What it is…
A pungent-ethereal The historical name of this acid is oil of vitriol.
How it operates
Because the hydration of sulfuric acid is thermodynamically favorable and the affinity of it for water is sufficiently strong, sulfuric acid is an excellent dehydrating agent. Concentrated sulfuric acid has a very powerful dehydrating property, removing water (H2O) from othercompounds including sugar and other carbohydrates and producing carbon, heat, steam.
In laboratory, this is often demonstrated by mixing table sugar (sucrose) into sulfuric acid. The sugar changes from white to dark brown and then to black as carbon is formed. A rigid column of black, porous carbon will emerge as well. The carbon will smell strongly of caramel due to the heat generated.
- C12H22O11 (white sucrose) + sulfuric acid → 12 C(black graphitic foam) + 11 H2O (steam) + sulfuric acid/water mixture
Similarly, mixing starch into concentrated sulfuric acid will give elemental carbon and water as absorbed by the sulfuric acid (which becomes slightly diluted). The effect of this can be seen when concentrated sulfuric acid is spilled on paper which is composed of cellulose; the cellulose reacts to give a burnt appearance, the carbon appears much as soot would in a fire. Although less dramatic, the action of the acid on cotton, even in diluted form, will destroy the fabric.
- (C 6H10O5)n + sulfuric acid → 6n C + 5n H2O
The reaction with copper(II) sulfate can also demonstrate the dehydration property of sulfuric acid. The blue crystal is changed into white powder as water is removed.
- CuSO4·5H2O (blue crystal) + sulfuric acid → CuSO4 (white powder) + 5 H2O
Why is this needed to be known
Flow. Flow is affected by viscosity. Viscosity is defined as:
the state of being thick, sticky, and semifluid in consistency, due to internal friction.
synonyms: thickness, gooeyness, viscidity;
a quantity expressing the magnitude of internal friction, as measured by the force per unit area resisting a flow in which parallel layers unit distance apart have unit speed relative to one another.
Viscosity greatly affects the speed at which the ink will flow from your pen. This of course affects how much ink you get on your support (writing surface) at a time. A lower viscosity means that the ink will flow much faster. A higher viscosity means the ink will flow slower. What your pen angle is to your ground also changes the ink flow of course so a slanted or level writing surface affects things as well. Of course it seems that the more parallel to the ground you are the lower viscosity you might want. However a I have found a higher viscosity seems to have been the norm in medieval ink making where writing on a slanted desk seems to have been the norm. But then again, there is surface tension to take into account. That can really affect things as well.
Flow is also affected by the surface tension of the ink. Surface tension is defined by Merriam Webster as:
If you alter the surface tension then the ink will change how it is attracted to your dip pen and how it is attracted to and interacts with your writing support. The same surface tension is going to act differently depending on what support (writing surface) you are writing on. If your surface tension is high enough the ink will just bead up on the support and never really interact with the support more than to sit on it. If the surface tension is lower the ink will more readily interact with the support. Of course if the viscosity is also very low then the ink might be absorbed by the writing surface all to easily. Surface tension can also affect how the ink transfers to the support from your pen. The ink may cling to your pen and then create blobs when you first start to write with it. Especially if the surface tension is high but the viscosity is low. Of course if the surface tension is low and the viscosity is high then you have the problem of the ink transferring to the writing surface almost too quickly but then acting like a syrup once there.
And that’s just some aspects of flow and how two parts of it interact.
Then there is the most taken for granted quality of the ink, color. If you’re making a black ink, black is black right? No, there are different kinds of black because of different shades of black and differing qualities such as flat or reflective. With iron gall ink the color black comes from the iron turning black instead say rust colored or even yellow. That happens because of the tannic acid as well as ambient oxygen in the liquid along with other things. Of course the liquid could be water, wine, brandy, beer or vinegar depending on the recipe. Of course those things really can affect the surface tension and the viscosity as well as the color.
For carbon inks the black color is a function of carbon being black. But what you grind it with (I do recommend a wet grind) can really affect how well the carbon incorporates itself with the fluid used to carry it. Water doesn’t like to incorporate carbon very well. Vinegar can help that along but even if you just use vinegar it isn’t a perfect fix. Of course you could add a surfactant such as ox gall. Of course ox gall surfactant greatly decreases the surface tension of the liquid it is added to. So now you have to balance that with the proper amount of viscosity and maybe even add something to increase the surface tension somewhat. Typically a binder of some sort.
Then we get to binders which help hold the inks in place as well as the things in the ink that give the ink color. Binders that I’ve seen include tree sap and egg whites. The most common tree sap mentions is gum arabic but any gum sap will work such as apple, pear and cherry. All of which were used in the SCA time period (1600 to the dawn of time) and all of them could be referred to simply as “gum”. So when you see “gum” in a recipe, keep in mind it could be any type of gum tree sap and how the ink will behave will vary greatly from one kind of gum to another.
Also glaire can be used. Glaire is the liquid substance after hyperwhipipng egg whites. Best directions I know of on the internet for making glaire can be found here. Of course glaire is not particularly flexible so something to add flexibility to your ink would be good. Wait, ink has to be flexible?
Of course it does. If the ink isn’t flexible its going to break and flake and fall of the page when you bend or turn the page.
Often honey is added to glaire to help with its flexibility. However honey is hygroscopic so you need to be careful how much you use. Hygroscopic is the quality of a substance to attact and hold water. Even from humidity in the air. As you can imagine an overly hygroscopic ink would be a very bad thing.
Gum saps on the other hand are pretty flexible and not hygroscopic. What binder you use of course is going to affect not only the surface tension but also the viscosity. Then again all the other ingredients are going to affect those things as well. Binders can also affect iron gall inks. The binder can really affect how the tannic acid and the iron interact with one another as well as how the iron and the water/air transfer oxygen to the iron. That in turn of course changes how the ink turns black an how black the ink becomes.. I’ve seen gum arabic really slow down and impede the ink from turning black. So I strongly recommend that you put in the binder last.
Also the support can really affect the color of the ink. For example pergamenta is notorious for not getting along well with iron inks such as iron gall ink. However, I have a friend and fellow ink maker in Atlantia who has no problems whatsoever with iron gall ink turning black on pergamenata. He is using the recipe for iron gall ink on paper from The Book of Secrets 1596 sold under the sign of the gun for that one.
Of course then there is what you cook or soak your ink in, As in the container. Often I hear people talk about iron posts but they were very uncommon I am told in period. Copper and brass ones were more common. Of course most recipes for iron gall ink call for using a earthen vessel new and without any glaze. They knew it mattered greatly because it could affect the end result of the ink. Do you boil of soak your galls? If you soak them for how long? Some recipes say soak an boil. Soaking usually means your going to get a mold growing on your galls and this is a good thing. I was doing research on the Library of Congress iron gall ink webpage seven years ago and found out that mold makes your iron gall ink richer and blacker.
Of course then there is the carbon inks such as sumi ink. The recipes for sumi ink can be very closely guarded secrets going back hundreds if not thousands of years I am told. I’m sure if I buy thousands of years for sumi ink recipes in use today but I suppose it is possible. We do know some stuff. Pine resin burned from clay lamps collected on copper pots is considered to produce superior quality sumi ink. Then they mix it with a specific quality and kind of clay and then either dry or bake them into small bricks to be mixed with water later or make it a liquid sumi ink. Apparently what kind of pine, or clay mix are still shrouded in secrecy by many sumi ink makers. It really can change the quality of the sumi ink and how it looks.
Colored inks come in natural and chemical as well as some which are a little of both. Hawthorn berry ink mixed with alum is one such mixed natural and chemical inks. Of course the same berry harvested even weeks apart can produce entirely differing colors using an otherwise same recipe. Ink made from brazilwood is really a chemical ink as the hematoxillin (the active color ingredient) is extracted from the brazilwood. It can vary in color from bright red to crimson, to purple to violet as an ink. It also makes yellow but it is a terrible yellow for using as an ink. Apple bark yellow is much better.
Then there is the quality of light fastness to consider. If the ink is on pages of a book those aren’t going to be exposed to light very much as the book will be closed and thus the pages hidden from light most of the time. But pieces that are displayed will need more light fast ink. Hawthorn berry ink isn’t very lightfast but generally speaking it doesn’t need to be if it is in a book. Purely chemical inks have fewer problems with light fastness but not none. Even very lightfast inks such as a good iron gall ink can be very lightfast but still break down over time due to exposure to photons.
And then of course there is permanency. According to “40 centuries of ink” English tax rolls after 1200 AD were required to be done in iron gall ink on sheepskin parchment preferably the fat side. Why? Because iron gall ink is more permanent than carbon inks which you can just scrape off without much effort or just wipe off with a wet cloth or sponge. Also the iron gall ink interacted with the sheepskin in such a way that any attempts to scrape off the iron gall ink would be able to be detected. You can’t detect very careful scraping on calf skin parchment. And the fat side of the sheep skin, as opposed to the hair side, is much better at holding the ink once it is on the parchment than the hair side as well.
And all of these things can be taken into account and balanced against one another if you are knowledgeable enough to do so. You carefully pick your ingredients and the process by which you will make your ink based on how you want your final product to interact with the support or supports it will be put on not to mention the type of pen it will be put on because inks do not interact with quills, metal dip pens and reeds the same way let alone with cartridge pens.
In ink making this component stops ink from running excessively and it darkens the ink.
eg: Latin Ink.
Take an earthen vase (or jar or pan) that can contain 8 pounds of water; then (add) half a pound of small gall nuts and crush them well; then boil until (the water, the mixture) is reduced by half; then take three ounces of gum Arabic and grind it well; and pour (add) the gum to the mixture in the jar and boil it until reduced by half. Remove the jar from the fire and take 4 ounces of vitriol and one pound of warm wine and mix them together in another jar and add little by little to the ink, stirring well. Leave it to rest for two days, and afterwards, every day, stir four times with a stick.