|
Post by miket on Jul 16, 2019 11:43:20 GMT -5
I'm trying to get what I think is calcite off of my Tee Pee Canyon agates. I tried oxalic acid (in wood bleach) with no results. Vinegar did a pretty good job but is taking forever. I bought some muriatic acid yesterday and wanted to ask few questions if someone has any experience with it. I'm definitely going to dilute it with water, is there a certain ratio that works best for rocks? The jug says 1/2 pint per gallon of water. Also, I'm planning on neutralizing the acid with baking soda. After that, what's the best way to dispose of what remains? Or does it even matter since it's been neutralized? And, yes, I'm planning on using gloves and glasses and keeping it away from pets and kids. Thanks.
|
|
|
Post by aDave on Jul 16, 2019 12:02:39 GMT -5
I don't have an answer for you, as I've not used it. But, I do want to remind you to add acid to your water and not the other way around.,
|
|
|
Post by miket on Jul 16, 2019 12:25:14 GMT -5
I don't have an answer for you, as I've not used it. But, I do want to remind you to add acid to your water and not the other way around., I am aware of that, but thank you for the warning! Might just have to poke around on the interweb and see what info I can find, I would just rather get answers from someone here on RTH that had used it before.
|
|
|
Post by HankRocks on Jul 16, 2019 12:30:00 GMT -5
Just be careful with any fumes given off, they are nasty and not to be inhaled. I have cleaned with muriatic before and have always used a loose covered container. You don't want a tight cover as the gas will build up.
You will be surprised at how much Baking Soda it will take to neutralize the solution completely. Also dump a bit at a time until you can judge the reaction. Too much Baking Soda and you will have an overflow of the container. I have usually just dry-caked the neutralized sludge and put it in the trash.
Just curious, would it not be easier to just cut off the areas of Calcite?
|
|
|
Post by miket on Jul 16, 2019 12:49:08 GMT -5
Just be careful with any fumes given off, they are nasty and not to be inhaled. I have cleaned with muriatic before and have always used a loose covered container. You don't want a tight cover as the gas will build up. You will be surprised at how much Baking Soda it will take to neutralize the solution completely. Also dump a bit at a time until you can judge the reaction. Too much Baking Soda and you will have an overflow of the container. I have usually just dry-caked the neutralized sludge and put it in the trash. Just curious, would it not be easier to just cut off the areas of Calcite? Thanks for the tips. I have worked with acid before (a long time ago at a circuit board shop in Colorado) so I'm familiar with most of the dangers. Cutting it won't work, the tee pees fracture too easily and I would destroy the patterns I'm trying to reveal. Here's my original post with some pics: forum.rocktumblinghobby.com/post/1060475/thread
|
|
|
Post by greig on Jul 16, 2019 13:05:42 GMT -5
Regarding muriatic, use it outside as the fumes in your house or garage will eat/corrode things you would rather not be affected. Use plastic or glass pail/bucket (not metal). If you get any on your skin, wash immediately with soap and water...It might not sting, but can be a chemical burn if allowed to stay too long. As for disposing, be aware that even when seemingly neutral, it will kill most plants. I know somebody who kills weeds with his leftovers, but not recommended because you will get blowback when you try to spray it. I usually pour it onto the ground and then run some water over the spot to dilute it further.
I usually use HCL diluted ( typically 4 or 5 parts water to 1 part HCL works pretty good). Always add acid to water and not the other way around (splashes). As such, if you want to speed up the reaction, you can add more HCL later to the solution. If it is not bubbling, I find the best way to tell if the acid is depleted or maybe the specimen has no more to give, I dip in a different rock which has lots of calcite - to see if that starts bubbling. I don't tend to use baking soda. Instead, I always have some marginal rocks around to stick into the solution when I am done my initial etching, just to see what they have inside. I hate wasting HCL as it is not free (that is the Scotsman in me). ;-)
For some rocks, you can add hydrogen peroxide to make a different kind of acid. I generally don't recommend doing this. Some people also suggest adding salt, but I haven't noticed a benefit.
Greig
|
|
|
Post by rmf on Jul 16, 2019 13:59:38 GMT -5
Muriatic acid is commercial grade HCl (Hydrocloric acid) and tends to be yellowish in color. Technical grade HCL tends to be water clear and is purer for lab work. Rocks get the cheap stuff. miket I would neutralize with calcium Oxide (quick lime, burnt lime, CaO) or calcium carbonate (CaCO3, agricultural lime) as these you can buy a 50# bag at Ace, Home Depot .... As HCl reacts if there is CaCO3 it strips the calcium and makes Calcium Chloride which is a salt so it will kill grass and is corrosive to metal, The Hydrogen combines with the CO3 to make water and CO2 (be aware you will destroy the planet). Always add acid to water not water to acid. This is always true but more true with Sulfuric Acid. The ratio suggested above is good you can always add more. Acid slows down as more is used up and it tend to buffer so if you give it time it will continue. If you use CaO you can take a drop of "spent" acid and drop it in the CaO and if it effervescent then the acid is still hot.
|
|
|
Post by miket on Jul 16, 2019 14:14:30 GMT -5
Regarding muriatic, use it outside as the fumes in your house or garage will eat/corrode things you would rather not be affected. Use plastic or glass pail/bucket (not metal). If you get any on your skin, wash immediately with soap and water...It might not sting, but can be a chemical burn if allowed to stay too long. As for disposing, be aware that even when seemingly neutral, it will kill most plants. I know somebody who kills weeds with his leftovers, but not recommended because you will get blowback when you try to spray it. I usually pour it onto the ground and then run some water over the spot to dilute it further. I usually use HCL diluted ( typically 4 or 5 parts water to 1 part HCL works pretty good). Always add acid to water and not the other way around (splashes). As such, if you want to speed up the reaction, you can add more HCL later to the solution. If it is not bubbling, I find the best way to tell if the acid is depleted or maybe the specimen has no more to give, I dip in a different rock which has lots of calcite - to see if that starts bubbling. I don't tend to use baking soda. Instead, I always have some marginal rocks around to stick into the solution when I am done my initial etching, just to see what they have inside. I hate wasting HCL as it is not free (that is the Scotsman in me). ;-) For some rocks, you can add hydrogen peroxide to make a different kind of acid. I generally don't recommend doing this. Some people also suggest adding salt, but I haven't noticed a benefit. Greig Thanks for the response. I do have a plastic bucket and am planning to do it outside. I still have a few 30 or so year-old scars on my arms still from the circuit board gig, if I remember correctly we used sulfuric acid. So I will be careful for sure. I have a ton of marginal rocks laying around, I like that idea! I think I'll start the process today after work and see what happens...
|
|
|
Post by miket on Jul 16, 2019 14:18:06 GMT -5
Muriatic acid is commercial grade HCl (Hydrocloric acid) and tends to be yellowish in color. Technical grade HCL tends to be water clear and is purer for lab work. Rocks get the cheap stuff. miket I would neutralize with calcium Oxide (quick lime, burnt lime, CaO) or calcium carbonate (CaCO3, agricultural lime) as these you can buy a 50# bag at Ace, Home Depot .... As HCl reacts if there is CaCO3 it strips the calcium and makes Calcium Chloride which is a salt so it will kill grass and is corrosive to metal, The Hydrogen combines with the CO3 to make water and CO2 (be aware you will destroy the planet). Always add acid to water not water to acid. This is always true but more true with Sulfuric Acid. The ratio suggested above is good you can always add more. Acid slows down as more is used up and it tend to buffer so if you give it time it will continue. If you use CaO you can take a drop of "spent" acid and drop it in the CaO and if it effervescent then the acid is still hot. Thanks! We'll see how it goes...
|
|
|
Post by rmf on Jul 16, 2019 15:03:26 GMT -5
miket One more thing. Never use Oxalic acid on limestone/calcite/aragonite It makes calcium oxalate (think Kidney stones) and it is hard to remove. Muriatic is good stuff!
|
|
|
Post by miket on Jul 16, 2019 15:26:40 GMT -5
miket One more thing. Never use Oxalic acid on limestone/calcite/aragonite It makes calcium oxalate (think Kidney stones) and it is hard to remove. Muriatic is good stuff! Too late, my friend... Hopefully the muriatic will take off any that it might have made! So much to learn, thank you.
|
|
NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
|
Post by NRG on Jul 17, 2019 23:01:48 GMT -5
I use it full strength. The weaker you make it, the longer it takes.
Once neutral you have a salt solution. Sodium carbonate and sodium chloride. Pour it into the toilet
|
|
|
Post by miket on Jul 18, 2019 8:31:40 GMT -5
I use it full strength. The weaker you make it, the longer it takes. Once neutral you have a salt solution. Sodium carbonate and sodium chloride. Pour it into the toilet Thanks
|
|