A bit more information on Baker's Marks

(After making the dough into loaves, but before baking) the bread then received a "mark" unique to each baker which permitted, at the time of inspection, a quick and indisputable identification of the bakery where the merchandise came from. The marking of bread, like that of beer barrels and many other non-alimentary products, only became obligatory throughout Europe in the second half of the 15th century. The bakers became constrained at the time they set up shop, when they "put out their shingle", to choose a mark. It was often the first letter of their name or even a figurative representation: "To one baker a crown, to another a fleur-de-lys, to another a crescent, to another a star, to another a cross, to another a small bird, and so each differs his mark from the others." (Amiens, municipal archives, BB11, folio volume 76: June 15, 1472). The mark or signet appeared in a small wooden or lead die, of which the mark was registered on a parchment at City Hall. It was severely forbidden for master bakers to change the mark without permission.

Sylvia Thrupp mentions baker's marks only briefly (she refers to them as seals) - (The seal was) "forced on him as a means of identifying him for punishment if his bread were unwholesome or short of weight. But if a man consistently made good bread, his seal would naturally come to be associated with his high standard, and would stand for the goodwill of his trade. To sell bread unsealed therefore exposed one at once to the suspicion of trying to pass off poor stuff; to use another man's mark was even worse, as it meant that the real owner of the seal was in damnger of being punished for defects not his, or that one was trading on another's reputation."

Thrupp states that baker's marks in England were "a combination of dots and initials, less elaborate than merchants' marks." She also cites a 1440 court case, where a baker named William Hobold sued another for using his mark (three prick-marks).

Since both sources agree that a baker's mark or seal should be simple, I thought it appropriate to use my SCA badge - a straightforward heraldic identifier.

Baker's marks are not shown in surviving paintings of the baking process, so I had to experiment with what little is available: a few descriptions in books such as the one above, and a surviving item in Paris' Musee du Moyen-Age (Museum of the Middle Ages). Here is what I came up with.

"Deux sceaux de boulangers (XIVe siecle)." Two 14th century bakers' marks, from the Musee du Moyen-Age.

The first incarnation was a hand-held stamp made from sterling silver. I didn't want to use lead, and wood is not as durable. My first impulse was to use pewter, since it is relatively cheap and easy to work. There are many extant examples of seals and badges worked in pewter. However, period pewter contains lead, not the best thing to have around food. There are more modern, lead-free pewter alloys, and I'd feel comfortable making that substitution. Straight tin would also be a workable alternative. I went with silver instead for two reasons: one, it seemed reasonable for a well-off baker; two, that was the preference of the jeweler making it. The goutte is an inch high, just under half an inch wide, and the handle is about an inch long. It weighs about 0.4 ounces. This one works well for small cakes, and non-yeasted products in general. I still use this baker’s mark for Shrewsbery Cakes, shortbread, and other non-raised goods.
The first stamp did not consistently produce a visible baker's mark. That led to the second version. Each mark was a one-inch, slightly convex circle with a raised goutte, weighing about a half-ounce. As cited by Desportes, these were simple dies. Unfortunately I don’t have any pictures, as the silver was melted down to make the third, final version. Here’s a crude drawing of what it looked like, though.
This third baker’s mark is more directly inspired from the period picture above. Like the others, the jeweler used silver. It is a 1.75-inch diameter disk with a raised design: my goutte in the center and the word "FERMENTAMINI!" or "RISE!" is written around the outside. This is the first word of my motto ("Fermentamini! O mea fermenta!" - "Rise! O my baking agents!") and also seemed appropriate for a baker’s mark. Even though this version is much larger than the second design, it still produces a very clear imprint. (It's just under a quarter-inch high.) And it’s more excessive, which personally I think is a good thing. Perhaps most importantly, this one most closely follows the picture of the French baker's mark. I have a batch of four, each weighing slightly over two ounces. The top picture is the actual mark; the second is reversed, so you can read the word around the edge.

All versions of my baker’s mark were made by Master Timothy Royar. Unfortunately, he is not currently available for any jewelry work.

I experimented with three different methods:

1: puncturing the crust on a baked loaf of bread.
Okay, assuming a reasonably warm oven and baking on brick or stone, you get a decently thick crust. (Loaf pans are a later invention.) My attempts to puncture the crust with a silver stamp didn't produce anything even remotely resembling a clear picture. I don't think that changing the base material to wood or lead would have a different result.

2: stamping the dough before it goes into the oven.
My initial thought, and one that dictated how my first baker's mark was made. If I stamped the underside of the dough before the secondary rising, the action of picking the shaped loaf up, stamping it, and replacing it inevitably distorted and tore the dough. Also, as the dough rose, the picture was distorted by the dough's stretching and expanding. I then tried stamping after the final rising, just before putting the bread in the oven; but that also failed. The bread still expanded in the oven, causing a distortion of the mark. Any exposure to air tends to dry the outside of the loaf a bit, so that the picture was less likely to stay clearly imprinted. This held true regardless of where I stamped the bread - upper crust, underside, whatever.

3: keeping the mark present as the loaf baked.
At this point I went back to the documentation, and "The mark or signet appeared in a small wooden or lead die" leapt out at me. Timothy made a set of four baker's marks as described above. I placed them on the baker’s stone and then each loaf went on top of one. The weight of the bread stamped the mark into the bread as it cooked, and having the mark physically there meant that the image did not distort as much during the baking process.
At this point I was convinced, but for completeness' sake I tried placing them on top of the loaf. It was not as successful - it worked but not as clearly or consistently. And there were times when the loaf did not spring uniformly; then the baker's mark might fall off (preventing a clear picture).

I place the four marks on my well-used baking stone. They seem to imprint better when pre-heated. The loaves are then eased on to the baker's peel for oven placement.
I carefully place each loaf on top of a mark. Ideally, each mark is directly underneath each loaf, placed in the center. Sometimes it even works that way.
After baking, I remove each loaf. Often the mark is stuck to the underside, but it will pop right off.

Voila! If done right, you should be able to clearly see my baker's mark. There shouldn't be any question as to who the baker is! As long as the bread isn't underweight - then I would get dragged through the streets with the offending loaf around my neck, like this poor fellow...

One possible drawback of my method involves the number of baker's marks required: one per loaf. Would this be an inordinate expense for a baker?

I don't think so. I use four at a time in a standard modern oven. Desportes cites marks being made from wood or lead. Wood certainly was cheap; I don't think lead was expensive. A fairly simple design such as those mentioned shouldn't take too long to create, further keeping the cost down. (Sylvia Thrupp says that English bakers used very simple designs such as dots and initials.) Even allowing for larger batches of bread, and wear and tear in the ovens, the projected cost seems reasonable to me.

I've been using my sturdy silver marks since 1996, I think. They've got lots of life in them yet.

One of the surviving marks above has a ring attached, suggesting that it was kept on a ribbon or similar tie. Intuitively, that gives me more of a problem - I wouldn't keep more than one around my neck, for example, and to me that would imply only one physical die. I don't have a good answer there.

Still, I'm comfortable with my reconstruction. Of course, this is only a theory. If I've missed any possibilities or you have other ideas, please send me a message!

Ashley, William. The Bread of our Forefathers: An Inquiry in Economic History. Oxford: Clarendon Press, 1928.
Beebe, Ruth Anne. Sallets, Humbles, & Shrewsbery Cakes. Boston: David R. Godine, 1976. ISBN 0-87923-238-2.
David, Elizabeth. English Bread and Yeast Cookery. Newton: Viking Penguin, 1977. ISBN 0-9643600-0-4.
Desportes, Françoise. Le Pain au Moyen Âge (Bread in the Middle Ages). Paris: Olivier Orban, 1987. ISBN 2-85565-350-9.
Hagen, Ann. A Handbook of Anglo-Saxon Food & Drink: Processing and Consumption. Norfolk: Anglo Saxon Books, 1992. ISBN 0-9516209-8-3.
Holt, Richard. The Mills of Medieval England. Oxford and New York: Basil Blackwell Ltd., 1988. ISBN 0-631-15692-5.
Jacob, H.E. Six Thousand Years of Bread. New York: Lyons & Burford, 1997. Reprint of the original edition of 1944. ISBN 1-55821-575-1.
Postan, M.M. and Rich, E.E., ed. The Cambridge Economic History of Europe, vol. III. Cambridge University Press, 1965.
Thrupp, Sylvia. The Worshipful Company of Bakers: A Short History. Croydon: Galleon Press, 1933.