The Torres Spanish Guitar and Relative Humidity

Torres Guitar in Spanish Museum - Lit
Torres Guitar in Spanish Museum - Dark

Fig.1 ArtRatio Display Case, housing an original Torres guitar, model SE-117, from 1888 (images courtesy of the Spanish Guitar Museum, Almeria


The concert guitar you see here is an original model SE-117, hand-made in 1888 during the second epoque of its maker, Antonio de Torres Jurado (Almeria, 1817 – 1892).

The guitar belongs to the collection of José Luís Romanillos and Marian Harris Winspear and was loaned to the Spanish Guitar Museum in Almeria (Spain) and installed in an Artratio Display Case during 2013-2015. Thereafter, the vitrine has housed a replica.

The Torres guitars are divided into two epoques; the first when Torres lived in Seville from 1852–1870; the second epoque when Torres moved back to his native Almería during 1871-1892.


The earliest known Spanish guitar / vihuela dates from around the mid-1600s but the guitar, as such, never achieved popularity as a classical instrument due to it’s limited sound projection, compared to other concert instruments of the time.

It is surmised that the famous classical composer and guitarrist Francisco Tárrega (1852-1909) helped to transform the Spanish guitar from the post-Beethovian era of early classical 19th century luthiers such as Pagés, Panormo and Lacôte, to the Romantic era, mainly thanks to the design invented by Torres (in his model FE 17). 

It was in 1862 that Tárrega visited Torres to buy a guitar and, upon hearing him play, Torres is reputed to have given Tárrega a guitar he was reserving for himself.

Even though Torres did not invent the basic design we now see in all Spanish classical guitars, he was the first to implement the fan-bracing techniques that give integrity to the guitar’s soundboard and thus achieve a balanced tone that was eventually copied by luthiers worldwide.

Housing the SE-117

The materials of the model SE-117 include a soundboard (made of fir), the finger board (made of walnut), the neck (made of cedar), the bridge (rosewood), the back (cypress) and finally the frets (made from brass). The SE-117 is varnished with shellac and alcohol.

This ArtRatio Display Case provides an extractable silica gel cartridge to control the relative humidity, which can affect all hygroscopic materials including wood, often resulting in dimensional expansion in the order of several millimetres. This can affect the integrity of the instrument.

The guitars made by Torres in Seville would have been subjected to relative humidity from 50%-80%, whereas the guitars made in Torres’ second epoque in Almeria (on the southern Spanish coastline) would have been created in relative humidities from 70%-75%.

Since the relative humidity depends on the ambient temperature, the electro-optic glass facade of the Display Case helps by limiting the infrared light entering the vitrine, reducing localised heating on the instrument and controlling the relative humidity within the vitrine.

What are the Effects of Humidity on Wood?

Relative humidity is defined as the ratio of water vapour density to the water vapour density in saturated air.

Less scientifically, the relative humidity is the amount of moisture in the air compared to what the air can contain at that temperature. When the air cannot ‘contain’ more moisture, it condenses into a liquid.

High moisture content in the air can increase chemical reactions that destroy wood-based works of art due to growth of fungi (especially molds and mildew).

Conversely, lower humidity can result in wooden works of art becoming more brittle and drying out.

Above all, rapid or seasonal movements in relative humidity can result in dimensional changes to composite materials having different thermal coefficients of expansion and contraction, so the best solution is to create a stable microclimate within the vitrine to arrest fluctuations in relative humidity.

Relative Humidity vs Temperature Graph
Temperature vs Humidity Graph

The Life of a Luthier: Antonio de Torres Jurado

Antonio de Torres Jurado- portrait
Antonio de Torres Jurado, Almeria (1817 – 1892)

Born in La Cañada de San Urbano (Almeria province in Spain) in 1817 and trained as a carpenter in Vera (Almeria), Torres was drafted into the Spanish army in 1834 during the Carlist Civil Wars.

Torres only served a few months though before having his service invalidated and he returned to marry Juana María López in 1835. Torres and López had three daughters, of which 2 died, followed by the death of Juana López herself in 1845, presenting Torres with some difficult years.

In 1845, Torres moved to Seville and started making the guitars of his First Epoque in 1856. In 1869 Torres moved back to Almeria and began his second epoque in 1875. Torres died in Almeria in 1892. 

Only one-fifth of Torres’ total production has survived to this day.