Right from the beginning, coffee pots were made for coffee. This particular coffee pot has a sharp pour spout which traps the floating grinds, and a flat squat bottom which traps the sunken grinds. This particular pot is highly unique to coffee and demonstrates the early attempts to make a brewer which the brew is easily drunk.
Whole styles of pots were developed in the 16 & 1700's in which the basic design was around the way coffee grinds react. The fat bulge with the pour spout in the middle was used to separate the coffee grinds from the drink. Most the time, coffee grinds were left to sit in a hot pot, so pot design became a way of filtering the coffee drink.
Undoubtedly, cloth filters were used to filter the coffee grinds out in many locations, but no evidence of a commercial device to do that is evident.
Then came the innovation which started off coffee brewer development. Someone poured hot water through a coffee grind filled sock and created the filter. In many parts of the world, still today, old socks are used to filter and brew coffee. To say the least, it is an interesting development.
The commercial name given to the device was Mr. Biggin. It is surmised that the name was really bagging but time lost the word to slovenliness and Biggin pots appeared for the first time around 1780. What can be said about these filter coffee pots is that they appeared simultaneously everywhere.
Although a great innovation, Biggin Pots had problems. They confined the coffee grind. If the coffee grind was too fine, the water could not penetrate the coffee and would simply run through the sides of the filter. If too coarse, the water ran straight through without brewing coffee.
This isn't a good statement about the state of coffee brewers but rather a statement about the state of coffee grinders. At the time, coffee grinders were not very good.
Another innovation which came on the scene after the Biggin was the metal water filter spreader coffee brewer. This device was not quite like the metal filters used to actually filter the coffee. This device was used to spread the water evenly over the internal coffee while it dripped down through the filter.
Unfortunately, old socks got rotten and began to add taste to the brew. People complained of the taste of cotton, wool, burlap, and such used to make the various filters of the day. Around 1802, a metal coffee filter was patented in France.
Shortly after the metal filter came the problem of floating grinds. Cloth filters didn't seem to have the same problem because they moved with the grind rippling with the pouring water. In 1806 another coffee patent used a tin hardened with bismuth called a rammer to compress the level of coffee. The basic object here was to keep the coffee grinds in place not to squeeze them.
Like magic, coffee inventors went nuts. All sorts of devices were developed to brew a better cup of coffee. Both the Biggin and Spreader use hot water poured over the coffee grinds. Madame Vassieux of Lyons developed a vacuum pot. The picture is of one of the oldest glass vacuum pots in the world. This pot is very similar to the Vissieux patent and may be a Vassieux machine.
Another name synonymous with vacuum coffee pots was Madame Richard. Vacuum pots and percolators came into being around the same time. There is a big difference between percolators and vacuum pots. In both, the water is pumped into the upper compartment. In this process, the coffee is being brewed at the correct temperature.
A vital factor in brewing a better cup of coffee is the temperature. In the vacuum coffee pot, when the heat source is taken away, the steam condenses in the lower compartment and creates a vacuum which draws the brewed coffee back down into the lower compartment.
The vacuum coffee pot had its problems. One serious problem was pressure. Although most vacuum pots were glass, metal ones were available. Seems, people liked seeing the coffee brew. Things like spring safety valves and tilt pour spouts got patents. Some had special tops which could be removed, allowing the coffee to stay in the top for stronger taste.
There is however, a major problem with glass and steam. Additionally, glass in the old days was not all that strong. Some pots blew up. But despite the danger, glass prevailed because people could see the coffee.
One of the objects of the vacuum pot was to heat the water and brew the coffee all at the same time. In the Raparlier vacuum pot (1859) the glass upper bowl on which a cup gradation were marked in order to determine how much coffee was brewed.
Another benefit of the vacuum pot was the size of the filter. The filter fits in the neck between the upper brewing bowl and the lower boiling and serving pot. This lower costs because it could be thrown away easily and was not all that expensive in the first place. In the Raparlier pot, the filter was hemp. Hemp is a plant generally outlawed these days, but normally it was used as rope. Hemp was easily rapped around in the filter neck, pulled out easily, and thrown away after each use. It beat an old sock any way.
A more technical name for this type of coffee pot was Hydropneumatique (Hydropneumatic) pot. This pot was in use right up through 1960's. Silex made a vacuum pot produced in the USA in the mid 1900's. This was a very popular style design.
One major innovation the vacuum pot was putting the two bowls side by side. This is known as the balanced beam coffee pot. The balanced beam vacuum pot worked on the same theory as the vertical vacuum pot but when the brew filled the brew bowl, the weight changed pulling a device which extinguished the heat source. Itís true automation for that time.
Around the same time the coffee vacuum pot was invented another pot which did the same thing was invented. This was the percolator coffee pot. This coffee pot worked on a different principle than the coffee vacuum pot. Instead of heating the whole bowl of water and forcing it up to a top bowl, the percolator heated just the water near the bottom of the hot water pot. Bubbles form at the bottom of any boiling water pot. All one needs do is boil water in a pot and see for themselves.
The bubble burst which has trapped steam in it is concentrated in a small tube running up through the center of the coffee pot. This sucked water up with the steam bubble. As the burst leaves the tube, the pressure changes and the water which is sucked up with the bubble spreads out over the top of a filter which contains the coffee. The water then percolates back down through the coffee grinds to bottom of the pot.
The coffee percolator design is around today. They work great. Some disadvantages with the old percolator were the inability to control weight shifts which didn't allow the device to work well automated. The second disadvantage was the large filter. The large filter cost more than a simple rope twin so the percolator took a while to catch on. It wasn't until mass manufacturing and distribution did the percolator become popular.
A third design came into being around the same time the vacuum and percolator pots came into use, this was the plunger filter. This filter contained the coffee grind between two filters on top and bottom of a compartment hooked up with a push rod.
The theory with the plunger or French Coffee Press was the force the coffee down into the hot water. The advantage with this device is short brewing times. Theoretically, the coffee grind can be removed quickly after brewing so the bitter taste does not appear. Unfortunately, moving enclosures were hard to manufacture.
The plunger has truly been one of the prominent coffee makers of all time. Its simplicity and by its very nature, it is impossible to make the coffee bitter. Due to another modern invention, the microwave oven, the plunger coffee pot work well in modern times.
Like all the devices which go into making a cup of coffee, the brewer lent itself to electricity. Here is one of the first electric filter coffee machines made by Willy Brandl. The major development which drove the electric coffee machine business was not the heat source but the switch that turned it off at the right time. A little mercury float switch is mounted into the center top piece which turns off the heat when the water level got too low. This device is the onset of coffee machines.
An extremely used modern day device is the drip brewer. The ground coffee goes in a container on top of the machine. If the machine does not have a hot water maker associated with it which usually pumps the water to the grinds, the hot water is pour into the top container which holds the grinds. The water then saturates the coffee grinds and drips out into another container.
These come in many different styles. Two distinct differences are those which heat the water in the machine and those which hot water is pored into them. Some use just a metal filter and others use a paper filter. Additionally, they can be made of metal or plastic. These are fairly simple and cheap. But itís not cheap as an old sock.
Another distinct variant are those which keep the brewed coffee hot by a hot plate where the brew container is and those that do not. Unfortunately, many of restaurants allow their coffee to boil to powder scum at the bottom of the coffee pot. Have you ever had some? Yuk!
Yet, another way of brewing coffee is the espresso machine. The difference between a filtered coffee and an espresso coffee is the water goes through the grains rather than around them. In espresso coffee, highly heated water is forced through compressed coffee such that the coffee grounds are irrigated. This device requires some mechanical switching and valves.
The espresso is simultaneously a solution of sugars, caffeine, acids, and proteins, an emulsion of oils and colloids and a suspension of coffee particles and bubbles of carbon dioxide gas. Because of the high pressure of the extraction, about ten percent of the oils are emulsified and the aromas attach themselves to the fats, which explain the fragrance of the aromas. The oils are partly responsible for the body of the coffee. This oil-fat arrangement gives espresso a velvety feel when sipped. Also, high viscosity lowers surface tension allowing deeper penetration into the taste buds. Thus, itís increasing the taste perception.
The pressure needed to force the water through the coffee grains increases with the fineness of the grind and the degree of compression. The higher the compression used, the more complete the flavor extractions.
The term "espresso" is some what ambiguous. This is probably because espresso means different things in the various languages in Europe. As it turns out, there is no probably about it. The following explanation was given in this section of the site from 1996 to the end of 1997. Just because of the story, it makes for interesting reading, and it may be true, but unlikely, as such, it is kept here.
Generally, the word is used to describe any coffee which is brewed by steam. Generally, it was thought that the word espresso meant fast or straight through. Factually, espresso is anything but a fast cup of coffee. Another meaning was interpreted from the word expire, which, after drinking several of these cups of coffee, people did. The jolt to the system of unsuspecting coffee drinkers must have been enormous. Heart attacks expired people. The general meaning is believed to be "expressly for you." Meaning, this small cup of coffee is made just for you.
The first known machine to do this was the idea of Louis Bernard Babaut in 1822. The machine was made commercial by Edward Loysel de Santais in 1843 and demonstrated to the world in the Paris Exposition in 1855. The machine packed a measured amount of coffee grinds in a special chamber, a valve allowed steam to press the water through the grinds with a special filter and wa-la, a cup of coffee ready to drink is made. It is fast. The 1855 Paris model was said to produce 1000 cups an hour. Thus, express was associated with the machine.
This particular coffee machine had several drawbacks. One drawback is it blew up from time to time. A steam fitting failed, or the chamber failed, or some bozo let it get too hot. Another drawback is it burnt the coffee from time to time. Especially if a bozo allowed the steam chamber to get too hot. The typical steam pressure was 1.5 to 2 atmospheres and increasing the pressure made for better extraction but burnt the coffee but a lot of bozos did it any way.
The device did work however. Additionally, it produced a superior cup of coffee when operated correctly. The reason it produced a superior cup of coffee is it extracted only the best from the coffee grind. The high pressure forced the water through the coffee grind rather than merely contacting it. This allowed some of the coffee to become emulsified. As the volatile aromas tend to attach themselves after roasting to fatty substances, emulsification drew out these substances and made the coffee smell better along with better body. The cup of coffee had a velvety texture.
Because the liquids viscosity is lower it has a lower surface tension, which allows the liquid to penetrate the gustatory papillae more deeply, consequently increasing the perception of coffee flavor. The presence of tiny bubbles of gas in suspension and emulsified colloids, mostly carbon dioxide, has the property of inhibiting the receptors of bitter taste in the gustatory papillae. Thus, the flavor taste tends not to be overly bitter. Additionally, the colloids and oil emulsified in tiny drops is responsible the finish by allowing the oils to penetrate deeper into the gustatory papillae which allows slower release of the aromatic substances attached to it.
Making espresso in the old days was a real art. The degree of roast, right grind size, the correct grind packing, the steam pressure, and the quantity of water use were all important. The old espresso machines allowed for much variance. Merchants who wanted to save on coffee beans simply used less grounds causing the forced water pressure not to totally penetrate the coffee grind. Merchants who wanted to give a larger cup of coffee simply allowed more water to go through the system thus diluted the brew and extracted more unwanted substances. So, to do it right, really required skill, knowledge, and interpretation on the part of the operator, thus, it truly qualified as an art.
Espresso machines were driven by steam. The two drawbacks, blowing up and burning the coffee, needed fixing. It was found by experiment that the two main components of good chemical action occurred at 90 +/- 2 degrees Celsius (190 - 196 degrees Fahrenheit) and 9-10 atmospheres (140 pounds per square inch). As the typical espresso machine was difficult enough at 2 atmospheres of steam, hotter both fried the beans and blew up constantly. In 1935, Francesco Illy, an Italian invented a machine called the Illetta which controlled these factors. Obviously, the machine's name is an adaptation of the inventorís name.
The Illetta solved the problems of the old espresso machines. The way the Illetta did this was to use mechanical advantage from air pressure as a source of pressure rather than steam to force the water into the grind. This solved three problems. The first was the exploding problem. Although air pressure was rather complicated and expensive it was more controllable than steam. Second, since there was no steam, the coffee did not get burnt. Steam was not the source of force so the water temperature could be held constant below boiling. And third, because the cylinder used could be made to precisely control the amount of water to maximize extraction for a given size of coffee grounds, the precise amount of water to maximize the extraction was done automatically.
Later, in 1945, the system was simplified by a machine called the Gaggia coffee machine. This created the pressure by lever action on a cylinder of water to force the water into the grind holder. Around the 1970's, Ernesto Illy further simplified the whole device and introduced the Espresso Coffee System. This coffee system incorporated the best of previous machines, added two layers of filter paper, and generally made the device simple, cheaper, and idiot proof.
One of the last adaptations to this coffee system for commercial and limited home use in 1950 by Ernesto Valente, was the addition of a rotating pump driven by an electric motor to develop the water pressure. This allowed a more continuous delivery of water. An additional commercial development is a rotating coffee grind delivery system so the coffee grinds would be compacted and replaced by the machine too. Thus, the system became almost totally automatic.
A secondary affect of espresso was the way milk was used. Mousse was term given to this presentation but later turned to froth. Mousse, both adds a smoother taste and minimizes heat loss. There are two types of Mousse. A short floating milk cover and with milk mixed in the coffee. This is not a case of just pouring the milk in or on the coffee. The mousse is the correct blend of carbon dioxide bubbles and milk. A special milk blaster was added to the machines in order to create a froth. The color of the mousse should be that of a milk chocolate bar. If it is too dark, this is evidence of over-extraction and if it is too light, then it isn't enough.
A further development in espresso was making multiple espresso cups at one time. In most coffee shops, two people came in. While the second cup is being made, the first is getting cold. Not good from a marketing standpoint. Thus, the two coffee cups at once version caught on quickly at commercial operations. Once two cups could be made at once, four was better. Unfortunately, multiple cups have a waist problem. But, that will be over looked.
So for simplification, the coffee brewer chronology is: First came just coffee and hot water. Then came an espresso maker which forced steam through the coffee grinds. Then came the espresso pneumatic press. The pneumatic press was safer than the steam device by far but it had a volume problem. So, multiple cup espresso makers were developed.