Introduction: How to Make Verdigris

Verdigris is a blue green pigment which has been used since ancient times, and is mentioned by Pliny the Elder in Roman times, and has probably been used since copper has been mined.

It is easy to make and is made as it provides a different colour to modern paints which don't use it due to its slight toxicity. It is also used to recreate the art of history.

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Accuracy of information

I make every effort to ensure the information contained in this instructable is correct and up to date. However, I accept no liability or responsibility for any problems due to any errors or omissions in the content of the instructable. If you are unsure of anything please research it further.

Risk of harm

I make every effort to ensure the safety advice and precautions contained in this instructable are correct and that you will not be hurt if you follow my safety precautions and any other sensible precautions. However, I accept no liability or responsibility for any problems due to any errors or omissions in the content of the instructable. If you are unsure of anything please research it further and do not do anything unless you are sure it is safe.

Although if you are sensible you should not hurt yourself.

Step 1: What Is It

It has been used thoughout history for its bright green colour and its resistance to fading when in an oils paint.

It is a mix of mainly hydrous copper(ii) acetate crystals with small amounts of other copper compounds such as, oxide, chloride, sulphide.


The modern French means green of grey but comes from the old French vert-de-Grèce "green of Greece" the English also comes from this. Many other languages call it "green of Spain" e.g. the German "grünspan".

Step 2: Necessary Substances

The easiest way to make verdigris is to react copper metal with acetic acid.

Copper is easy to get and common sources are scrap copper piping and old copper coins. If you are using old 1 and 2 pence coins it is worth using a magnet to see if they are solid copper as more recent ones have iron cores and so are magnetic.

The easiest way to get acetic acid is to use vinegar. However, vinegar is not very concentrated and even distilled white vinegar is only around 10% acetic acid. Other vinegars can be used but tend to be slower, although they can provide slightly different colours due to impurities. The picture of verdigris in the intro is a sample made with distilled vinegar.


Due to the strength of the vinegar, it takes quite a while so some people use hydrogen peroxide as a catalyst to speed up the reaction. However, as I was making a small amount, I did not bother, as it only took about a week to make a few grams. Also keeping the reaction warm (around 30* C) helped to speed up the reaction.

Step 3: Reaction

The best way to do the reaction, I think, is to seal the vinegar and copper in a container so that the vinegar cannot evaporate. Ideally use a chemically inert container such as a glass jar.

Due to the low concentration of acetic acid in vinegar it is easier to add an excess of copper which can then be removed when the reaction stops as the verdigris will be in solution. As all the vinegar will have reacted the liquid should just be verdigris dissolved in water although there will probably be a few impurities.

I left mine in a sealed glass jar for about a week before removing the excess of copper. (I used old two pence coins)

Step 4: Crystallisation

Once you remove the copper you will be left will be left with the verdigris dissolved in water. You could use it as it is as a dye however it is very dilute. I left mine on a radiator with no lid for about two days to fully evaporate.

Occasionally, especially if the mixture has been left for many days there will be cuprous oxide (CuO) present, as the copper will react with water. This can muddy the colour of the verdigris as it is a yellow to red colour. The good news is that it can be solved by adding water to the mixture as the copper oxide will not dissolve but the verdigris will and so can be separated by filtration or decanting. This cuprous oxide tends to be a yellow colour when in a very fine powder, but if the crystals are larger it will appear more red. Once separated from the verdigris it can be used as a pigment in its own right or can be used for its anti-fungal properties.


As the crystals I was left with were rather small I put them in a small glass bottle as they were. For use as a pigment you would want to grind them into a powder but I prefer to keep it as small crystals as it is less messy if I spill it. The crystals are easy to grind into a powder which is a lighter blue than the crystals.

Comments

author
floydaroo (author)2017-05-20

how long should I let it sit? Until it is blue/green?

author
Edbed (author)floydaroo2017-05-21

Yep, you can essentially leave it as long as you like. The copper will probbaly be in excess so after a while all the vinegar will have reacted, this is when I normally stop it, remove the copper and add it to more vinegar in a different container and let the verdigris solution (which will probably be so concentrated that verdigris crystals have already started to from) evaporate to yeild dry verdigris.

author
floydaroo made it! (author)2017-05-18

I used pennies, and vinegar. I also used hydrogen Peroxide and kept it in a bowl of how water. This is after 20 min

image.jpg
author
Edbed (author)floydaroo2017-05-19

That looks great, so much faster than leaving it without hydrogen peroxide.

author
LcoyoteS (author)2016-09-22

I am trying this with copper dish scrubbers, but so far all it has yielded is rust-colored scum. Is this normal, or are the scrubbers not actually copper? They have been sitting in the vinegar for two days now.

author
Edbed (author)LcoyoteS2016-09-23

The rust colour can be made from the smallest amount of iron and so if there is any iron in the vinegar, nicely coloured verdigris will not form. The dish scrubber is probably the source of this iron as copper is quite expensive so the scrubber is likely to be mainly iron just coloured copper.

author
LcoyoteS (author)Edbed2016-09-24

Thanks! I suspected as much...

author
Edbed (author)LcoyoteS2016-10-01

I have just had a thought. The rust colour in your instance is most probably due to iron contamination, but it might also be due to formation of copper (I) oxide which is a yellow to red colour. This can form from the water reacting with the copper, perhaps due to the large surface area of the scrubber more is produced than my method of using coins. The good news is that if that is the problem it can be solved by adding lots of water to the mixture as the copper oxide will not dissolve but the verdigris will and so can be separated by filtration or decanting. (I will add something to this extent to the instructable)

author
LcoyoteS (author)Edbed2016-10-15

It was iron contamination, but I got some nice rust, which I used to acid stain a concrete pot I made. I am using copper pipe pieces now to get some nice verdigris crystals. I am also getting a lovely deep blue-coloured liquid from adding ammonia to the jar. It seems to be taking forever to form crystals from the vinegar and ammonia solution, though.

author
Edbed (author)LcoyoteS2017-03-25

A note to add to my previous
comments, the deep blue might be the result of two things.


Firstly the reaction between
the hexaaquacopper(II) complex ions present (for the sake of
simplicity I won't go into that more than to say it is formed as
there are Cu2+ ions present in verdigris, if you are interested have
a read of this
http://www.chemguide.co.uk/inorganic/complexmenu.html),
which gives the general blue colour, and the added ammonia produces
tetraamminediaquacopper(II) complex ions which give the deep blue
colour to the solution.


Secondly if there were any
copper(I) oxide present the ammonia will dissolve this to give Cu1+
ions which form a colourless complex (diamminecopper(I) ions). These
are then easily oxidised by the air to form
tetraamminediaquacopper(II) ions.

The slowness in crystal formation might be just because there is more water present from the vinegar and then also dilute ammonia (which I assume you are using).

author
LcoyoteS (author)2016-10-21

Sadly, my knowledge of chemistry is very limited, so I have no idea what the chemical reactions are. I tried adding ammonia to the vinegar because I came across a website that said people in the Middle Ages sometimes exposed copper to ammonia fumes in order to get a deep blue pigment. Oddly, one of my containers of the deep blue liquid seems to be staying that colour, but another one is, like you say, turning into the verdigris colour.

author
Edbed (author)2015-05-20

I'm planning on making some oil paint but don't have the necessary stuff. But I have made a sort of water colour by mixing it with water and gum Arabic.

2015 22:27.jpg
author
skykist (author)Edbed2016-02-21

. Should work just as the old masters used it.

To make your oil paint is rather simple. Just make your powder as fine as you can get it and mix in linseed oil until it is the proper consistency

author
LcoyoteS (author)skykist2016-10-15

Do you use plain linseed oil or boiled linseed oil?

author
GummyB (author)2016-03-28

iv found placing small jar in an icecream container with vinigar then add copper pipes iv flaterned in there too beside it with the lid on . let sit and scrape off every week to grow more. this way u dont need to evaporat any liquid

author
ArtisanEclectic (author)2015-06-09

I have used vinegar to "age" copper and brass before, but I never knew you could evaporate the liquid and get crystals. I'll have to remember this next time. Thanks for posting.

author
bravoechonovember1 (author)2015-05-24

wow!

i once made acetic acid and it turned blue but i didn't know i could do this!

author
Edbed (author)bravoechonovember12015-05-24

It is just amazing how you can put copper in a clear colourless liquid and make it go blue.

author
bravoechonovember1 (author)Edbed2015-05-24

yeah amazing!

author
rafununu (author)2015-05-22

In french : Vert de gris (green of grey)

author
Edbed (author)rafununu2015-05-22

The modern French means that but comes form the old French for vert-de-Grèce "green of Greece". The English also comes form this. Many other languages' names mean "green of Spain" (German grünspan, Danish spanskgrönt, Dutch spaansch-groen).

author
tomatoskins (author)2015-05-20

This is a really cool reaction! I've never heard of this before. What do you plan on doing with your Verdigris?

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