Two decades ago it seemed that the difference between tubelined and embossed (relief-moulded) tiles was quite well understood by antique dealers and collectors, today maybe that is not the case. I doubt that it was ever fully understood by consumers for there are indications that even in 1905 the distinction was not clear to all as some tubelined tiles by Alfred Meakin have Tube Lined stamped verso probably to indicate that they were limited editions and more expensive.
Edwardian tube lined tiles are relatively rare in proportion to embossed tiles certainly less than 1% were tubelined and the most often found tubeline tiles are simple designs. I am not sure if I have ever seen a victorian tubelined tile the earliest I can vouch for is 1902 and that on a plastic clay body rather than dust-pressed. Original embossed tiles are now often called tubelined in order to boost their status, to suggest rarity, and with internet self publishing not least in online auctions the vast majority of tiles described as tubelined are not tubelined but are embossed. Most reproduction art nouveau tiles are tubelined versions of embossed tiles so they aren't really reproductions, one could say reproductions of the designs but not reproduction of the tiles.
A description often seen alongside reproduction tubelined tiles says the following:
Art Nouveau tiles used a process of tube lining where slip was trailed onto the surface of the tile. This formed raised lines separating the areas where different color was wanted. Colored glazes were poured into the areas of the tile formed by the tube-lined decoration. These tube-lined tiles later gave rise to the moulded Art Nouveau tiles as a cheaper alternative.
This is wrong in almost every every detail yet is repeated by manufacturers and retailers in order to sell products inferior to those they are 'reproducing'.
Tubelined tiles are essentially two dimensional objects, a flat tile blank with piped on outline. It is ridiculous to suggest that a two dimensional decorative object is inherently superior to a three dimensional decorative object. Have all the tile manufacturers suddenly developed a sense of altruism, the advancement of the art more important than profit? I don't think so, it is simply the case that it is cheaper and more profitable to make tubelined tiles.
Glaze quality particularly intensity of colour and translucency are essential in achieving the best effects, as tubelined tiles have flat surfaces translucency is not so important and glazes can be simpler and so cheaper. The more translucent the glaze is the more it tends to run and so bleed and leech in to surrounding colours, a well applied tubeline prevents this so original tubelined tiles often have some of the best glazes. Modern glazes still can not match the brilliance of early twentieth century lead glazes and those used on most reproduction tubelined tiles are considerably more opaque than the originals.
Art nouveau tiles were mostly made by a moulding process the first examples being made in the late 1890s, it was a complicated and expensive process involving sculpting a three dimensional pattern and making a die. Most dies were made from metal, the harder the metal the more durable the die so a larger quantity of tiles could be made before the dies wore out. There were various techniques for making the die but essentially the harder the metal the more difficult and expensive the die was to make.
The die was put in to a press which was then filled with dust clay the tile then produced being decorated with the reverse image of the die, after firing the biscuit tile the glazes were painted by hand and the tile fired again to melt the glazes. There are also tiles embossed with just an outline and no bas relief, these were the cheapest to make requiring just an outline to be cut in to a slab of metal for making the die, the first seen were floral designs introduced by Pilkington in 1893, Mintons also extensively used the technique. The tiles demanding the most technical skills and craftsmanship were embossed without a raised outline and painted with richly coloured and brilliant glazes.
Embossed tiles are almost invariably more complex designs than tubelined. With an embossed design a great amount of skill and care could be put in to making the die in the knowledge that many thousands of tiles made with that die would faithfully represent the wishes of the designer. With tubelining the designer trusted in the skills of unknown decorators working on a piecework basis to recreate the design, sloppy tubelining and glaze painting result in some of the worst art nouveau tiles being tubelined.
Embossed tiles being three dimensional the glazes melted and ran in to the hollows creating a graduated range of hues in a single colour glaze, as the glazes could run together colours that may react with each other could not be, or at least were very difficult to be used together. Embossed outlines were commonly used together with bas relief creating a best of both worlds scenario, the outlines to contain the molten glazes and the bas relief to create the range of colour tones. The outline could only be the same colour as the base clay, usually white, which could leave a stark outline showing between coloured glazes, a few tiles with embossed outlines are found with the outlines overpainted in a dark stain to mask the stark reverse cartoon-like effect of a bright near white outline.
Tubelined tiles are made by piping an outline in slip clay on to an ordinary plain blank tile similar to icing a cake, glazes are than painted in to the sections created. The effect is generally less dramatic than embossed tiles with areas of flat colour surrounded by the raised outline. The commercial benefits of tubeline are lower set up costs for small production runs, the flat surface and raised outline to contain the glazes make painting easier and so cheaper.
With the tubeline technique small production runs of a pattern could be made including limited editions and one-offs, with the raised outline more adventurous glazes could be used the outlines separating glazes that may react adversely with each other. Outlines were most frequently applied using a different colour of clay, the designer could specify the outline colour as part of the overall design, some examples use more than one colour of outline. Tubeline was used for larger panels where the cost of making tools for each tile would be prohibitive. Whilst applying the outline required skill painting tubeline tiles was much easier than embossed tiles it being like painting by numbers.
So sometimes tubeline was cheaper, sometimes it was more expensive. Most reproduction tiles are tubelined because they are cheaper to make given the smaller market size than that in the early 1900s when tiles were the most cost effective means of creating easy to clean and durable wall finishes. The better art tile makers used both techniques according to whichever would produce the desired result. From a collectors point of view tubeline tiles are more likely to feature rare designs and use more brilliant colours but there are also embossed patterns that are rarely seen and quite common embossed tiles in especially brilliant and rare colours that are equally sought after by collectors.
In a wholesaler's catalogue dating from 1905 there are two tiles at the top price of fifteen shillings per dozen, one is embossed, one is tubelined, another monochrome émaux ombrants in blue is thirteen shillings per dozen, it is therefore clear that the base process did not determine the price indeed the common factor is the quality of the glazes. Another tile is priced at seven shillings per dozen and a very similar tile from the same manufacturer is priced at seven shillings and sixpence per dozen, the cheaper has yellow and orange flower, the dearer has purple and mauve flower there is no difference in production costs other than the glaze colour. It has been noted that the purple flower tile, which is seen from time to time, is more prone to glazing flaws than yellow tiles.
Of the three most expensive tiles the embossed tile has two shades of purple, an expensive colour, two greens blended in the leaves and three dappled colours to the background. Dappling well is more difficult than it may first appear at least to make it look good, the background is also textured making for more expensive modelling and die. The tubelined tile is fairly complex to pipe, being symmetrical greatly increases the difficulty for one can readily compare the to sides for accuracy, and also has fabulous glazes. Émaux ombrants glazes were the most difficult to make and the moulding had to be particularly finely executed. The cheapest majolica glazed tile in the catalogue at five shillings and sixpence per dozen, a little over one-third of the price of the finest, has a embossed outline with no bas relief, the kind of tile that is commonly erroneously called tubelined now. The finest majolica tiles are embossed and decorated with brilliant colours and glazes, it is impossible to produce anything comparable using the tubeline process.