tiles-art - 5/9/97
“To Make Tiles, Bricks or Other Building Materials of Clay” by Tryffin ap Myrddin.
This file is a collection of various messages having a common theme that I have collected from my reading of the various computer networks. Some messages date back to 1989, some may be as recent as yesterday.
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Mark S. Harris AKA: THLord Stefan li Rous
Stefan at florilegium.org
Date: Thu, 13 Mar 1997 16:01:41 -0600 (CST)
From: Wendy Robertson & Tim Weitzel <wcrobert at blue.weeg.uiowa.edu
To: SCA arts list <sca-arts at raven.cc.ukans.edu
Subject: Medieval Tiles (was Salt Firing and Kilns)
Cindy Morely Wrote:
>I have been interested in doing tiles for a while, but never have gotten
>around to it. I did find this neat book called Medieval English Tiles (or
>something like that), that had some great info in it. The picture of the
>only surviving wood-block stamp was real interesting. I'v been hoping to
>bribe some of my woodcarving friends into carving it for me so I can make
>some tiles from it.
>Do you have any suggestions for a beginning tile maker? I'v been throwing
>pots for a while now, so I am familiar with clay and glazing etc., but I
>know very little about tiles, especially period tiles (other than the one
>I mentioned above).
To make tiles, bricks, or other building materials of clay
The most common period depiction of making brick, which is generally assumed to
be highly similar to making tiles, is found in a 15th c. manuscript from the
Netherlands (Additional MS 38122, f.78 verso*). It shows the tiles and bricks
stacked and drying. A kiln is being fired in the right background. In the
left background, a worker is forming the bricks on a table.
the process of making the tiles is described briefly in Basing 1990* and
is echoed and elaborated in Eames 1992.**
Starting in the fall, the clay is dug and hauled to the tile works. It is left
in the winter weather to crumble by rain and frost. Around the end of
December the clay is turned over. In spring, water is added back to the clay
and it is worked up to the proper consistency. Stones and organic matter are
removed. Sand may be added. When the proper texture is achieved, the clay is
cut into pieces and is ready to be formed into wooden frames. The frames are
set on a table. The frame and the table are both finely sanded (this is
assumed from the fine sand baked into the surface of the tiles, and it makes
sense to help prevent the clay sticking to the tools. The mold frames are the
shape of the final tile, so they are square, round, rectangular, or whatever.
The roof comb tiles are especially elaborate. Floor tiles for mosaics can be
elaborate too. A wire is drawn over the top of the form to cut off the excess
clay. Surviving late 19th-early 20th century wood forms had metal frames
attached to the top to assist in cutting off excess clay. The same tool kit
had a metal bow into which the wire was attached to assist drawing it over the
mold frame. It is assumed these tools are highly similar to the ones used
in the middle ages.
The tile (or brick) is removed from the frame. A smooth piece of wood, called
a strike, is wetted and run over the surface to smooth the tile. The tiles may
be shaped or decorated now. Shaping: Roof tiles, for instance are pushed
together on the sides so as to make the middle taller and arched. Many floor
tiles have incised lines, cut hemispheres, or punched holes in the bottom of
the tiles. It is speculated that this is to help dry the tiles or to assist
mortar adhesions when installing the tiles. Decoration: Stamps of wood or
metal*** are used to apply decoration. The design may stand above the tile
surface or be pressed into the tile surface.
Wood stamps appear to be better for high/deep relief impressions, such as a
fleur-dis-lis surrounded by a line-box. The one surviving English stamp for
making relief tiles dates to the mid-17th to18th centuries, although it may not
be that different from medieval stamps for relief tiles. Relief tiles do not
seem to be as popular as inlaid tile designs during the Middle Ages
(although there are some pre-Conquest relief tiles at Winchester, and a
group from c.1200 York. I also am aware of some tiles from an abbey floor
that was built in the 7-8 c.). Relief tiles were produced on a commercial
scale in the 14th century. The one existing relief design stamp is 16 x 16.25
cm square and 4.3 cm deep. The mold received considerable pressure when
being pushed into the clay based on cracking along the grain of the wood.****
This suggests the tiles were allowed to dry quite a lot before they were
decorated. This makes sense because there would be little chance of the clay
sticking to the tile. It would also explain why there are so few left for us
to look at. A stamp for making inlaid tiles has been found at Winchester. It
appears that while relief designs occurred frequently, impressed designs were
more common. Sometimes, the depressed designs are filed with clay, giving
white on red tile designs that seem to have been popular.
Metal stamps appear to be good for "incised" designs, where fine lines are
actually pressed into the tile surface. These also can be used to score the
tile to make accurate breaking of the tiles easier during their installation.
This would be more of a shaping than a decoration technique, but sometimes is
Scraffito is a type of decoration that was used in period but is fairly rare.
In this technique, the white clay is made into a slip with the addition of
water. Then the slip is applied over the surface of the tiles and allowed to
dry. A line design is incised into the surface of the tiles. Then, the
background is carefully scraped off revealing the orange clay beneath. The
characters and objects are left white, with orange outlines. The Trynge (sp.?)
tiles have a series of drawings scribed into them that tell a story in
pictures, in this case it was a religious story.
All of the above decorations can be done without the use of tin or lead glazes.
Moorish and some Spanish and Italian tile were very brightly colored. The
Moors in particular made wide use of plants and astronomical objects in huge
wall coverings of tile. Bad news. Multicolor (polychromatic) tiles always
used lead or tin glazes. More subtle glaze colors occur in late northern
European and English tile floor mosaics and pavements. These likely used lead
as well, but may possibly be reproducible with medium to high-fire clay bodies
unlike the modern brightly colored glazes that "burn out" fairly easily.
Henry VII and Elizabeth I both had elaborate floor decorations made with
many colored and shaped tile designs. It is likely possible to make glazes
for these projects as well. They would take a huge amount of space and
even more time and energy to create.
Suggestions: Medieval tiles are often quite thick and meaty in feel and
appearance. This lends problems with drying time and loss when firing. Don't
be fooled by modern tile which makes use of automated production lines and
engineered clay bodies. Every indication given shows that there was not a
high amount of tinkering with the native lowland English clay. This means that
firing the kilns must have been a highly skilled trade. They didn't have
temperature cones either, and had to have judged temperature by sight alone.
Glazing tiles is certainly not necessary to make medieval tiles and this is one
way to avoid lead glazes. It is possible that some of the colors can be
reproduced in modern glaze recipes that match the firing temperatures of a
given clay body. This may take a fair amount of experimentation and delving
deep into "glaze theory" in order to come up with your own glaze recipes that
do specifically what you want them to do.
Wall tiles would be smaller than floor tiles and, again, both are thicker than
modern tile. Roof tiles, on the other hand, don't seem to have changed much at
all but roof combs are not seen as often. The clay bodies are almost always
earthenware. Only the Germans and Low Countries made much use of stoneware in
period! It worked well with all their salt glazing. With the exception of some
coal-fired kilns, the tiles are wood fired. Because they were into very high
production, they used lots of wood and had big kilns.
If your are really into the building tile thing, you might try what I have done
and actually set your tile using period mortar. In Basing 1990* this recipe is
given as 2-3 parts sand to 1 lime and sufficient water. Adjust as necessary.
If done properly, the mixture becomes firm and will hold. Too much sand or
water, and it crumbles too easily. A mixed sand may be better in some
instances than one that is all course or all fine. Note that this mortar
will never get "hard" like modern concrete which uses portland cement.
For roofs, they would sometimes pack the roof tile with moss or point the ends
with mortar. And don't use mortar it if you are building a kiln. Just
use clay in between the bricks.
Hope this is entertaining for at least some of us,
Tryffin ap Myrddin
Shire of Shadowdale
Kingdom of Calontir
M.K.A. Tim Weitzel
I highly recommend looking at each these books yourself. The first two in
particular are written in a very accessible style, really! I imagine anyone
who is interested in this subject will quickly get through these two books and
be asking for more. Conveniently, both have bibliographies for further
reading. The rest are excellent if you wish to specialize in mid-late period
English glazed tiles.
*Basing, Patricia, 1990._Trades_and_Crafts_ in_Medieval_Manuscripts_. New
Amsterdam Books: New York.
**Eames, Elizabeth, 1992. _Medieval_Craftsmen:__English_Tilers_. University
of Toronto Press: Buffalo.
***Eames, Elizabeth 1980. _Catalogue_of_Medieval_Lead-Glazed_Earthenware_Tiles
British Museum Publications: London.
****Keen, Lawerence. 1969. Seventeenth- and Eighteenth-Century Lead-Glazed
Relief Tiles from North Devon in _Journal_of_the_ British_Archaeological_