Anyone wishing to make a collection of English mustard pots will necessarily start towards the end of the 18th century since, although wet mustard had been a common adjunct to food in England since at least the 13th century, notwithstanding that the Romans used it, there are almost no examples of wet mustard pots extant until about the reign of Geo III.
This may be explained by, on the one hand the use of dry mustard during the first half of the 18th. century and on the other, the likelihood that any earlier examples found their way into the melting pot for reasons of fashion.
In the 'Great House' of mediaeval times there would have been a 'Mustarder' who was responsible for keeping the household supplied with mustard. He would make his mustard by crushing the seed in a mortar with a pestle or by means of a quern. The resultant powder was then mixed with peasemeal, dampened and rolled into balls about the size of a golf ball. Often these balls were then gilded to stop them drying out. It seems likely, therefore, that mustard was mostly used by the rich.
When the mustard was required the ball would be crushed and mixed with either vinegar or milk although wine, cider or apple juice were sometimes used as also was honey.
What sort of vessel was used to serve the mustard is by no means certain as none has survived but a possible explanation for the introduction of dry mustard possibly in the late 17th century was the introduction of the blind caster.

In my article on casters ( ASCAS Newsletter 85 June 2011) I referred to 'the blind caster' which, it is believed, was used to contain dry mustard and I stated that the earliest example of this type of caster that I had seen was dated 1726. I have now had drawn to my attention a blind caster by Charles Adam dated 1717 (Fig I) which almost certainly was for the use of dry mustard and may well have been designed to serve either as a caster without its sleeve (Fig II) or as a dry mustard pot with the sleeve inserted.

Fig. I and Fig. II

Pictures courtesy of Steve Swan ASCAS member

Although the town of Tewkesbury in Gloucestershire is usually thought of in connection with mustard because the plant was grown there commercially it was in Durham that the first commercial mustard powder was produced somewhen at the beginning of the reign of George I when, in about 1720, a Mrs. Clements of 73, Sadler Street, found a method of producing a fine mustard powder which she marketed nation-wide. It has been believed that it was this product that was the dry mustard for which the blind caster was designed and that the use of dry mustard dated therefore from circa 1720.

However the blind caster with its spoon to which I also referred in my article is of the 'Lighthouse' design and its maker F G has been identified as Francis Garthorne. This makes it a 17th century piece so that dry mustard must have been in use much earlier than previously thought. This allows that, notwithstanding the absence of Geo I wet mustard pots, wet mustard was probably what Mrs. Clements' product was used for and thus it is likely that both wet and dry mustard were common for most of the 18th century. Michael Snodin notes that "A 'little mustard spoon' is mentioned in a newspaper of 1678" and the same author also records "A 'mustard cup with lid and spoon' is listed in an inventory of 1721". (see note 1)

The Colman mustard firm had, until it was asset stripped, a comprehensive collection of silver mustard pots in which was a single example of 1724 but it is highly unlikely that a collector of today will come across such an early example.
The next example in the Colman collection was dated 1758 and even this is sufficiently early that a collector will have to exercise considerable patience if he or she wishes to start here.
I should, perhaps, say here that 18th century mustard pots anyway are anything but plentiful but from about 1761 onwards they were made in sufficient quantity that examples can be found.
Beware however because they are frequently damaged.
The early ones are of a simple 'drum' construction with an 'S' scroll handle which at its upper end is contiguous with the hinge, usually with a thumb piece, which secures a flat or slightly domed top.

On these early examples the aperture for the spoon is cut out of the top rim of the body rather than out of the edge of the lid as became the case from the last quarter of the century onwards and is common today. This necessitated that the glass liner had also to be fretted out to accommodate the spoon. Experiment has shown that the change was probably introduced because if the spoon is left in a pot of the early design the lid does not close adequately and this would allow the mustard to dry out (Fig III). These pots were usually plain and undecorated although some do have engraved patterns on them. They were fully marked underneath and the tops should be hallmarked with the lion passant only on the inside. Some tops are also struck with the maker's mark.

The difficulty with assembling a collection of mustard pots is that, unlike other hollow ware they did not follow a discernible evolutionary pattern. Although the various styles of the late 18th century are represented in mustard pots they did not follow each other in a neat date order but exist side by side so that at any given time there are several representative patterns bearing the same date letter.

The only feature which is peculiar to mustard pots is that, whereas most have hinged lids many of which incorporate a thumb piece for raising the lid (Fig IV), only a few will be found with just a finial, some have lift off lids and these have finials. It should be noted, however, that some rare examples have both thumb piece and finial.
By the seventeen eighties it is also possible to find examples which are mounted on feet.

Fig III: Mustard Pot (unascribed) London 1770 showing the rim of both the silver and the liner fretted out to accommodate the spoon

Fig IV: The 1770 mustard pot of fig III showing the hinge and thumb piece for raising the lid

For some reason the contemporary mustard spoon is almost always missing and for the purest this makes the pot incomplete although the fact that the spoon is missing has no affect whatever on the place the pot occupies in the historical sequence of design as the spoon was made to match other existing flatware and not the pot. Hall-marks appear underneath the vessel until about 1770 after which date they will usually, but not always, be found, as with cream jugs, round the top rim to the right of the handle. In examples that are other than round, the handle is sometimes at one end and sometimes in the middle of one of the sides. Handles are usually of the 'S' shape and are fairly utilitarian having little decoration.

With the introduction of glass liners the makers of salts, sugar baskets and mustard pots were able to give full vent to their artistry and many designs of open-work containers were produced ranging from fairly simple piercing to some quite ornate and pretty fretwork since they could now rely on the glass liner to hold the contents and could also use it very effectively as a backdrop to their cut out patterns.
Pots of this type can be both round and oval and both flat and domed lids can be found. The glass liners are usually blue but red, green and clear, though rare, are not unknown. Care must always be taken to ensure that the liner fits the pot snugly as they, not unnaturally, easily become broken and replaced.

Although these glass liners were found to be very useful in the open-work pots they were also used in the solid sided ones as well and, in fact, it is uncommon to find such a pot without a glass liner. There were some made, usually the early ones, that were gilt inside so that a mustard pot with neither gilding nor liner is to be avoided. It is almost certainly missing its liner and although replacements can still be obtained it is far easier to wait for a complete one to turn up to fill a space in a collection.

By the end of the 18th century the neo-classical influence was manifest on all types of English hollow ware and mustard pots were no exception. Fig V is a good example and shows the finial by which the hinged lid was raised and also shows that the spoon is now accommodated by cutting out a slot in the lid so that the glass liner is left complete and the lid closes firmly.

Fig V: Mustard Pot by Abraham Peterson London 1794 showing the spoon aperture in the lid

In conclusion; because mustard pots are not as common as other hollow ware they are relatively expensive and patience is required in building a collection. However because they were made in a diversity of patterns an interesting and attractive collection of them can be made.