Fellowship of the Things

Vinegar
I personally have found that double strength cleaning vinegar works the fastest (because it's 10% acetic acid). The following vinegars have also worked:

• Regular white vinegar (5% acetic acid)

• Pickling vinegar (7% acetic acid)

• Regular cleaning vinegar (7% acetic acid)

Do not use any food based vinegars, such as red wine vinegar or apple cider vinegar. Those  are also acetic acid based, but commonly contain other ingredients that will contaminate your verdigris. 

When in doubt, check the label. As long as the ingredients are solely acetic acid and water, you are good to use the vinegar in hand.

Bare Copper Metal
Any pure copper will work for making verdigris. However, you need the pieces big enough that they stand out of the vinegar. The crystals are formed from exposure to the acid fumes and do not build up when soaking directly in the vinegar. 

• Sheet - Bend into an arch shape, that way it can be flipped any direction and still a good chunk of the sheet is still exposed to the fumes.

• Wire - If using scrap wire left over from electrical work, make sure you strip all coatings from it before using.  Bend the wire into a spring shape, so again it can be flipped any direction and still a good chunk of the sheet is still exposed to the fumes.

• Pennies - Not recommended. They will work, but you will need something made of copper or glass to suspend them in the fumes and are a pain to move around and clear off the built up crystals. If your stand is copper, then you might as well just use the stand to build the crystals on.

Glass Containers
I recommend creating your verdigris in glass containers because glass is inert and will not react with the acid or copper. Plastic or other materials may contribute contaminates. I have not experimented with other container materials because glass containers are easily obtained for cheap at the dollar store.

Pour a small amount of vinegar into your glass container (with lid). I usually pour enough that there is a 1/4" deep layer across the full bottom. Place your scrap copper in the vinegar in such a way that the majority of the copper is not touching the vinegar. 

Seal the glass container with the lid and wait. 

Seriously, wait.
Keep waiting.
Wait some more. 

Depending on the strength of your vinegar, a gorgeous teal coating should start appearing on your exposed copper pieces in 6-10 hours. 

Once a nice teal coating has started forming on your copper, give your container a good shake. This will coat the copper with vinegar, which will dissolve the coating and bring the colour with it as it drains back to the bottom of the container. 

Open your container and flip your copper pieces so that some of the coated copper is now sitting in the vinegar and the bare copper is now exposed to the air. 

Do not get lazy (like me) and just shake the container. The verdigris needs fresh air added to the container to help with the fuming process. You can get away with it every second time, but if you don't add more oxygen, the process will stall.

Note: You can do this step anytime. If you wait longer the pigment will continue to build on the copper. Once it has completely covered the copper with a thick crust and turned a really deep teal, then it won't really build any more pigment; but it will do no harm to continue just sitting there until you get around to shaking things up.

 Yes, I know... more waiting. 

Wait, wait, wait.
When the teal coating has started to build, you can repeat step 3 . 

Then wait some more, and then repeat step 3 again. 

And again,
And again.

Keep repeating the process until your vinegar has turned a really pretty teal colour. You can stop at any point, but the more intense colour you can get your vinegar to turn (more concentration of verdigris in the solution) the better your final results will be. 

Note:
This process could take a week or longer to build the concentration you desire.
Remember, patience...

When you are happy with the colour (concentration) of your vinegar, open the container and remove the copper pieces. Pour your vinegar into the second glass container (with no lid). 

Optional:
If you have issues with dust, pet hair, bugs, or other contaminates; place the glass container into a produce or mesh bag. This might slow down the evaporation process, but will keep your solution clean.

Note:
The photo to the left is a little "weak". I usually leave my solution to turn a much deeper teal, but I was impatient for creating this tutorial. This colour is fine, but the more patience you have, the better the final product will be.

Additional Note:
At this point, feel free to put your copper back into the glass container with the lid and start that container back at step 1. This project is a lesson in patience and it takes quite a bit to get even a small amount of verdigris. Having one container building up the concentrated solution and another evaporating the vinegar will speed up the process. 

Yup, you got it. More waiting.
Leave the container to evaporate undisturbed. 

This process will take a week or longer and is affected by surface area, ambient temperature, air humidity, and how much solution you're trying to evaporate. 

Very suddenly, you will notice a speckling of black flecks throughout your solution. Do not panic, these are the verdigris crystals starting to form. Continue to leave the container to evaporate undisturbed and the crystals will grow.

Note:
Do not try to use the oven or dehydrator to speed up this process. I have tried it and just ended up with sticky black crud. Nothing more frustrating than spending weeks building up a good saturation and then having it turn bleh and having to start over.

Additional Note:
I recommend that as your other glass container that is building a concentrated solution is ready, pour it into this container. Just add it to the solution already in this container, even if it is almost dry. Adding more solution will help your crystals grow even bigger. 

Bigger crystals means a more consistent colour with less impurities. 

Once your container is bone dry, you should see crystals and lighter residue on the bottom as well as more intensely coloured residue on the sides of the container. 

Scrape your crystals off the bottom and any easily removed residue from the sides and transfer the material into a storage container. Don't worry about scraping up the lighter residue.

No need to clean the container. Just pour in more solution as it is ready. The new solution will dissolve the remaining verdigris and the process will continue. 

Note:
The photo to the left is still quite small for verdigris crystals (most are about the size of a sesame seed). I would normally add more solution and let it go back to evaporating, but I was impatient for getting photos and creating this tutorial. I usually try to get my crystals to the size of lentils, but you can collect your crystals at any size.

Chances are, a few weeks have passed since starting this project.
Well... sorry, chances are you will have to wait longer. 

While you can continue to the next step as soon as you have your first batch of crystals, I recommend repeating all the steps above until you have more volume than you're going to need for your project. 

The different batches all have very slightly different shades of teal; very slight.
Think of it like dye lots. 

If you collect your crystals and wait until you have enough before grinding, you will ensure that all the verdigris for your project will have the same colour and composition. If you grind in batches, you run the risk of it not quite matching or reacting the same as a previous batch did.

Suggestion:
To decrease your wait time, I recommend multiple containers building solution and multiple containers evaporating and growing crystals.

Using your mortar and pestle, grind your verdigris crystals into a fine powder.

You want to ensure a consistent grain in your powder, so make sure you grind away any lumps. 

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