Laws of the Mezuzah: Preparation of the Ink


The Mezuzah must be written in black ink.



 The ink

The ink used in the writing must also be made according to specific Laws. Among other things, it must be black. The quill used for the writing is also made a certain way (but that's mostly for practical reasons, not for legal reasons). And the writing of the Mezuzah itself must be performed according to many very exacting Laws.



Divoh: Sofer's Ink

Ink in Hebrew is Diyoh. Each scribe used to have his own formula for making an ink with the desired qualities of clarity, easy flow, intense color and tackless film on drying.  These were usually handed down through generations of disciples from teacher to students. Unlike in yesteryear when each sofer produced his own ink, some of it being better than others, today the sofer purchases ink at a store that carries safrus supplies. 


http://www.stamforum.com/2012_03_01_archive.html gives a detailed description of how to make the Dyoh by Yalkut Yosef


Remember each sofer has his own formula for making ink.


1. Oak Galls -Afeitzim


Oak galls are formed when the tiny torymus sp. a wasp, lays her eggs in the twigs or leaves of a living oak tree.



Here is the torymus sp. perched on a blade of grass, which gives the scale of the insect.

  The tree tries to eliminate the invader by producing a gall around the eggs.  This gall happens to be extremely high in gallo-tannic acid. It is is this gallo-tannic acid that we are interested in for making ink.  Certain types of oak trees produce galls with greater concentrations of this tannic acid and consequently are more sought after.  The most effective for ink-making are the Aleppo galls from Turkey.  Nonetheless, here in California there is a ready and abundant supply of perfectly adequate galls that the would be ink-maker can find simply by walking through virtually any area with oak trees. I find it's best to gather as many as one can, because those which are not used up now, will keep and will come in handy when its time to brew another batch of ink. 


2.  Copperas -Kankatum

Despite its name this mineral salt is actually derived from iron not copper.  In older texts it is often also called vitriol.  In scientific parlance it's called ferrous sulfate.  It's a slightly greenish white crystal produced by soaking iron in a 30-40% aqueous solution of sulphuric acid, allowing the water to evaporate and collecting the crystalline residue left behind. 




These ferrous sulfate crystals are approximately a centimetre across, for our purposes we will use copperas reduced to about the consistency of table salt.




For a fuller, and quite interesting description of how ferrous sulphate is produced I recommend the following CR Scientific Experiment page www.crscientific.com/ferroussulfate.html




3. Gum Arabic -Gummi




Again the name of this ingredient is misleading as it comes not from Arabia, but Africa.  The name may have originated from the gum having at one time been procured from Arab traders. This particular gum is exuded from the acacia tree, which grows in hot dry climates. 


The branches and trunks are deliberately scored to cause the sap to ooze, the resulting tears as they are called are collected, dried, sorted and exported to the world.  In addition to its use in ink and other artist's materials, gum arabic is frequently used in foods, particularly candies, but also in cough drops where the gum soothes the irritated mucous membranes. 


For our purposes, gum arabic is essential for at least three reasons, a) it keeps all the ingredients evenly supsended in solution; b) it increases the viscosity of the ink which makes it flow more evenly from the quill and keeps it from bleeding into the surface of the parchment; c) it increases the brilliancy and gloss of the ink.  From the perspective of conservation the high proportion of gum arabic in sofer's ink acts as a buffer which prevents ferro-gallic acids in the ink from corroding the parchment, a problem frequently seen in older documents.

For this recipe we are going to add a fourth ingredient to intensify the colour of the ink, namely logwood.


 Logwood comes in the form of shavings taken from the tropical haematoxylum campechianum.


Here's the basic formula for ink. I've reduced it somewhat as the original recipe I have yields some ten gallons of ink.  I write a lot, but that's more ink than I could use in two lifetimes. This will produce about 2 quarts of fine, durable ink.

3 oz oak galls
1 oz logwood shavings
2.2 oz gum arabic
1.9 oz copperas

The trick to making really, really good iron gall ink is long, slow cooking of the galls and logwood.  Some recipes I've seen call for just tossing all four ingredients together in a jar of water and allowing it to 'macerate' for a few weeks.  This is great if you want to write with a disappointingly grey ink.  However, if you're like me and want an rich, deep black ink, straight from the bottle then we need to prepare the ingredients a bit more.

Stage One: Assemble, weigh and prepare the ingredients for cooking.

**Be sure to use containers specifically designated for non-food use.  There's a good chance that these ingredients will leave a residue that would not be so good to ingest.  So just like our meat and dairy dishes, we keep our ink pans separate.

We'll be using one ounce of logwood to make this ink.  Be sure to get the good stuff for this.  The best logwood comes from the heartwood carefully planed into shavings.  This grade costs about five dollars an ounce, but is much stronger and more light-fast than cheaper varieties.  To prepare the logwood, it needs to be soaked overnight.  Use enough water to saturate and cover the wood shavings, but there's no need to go crazy and use a fifty gallon drum for one ounce of logwood.  A small Rubbermaid dish will be perfectly adequate.

Soaking the logwood overnight is an essential part of the process.  Do not skip it or you will achieve inferior results.  In the picture above you can see that the logwood has turned the water a deep, reddish colour.  It is this property that gives the logwood it's scientific name Haematoxylum, which means 'blood wood' in Greek.

Now on to the oak galls.  We need three ounces. As with everything here weigh accurately!

As you can see it doesn't take many, 59 galls in total, all of them smaller than an acorn.  If we estimate that it takes something on the order of half a pint of ink to write a Torah scroll and that there are eight pints to a gallon, and that this recipe makes 1/2 gallon, then with just these 59 oak galls we could write 8 Torah scrolls! Not bad for a little wasp. 

As one cannot simply write with oak galls in their solid state, we need to crush them coarsely in preparation for cooking.  I find it easiest to simply use a pair of nutcrackers.  Be warned, the galls are incredibly hard!  You could easily hit them hard with a hammer repeatedly and experience no result, or else no result that was afterwords retrievable.

This is what the galls should look like once they've been broken up a little.  Now, if you're feeling terribly Medieval, as I was,  you may of course proceed to grind them to a fine powder using a mortar and pestle.  Otherwise, you may feel free to use a spice mill. 

In any event, which ever course of reduction you choose, the above should be the final result.  It may be wise during this stage to wear some type of protective mask, as you wouldn't want to inadvertently breathe in powdered oak gall, it does after all contain gallo-tannic acid.  From experience I can confirm that the dust does irritate the respiratory passages.

Once done, the powder should be put in a suitable container and covered with hot water, which we will allow to steep overnight.  We have begun to extract the tannins in the oak galls.


At this point the logwood and the oak galls have been reduced finely and soaked in hot water over night.  We are now ready to begin the cooking process.  The cooking process involves three separate boilings.  In the first, take the galls and the logwood and put them into a 4 quart stainless steel pan and add four cups of water, distilled if possible.  Chlorine, flouride, salts and minerals in tap water do funny things to ink over time.

First Boiling:  Over a medium fire, boil the galls and logwood for one hour.  Replenish any liquid lost to evaporation.  Strain the liquor and set it aside.

Second Boiling:  Using the same galls and logwood add 2 1/2 cups of water and boil for half an hour.  Strain the liquor and add it to the first.

Third Boiling:  This time add only 1 1/2 cups of water to the galls and logwood.  Boil for half an hour,  and add to the rest.  Allow the whole lot to cool and steep over night.


The next day, using a bit of flannel, filter the liquor into a separate container.  Then squeeze the galls to extract whatever potency they may have left.


The liquor as you can see has turned a very deep brown.  If it comes in contact with your skin it will leave it looking quite orange and shiny.  Add water if necessary to make up the full two quarts.  Using a pitcher marked for quarts is useful at this stage.


The next day, I measured out the 1.9 ounces of copperas and crushed the 2.2. ounces of gum arabic to powder then dissolved it in about 1/2 cup of hot water.

Return the gall liquor to the fire and heat it until it is quite hot.  Then add the copperas and stir vigorously.  The dark brown of the galls will turn deep black in seconds as the chemical reaction between the gallo-tannic acid and the ferrous sulphate takes place.  Then pour in the tincture of gum arabic and stir.



This change took place in about 3 seconds. 

In theory, you could begin writing with this ink immediately, however, I would recommend letting it age a bit.  Leave the pan uncovered for a couple of days stirring occasionally.  Oxidisation does seem to improve the the darkness of the ink. 

Then sample: 



There are a LOT of ink recipes out there.

This is the most basic one and is from the sefer Chasdei Dovid:


3 g Gum Arabic

3 g Oak Galls

3 g Iron Sulfate

0.25 liters filtered or distilled water

Crush the galls as finely as possible.


Mix all the ingredients together into a sturdy pot.


Cook the mixture for a long time on low to medium heat until you have only a gloopy sort of residue left.


Strain out all the solid material using a fine mesh.


Pour the strained residue into a clear glass bottle and seal it tightly. Let it sit for about 6 months until it turns jet black.


If a Sofer doesn’t have 6 months to wait, the alternative is to buy ready-made ink.



Nahari Ink

Nahari ink is a quality type ink with good flow that dries to a velvety black finish. It is available in three different densities (regular, thinner and thicker) and is ideal for all types of sofrus writing. Comes in a plastic bottle with recloseable cap.

Hadar ink

Hadar Ink

Hadar ink is an extra fine, high quality ink which can be used for all types of sofrus writing. It has superb ink flow and dries to an ultra-smooth, velvety black finish. Comes in a plastic bottle with a resealable cap.