Don't get Confused

A guide to those words which sometimes confuse


A blister is a glaze fault sometimes created due to over glazing or severe over-firing which can cause the glaze to boil and create bubbles, some of which burst to form craters. The surface of the glaze is very unpleasant and looks like a boiled mass of bubbles, craters and pinholes. Whereas a bloat is a body fault looking like a very big blister or bulge. Caused by gas bubbles forming in the body and getting trapped under the surface of the piece by the vitrifying clay surface during firing.


Actually the same thing! But 'biscuit' is the Potteries way of saying it. Biscuit ware is undipped pottery which has been fired once, not glazed. Biscuit is the clay piece when it has been fired once to give it sufficient strength to be glazed or decorated. Biscuit ware feels dry and coarse. Jasper and Parian wares are left purposely in their 'biscuit' state but they are a particular ceramic recipe called stoneware which is particularly strong and non-porous. Earthenware biscuit is porous. Biscuit firing temperature? Earthenware around 1100°C to 1150°C, Bone China around 1200°C to 1250°C.


The word kiln is used generically to name the structure or equipment in which pottery and other ceramics are fired.

The terms, bottle oven and bottle kiln, are often used interchangeably. To most of us they mean the same thing - a complex brick-built, bottle-shaped structure for the firing of pottery or associated materials. Most of us assume them to be the same and to do the same job. And although both ovens and bottle kilns have that curious bottle-shaped chimney, and both were fired with coal, there is an important technical difference between the two.

As with all Potteries terms the usage of the words kiln and oven varied from factory to factory and from town to town but over time the terms became interchangeable.

BOTTLE OVEN  In the north Staffordshire pottery industry, the term bottle oven meant the potter's biscuit or glost oven which was fired with coal to produce long flames that passed from the firemouths directly into the firing chamber. Heat then passed up through the setting and out through the bottle-shaped chimney. The eat was used once. Pottery inside the chamber needed to be protected from the flames, smoke, sulphur fumes, ashes and dust in fireclay boxes called saggars.

There were other types of bottle ovens which included downdraught, two-tier structures and salt glaze ovens. Temperatures of around 1000°C to 1400°C were reached in bottle ovens.

BOTTLE KILN  In the north Staffordshire pottery industry, a bottle kiln was constructed differently from an oven. There were several types.

A muffle kiln was constructed in such a way that the flames and products of combustion were prevented from entering the firing chamber by being circulated through enclosed flues which surrounded it. The products placed inside the chamber were thus kept away from the filth of fire and did not need to be protected in saggars. Muffle kilns were used for the firing of onglaze enamel decoration and for 'hardening-on' underglaze transferware. Temperatures typically around 700°C to 850°C (1300°F to 1560°F) were reached in muffle kilns.

A calcining kiln was used by potters' materials suppliers. For example flint stones or animal bones were calcined in kilns to make them friable and able to be crushed and ground ready for use in pottery recipes.

There were also frit or lime kilns.

OTHER TYPES OF KILN Kilns for the firing of bricks and tiles were not bottle shaped at all but were described as beehive kilns. They generally operated by down draught and had a separate tall chimney and no hovel.

As with all Potteries terms their usage varied from factory to factory and from town to town but over time the terms became interchangeable.

NO TWO ALIKE  No two bottle ovens or bottle kilns were alike. They were all built differently, the vast majority without architect drawings. Many were built 'by eye' and based only on the experience of the oven builder and the requirements of the factory owner. An old bottle oven builder, Tom Clewes of Longton, told me at the Last Bottle Oven Firing in 1978 that "They just went up. You won't find any of these ovens drawn on paper since you just built them. We did it on a day-work basis and got on with it."

The decorative brickwork at the top of the hovel chimney was created on the whim of the builder and owner.

In their heyday, the different types of bottle oven and bottle kiln were not specifically listed or classified. People in the pottery industry knew exactly what they were, so why bother listing them!

Of the 2000 or so coal-fired bottle ovens and kilns which once littered the skyline of the Potteries only 47 remain standing complete today (2020). Firing them is no longer permitted, the Clean Air Act of 1956 signalled their decline. They were replaced with kilns using the alternative fuels of electricity, gas and oil.

1) Alfred Clough, the 'fireman' responsible for the Last Bottle Oven Firing in The Potteries in 1978. He was a local pottery manufacturer and at one time owned over 30 pottery factories. 
2) In 1921 Ernest Sandeman described the various types of oven and kiln in his book 'Notes on the Manufacture of Earthenware'


Beware this can be complicated! In the Staffordshire Potteries, the word POTTERY is the noun generally used to describe any type of 'body.' For example, it could mean earthenware, china, stoneware, or porcelain. So, pottery does not describe an individual ceramic recipe, it is a collective noun. In the United States the word CHINA is used in the same way that pottery is used in the Potteries. It is their collective noun. However, in the Potteries the word CHINA is the name given to a particular and specific pottery recipe. For instance bone china. (Note that there are other recipes of china, for example fine china, vitreous china, or stone china.) In the UK, generally, the word PORCELAIN is used to mean fine, up-market porcelain or china whereas the word POTTERY is used to refer to earthenware or stoneware. Yes, it’s complicated. More about recipes? here>


Clay is one of the raw materials which go into making a ceramic body, using a recipe.


Pottery which was found to be cracked after its glost firing was usually scrapped as useless. It was described as LUMP or PITCHER and usually sent to the shraff tip. However, some entrepreneurs in the industry were able to make money from selling cracked pottery - depending on how cracked it really was! Here, to explain is a quote from Brian Milner. He was one of those entrepreneurs in the 1960s, 70s and 80s. "We used to buy China teacups from Ridgways. These were termed "crack cracked" and "sound cracked". I am not kidding. They were [packed] 40 dozen in a teachest and we used to buy about 12 chests every 2 weeks. We would sound every one of the "crack cracked" and find a lot of sound ones which we used to decorate and we were still able to sell the really cracked to market men."


A potter's dinner is eaten in the middle of the day, at lunchtime. Lunchtime is regarded as a posh dinner time. Tea is eaten at dinner time. Dinner in the evening would be regarded as posh. More here>


Very (very very) broadly speaking there are three types of pottery: earthenware, stoneware and porcelain.

  • Earthenware is a clay body fired at a comparatively low temperature, about 750 to 1100°C. It is porous and has to be glazed to make it impervious to liquids.
  • Stoneware is hard, impervious and made from a clay and flint mixture, fired at a high temperature of 1,200 to 1,400°C. Vitrification (the formation of a glassy outer surface) occurs at these high temperatures, so it does not have to be glazed unless a fine or coloured surface is required. 
  • Porcelain is fine ceramic and originated in China in about AD 700. It is made from fine white-firing clay, fired at a high temperature, and is translucent. Bone china (invented by Spode in the Stoke-on-Trent Potteries around 1800) is regarded as English Porcelain. 


Names given to the parts of flatware (plates, saucers dishes etc)
  • Edge The outermost part of the piece.
  • Rim The part between the edge and the verge. May be used for the placing of salt or mustard.
  • Verge The part creating the slope between the rim and the centre of the flatware.
Interestingly, after WW2 the depth of the verge was increased to cope with the American habit of only using a fork to eat and needing something to push the food against. Many thanks go to Andy Finney for sending me this snippet. 
Names given to the parts of flatware


Opposites. Faulty products, mainly flatware (plates). Words used to describe distorted plates as seen in a bung, usually in the biscuit state, probably before selection (inspection). Gappers is used when the distortion makes rims of plates separate from each other in the bung to create an obvious gap. Kissers is used when the distortion makes the rims of the plates touch. These words are possibly peculiar to the Steelite, and possibly the Royal Doulton, pottery factories. Many thanks go to David Tabbernor for sending me these. October 2019


A humper is a fault on pottery flatware. It appears as a domed base, causing the plate (or other flatware) to bow upwards. It looks ugly and causes gravy to accumulate in a ring around the edge of the plate. Regarded as seconds, or if its really bad, lump. On the other hand, a whirler is the exact opposite. It's also a pottery flatware fault, but this time refers to a plate with a bowed base so that it doesn't sit flat on a table but spins or whirls around. Giddy making.  Causes gravy to accumulate in a pool in the middle of the plate.


A jigger is a potter's machine for making flatware. A jolley is a potter's machine for making for holloware. Look for the OLL in jOLLey and hOLLow and you'll remember it! (Interestingly, and to confuse matters, in the 1840s Jolley was the word used for making flatware.)  More here>


Maiolica pottery has its origins in Spain and Italy. It is earthenware, fired to the biscuit stage, then covered with opaque, white, tin glaze and then superbly painted directly onto the unfired glaze surface with decoration in Renaissance styles. The decoration is so detailed that it is akin to a painting. The piece is then fired again. Majolica pottery has its origins in Victorian Britain. It is also earthenware and also fired to the biscuit stage. But it is then decorated with richly coloured, glossy lead glazes, frequently in a relief decorated and naturalistic style. The piece is then fired again. The names of these two types of pottery are very often confused and, quite frankly, misleadingly mixed up. Take care with this one, there is a lot of incorrect information posted on the web! This is a helpful site here>

Majolica on the left vs Maiolica on the right


An American Muffin is a small domed spongy cake made with butter, plain flour, baking powder, bicarbonate of soda, sugar, salt, milk, and a large egg. An English Muffin is leavened bread, beloved by the English aristocracy particularly in the early 20th Century and served in a Muffin Dish. A Muffin Dish should not be confused with the Muffin which is a small pottery plate measuring 5 or 6 inches in diameter. A Muffin is similar to a TWIFFLER or TWIFLER or TWYFLER - but of different diameter.


A bottle kiln is the same as bottle oven. But not quite! The words do tend to be interchangeable. But the word oven usually meant the biscuit or glost firing ovens and the word 'kiln' usually meant the enamel firing kiln, hardening-on kiln or calcining kiln. But usage did vary from factory to factory, so its complicated and difficult to be precise. More here> at The Potteries Bottle Oven website.


Pegging is the process of repairing a crack in a clay piece by filling it with slip and smoothing it over before the piece is fired. Hopefully it will be invisible after firing.  Stopping is the process of filling a crack in a fired piece using a mixture of pre-fired body, ground to a fine particle size, and mixed with a resin which sets hard and seals the crack. Many thanks to David Broadhurst for suggesting these two words for inclusion. March 2016 Additional:  "Pegging can also be done in the dry clay state by scraping the crack with a wooden peg and then rubbing usually with a bone handled knife. Bone handled knives were also used to repair fish cracks on the outside rims of closets."


A placer is the person, usually male but could be female, who places individual clay pieces or dipped biscuit pieces into saggars before they are placed (or set in) the oven for firing. If the firing was glost then he or she would also need to place wads of wad clay on the top rim of the saggar before it was taken into the oven. A placer is also the man who fills or sets the oven with saggars containing the ware which had been placed into the saggars by the placer. (Sorry, but I agree it can be confusing to a beginner!) The placer works for the cod, his boss.


The description of a classification of the quality of pottery ware - the seven grades of pot!

  1. BEST - First quality pottery. Good ware. Sometimes called FIRSTS. But there is no such thing as a perfect pot since every piece will always have some sort of slight blemish - this is the very nature of pottery.
  2. BEST SECOND - Not bad enough to be a SECOND and not good enough to be best.
  3. SECONDS - Imperfect pottery. Not BEST and not THIRDS or LUMP! Slightly blemished or faulty and sold at a slight discount.
  4. WORST SECONDS - Sometimes called WORSER SECONDS. Slightly more imperfect than SECONDS. Then there was a DEGREE WORSER which was worse than WORST SECONDS. Or even WORSER WORSER. But not THIRDS, just yet.
  5. THIRDS - This signifies that the ware is well below the usual BEST standard, and not even good enough to fall within the description of SECONDS. But better than LUMP. The ware was/is still marketable, however, and was sold to hawkers or market stall holders for sale on the 'stones'. Badly twisted ware, crooked holloware, nipped ware and whirler plates fall into this category.
  6. LUMP - Massively faulty pottery. So bad that it is worse than WORSER SECONDS. Or even THIRDS. This is almost, but not quite, the lowest quality of ware that leaves any potbank, and usually it is ware that has just managed to escape being deliberately smashed. Whilst there may have been possibilities in some china shops of disposing of SECONDS, or even THIRDS the risk of dealing in LUMP is "too great to be incurred lightheartedly." Top-end, high-grade potbanks see to it that LUMP is sent to the shraff tip, "in spite of the fact that enquiries were freely received from the poorer districts or export for mixed grades of lump."  Usually, about 100 years later,  lump re-appears on TV shows as 'rare and valuable.'  That’s irony!
  7. PITCHER Worse than lump. To be thrown away. Broken. Useless. But strangely saleable, at a price, in some quarters!


A putter up is an occupation, usually female, in the dipping house.  She either takes biscuit holloware (cups for instance) from a ware basket, and places them onto a board in front of the dipper ready for dipping or she takes the recently dipped holloware and places it onto trays or bats or ware boards before they are taken away to dry before the glost fire. A sitter up is a bottle oven fireman's assistant (maybe the fireman's apprentice). He kindles, cajoles, guards, tenders and baits the oven while the fireman takes a break during the firing cycle. The sitter up will get the oven up to a high temperature after about 20 hours of firing, then the fireman takes over to finish off the fire completely.  See also RUBBER UP here>


This is all about Bottle Ovens. Ridding was an essential process in the life of a bottle oven. It entailed the thorough repair and relaying of the flues, oven bottoms, and bags. This was a major operation which put the oven out of use for some considerable time. It needed to be done every three years or so - depending on the work that the oven had been put to. In 1920 ridding would cost around £30. A rebuild was, as it says, a complete rebuild of a bottle oven, excluding the hovel, and was required, on average, every 20 years. More here> at The Potteries Bottle Oven website.


Don't get confused. They all mean the same thing. A rubbish tip of waste potters moulds, broken saggars and faulty ware such as lump or wasters. A heap of broken crockery! Photo here >

SAGGAR and SAGGER Same thing!  But saggar is the preferred spelling of those in the know.


The saggar shop was where saggars were actually made. It was where the saggar maker and his saggar maker's bottom knocker created clay saggars which needed to be fired before use. The saggar house was where they were used. It was here that they were placed (filled) with either clay or glazed biscuit pieces ready for placing (setting) in bungs, in the bottle oven, prior to firing.

Saggar House - placing ware into saggars
before being taken into the kiln for placing before firing.
Photo: source unknown  Date: unknown


A sink is used in a kitchen, not a bathroom. A washbasin is used in a bathroom. A lavatory is not a toilet, it's a washbasin but not a sink. Confused?  Here is a more in-depth explanation but it's messy, complicated and a tad confusing, so bear with me!  In the good old days, in the UK sanitaryware industry, sanitary pottery casters and warehouse packers, called a WASHBASIN a TABLE. But why? Well, in the late 1800s when large WASHBASINS were designed to stand on legs rather than a single column pedestal (as is common in the UK today, 2015) the washbasin actually looked like a TABLE. But actually, the correct word, in those days, for a WASHBASIN or TABLE was LAVATORY. The word LAVATORY is derived from the Latin word LAVARE, meaning 'to wash.' Nowadays, a TOILET is often mistakenly called a LAVATORY since this is regarded as polite. But technically, it is incorrect. Of course, while it would be correct to wash your hands in a LAVATORY or WASHBASIN or SINK (see below) it would be odd to wash your hands in a TOILET, or worse still, to do something 'exceptional' in a LAVATORY,  WASHBASIN or SINK.


Sorting is the removal of stuck-on pips which have been used to keep pottery apart during a glost fire. Its the same as as 'ginneting.'   But selecting is the inspection of the product after a processing stage to look for faults.


The Staffordshire pottery industry had a uniquely peculiar system for describing the sizes of its products. To an outsider and the uninitiated, it was complicated, messy, inconsistent and arbitrary. To those in the know, a manufacturer and his workers, it was easy to understand but skewed to the benefit of the boss.

The nominal Trade sizes of flatware, such as plates and dishes, differ from the Actual sizes in inches. For example, a Trade 8” plate usually measures Actual 9” and a Trade 10” plate measures Actual 10.5” or more. Similarly, a 16” Trade oval meat dish would truly measure 18” Actual and the whole nest of dishes will be greater in Actual size than the nominal Trade size.

But, probably, the most perplexing point is encountered in connection with holloware. Jugs. teapots, pudding bowls and the like are described under trade terms such as 24s, 30s and 36s, each gradation occurring in spans of sixes. And, counter-intuitively, the smaller the number the larger the size! The full range of Trade Sizes was 6s, 12s, 18s, 24s, 30s, 36s, 42s, 48s, 54s, and 60s.  The underlying principle of this arrangement appears to have come down through the generations, and the apparent inconsistencies are accounted for by the fact that originally, pottery was sold by the basket, in what were known as "warehouse dozens”. The large size jug or teapot or bowl would be twelve to the dozen, and called a 12s; the next smaller size would be eighteen to the dozen, and styled an 18s; the pint size would be twenty-four to the dozen, and called a 24s and so on down or up the scale. To add to the confusion, one manufacturer's sizes do not necessarily conform with those of other manufacturers; the shapes may be modelled to bigger or smaller capacities.

During the early 20th Century the system was changed and articles were sold in dozens of twelve, yet the old method of describing the sizes persisted well into the 1990s.


These are three different sizes of plates. Read on.  In 1843 the Potters' Union began putting right the wrongs which they believed their employers had forced upon their members. One concerned the sizing of flatware and the price which a potter would be paid for making each size of plate.  Here is an extract from The Staffordshire Potter by Harold Owen, originally published in 1901.  "The Mystery of the Muffin. The Union of 1843 found, at its birth, a strike already in progress … but there was a new grievance. In the trade, the different size of plates are distinguished by separate names. The largest size is called a "plate," the next a “ twiffler," the smallest a "muffin." One of the employers, whose workmen had struck, re-christened the series. He called the plate a twiffler, the twiffler a muffin, and the muffin, in the words of the workmen, he “sent to God knew where.” In other words, the men were told that they must make plates at the same price as twifflers, and twifflers at the same price as muffins. There was no alteration in the sizes - the nomenclature and prices alone were affected. This is an interesting circumstance, inasmuch as it is the earliest recorded example of a practice in the trade which subsequently became very common as an oblique method of a reduction in wages."


Wad is a rope-like strip of specially-formulated fireclay or saggar marl squeezed through the die in a wad box. Wad is used as a cushion between saggars when they are placed together, one on top of an other, in a bung, in the oven. In addition to the effect of levelling the bung, wads also seal the uneven joint between the saggars, thus preventing smoke and fumes from the the fires coming into contact with the ware during firing. Dod is a soft clay squeezed through the die in the dod box to give a strip of the required cross-section shape. The strips are cut into lengths and bent by hand while soft to form a handle for a teacup or jug.


The wicket is the open entrance into a bottle oven. Whereas the clammins is the name of the brickwork built to seal the wicket before firing.


Where is the wear on this ware?  Not so bad when you read it to yourself. But say it out loud and the listener can easily become confused!  Ware is the potbank word here, meaning pottery product. It might be earthenware, chinaware or perhaps clayware. And it could all be stored in a warehouse before being sold to middle men who peddle their wares.