Warning! Please use the Type CD string only for basses, not octaves. Maximum tension should not exceed 4.5 kg.
Also, while the actual diameters of Type CD strings are somewhat less than a string of equivalent plain gut diameter, densified about 10% for the smallest gauges to about 30% for the largest gauges (200CD measures 1.56mm actual), they are not as thin as a wound string of equivalent plain gut diameter. If your tie block holes are very small and are sized to fit only a wound string, Type CD strings are almost certainly too large to fit. Make sure that the holes will be large enough before ordering. If you have questions, please inquire before purchasing. 
INTRODUCTION
The invention of wound strings caused, from the end of the 17th century, the abandonment of the ancient manufacturing techniques of traditional gut bass strings.
This explains why modern plain gut strings fail to produce an acceptable acoustical performance in the low registers, thus making it necessary to use wound strings for musical repertoire that pre-date their introduction; this, in turn, causes an obvious paradox as well as serious tone and balance problems between high and low registers, especially on lutes.
We believe that the old all gut lute basses had increased density to achieve better performances.
Here are some points:
A large number of bass string hole diameters measured from original Lute bridges dating from the late 16th and 17th century shows that those holes are too small to allow plain gut strings a sufficient working tension at the proper pitch. A plain gut string of small enough diameter to fit these holes should have a tension ranging form .9 to 1.2 Kg only. This mean to drop a moderrn lute of 9 till 11 semitone that need to achivie  such range of tensions.
2. Musical iconography from the 17th century and a bit later often shows the Lute bass strings of quite different color from that of plain gut, varying from dark red to brown. They are also positioned where today we find the wound strings, i.e. from the 6th course down\.
3. Some treatises of the XVII Century state that the Lute strings had a remarkable sustain and acoustical power, able to equal the sound of the upper strings (see Mersenne ‘Harmonie Universelle’, Paris 1636; ‘The Mary Burwell Lute Tutor’, c.a.1670; Thomas Mace: ‘Musick’s Monument’ London 1676).
4. In several paintings of the 17 th C., most of the Lute bass strings have a relatively small gauge if compared with the gauge that a plain natural gut string should have.
All these considerations suggest that gut bass strings were densified in some manner: the loading of gut, a technological strategy that we believe was employed by the stringmakers of the era in order that the Lute bass strings were sonically much more prominant.
 
WHAT ARE THE CD TYPE STRINGS?
The CD bass Lute & Baroque guitar strings are smooth synthetic loaded strings characterized by a high, standardized specific weight, achieved by a loading extruding process with very thin metallic copper powder made in the range of 115 CD to 220 CD.
Diameters smaller than 115 CD are manufactured with an half loading degree, in order to be useful for the 4th and 5th Lute courses (called in the past ‘Meanes’) .
We do not use Mercury or Lead compounds; we use thin metallic completely non-toxi copper powder.
The surface has the same texture as rectified gut
 
 
     
 
 ACOUSTICAL PROPERTIES AND FIELD OF APPLICATION
Strong, warm  and percussive tone, without the excessive brightness typical of modern wound strings, perfectly coherent with the tone and dynamics character of gut strings as well as synthetic strings. Excellent tuning stability; far better than any plain gut, other synthetics or wound strings available today.
 
WHAT IS A 140 CD?
To keep calculations simple and make it possible to use any available string-calculator, CD  synthetic loaded  strings, as well as wound Nylgut ones and the D type, are referred to by a letter following a number indicating the theoretical equivalent diameter of a solid plain gut string.
E. g. “140 CD” stands for a loaded string (indicated by the letter “CD” ) corresponding to a high twist gut of 1.40 mm. in diameter.
The actual diameter of the strings is, of course, smaller but under playing conditions it will have the same working tension as a gut string of 1.40 mm. diameter at equal pitch and same string length.