Iron Gall Ink - The nerdy Parts

So you want to make ink.

We commend, applaud, and rejoice with you for choosing to take on this perilous quest. First in your quest to make ink you search the vast resources of the world’s libraries (er…the internet?) and you find recipes like the following:

To make inke to write on paper.

Take halfe a pint of water, a pint wanting a quarter of wine, and as much vinegar, which being mixed together make a quart & a quarter of a pint more, then take six ounces of gauls beaten into small pouder, and sifted through a sive, put this pouder into a pot by it selfe, and poure halfe the water, wine and vinegar into it, take likewise four ounces of victriall, and beat it into pouder, and put also into a pot by it selfe, whereinto put a quarter of the wine, water & vinegar that remaineth, and to the other quarter, put four ounces of gum Arabike beaten to pouder, that done, cover the three pots close, and let them stand three or four daies together, stirring them every day three or four times, on the first day set the pot with gauls on the fire, and when it begins to seeth, stir it about till it be thouroughly warme, then straine it through a cloath into another pot, and mixe it with the two other pots, stirring them well together, and being couered, then let it stand three daies, till thou meanest to use it, on the fourth day, when it is settled, poure it out, and it will be good inke. If there remaine any dregs behind, pour some raine water (that hath stand long in a tub or vessel into it, for the older the water is, the better it is, and keepe that until you make more inke, so it is better the clean water.

To make inke for parchment.

Make it in all points like to the inke aforesaid, only take a pint of water, & of vinegar and wine more, that is of each halfe a pint.

From: A Booke of Secrets: Shewing diuers ways to make and prepare all sorts of Inke, and Colours: as Black, White, Blew, Greene, Red, Yellow, and other Colours. Also to write with Gold and Silver, or any kind of Mettall out of the Pen; with many other profitable secrets as to colour Quils and Parchment of any colour: and to graue with Dtrong Water in Steele and Iron. Necessarie to be knowne of all Scriueners, Painters and others that delight in such Arts. Translated out of the Dutch into English, by W.P., London, 1596.

It isn’t exactly eyes of newts and the blood of a dragon stewed together under a waxing gibbous moon or anything, but it doesn’t feel far off from that. And this recipe is one of the most straightforward I know of to our modern “follow this recipe, have success making cupcakes” mentality. Frankly, that wasn’t the mentality in the middle ages and renaissance. The mentality was, “here are some guidelines, take these and everything you learned from your master when you apprenticed” and you will succeed. But enough of the history of technical literature and recipes…

Right…so allow me to translate this recipe into terms we might better understand

Ingredients:

1 cup of water

1 ¾ cups of wine

1 ¾ cups vinegar

6 oz (by weight) of oak galls, powdered

4 oz (by weight) of Iron(II) Sulfate

4 oz (by weight) of gum Arabic, powdered

1.) To a pot add ½ cup of water, 7/8 cup of wine, and 7/8 cup of vinegar, and powdered oak galls

2.) Bring this boil to a mixture and allow to cool.

3.) Strain through a cloth (muslin, an old t-shirt, paper towel will all work), collecting the liquid

4.) Mix the remaining water, wine, and vinegar.

5.) Split the remaining water, wine and vinegar into two parts

6.) Into one half of it dissolve the Iron(II) Sulfate

7.) Into the other half dissolve the gum Arabic.

8.) This dissolving step may take overnight.

9.) Once the gum Arabic and iron(II) sulfate have dissolved, you should have 3 liquids without any solids in them.

10.) Mix all three liquids together.

11.) Allow this mixture to stand for 3 days, stiring it 3-4 times a day. Transfer to your ink storage container (Sealed preferably)

Translated, no problem… this recipe is a sound recipe, and should work quite well (a little heavy on the gum Arabic for my taste, but it will work).

Now for the sciencey part and WHY this is a good recipe. If you don’t care about the experimental archaeology and the chemistry of ink…er…I’m sorry you accidentally read this far?

The chemistry behind the ink: Why it changes colors

In the ink solution the Fe2+-gallic acid complex are soluble, and have little to no color. When things are acidic, and the Fe2+ oxidation state if favored over the Fe3+ state when the solution is acidic. Once the iron oxidizes from Fe2+ to Fe3+ and you get the Fe3+-gallic acid complex you get a black, insoluble pigment. It is this pigment that forms when you write and see the color change from grey to a rich black color when writing with iron gall ink. This is the “sludge” that forms in the bottom of the ink jar, as well as the skin that forms on top of the ink when you leave it open for too long or when you first make it. (The film that is fuzzy from setting around for a very long time is called mold….we will talk about how amazing that is later)

Now let’s see how each ingredient contributes to this process, and what was used in the middle ages:

Water: The carrier for the ink so it isn’t too thick

Water is water right? Nope. Most historic ink recipes call for rain water, or fresh rain water, or old rain water, or some sort of freaking rain water. What this means for you is that you should be using distilled or reverse osmosis purified water. Why you might ask? Because your tap water, and the water they had access to in streams and rivers have a myriad of minerals (mostly calcium, magnesium, iron) that can and will completely ruin your ink. Calcium in particular causes things to come out solution and precipitate as solids in our ink. You might think, hey, I already have iron in there, what does a little more hurt. Iron is tricky like that, in your water it is Fe3+ ions we need Fe2+ in our ink to start. (don’t get me started on iron oxidation states, it gets ugly) Long story short… use distilled water, not drinking water, not spring water, and probably not rain water either, it is way dirtier than it used to be.

Wine: flow modifier, preservative

Wine hasn’t changed a lot over the years…take some grapes, let them rot, filter/decant/rack the liquid off of the solids, add some sulfite preservative so that a higher percentage of bottle make it to market, bottle and drink. Ok so the preservative part has changed… but honestly it won’t hurt this process very much. You can go out and buy imported old world wine that doesn’t have preservatives in it if you want (I have) but it doesn’t change the noticeably. Also, not only can you use wine that has gone “bad” (aka tastes like vinegar), but it is actually the best wine to use for making ink. Red wine tends to work better than white wine, as it helps the flow of the ink, it also pairs better with the taste of parchment.

Vinegar: Volatile oxidation state stabilizer for Fe2+ ions

You almost reached for a bottle of distilled white vinegar didn’t you, and then you decided that I would be picky about this one. Now you can’t decide if the organic apple cider vinegar good enough and you desperately hope I don’t recommend your $50 bottle of imported balsamic vinegar.

Historically wine vinegar was probably the most common vinegar, but as long as you are using some wine, white vinegar works just fine for our purposes. We need an acid, that can, and will evaporate once you write with the ink, allowing the ink to oxidize and become water proof and permanent. Any vinegar will contain acetic acid which fulfills this purpose.

Oak Galls: Where the gallotannic acid comes from

There are numerous varieties of oak trees and gall wasps, and therefore numerous varieties of oak galls. You have to know what you are working with before you can create a sound formula for ink. In medieval Europe the Aleppo galls from the Aleppo oak tree in the Aleppo region of Turkey were considered the best galls. And they still are. But why? The gallotannic acid content of oak galls vary widely from 3% to 90%. Aleppo oak galls are in the 80-90% range. What this means is that you get more of what you want, and less other stuff to contaminate the ink. You can successfully make iron gall ink from sumac leaves and acorns. Sumac leaves have to many polysaccharides and therefore varies over time and rots something bad. Ink made from acorns is downright oily from all of the oil and lignin content of the acorns themselves. Aleppo oak galls just make a better, more consistent ink.

Iron (II) Sulfate: where the magic happens

This is the metal salt that makes the magic happen. It is also known as green vitriol, copperas, ferrous sulfate, vitriol of iron, etc. Honestly all we really need is an iron (II) ion of any kind, Fe2+. The reason we use Iron (II) Sulfate is that it is what is historically used, and is still the cheapest source of these ions for our purposes. Historically the purest form of the hydrated salt was created by soaking raw iron sulfate in water and growing green copperas crystals on ropes suspended in barrels. ACS/USP grade modern stuff is 98-99% pure, which is close enough for us. The biggest issued that used to occur was copper contamination in the iron (II) sulfate which will cause your ink to eat through parchment. How much iron(II) sulfate depends heavily on how much gallotannic acid you have in your oak galls, an ideal amount is around 70-90% of the equal molecule amount (stoichiometric amount). This is because free iron will cause rusting and premature degradation of the parchment or paper. Mass wise, if you are using Aleppo galls 100 grams of Aleppo galls needs 60-90 grams of ferrous sulfate depending upon how the crop of Aleppo galls grew that year, when they were harvested, how dry they are, etc.

Gum Arabic: The thickener, the flow modifier

Gum Arabic has always been a flow modifier, thickener, and sticking agent in inks and paints. That is exactly what its purpose is here. It doesn’t have to be gum Arabic though. Gum Arabic comes from the acacia tree, but many fruit trees such as plum, peach, and almond trees will produce a perfectly acceptable water soluble gum. But gum Arabic produces its effect with less gum needing to be used, and is available in larger more cost effective quantities.

Clove oil and thyme oil: Preservatives

Historically clove and thyme oil are used as preservatives in inks, paints, elixirs, and balms. Thymol and clove oil are still sold and used as natural preservatives. Although this particular recipe doesn’t list these as preservatives, they are listed in many other historic recipes for iron gall ink.

Mold and time: Secret Chemical agents

Mold is your friend when making iron gall ink. But it’s nasty and yucky and smells bad right? Well, mold takes the tannic acid in your oak galls and converts it to gallic acid. You see, tannic acid complexed with iron produces a dark brownish-black color, and gallic acid complexed with iron produces a rich blue-black shimmering color. Mold is good for your iron gall ink, just not for you. You won’t see much difference between letting your oak galls mold first, or letting the ink set afterwards, but when I make iron gall ink, I let the oak galls mold for a month before I make ink from them, which prevents mold in the bottles as well as lets me skip the step of powdering the oak galls.

Another post, soon to come, will include instructions with pictures on how to make ink using our ink kit.