Although steel strings heralded a new era of bass playing, they were not without their problems. Barrie Kolstein examines the effect they had on the instrument’s structure

Throughout its life, the double bass has undergone numerous periods of structural change, especially in contemporary times. The largest and most important transition, however, occurred in the late-1950s and early 1960s with the development of steel strings. They revolutionized the bass and offered the bassist a higher level of musicianship, opening up new levels of technique and performance rarely achieved in the past 200 years of the gut-string era. However, the new-found tension of steel strings affected the structure of the older and more fragile basses, resulting in several external and internal structural changes. One of the main external procedures, still commonly used today, was the removal and re-elevation of the neck to a higher pitch and elevation in accordance with the school of steel string playing (see Photo 1). This not only offers the player an increased facility, particularly in the upper register, but also regulates this newfound tension of steel string playing. Other external changes include the development and use of the raised or tension-compensation saddle that lifts the angle of the tailpiece.

This reduces the tension that is generated by a more acute angle from the bridge to the saddle, which in turn reduces the internal tension produced within the bass (see Photo 2).

Also, the use of flexible, multi-stranded steel wire in the tailpiece helps to reduce the tension within the bass (see Photo 3). Throughout the 1940s and 1950s, adjustable bridges became a common addition to the external changes on the bass, allowing the adjustment of the string action to the favored heights. However, the lower string heights meant that fingerboard adjustments needed to be much more accurate to avoid buzzing on the fingerboard at this new, lower-tension height. The higher tension of the steel strings also creates a number of internal structural problems.

Many basses, particularly those that were older or more delicate, developed sinkage to the top plates at the lower end of the bass- bars {see Photo 4), which in turn often caused cracks to develop in this and other areas of the table. This was primarily due to inadequately designed bass-bars created for the lower tension of gut strings. Often bass-bars were carved from the same piece of wood as the top table; these are referred to as an integrated bass-bars.

To correct this problem, the top plate needs to be removed and all the cracks on the top have to be rejoined and restored, while the sunken area of the table needs to be pressed to correct the sinkage of the top. This procedure usually requires the use of a reverse impression plaster cast (see Photo 5). Once created and allowed to dry to full hardness, this cast is re-carved, taking out the inaccuracies of the sinkage that exists in the actual top. The top is then placed within the cast and a dual pressing procedure, using the moist heat of steam, occurs over several stages to remold the top table back to its original arch and curvature. This moist heat process softens the molecular structure of the top-table wood, allowing the affected top-wood area to be successfully pressed into the corrected plaster cast. Once the top is fully pressed to correct the existing sinkage, a second stage of pressing, referred to as ‘sandbagging’, takes place. Sandbagging uses dry heat to heat the sand, usually in a burlap bag, to a moderate temperature and repress the top in the same plaster cast (see Photo 6)

The heated sand is flexible so as to contour itself with a wood­clamping board on top, pressing the top once again with a dry heat into the reverse impression plaster cast. This not only dries out fully the moistened top wood, but also creates a tempering effect on the re-contoured top wood. It hardens the wood and stabilizes the new curvature and arch of the top table. This process is often followed by graduation.

It is a common misconception that graduation of a top table involves the removal or thinning of a top plate. How ‘ever, in most cases, to restore the sinkage to a top table, a quality top wood is added to the restored area, thereby protecting its structural integrity. Again, the reverse impression plaster cast plays an integral part of properly fitting  the additional wood as it allows the wood to be added and glued into its proper position without distorting the top table.

Once accomplished, this newly added, seasoned patch wood needs to be re-graduated to a proper thickness. This is followed by the tap-tone pitching (tuning of the added wood to generate a particular desired tap-tone pitch to the top table) and then a highly seasoned bass-bar needs to be installed (see Photo 7). Although this new bass-bar might be of a somewhat healthier dimension than the original, it needs, most impor­tantly, to be accurately fitted to the interior contours of the top table.

Also, to create structural stability, the bar needs to be fitted with several millimeters of spring (see Photo 8) so that when the bass-bar is glued into position on the top table it will be fitted to the exact curvature of the interior surface of the top. However, what will transpire is that the top plate will literally arch up to meet the accurately fitted bass- bar, creating not only the structural integrity to compensate for the additional tension of steel strings, but a higher level of projection of sound from the bass.

The back table, especially in flatback basses, also faced similar problems, with the lower crossbar section becoming distorted or showing signs of sinkage (see Photo 9) because of inade­quately designed lower crossbars. This not only created a structural deficiency in older basses, but also created a bad reputation for flatback basses. With a similar process of the installation of a sprung cross-bars on the back table, the flatback table is transformed into a modified round back. The spring in the cross-bars creates a rounding effect to the flatback design (see Photo 10), which in turn makes the table physi­cally more stable and substantially stronger, as would be the case with a roundback instrument.

Although the introduction of steel strings necessitated the aforementioned external and internal structural changes to the bass, without them the great master basses would not have been able to progress gloriously into the present era of the Modern School of Steel String Playing.