Cleaning field-collected specimens is at the top of the mind for most rock collectors. It’s seeing the hidden beauty under dirt and bits of loose matrix that help us find the great ones, but it seems everyone uses their own cleaning solution.
Bleach is one of the more common ways to clean agate, but is it the best? Read on and I’ll show you the ropes.
Let’s Define Bleach
To avoid any confusion: this entire article covers only the use of household bleach for cleaning stones. That’s a 5-6% sodium hypochlorite solution commonly used for cleaning around the house. It’s also used as a disinfectant.
Can You Use Bleach to Clean Agates?
You can use bleach to clean agates without the risk of damage. It can affect the dye in dyed stones, so be sure that you only use it on natural stones unless you’re trying to strip the dye from a cleaned agate.
Bleach is relatively non-damaging when it comes to silica-based stones, but it will dissolve many other minerals.
Bleach is probably in the top three chemical methods that are used to clean stones. It falls behind white vinegar, but it’s probably more common than using a citric acid component.
What Solution of Bleach Should I Use for Soaking Agates?
A 1:10 ratio is suitable for soaking stones, provided you’re starting with household bleach (ie: 5-6% NaHCO solution). Using straight household bleach creates a lot of fumes that can hurt your lungs and may damage your skin. It also risks more etching non-silica minerals contained in the stone. Always use gloves and a mask when dealing with bleach.
The solution is easy to create, relatively safe to let sit for a few days and doesn’t take much longer than straight bleach. You can tinker with the recipe to your own tastes, but do not add any other chemicals to the solution.
Sodium hypochlorite is extremely reactive, and combining it can lead to dangerous results. The most notable is vinegar, which creates a toxic gas when mixed with bleach.
Leave the experiments to chemists and work with only one chemical at a time when cleaning stones, and even then leave a day or two of soaking in clean water in between.
How Do I Use Bleach to Clean Agates?
Grab a 5-gallon bucket, fill it up to a few inches over the top of your stones with a 1:10 bleach solution, and let it sit for 2-4 days. There’s not a whole lot more to it. Chemical methods of cleaning are great for being low maintenance.
If you feel you have to do something then you may want to swirl the bleach a bit once or twice per day. I’ve never noticed any difference in the end result, but I’m certainly guilty of having the urge to “make it do something” in the past.
Afterward, you’ll want to soak them in clean water for another day or two. You may need to change the water if the stones still smell of bleach, but it’s rare for agate to be porous enough to hold onto the chemical smell.
Should I Scrub My Agates in Bleach?
I’ll let you in on a secret: the best way to clean stones is always dish soap and a good scrub brush. Scrubbing your stones in bleach won’t do anything extra, except sterilize the surface of the minerals more quickly.
Bleach offers you no advantage if you’re already putting in the manual labor to clean stones in the first place. It’s mostly used for larger batches of stone that may require hours of scrubbing.
You may still want to scrub them afterward, depending on the surface conditions of the stone. You’ll have to put out a lot less effort to get them to display condition, however, than if you started with a dirty stone.
How Does Bleach Compare to Vinegar for Cleaning Agate?
Bleach does a great job at removing most surface contaminants, but vinegar seems to dissolve matrix more thoroughly. Bleach will do a better job at killing any pathogens on the surface of the stone, which can be a concern when you’re collecting in areas with livestock.
Stronger bleach solutions are sometimes used to remove dye from agate, often stronger than household bleach. Vinegar won’t do that for you, but the truth is that most dyed agate is just off-white to white chalcedony and lacks visual interest after being stripped of dye.
Both are relatively weak compared to some of the other chemicals used for cleaning. That makes them much safer for household use, especially for those who don’t have any chemical experience.
I prefer vinegar for most agate nodules, since removing the matrix is often the hardest part of cleaning them. That said, the difference is usually minimal.
Is There Anything Bleach Won’t Clean Out of Agates?
Bleach usually won’t do much to iron oxide stains. In theory, it should be able to remove some of the ugly orange stainings that sometimes occur within quartz and agate specimens. In practice, I’ve often found that those are best tackled as a separate issue.
These stains occur due to the formation of iron oxides in the stone and don’t scrub out with brushes either.
Iron staining is best handled with a strong rust remover. Iron Out has been a favorite for many rockhounds and it works well. That said, using a strong acid in that manner is beyond the scope of this article.
Can I Use a Bleach Solution to Clean Other Stones?
In some cases, it may not be a bad idea. In others, it may dissolve the stone entirely. Minerals all have different chemical compositions, so you’ll have to research each individually.
This gets complicated when you’re dealing with more complex specimens with many minerals. Those are best cleaned manually.
In other words, you’re on a case-by-case basis when using household bleach to clean minerals. That said, it won’t damage most silica-based minerals. That makes it suitable for quartz, chalcedony, agate, and jasper.
So, What’s the Best Way to Clean My Agates?
Nothing tops manual cleaning in my experience, but it can be a time-consuming affair. All you really need is some dental picks, a few wire brushes, and a bucket full of soapy water fo the vast majority of agates.
That said, soaking in bleach can save you work down the line if you have a large number of nodules to get cleaned up. I wouldn’t bother with bleach unless you’re working on multiple specimens.
It’s still one of the best ways to clean large amounts of stone! But it won’t do as thorough of a job as good old-fashioned elbow grease.