Creative Education
2013. Vol.4, No.8, 475-483
Published Online August 2013 in SciRes (http://www.scirp.org/journal/ce) http://dx.doi.org/10.4236/ce.2013.48069
Copyright © 2013 SciRe s . 475
Development of a Prototype Pots and Potsherds Kilns for
Facilitating Ceramic Wares Firing in Tertiary Institutions in
Nigeria
Onofeagen John Ohimai1, Isah Bolaji Kashim2, Tolulope Lawrence Akinbogun2
1Department of Gla s s and Ceramics, Auchi Polytechnic, Auchi, Nigeria
2Department of Industrial Design, The Federal Universit y of Technology, Akure, Nigeria
Received May 30th, 2013; revised June 30th, 2013; accepted July 7th, 2013
Copyright © 2013 Onofeagen John Ohimai et al. This is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
The purpose of this research is to design and produce a gas and wood fired kilns with waste pots and pot-
sherds that are as efficient as electricity and gas operated kilns which are built using conventional refrac-
tory bricks. Waste pots and potsherds were collected from two different pot producing communities, that
is, Ojah in Akoko Edo and Imiegba in Etsako Central Local Government Ares of Edo State. To determine
the suitability of the sample pots and potsherds collected for the construction of the kilns, the following
tests were carried out: shrinkage, porosity and insulating tests. Two kilns were designed and constructed,
a gas and wood fired kilns. The firing space and the outer wall of the gas kiln were designed to be circular
with one burner port using only potsherd and mortar without using whole pots. The wood kiln was de-
signed to have circular internal firing chamber, two fire boxes and a chimney. The kilns were subjected to
series of gloss firing with wood and gas as sources of fuel and the maturing temperatures were recorded.
The efficiency of the kilns constructed revealed that they were capable of firing to temperature above
1200˚C that was originally planned for it to be attained coupled with uniform heat distribution experi-
enced without any indication of cold spot. These kilns are capable of sustaining the deficiency arising
from lack of imported kilns that could be used to accomplish finished ceramic productions as it is being
currently encountered in Nigerian tertiary institutions and cottage level industries.
Keywords: Potsherds Kilns; Prototyping Ceramic Education; Sustainability
Introduction
Firing clays for hard, durable and improved aesthetics is an
art that cuts across cultures and races. According to Akinbogun
and Kashim (2006), no ceramic process is ever complete with-
out subjecting them to heat treatment such that they become
impermeable to liquid. Firing, therefore, is an indispensable
factor in the practice of pottery and ceramics.
Electricity supply in Nigeria since the late 1980s has become
highly inadequate, epileptic and unreliable for kiln firing. With
the high cost of importation resulting from high foreign ex-
change rate, maintenance of electrical elements for kilns and its
accessories as well as the running cost of alternative fuel there-
fore makes research into affordable ceramics kilns for tertiary
institutions and practitioners in Nigeri a n s i n evitable .
Ceramic production has thrived significantly from the late
1970s to 1980s both at industrial and cottage levels. Unfortu-
nately, the decline in the Nigeria economy from the late 1980s
to date has forced most of the existing industries to close down
as a result of unsteady power supply from electricity and exor-
bitant cost of diesel and kerosene used in supplying kiln burn-
ers.
Various efforts and researches have been carried out over a
period of time to develop different types of kilns that would cut
down on cost and make local production comparative to the
imported ones. Agberia (1993) opines that this effort has not
yielded much result that is worth celebrating. This position was
also buttressed by Akinbogun (2004) while commending the
efforts of the ceramist at embarking upon construction of kilns
by themselves. He however noted the short coming in their
kilns to be limitation in their efficiency level, with firing tem-
peratures limited to earthen ware temperature. He added that
some of the kilns contain only a single wall of insulating bricks
with very short life span. These deficiencies put together that he
concluded are enough to make firing of ceramic wares tedious
and less rewarding.
As observed from a trip to Kenya during a conference by In-
ternational Society of Ceramics Art Education (ISCAE) and
tour of some ceramic cottage industries during the conference,
it indicated a lot of viability and hope for production and sales
of ceramic products. The kiln used in one of their cottage in-
dustries, Earthenworks Pottery Company Limited at Nyali
Beach (behind Nakumatt) Mombasa, was made of potsherds
and it worked adequately for them at accomplishing firing low
temperature bisque wares. The excitement of the tourist at these
large ceramics pieces made it expedient also for some ceramists
in Nigeria to try the Kenyan experience and see how it goes.
Since Nigerians are more interested in high temperature ceram-

O. J. OHIMAI ET AL.
ics, this research was conceptualized on an attempt to use the
same material to build a kiln of higher temperature capacity that
can reach glaze point of between 1200 - 1300 degree centigrade,
bearing in mind that there are plenty of waste pots and pot-
sherds in local pottery making centres, such as Ojah, Imiegba in
(Edo state, Nigeria) and many others which have become trash
and constitute environmental nuisance. This potsherd’s was
however harnessed for construction of kilns which reduced the
problems arising from ineffective and inefficient kilns and cost
of production, thereby made the firing of ceramic work more
rewarding especially at the Federal University of Technology,
Akure where this prototype kiln was built. The potsherd kiln
below in Plates 1 and 2 was the sample produced at Earthen-
works Pottery Co., Ltd., Mombasa, and Wamumu Rehabilita-
tion Centre, Kenya which was the source of inspiration for this
research.
According to Ohimai (2011), a kiln constructed with pot-
sherds and pots was described as a firing chamber or furnace
composed of pots and jumble potsherds that were capable of
resisting, accumulating, retaining and conserving heat input
from the heat source. Other refractory materials such as kaolin,
Plate 1.
A view of kiln from Earthenworks Pottery Co., Ltd., Mombasa, Kenya.
Source: Ohimai, 2011.
Plate 2.
Researchers examine the wreckage of kiln at Wamumu rehabilitation
centre, Kenya after first firi ng. Source: Ohimai, 2011.
ball clay and saw dust were sourced from Afowa in Edo State
and Akure respectively in the construction process.
The aim of this project was to construct an efficient pot and
potsherd kilns that can be used as an alternative to electric kilns
with a view to cut down on overall cost of energy consumption
required to accomplish ceramics firing in the tertiary institu-
tions in Nigeria. The following objectives were accomplished
in the course of this research:
 Collection of waste pots and potsherds for kiln construction
 Design a gas and wood kiln suitable for potsherd kiln con-
struction
 Production of the kiln with good heat circulation up to stone
ware and porcelain temperature
 Assess the insulating capacity of the earthenware pots and
pot sherds when used as kiln wall and
 Determine the cost effectiveness of the kiln
Methodologies Adopted for This Research
In order to determine the suitability of the pots/potsherd sam-
ples collected for the kilns construction and the mortal fitness,
as well as avoid excessive heat loss from kiln walls during fir-
ing, the following tests were carried out on the clays used for
the pot and the mortar.
 Shrinkage tests
 Porosity or water absorption tests and
 Insulating tests.
Collection of waste pots and potsherd for kiln construction
was sourced from local pottery centers in Edo state. The sorting
of suitable pots and potsherds for the construction was done
according to the research needs on arrival at the project site.
The pots and potsherds sourced were of different sizes and
shapes depending on their initial primary function. They pots
and potsherds were from Ojah and Imiegba communities repu-
tably known for the production of pottery in Akoko-Edo and
Etsako Central Local Government of Edo State respectively as
shown in Plates 3 and 4.
Objective 2: The designed high fired temperature kilns was
operated on gas and wood as source of energy. To accomplish
Plate 3.
Imiegba potsherds dump. Source: Ohimai, 2011.
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O. J. OHIMAI ET AL.
Plate 4.
Ojah Potsherds dum p (over 100 years).
the construction of these kilns, an extensive literature search on
kilns that uses gas and wood was carried out. For suitability, in
terms of the internal space and kiln chamber, a round kiln was
preferred because of its efficient heat circulation as recom-
mended by Cardew (1971) who strongly posited that a round
kiln has more even heat distribution advantages. Plates 5 to 20
indicate the pictorial process used in the construction of the kiln
from its foundation to finishing as highlighted below.
The firing of both kilns shows that there was possibility of
firing kilns constructed using pots and potsherds with gas and
wood, coupled with very good and uniform heat distribution.
Both kilns as observed by the researchers became more effi-
cient with subsequent firing exercises. The kilns performance
improved without either crumbling or forming glass phase. In
all, four gloss firings were carried out; three gas firing and one
wood firing. Plates 21 to 26 clearly show the stages at which
the ceramic wares were loaded in the kiln, clamped and subse-
quently fired to finished gloss wares.
To assess the insulating capacity of earthenware pots and
potsherds used as kiln walls, one was constructed with pot-
sherds and the other with pots and potsherds. They were both
subjected to series of gloss firing. The two kilns were not sub-
jected to initial bisque firing before the gloss which is usually
associated with firing in conventional kilns. To determine the
amount of heat rise or retention inside the kiln and the external
kiln temperature, several firings were carried out in the kiln and
careful observation of the firing to porcelain temperature of
1353˚C was done. It was difficult to conclude whether potsherd
kiln will be as durable as kiln constructed with bricks, as the
constructed kiln did not show any sign of depreciation. How-
ever firing with kiln constructed with potsherd was observed to
be cost effective and fast firing. Since it is a popular adage that:
“Time they say is money”, the kiln did not only fire to 1200˚C
as desired but was fired to porcelain temperature of 1353˚C at
record time of three (3) hours without crumbling or forming
glass phase. The firing procedure is pictorially explained from
Plate 27.
The kiln proves very efficient at producing a very good gloss
ware as shown in Plate 28 in the kiln constructed with
Plate 5.
Ramming mor tar for kiln base.
Plate 6.
Boarded kiln chamber and potsherd. Source: Ohi-
mai, 2011.
Plate 7.
Gas kiln war under construction.
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O. J. OHIMAI ET AL.
Plate 8.
Arch frame in position. Source: Ohimai, 2011.
Plate 9.
Filling and ramming of kiln arch.
Plate 10.
Completed gas kiln without chimney. Source: Ohimai,
2011.
Plate 11.
Laying the fir s t course of pots.
Plate 12.
Kiln pillars. Source: Ohimai, 2011.
Plate 13.
Laying of kiln pillars continued. Source: Ohimai, 2011.
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O. J. OHIMAI ET AL.
Plate 14.
A view of the expected flue leading to
the chimney.
Plate 15.
Gradual building up of the wood kiln wall.
Source: Ohimai, 2011.
Plate 16.
Gradual building up of the wood kiln wall.
Source: Ohimai, 2011.
Plate 17.
Gradual closing up of the wood. Source:
Ohimai, 2011.
Plate 18.
Filling of wood kiln arch.
Plate 19.
Completed kiln without chimney. Source: Ohimai, 2011.
Plate 20.
Completed kilns with chimney. Source: Ohimai, 2011.
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O. J. OHIMAI ET AL.
Plate 21.
Glaze works in kiln before firing. Source: Ohimai, 2011.
Plate 22.
Kiln ready for firing. Source: Ohimai, 2011.
Plate 23.
Firing in progress.
Plate 24.
Glazed work and melted Orton cones inside the kiln.
Plate 25.
Glazed wares before firing. Source: Ohimai, 2011.
Plate 26.
Glazed ware from second firing.
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O. J. OHIMAI ET AL.
Plate 27.
At 1350˚C, the researcher observed by physical contact that the external
walls of the kiln still felt cold.
Plate 28.
Glazed wares from third firing. Source: Ohimai, 2011.
pot and potsherd.
Plates 29 and 30 show the measuring devices used to deter-
mine the kiln temperature, and Plates 31 to 32 show the wood
stoking process while Plates 33 to 34 show the gloss ware in-
side the kiln after firing.
The cost effectiveness of kilns constructed with pots and pot-
sherds using wood as a source of fuel for kiln firing was highly
economical because wood can be found almost everywhere in
the country, couple with large number of wood off-cut gener-
ated at various saw mills within the research study area.
Though the use of wood might constitute hazards to the envi-
ronment especially with the current campaign on global warm-
ing, but the current use of wood will go a long at resolving the
production crises been experienced by institutions offering
Plate 29.
Maximum temperature attained with the
thermo couple with digital thermostat at end
of third firing. Source: Ohimai, 2011.
Plate 30.
Cones used for 4th firing. Source: Ohimai, 2011.
Plate 31.
Wood used for firing.
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O. J. OHIMAI ET AL.
Plate 32.
Stocking during 4th fir i ng. Source: Ohimai, 2011.
Plate 33.
Fired kiln and ware. Source: Ohim ai, 2011 .
Plate 34.
Glazed wares from 4th firing.
ceramics in tertiary institutions in Nigeria. The wood for pre-
heating the kiln were fell off from trees around the Department
of Industrial Design Studio of the Federal University of Tech-
nology, Akure. The hardwood used is available as sawmill
wastes in Akure, though it was observed by the researchers that
they were still damp at the point of collection. This was eventu-
ally an advantage as supported by Rhodes (1981) that if the
wood used for firing in kilns is slightly damp, the heat ex-
pended in volatilizing the water as steam lessens the amount of
heat available for the kiln, while a properly designed kiln fired
with dry wood of right size will advance in temperature very
quickly. Hence the dried wood cut into sizes was sourced along
the way from Auchi to Akure from peasant farmers. The gas
used for the firing was sourced from Adebowale Gas Depot,
Akure. Wood of less than one thousand (N1, 000) naira was
used to fire the wood kiln to about 1230˚C. In the case of the
gas kiln, 50 kg was bought with ten thousand, eight hundred
(N10, 800) Naira only. Three gloss firing were carried out to
1221˚C, 1236˚C and porcelain temperature of 1353˚C respec-
tively with less than 25 kg of gas. The three gloss firing with
gas cost an average of one thousand, eight hundred (N1, 800)
Naira only per firing which was a good achievement in cost
reduction over electricity and other mode of kilns used before
this research effort.
Findings
There are plenty of waste pots and potsherds in local pottery
making centres such as Ojah, Imiegba and many others which
can be harnessed for the production of pots and potsherds kiln.
During the construction process, there were initial problems
of cracks and incompatibility of mortar used to hold pots and
potsherds together. Some of the pots also developed cracks due
to shrinkage from the mortar used. However consistent mend-
ing and wedging of the cracks resulted in compacted walls that
were stable after firing.
That kilns constructed with pots and potsherds can be sub-
jected to straight gloss firing without consideration for the ini-
tial bisque firing usually associated with most conventional
kilns, though the preheating hours of the first initial firing was
longer.
The gas fired potsherds kiln as observed in the course of this
research attained a porcelain temperature of 1353˚C within
three hours of firing without any defect such as crumbling or
forming glass phase, a phenomenon that is very common with
most locally constructed conventional kiln. This is because
most locally built conventional kilns are limited in efficiency.
The intended maximum firing temperature of some of the kilns
when they are designed and constructed are hardly achieved
due to inadequacies.
It was possible for heat in the kilns to rise to porcelain tem-
perature of 1353˚C without the outer walls surface getting hot.
The simplicity and effectiveness of the kilns are based on some
factors. It is a downdraft kiln made of new material innovation,
inner circular wall allow for easy heat circulation coupled with
thick walls usually associated with circular kilns without metal
frame. The firing with kilns produced with pots and potsherds
are cost effective and very efficient. Less than 25 kg of gas was
estimated, at five thousand four hundred (N5, 400) naira only at
1221˚C; 1336˚C and 1353˚C, within the time duration of 3
hours, 3 hours 32 minutes and 3 hours respectively. While the
wood of less than one thousand (N 1, 000) Naira was used to
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O. J. OHIMAI ET AL.
Copyright © 2013 SciRe s . 483
fire the wood kiln to 1230˚C within 8 hours.
It was discovered that while it is more economical to fire
with wood, it is more efficient and less stressful to fire with
gas.
Recommendation
A quasi experimental research on pot and potsherd kilns re-
veals that the kilns are highly effective and efficient in the fir-
ing of stoneware ceramics. They are also cost effective to oper-
ate for Institutional and cottage level pottery centres. Thus, for
the design of pots and potsherds kiln, the principles stated be-
low are recommended:
 That round kilns are better than rectangular kilns as rec-
ommended by Cardew (1971) and that principle rightly ap-
ply to these kilns during the series of firings carried out.
Conclusion
This study explored the possibilities of designing efficient
ceramic kilns with the use of earthenware pots/potsherds. The
assessment of the kiln at the end of the research reveals that
pots and potsherds kilns are highly effective and efficient in the
firing of high temperature ceramic products at very low cost.
The study also reveals that the volume of potsherds and waste
pots that end up in “pot cemeteries” are enough to stimulate
pots and potsherds kiln production. This could liberate small
scale ceramic industries, studio potters and students of ceramics
in various tertiary institutions from the present decline that is
rocking ceramic production outlets in Nigeria. It will encourage
waste management as well as help in sustaining national de-
velopment and sustainability of ceramics and ceramics produc-
tion.
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