Late Roman Craticula (Gridiron)

Finished Piece

This piece is a reproduction of a cooking gridiron (craticula) excavated in Icklingham, Suffolk,

England, and currently in the collection of the British Museum1

.

While a precise date is not known, the museum estimates it to be 4th century, shortly before or

concurrent with the withdrawal of Roman control over the area. The piece shares clear elements with

grid irons or stoves found across the Roman Empire, and dating as early as the destruction of Pompeii.

The unique feature of this particular piece are the “omega” shaped central bars.

© The Trustees of the British Museum (CC BY-NC-SA 4.0)

Period Techniques:

A blacksmith in Roman England would have been working with wrought iron. The only tools required

for this piece were a hammer, tongs, a forge, a bellows, and an anvil. The fuel would have been coal or

charcoal, as both were available in Roman England.2 The piece is largely forge welded from pre-made

bars, with bent and tapered elements. There is a central band that is consistent with bent over staple

banding that is common in assembled ironwork. It appears to be relatively solidly attached to the

piece, but I believe that is the result of use and aging, as heating, even just to cooking temperatures can

create welds over time, and rusting can create a conglomeration affect among disparate iron pieces.

Finally there is a welded ring with a clinch nail type clip attaching it to the piece.

Figure 2: "Funeray Stele of a Blacksmith" 1st century CE CC BY-NC-SA 4.0 Carole Raddato

Modern Compromises:

Unfortunately, wrought iron is no longer widely available, so I used mild steel instead. The silica slag

in wrought iron makes it largely self fluxing and relatively easy to weld. In addition, a period

blacksmith may have used silica (sand) as an additional flux, but there is no way to tell for a given

piece. Since mild is more difficult to weld, I used borax as a flux, offsetting some of the difficulty. I

also used a hand crank blower in place of bellows for convenience, and a modern (London pattern)

anvil. Otherwise the tools I used are largely consistent with those found in images of Roman forge

work. I also used industrially produced steel bar. This was purely a labor saving decision, as the

construction of this piece clearly started with similar bars, even if the smith had to produce them

personally.

My Tools

Methods:

The central bars were bent into a matched pair and tapered. Each bar was then welded to the third and

fourth bars. A square hole was punched and drifted into the fifth bar to provide a mounting point for

the hanging ring, but the ring was not attached at this time. These bars were welded one at a time to the

existing assembly, then this was repeated with the last two bars. The feet were then hammered and

bent up, and then the legs bent down to achieve the final shape.

After the core was complete, the ring was welded separately, and the clip was formed as a flat piece,

prior to being folded around the ring. The ring and clip were inserted, heated, bent around, and cut

with a chisel to fit the piece. Finally, a central band was made, hammered into a square staple, and bent

over in a traditional blacksmithing technique.

Work in Progress

Difficulties and Learning Experiences:

I significantly improved my welding techniques, particularly an approach of closing the weld with

tongs while the piece was still in the fire. This potentially allows for more precision in placement, and

multiple attempts without significantly deforming the metal. While I am happy with the end result, I

did end up with the final piece slightly larger than the original (16” long dimension versus 12”). In

addition, my “omega” bends are slightly smaller relative to the finished piece, and the two side bars are

not parallel. Finally, the pre-punched ring mounting hole ended up off center during the final assembly.

I still believe this is the correct approach, as trying to punch that hole on the finished piece would be

extremely difficult, but in the future I would take more care in making sure it’s centered during

assembly.

Other Thoughts:

This piece was made with bars of uniform dimensions, and based on my work, I believe equal starting

lengths. This makes me think it is likely that the smith doing the work was purchasing bar stock from

another source, as that level of uniformity makes more sense if it’s specified to ensure a standardized

purchase. It also results in a piece that takes more metal than a more standard style using smaller

central bars (see figure 4).

While the omega shaped bars are decorative, it seems likely that they were also intended to serve as

receptacles for conical or round bottom pots common in Roman kitchens. A ring that appears to be for

this purpose is found in figure 5, and similar rings are found in a stove from Pompeii, and heated food

counters from the same city.

That being said, the choice to band the central bars rather then weld them is surprising because it

interferes with both placing round bottom pots into the omega shapes, and with putting a flat pot on the

gridiron. I am inclined to think, admittedly without evidence, that it might be a later addition to the

piece.

Similar Extant Pieces:

Excavated at Trimontium (Newstead) England

This piece represents the most common design found in multiple locations, and over a time period extending beyond the (western) Roman Empire, with tenoned cross bars.

Excavated at Castra Vetoniana, Pfunz Germany

Uses the same sort of forge welding assembly found in the recreated piece. This piece was identified

as a window grid by the original researchers, but I believe it is a gridiron.

Excavated at Calleva Atrebatum, Silchester, England

This piece has a center ring reminiscent of the omegas found in the recreated piece, and

similar hanging rings. However the pieces are tenoned like the common simple grid.

These pieces were all found along the Roman frontiers, frequently in military posts, making it possible

these were Legion equipment.

Most references were pulled directly from a curators note on the item in question, with additional web

searches on key terms. In order to track down reference 4, which had an incorrect name in the curators

note, I reached out to the Trimontium Museum, who pointed me to an online copy of the work. The

error has now been corrected on the British Museum website.

Making Your Mark (Or Punch - Counter Punch)

If you're producing work that's going out in public, at some point you want to be able to sign it.  For most metal workers, that takes the form of a touchmark.  This is a punch or tool that repeatably creates a unique mark stamped into a piece.

The earliest such marks appear to have been for consumer protection, designating the purity of a precious metal item.  In the medieval period, rather than being marked by a government inspector, they would have been marked by the master smith, who was responsible for the quality of objects leaving his shop, regardless of who did the actual work.  By the early modern period, this translated into a unique mark for each metal worker.

Whether medieval blacksmiths would have had such a mark, I can't say, but they certainly would have been the ones producing the marks for others, since you generally want your mark to be a harder metal than your work piece.  This is needed both to make the mark durable, and to keep the detail crisp.

Another consideration is the size.  This mark is not a decorative element on your piece, so it should be small enough to be put somewhere out of the way.  You also want to be able to mark it on pretty much any piece you might make.  So the more delicate the work you do, the smaller the mark should be.  This can require fairly fine detail, which can be hard to produce.  One option is to engrave it into an annealed punch, and then harden the result.

However, a mark can also be created with custom chisels and punches.  Many marks are simply overlays of straight lines, and could be carved separately on each piece.  But, since that would be time consuming, you can use those chisels to make another punch, one with your mark on it (inverse), and then use that to mark.

Or, in my case, make a punch to make a punch to make a punch.

I started with a simple D shaped punch, with a slight angle carved into the back.  This punch, like all punches I make, is hardened before being used, to increase its lifespan when punching hot metal.

D Punch.  Edited to clarify punch face.

 This punch was then used, twice, to punch the interior of two Ds, back to back.  One of these Ds was ground off to form serif tails, and the other ground tight to the outside to form a D shape.  It's necessary to do the interior punch first, before grinding the exterior, because the punching process can distort the outer surface if it's thin.

This second punch is then retained because it allows me to recreate multiple maker's marks as the first one wears out.

Second Punch After Grinding

Then that punch was used to punch the final D into the actual maker's mark, which is then ground to a tight square.  This results in a final punch which produces a depressed square with a raised stylized letter D on the work piece.  My maker's mark.

Final Punch, plus sample marks on clay

At this point I've gone through the process 3 times, each time the mark has gotten smaller, so it will fit on more of my work.

I think this most recent one should last me awhile, assuming I don't lose it.

Salvaging a Project

This one started as part of the Fitchburg Forge-In, a competition I do every year.  This was the two hour session.  But it's fair to say I wasn't happy with the result. I accidentally used the wrong stock for practice, so I screwed up the cups, and ran out of time to do cleanup.  So I took another hour or so to go back and clean it up.

The first step was some grinding and filing to bring the points into line.

Then straightening out and cleaning up the arms, combined with removing the existing, unsalvageable candle cups.  One went ahead and removed itself, leaving behind a gorgeous blue temper color, so I cut the other to match.

A spring fuller to clean up the shoulder, and a top and bottom swage to push the arm to round, so I could cut a 1/4-20 thread on it.

Then came making the new cups.  This was done by swaging a piece of candle diameter pipe down to  a diameter small enough to take the same thread.  You actually go a little undersized, then use the remaining hole as a pilot for the tap drill.  This is obviously not a medieval solution to this problem, although you could take the same basic approach and peen over the arm inside the cup.

Work the opening of the cup over the horn for a nice decorative shape, cut the two halves of the pipe apart for the two cups, drill and tap, and you're good to go.  A little bit of oil baked on for a nice finish, and I'm much happier with the final product.