're trying to stop yeast or bacteria, why don't you try adding something like rubbing alcohol? The barrel is synthetic rubber, same as a tire, the alcohol won't hurt it. Also use the hottest water you can. It will have fewer gasses in it, and as it cools, it contracts. Rubber doesn't melt, and high temperatures won't deform it either, so water hot enough to kill organisms won't hurt the barrel.
Gasses are much more compressible than liquids, so when you leave more airspace in a barrel, there is more room for gas to compress. Leave less airspace, and the same amount of gas will be under greater pressure -- exactly as you describe. More of it gets dissolved into the water too, so when you open the barrel, the gas comes out (hence the bubbles you observe) just like when you open a beer, which is not a far fetched analogy considering the situation. Anyone for an AO Stout?
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The Dad_Ohs
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Post by The Dad_Ohs on Dec 12, 2012 21:17:00 GMT -5
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The Dad_Ohs
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Post by The Dad_Ohs on Dec 12, 2012 21:39:18 GMT -5
btw.... I was posting another thread when I remembered Lime, Water, Gypsum, All parts of making concrete/cement, have 1 thing in common with the problem you are having.... Heat!!! yeah I know, what the hell are you talking about.... Limestone/Lime is used in cement because it causes a chemical reaction that produces heat within the cement/concrete, this heat causes the water to evaporate drying/curing the cement/concrete. I can remember being out in the winter and my dad in a hole @ 35 degrees in a t-shrit and pants smoothing the concrete floor he just poured and as it begins to cure the hole temp rose about 10-15 degrees, making it quite arm when out of the wind.
Basically... the heat build up in a closed container would cause the barrels to expand. The sugar, I guess, is making the water more PH Nuetral, in addition to being a lubricant, after the vinegar brings out and removes the Lime and the heat by-product. Science geek poking out...<whap!!> that's better!!
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Deleted
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Post by Deleted on Dec 12, 2012 22:13:02 GMT -5
James sent me a box in trade for a sphere.
We learned in another thread there is no limestone. I put pool acid (Muriatic Acid or HCl) on his stones and the test was negative for limestone. No bubbles.
I am wondering if there is not a chemical reaction to the Silicon Carbide grit. A little bit of googling shows that a high pH solution will "attack" silicon carbide coatings. The vinegar and subsequent lower pH may be protecting the SiC from high pH reaction.
A little bit more googling shows that Borax solution is pH 9.5. Not super high, but above neutral.
@ Daniel No AO Stout for me, but I will take a Negro Modelo!
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Dora
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Post by Dora on Dec 13, 2012 1:38:52 GMT -5
I saw the responses early, they were very interesting! Well, now that I have some free time let me provide a little more input on the subject as I’d experienced the same problem before. I been tumbling rocks on and off for at least a decade, so I’m not new at this. I had experienced gas buildup with loads of mixed rocks a few times but not as severe as this case, baking soda solved my particular problems. It’s totally possible that it will not solve all similar problems as every single load will be totally different in its particular constituents to the next one. Safe experimentation will bring more answers to our new problems. The first thing I need to say is NOT to add baking soda to the barrels with vinegar, it will create a not-wanted reaction. As a child I used to fly those white rockets sold in the chemistry kits by Sears, they were propelled by that combination! So please do not try that in the barrel. Now, as I know that there are new members coming every day that are new to tumbling who haven’t heard yet about the use of baking soda to deal with the gas related problem that some of us experience at times. I'm going to provide a little information on it. I had seen information on the use of baking soda for tumbling going as far as 1955, but it probably goes way back for much longer. So there’s no need to take my word for baking soda, here is what some experienced tumblers are recommending trying: Quote from the book Modern Rock Tumbling by Steve Hart: Page 20 “Let your tumbler operate 24-hours a day for the next 7 days, checking daily for leaks and to see if the barrel looks like it's inflating, If you see the bottom beginning to bulge or bow outward, it's time to remove the lid and "burp" the batch (a 1/2 teaspoon of baking soda should cure this gas-generation problem). Quote from GenWorld: “If baking soda is available, add about a tablespoonful to the mix. The soda will help neutralize the gases that might be formed.” www.gemworld.com/tumbling.aspQuote from Santa Rosa Mineral And Gem Society Flyer: “It is also wise to add a tsp of baking soda or a tums tablet to cut down on gas buildup.” “-Barrel bulges and looks ready to explode! Gas buildup in the barrel is common and usually happens during the first few days of the rough grind. Add a teaspoon or two of baking soda in the barrel when you load it to prevent gas buildup. It is a good idea to keep an eye on your tumbler for the first 4 hours and burp it as needed. Gas is caused by reacting organic compounds on the rocks.” www.srmgs.org/flyers/tumbling.pdfQuote from WikiHow: “Experienced tumblers recommend adding some baking soda to the mix to prevent gas build-up.” www.wikihow.com/Tumble-StonesQuote from About.com Chemistry: “You can add baking soda, Alka-Seltzer, or a Tums to a load to prevent gas build-up.” chemistry.about.com/library/weekly/aa011803a.htmQuote from Mama’s Minerals: “If the barrel shows any sign of swelling, open it to vent the buildup of gas, and then add a pinch of baking soda.” mamasminerals.com/pages/How-To-Polish-Stones-with-a-Rotary-or-Vibratory-Tumbler.htmlQuote from eHow: “To prevent gas build-up, add baking soda or Tums to every stage but the polishing.” www.ehow.com/how_2278778_use-home-rock-polisher.htmlQuote from J.J. & L. ROCKS & MINERALS”: “The tumbler grinding steps sometimes produces a “GAS” which at the right conditions will pop the lid off. To eliminate the gas you can add a “Tums” or a teaspoon of baking soda with the grit. (Do not add to the polish)” www.jjlrocksandminerals.com/how_to_-_info_22.htmlAs I said before, this will probably not solve every single case of gas buildup, but worth trying. And remember: Vinegar + Baking soda = BOOM! ;D
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Post by mohs on Dec 13, 2012 10:52:37 GMT -5
I add a little olive oil rock salad tumble
good info Ed
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jamesp
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Post by jamesp on Dec 13, 2012 21:46:36 GMT -5
Just got back in town.Still got a vacumn,all 3 barrels.The menu FOR 16 POUNDS ROCK WAS: 3 CUPS VINEGAR,TUMBLE IN FOR A MINUTE,OPEN BARREL AND LET SIT FOR 24 HOURS THEN ADD 2 CUPS SUGAR,CAP BACK ON AND TUMBLE AWAY. It is going on day 4.I was poping caps before 24 hours was up.It was a desperation move.I have no idea why it would work.I showed my wife what a bulging cap looks like;she checked it a couple of times a day while bi was gone.All is good.Yeah!
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jamesp
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Post by jamesp on Dec 15, 2012 9:13:04 GMT -5
Finally recharged the lid popping loads.Almost 24 hours with no problems and no additives.For some reason baking soda did not work and the overnite vinegar soak/then add sugar trick worked when i was popping lids.Hopefully that is over.Thankyou very much for the input.I used to run newspaper in my tumblers for a thickener before the sugar idea came up.Also used peat moss.So i am used to acidic loads with the newspaper and certainly the peat.The newspaper is not to uncommon of a practice.It would sometimes breakdown unpredictably and frost rocks so i opted for other methods-namely keeping the barrel 75-80 percent full in coarse and 220,sugar and plastics for 500 and AO polish. But i did want to mention the organic additives of newspaper and peat.And that i rarely had barrel pressures.My water is acidic too.And that is a huge impact.Florida river water is commonly below PH 5,Florida well water at camp is PH 8,here in Atlanta PH 6.2.The water is a huge input to the tumbling barrel.Then of coarse rocks from simple compounds to radioactive...I think a chemical engineer would run from making an analysis on this monster,lest you paid him well! Again,thanks for inputs.
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Post by mohs on Dec 15, 2012 10:20:21 GMT -5
vacuum & gas my experience with tumbling is limited but its interesting reading your experiences
Ed
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