Activating Charcoal

Not actually Erin.

Picture by KJ Photography

& is used with permission.

You've made charcoal. But how do you activate it Before we go into that, a few disclaimers:

1. Store-bought activated charcoal will always be superior to home made. This is because you cannot control the environment and perform the procedure under rigorous conditions. 
2. That said, this method will produce activated charcoal that is moderately effective for water filtration or poison treatment. This is for those "It's better to have this than to have nothing" situations. 

Ingredients

• Charcoal
• Mortar and pestle (or other grinding implement)
• A glass* jar with a solid lid, such as a Mason jar
• Steel or ceramic* mixing bowl
• Calcium chloride, aka Pickle Crisp.
• Water
• Measuring cup
• Heat-resistant gloves and eye protection
• Mixing spoon
• Coffee filters
• Cheesecloth (a bedsheet will do in a pinch)
• Cookie sheet

*You may use plastic if they are sturdy enough. What's important is that you not use aluminum containers, as that metal is reactive with heat and you don't want it leaching out of the container, into the water, and then into your activated charcoal. 

Instructions

1. Make or acquire charcoal. If bought at the store, make sure that it is pure hardwood charcoal and not soaked in lighter fluid or other additive chemicals. 
2. Powder the charcoal. This is messy business, so wear your grungy clothes. Grind the charcoal as finely as you can, because  this process is not 100% effective and you need the smallest pieces of charcoal you can get. Place the powdered charcoal into steel mixing bowl and set aside. 
3. Make a 25% solution (by weight) of calcium chloride. Weigh 3 parts of water and mix in 1 part calcium chloride. For example, you can dissolve 100 grams of calcium chloride in 300 grams (same as 300 ml) of water, or 3.5 ounces of calcium chloride in 1.3 cups of water. Seal jar lid tightly, then shake to mix. 
4. The jar will heat up. This is normal. Wear gloves to protect your hands, and goggles to protect your eyes in case of a spill! (Calcium chloride is non-toxic, but no one wants hot salt water in their eyes.) Occasionally unseal the jar to release internal pressure, then reseal. 
5. Make a paste. Slowly pour the calcium chloride solution onto the powdered charcoal and mix until a spreadable paste has formed. 
6. Allow to dry for 24 hours. Cover if possible.  
7. Spread the paste on the cheesecloth.  Use materials with the tightest weave possible. It's important that you use nothing which has scented detergent, bleach, or other substances on it, as the charcoal will adsorb that and you will lose efficiency.
8. Place cheesecloth over bowl and rinse with clean water. Use the same amount of water as you did in step 3. The cleaner the water, the better. Ideally it ought to be carbon-filtered, distilled, or reverse-osmosis filtered. Do not use chlorinated city water!
9. Pour caught water through a coffee filter to recover bits of charcoal you'd otherwise lose. The finer your carbon, the finer your filter must be when you rinse it, and this will enable you to catch as much as you can. If you have a large enough filter, you can simply use it instead of the cheesecloth to combine this step with the rinsing. 
10. Bake at 250° F for 30 minutes. Place the coffee filter on the cookie sheet alongside. Let cool, then break apart. Store in an airtight and waterproof container. 

Your activated charcoal is now ready for use!