Ignace Pleyel (b. Ignaz, 1757-1831), born in Austria, only started building
pianos at a relatively late stage of his career : he first set up as a piano
manufacturer in 1805, aged 52.
He started off in life as a pianist and composer (he was Haydn’s pupil at
Eisenstadt), whose talent was acknowledged by Mozart, and whose music
was highly successful throughout Europe.
After living for a while in Strasbourg (assistant to FX Richter), he moved to
Paris in 1795 and set up a music edition firm that he kept till the end of his life.
Ignace Pleyel obviously  didn’t have the right training to design his own pianos,
so he teamed up with Charles Lemme, a well-known piano builder, in 1805.
The two men split up in 1808, and the legal documents written out at that date
make perfectly clear the nature of their business relationship : Pleyel’s role in
the association was to bring in « the necessary finances », and Lemme « only
put in his industry ».
Little is known of this three year association, and only one piano carrying the
name of both men is known of.
After the split up, Pleyel took on foreign workers, and set up his own business
building square pianos and harps. This was unfortunately a difficult time from
an economic point of view, and the business didn’t do particularly well : in
1822, when Ignace formed a partnership with his son Camille (1788-1855) and
gradually retired from the business, Pleyel had only sold approximately 600
pianos (probably all squares).
The Pleyel piano firm really started taking off in the late 1820’s : their
association with the famous teacher Kalkbrenner (1825; a closer partnership
was signed in 1829) brought in fresh money and clients, they got a gold medal
at the 1827 expo, and they started building grand pianos from the mid 1820’s.
At the death of Ignace Pleyel in 1831, the firm was really running on straight
rails, with production figures increasing steadily. But the real takeoff of the firm
took place the following year, in 1832, with production figures soaring, and
Chopin, who was to become the firm’s best publicity agent, giving his first
concert at the Salons Pleyel, rue Cadet. So although the labels on « Chopin
type » Pleyels read « Ignace Pleyel », they were actually built by Camille.
The 1830’s are definitely my favourite period for Pleyel pianos, because of the
permanent experimentation that was going on : no two pianos are alike.
Casework is usually superb, and  there are many technical innovations of
interest to the restorer or collector : soundboards veneered in mahogany or
rosewood, hollow hammers, strings going alternately over and through the
bridge, ivory agrafes, experimental actions (mécanique à grande puissance),
different position and number of bars, etc…..
By about 1842, the models became more standardised, and only really differed
by the casework and length.
In 1834, the factory and salesroom, that had up till then been dissociated,
were brought together on new premises that Camille and Kalkbrenner bought
rue de Rochechouart. The same year, Pleyel won another gold medal at the
Paris expo, that was immediately mentioned on the Pleyel label (the
successive medals of 1827, 1834, 1839 and 1844 give a quick way of dating
an early Pleyel piano, if the label hasn’t been replaced of course).
Camille Pleyel, who was involved in piano construction at a much earlier age
than his father, obviously had a closer involvement in their design, and a
famous letter, written in 1841 indicates just how involved he was : « what need
is there […] to tell you about my febrile joy when the fourth C, for example,
sounds 2 or 3 seconds longer than another? You must forgive us these sorts
of hallucinations that very occasionally give us solace for our disillusions and  
disappointments […]
Why is it that if you take two pianos from the same factory, made on the same
model at the same time, and looking absolutely identical, the vibrations of one
of them are much longer than the other? ».      
Foreign workers played a major role in the development of Pleyel pianos :
Prilipp and Baumgarten worked for Pleyel from the early days, the English
piano makers Bell and Sohn took part in the development of the Pleyel grand,
and the extant pianos are stamped with the names of the chief workers, who
definitely don’t sound very French  : Donoghoe, Pfister, Baert…..
This is the great paradox of the French piano industry in it’s gold age (1830-
1850) : the Hungarian Franz Liszt and the Pole Frederyck Chopin played in
Paris on the pianos of the Austrian Pleyel and the Strasbourgeois Erard,
whose major rival in Paris was Johann Heinrich Papen…

In 1855, at Camille Pleyel’s death (the same year as Pierre Erard, and by an
extraordinary coincidence, Sebastian and Ignaz both died the same year, in
1831), the firm was inherited by Louise Pleyel, Camille’s daughter, in
association with Auguste Wolff.