From my research, no one can exactly tell when people started trying to press cloth smooth. But it is believed, Chinese during the ancient time were using hot metal for ironing before anyone else. Pans filled with hot coals were pressed over stretched cloth (Pans as shown in pictures below). Thousand years ago, this method was already well established.
The ancient Chinese iron.
The ancient Chinese iron.
The ancient Chinese iron.
The ancient Chinese iron.
Meanwhile people in Northern Europe were using stones, glass and wood for smoothing. These continued in use for ironing in some places into the mid 19th century, long after Western blacksmiths started forging simple flat irons in the late Middle Ages. Plain metal irons were heated by a fire or on a stove. Flat irons were also called sad irons or smoothing irons. Metal handles had to be gripped in a pad or thick rag. Some irons had cool wooden handles and in 1870 a detachable handle was patented in the US. This stayed cool while the metal bases were heated and the idea was widely imitated. The "sad" in sad iron (or sadiron) is an old word for solid, and in some contexts this name suggests something bigger and heavier than a flat iron.
Flat iron or sad iron.
Flat iron or sad iron.
Flat iron or sad iron.
Flat iron or sad iron.
You'd need at least two irons on the go together for an effective system: one in use, and one re-heating. Large households with servants had a special ironing-stove for this purpose. Some were fitted with slots for several irons, and a water-jug on top.
At home, ironing traditional fabrics without the benefit of electricity was a hot, arduous job. Irons had to be kept immaculately clean, sand-papered and polished. They must be kept away from burning fuel, and be regularly but lightly greased to avoid rusting. Beeswax prevented irons sticking to starched cloth. Constant care was needed over temperature. Experience would help decide when the iron was hot enough, but not so hot that it would scorch the cloth.
If you make the base of your iron into a container, you can put glowing coals inside it and keep it hot a bit longer. This is called charcoal iron. It has hinged lid and the air holes to allow the charcoal to keep smouldering (as shown in the pictures below). These are sometimes called ironing boxes, or charcoal box irons, and may come with their own stand.
Charcoal iron.
Charcoal iron.
Charcoal iron.
Charcoal iron.
Charcoal iron.
Charcoal iron.
Charcoal iron.
For centuries, charcoal irons have been used in many different countries. When they have a funnel to keep smokey smells away from the cloth, they may be called chimney irons (as shown in the picture below).
Chimney iron.
Antique charcoal irons are attractive to many collectors, while modern charcoal irons are manufactured in Asia and also used in much of Africa. Some of these are sold to Westerners as reproductions or replica "antiques" (as shown in the picture below).
Reproductions of charcoal iron.
Some irons were shallower boxes and had fitted "slugs" or "heaters" (slabs of metal) which were heated in the fire and inserted into the base instead of charcoal. It was easier to keep the ironing surface spotlessly clean, away from the fuel, than with flat irons or charcoal irons. Brick inserts could be used for a longer-lasting, less intense heat. These are box or slug irons, once known as ironing boxes too. In some countries, they are called ox-tongue irons after a particular shape of insert.
Late 19th century, iron designs were experimented with heat-retaining fillings. Designs of this period became more and more ingenious and complicated, with reversible bases, gas jets and other innovations. By 1900, there were electric irons in use all around the world.
Blue and white character dish. 
The glazed base which shows a simple character, which is likely to be the studio name.
