Concertina Bellows
The bellows of a concertina are considered to be the ‘soul’ of the instrument. At a basic level, they supply air to the reeds and control the dynamics. The amount of pressure generated by the bellows determines the loudness of the sound; more pressure = louder sound, less pressure = softer sound.
At a higher level, the bellows determine the intensity, attack and ‘shape’ of the sound. Advanced bellows technique is much like bowing technique on a violin.
The level of performance determines the quality requirements for the bellows. A beginning player is mainly concerned with basic dynamics, aiming for dynamic consistency. The bellows requirements for this level are stability, consistency in tension, and of course air tightness.
At the other end of the spectrum, an advanced player needs to be able to perform intricate bellows articulations, shape sound, micro dynamics, etc. At this level, the bellows need to have a low base tension and high sensitivity, consistent over the full expansion range.
Because of these different requirements, there are different types and qualities of bellows available, with different structural designs, materials and construction methods.
At a higher level, the bellows determine the intensity, attack and ‘shape’ of the sound. Advanced bellows technique is much like bowing technique on a violin.
The level of performance determines the quality requirements for the bellows. A beginning player is mainly concerned with basic dynamics, aiming for dynamic consistency. The bellows requirements for this level are stability, consistency in tension, and of course air tightness.
At the other end of the spectrum, an advanced player needs to be able to perform intricate bellows articulations, shape sound, micro dynamics, etc. At this level, the bellows need to have a low base tension and high sensitivity, consistent over the full expansion range.
Because of these different requirements, there are different types and qualities of bellows available, with different structural designs, materials and construction methods.
Bellows performance explained
Bellows Travel
Bellows travel (BT) is the open and close movement of the bellows. Maximum BT is the expansion of the bellows from fully closed to fully extended. The full expansion of the bellows is divided in 3 sections. The length of these sections varies, depending on the quality of the bellows.
The first section of the bellows expansion starts at the fully closed position. The 3rd section ends at the fully extended position. The 2nd section is the part of the extension in the middle, between sections 1 and 3. On high end bellows sections 1 and 3 are very short, most of the bellows travel is in section 2. On lower quality bellows sections 1 and 3 are much longer, reducing the length of section 2.
Tension
All concertina bellows have some 'base' tension, caused by the construction and materials used. Concertina bellows consist of individual card stock panels (72 for a hexagonal 6 fold bellows), connected with leather and linen hinges, leather gussets, and silk corner tabs. These connections can create tension when moving the bellows, which is mainly noticeable at the fully closed and fully open position (section 1 and 3). Movement in the middle part of the bellows (section 2) has no tension (high end bellows) or very low tension (lower end bellows).
Tension in section1, moving toward the fully closed position is called closed tension (CT), and the tension in section 3, moving towards the fully open position is called open tension (OT). Section 2 is called tension free travel (TFT).
Bellows performance is determined by how much of the BT is in section 2 (TFT), and is indicated in percentage of the total BT. Bellows tension interferes with bellows articulation and nuanced dynamics. High quality bellows have low CT (closed tension) and OT (open tension), and high TFT (tension free travel) percentages.
Examples:
Bellows A: BT is 20 cm, and CT starts at 1cm from fully closed and OT at 4cm from fully open, the tension free travel is 15 cm (20cm - 1- 4 = 15cm) or 75%. The TFT is 75%.
Bellows B: BT is 18cm, CT starts at 1.5cm and OT at 1.5cm. TFT is 18cm -1.5-1.5 =15cm or 83.33%.
Although the BT of bellows B is 10% shorter than bellows A, the TFT is 5%+ longer.
Stability
bellows stability is a basic requirement for performing both dynamics and bellows articulation. Instability is usually caused by 'wrong' matererials used for top and bottom hinges, and gussets which can cause stretch between the indiviual parts.
Bellows travel (BT) is the open and close movement of the bellows. Maximum BT is the expansion of the bellows from fully closed to fully extended. The full expansion of the bellows is divided in 3 sections. The length of these sections varies, depending on the quality of the bellows.
The first section of the bellows expansion starts at the fully closed position. The 3rd section ends at the fully extended position. The 2nd section is the part of the extension in the middle, between sections 1 and 3. On high end bellows sections 1 and 3 are very short, most of the bellows travel is in section 2. On lower quality bellows sections 1 and 3 are much longer, reducing the length of section 2.
Tension
All concertina bellows have some 'base' tension, caused by the construction and materials used. Concertina bellows consist of individual card stock panels (72 for a hexagonal 6 fold bellows), connected with leather and linen hinges, leather gussets, and silk corner tabs. These connections can create tension when moving the bellows, which is mainly noticeable at the fully closed and fully open position (section 1 and 3). Movement in the middle part of the bellows (section 2) has no tension (high end bellows) or very low tension (lower end bellows).
Tension in section1, moving toward the fully closed position is called closed tension (CT), and the tension in section 3, moving towards the fully open position is called open tension (OT). Section 2 is called tension free travel (TFT).
Bellows performance is determined by how much of the BT is in section 2 (TFT), and is indicated in percentage of the total BT. Bellows tension interferes with bellows articulation and nuanced dynamics. High quality bellows have low CT (closed tension) and OT (open tension), and high TFT (tension free travel) percentages.
Examples:
Bellows A: BT is 20 cm, and CT starts at 1cm from fully closed and OT at 4cm from fully open, the tension free travel is 15 cm (20cm - 1- 4 = 15cm) or 75%. The TFT is 75%.
Bellows B: BT is 18cm, CT starts at 1.5cm and OT at 1.5cm. TFT is 18cm -1.5-1.5 =15cm or 83.33%.
Although the BT of bellows B is 10% shorter than bellows A, the TFT is 5%+ longer.
Stability
bellows stability is a basic requirement for performing both dynamics and bellows articulation. Instability is usually caused by 'wrong' matererials used for top and bottom hinges, and gussets which can cause stretch between the indiviual parts.
Bellows design
The design of the bellows and the number of sides it has (6, 8, or 12) affects performance of the bellows. Fewer sides result in sharper corners, e.g. the angle between the sides on 6 sided bellows is double that of a 12 sided set. Sharper corners create more CT and OT tension. The tension is caused by both the outer and inner hinges being pulled and compressed, movement between panels, panel tip separation and gusset stretch.
Hexagonal (6 sided) bellows have a higher base tension than octagonal (8 sided) bellows, which have a higher base tension than dodecagon (12 sided) bellows.
Preferably, bellows should have shallow corners (high number of sides), are made out of thin (less compression tension) airtight, stretch free (stable) non-porous leather. High end bellows are made with low volume hard glue, hard linen (non-stretch) inner hinges, panel tip support (usually silk).
High end bellows are NOT built on a 'bellows rig', which does not allow for any adjustments during the build process. Tension free bellows construction requires constant adjustments to compensate for differences in materials and variations in leather thickness. Building bellows without a rig requires a much higher skill level.
Hexagonal (6 sided) bellows have a higher base tension than octagonal (8 sided) bellows, which have a higher base tension than dodecagon (12 sided) bellows.
Preferably, bellows should have shallow corners (high number of sides), are made out of thin (less compression tension) airtight, stretch free (stable) non-porous leather. High end bellows are made with low volume hard glue, hard linen (non-stretch) inner hinges, panel tip support (usually silk).
High end bellows are NOT built on a 'bellows rig', which does not allow for any adjustments during the build process. Tension free bellows construction requires constant adjustments to compensate for differences in materials and variations in leather thickness. Building bellows without a rig requires a much higher skill level.
3 qualities of concertina bellows
Basic bellows
Basic bellows are ‘accordion’ type bellows. They consist of folded cardstock panels with leather or synthetic gussets. There are no leather or linen hinges, the folded cardstock acts as the hinges, This type of construction is very economical, but adds a lot of tension the the BT.
Basic quality bellows offer airflow to the reeds and basic dynamic control, but are not suitable for more refined bellows control. Basic bellows have a TFT of 40-60%. We use basic bellows on our starter models.
Intermediate bellows
Intermediate bellows are of the traditional concertina design. They consist of individual cardstock panels, rather than folded cart stock, connected with leather or linen top and bottom hinges, leather gussets, panel covers and leather bindings. The leather is often sheepskin, which is economical, but has a lot of stretch. Glues used are often of the cement type, which have a strong hold but do not fully harden.
These bellows are (almost) always made on a ‘bellows rig’. This is a ‘maximum stretch’ or ‘50% stretch’ mold on which the panels positioned before they are connected with the hinges and gussets. After the glue dries, the bellows are removed from the rig and placed in a press or under weights. Because the bellows are made in the open position, they tend to have a lot of CT, caused by tension in the hinges panel tip movement and gusset tension. Pressing the bellows in the closed position stretches the leather hinges and gussets. Rig made bellows usually require a case with blocks to keep the bellows in closed position because the they will always want to open a little. Typical intermediate 'Bellows rig' made bellows have a TFT of 60-70%. Intermediate bellows are the most common type of bellows found on vintage and modern concertinas. Our first tier intermediate models (Minstrel, Busker, Troubadour) feature intermediate bellows.
High end bellows
High end bellows are also of the traditional concertina design. They consist of individual skived card panels, connected with either leather or hard linen top and bottom hinges, leather gussets, silk tabs, leather or leatherette panel covers and leather bindings.
The leather is selected goatskin, which has no stretch, can be skived very thin without losing strength or becoming porous. Natural water based glues or hyde glues are used which harden fully with no shrinkage.
Besides the materials, the big difference is the way they are constructed. No rig is used for high end bellows.
Each set of bellows is measured individually to fit with a perfect ‘waist’ on the bellows frames. The waist determines the panel size. No two sets of bellows are identical in size.
All panels are connected by hand on a flat surface instead of on a bellows rig. The position of each panel is adjusted to compensate for the different materials and slight variations in leather thickness.
This results in hinge connections without tension. Panel tip spacing and gusset angle is determined by the maker and varies for each set of bellows. Other variable factors are the number of sides (6,8,12), thickness of the leather, and type of concertina (anglo bellows are different from English and duet bellows).
Bellows constructed this way have very little travel tension.
Making high end bellows requires a lot of knowledge, skill and experience. It takes several hundred sets of bellows to develope the skills necessary to make tension free concertina bellows.
Our shop makes on average 100+ high end Wakker Bellows per year (3000+ total) for new and vintage concertinas, in 6, 8, and 12 sides, with 4-10 folds. Sizes range from 8 key miniatures to 80+ key duet concertinas.
Our second and third tier intermediate models (Clover, Peacock, Rose, and the Custom versions of these models, feature our standard Wakker bellows which have a TFT of >90%.
Basic bellows are ‘accordion’ type bellows. They consist of folded cardstock panels with leather or synthetic gussets. There are no leather or linen hinges, the folded cardstock acts as the hinges, This type of construction is very economical, but adds a lot of tension the the BT.
Basic quality bellows offer airflow to the reeds and basic dynamic control, but are not suitable for more refined bellows control. Basic bellows have a TFT of 40-60%. We use basic bellows on our starter models.
Intermediate bellows
Intermediate bellows are of the traditional concertina design. They consist of individual cardstock panels, rather than folded cart stock, connected with leather or linen top and bottom hinges, leather gussets, panel covers and leather bindings. The leather is often sheepskin, which is economical, but has a lot of stretch. Glues used are often of the cement type, which have a strong hold but do not fully harden.
These bellows are (almost) always made on a ‘bellows rig’. This is a ‘maximum stretch’ or ‘50% stretch’ mold on which the panels positioned before they are connected with the hinges and gussets. After the glue dries, the bellows are removed from the rig and placed in a press or under weights. Because the bellows are made in the open position, they tend to have a lot of CT, caused by tension in the hinges panel tip movement and gusset tension. Pressing the bellows in the closed position stretches the leather hinges and gussets. Rig made bellows usually require a case with blocks to keep the bellows in closed position because the they will always want to open a little. Typical intermediate 'Bellows rig' made bellows have a TFT of 60-70%. Intermediate bellows are the most common type of bellows found on vintage and modern concertinas. Our first tier intermediate models (Minstrel, Busker, Troubadour) feature intermediate bellows.
High end bellows
High end bellows are also of the traditional concertina design. They consist of individual skived card panels, connected with either leather or hard linen top and bottom hinges, leather gussets, silk tabs, leather or leatherette panel covers and leather bindings.
The leather is selected goatskin, which has no stretch, can be skived very thin without losing strength or becoming porous. Natural water based glues or hyde glues are used which harden fully with no shrinkage.
Besides the materials, the big difference is the way they are constructed. No rig is used for high end bellows.
Each set of bellows is measured individually to fit with a perfect ‘waist’ on the bellows frames. The waist determines the panel size. No two sets of bellows are identical in size.
All panels are connected by hand on a flat surface instead of on a bellows rig. The position of each panel is adjusted to compensate for the different materials and slight variations in leather thickness.
This results in hinge connections without tension. Panel tip spacing and gusset angle is determined by the maker and varies for each set of bellows. Other variable factors are the number of sides (6,8,12), thickness of the leather, and type of concertina (anglo bellows are different from English and duet bellows).
Bellows constructed this way have very little travel tension.
Making high end bellows requires a lot of knowledge, skill and experience. It takes several hundred sets of bellows to develope the skills necessary to make tension free concertina bellows.
Our shop makes on average 100+ high end Wakker Bellows per year (3000+ total) for new and vintage concertinas, in 6, 8, and 12 sides, with 4-10 folds. Sizes range from 8 key miniatures to 80+ key duet concertinas.
Our second and third tier intermediate models (Clover, Peacock, Rose, and the Custom versions of these models, feature our standard Wakker bellows which have a TFT of >90%.
