How to Determine Posament Knot Sizes
In order to make the spiral Birka posaments, the only truly necessary item is the spiral wire. The spiral wires from Birka are made of a very fine silver or gold wire with a round cross section wound around a silk core. An imperfect but adequate modern substitution for this is tenntråd, a silver/tin alloy round wire wound around a fiber core. It is often used in Sami-style bracelet weaving and comes in several sizes, denoted by the diameter of the constituent wire.
Wire diameter (mm) | Spiral diameter (mm) |
0.25 | 0.8 |
0.3 | 0.9 |
0.35 | 1 |
0.4 | 1.2 |
0.45 | 1.3 |
0.5 | 1.4 |
0.6 | 1.6 |
To determine the correct size of spiral wire to make the reconstructions, several steps were required. First, a gauge of all possible commercially available spiral wires was made. (All displays are presented within an 8″x10″ photo frame.)
Then a swatch of each pattern was produced on the 0.25 spiral wire. (Please note that as of 2/24/2020, there are new interpretations of P1, P2, P3 and P14.)
Then, based on the % difference between the swatch exemplars and the extant examples and compared with the % difference between the gauge examples, an estimation of the correct spiral wire size was made.
Posament number | Height of 0.25 exemplar (mm) | Extant piece grave ID | Height of extant piece (mm) | Extant piece – loose or tight? | % Change needed | Reproduction tråd | Height of reproduction (mm) | % difference from extant | Weight of reproduction (gm) | Length of material (cm) |
P1 | 4 | 798 | 2 | tight | -50% | NA* | NA | 100% | 0.5 | 30 |
P2 | 6 | 798 | 4 | tight | -33% | NA* | NA | NA | NA | NA |
P3 | 2 | 886 | 2.5 | tight | 125% | 0.3 | 2.5 | 100% | 0.475 | 22 |
P9 | 5 | 643 | 7.5 | loose | 114% | 0.25 | 7.75 | 103% | 0.925 | 56 |
P10 | 6 | 520 | 7 | tight | 116% | 0.3 | 7.75 | 111% | 0.964 | 44.5 |
P11a | 13 | 944 | 13 | tight | 0% | 0.25 | 13 | 100% | 0.985 | 59.5 |
P12 | 6 | 1040 | 8 | tight | 133% | 0.35 | 8.25 | 103% | 0.973 | 34 |
P13 | 6 | 944(?) | 7.5 | tight but spaced | 125% | 0.3 | 7.25 | 97% | 0.864 | 39.5 |
P14 | 9 | 524 | 10 | tight | 111% | 0.3 | 10.5 | 105% | 1.469 | 67.5 |
P15 | 9 | 944(?) | 12 | tight | 133% | 0.3 | 11 | 92% | 0.906 | 41.5 |
P17 | 6 | 561 | 8 | loose | 133% | 0.35** | 11 | 138% | 0.507 | 17.5 |
P18 | 17 | 832 | 19 | loose | 111% | 0.25 | 19 | 100% | 1.347 | 81 |
P19 | 9 | 1125 | 19 | loose | 220% | 0.5 | 20 | 105% | 2.56 | 51 |
P20 | 11 | 520 | 15 | loose | 130% | 0.35 | 16 | 107% | 1.941 | 67.5 |
P21 | 8 | 524 | 14 | loose | 187% | 0.45 | 14 | 100% | 2.182 | 50 |
P22 | 12.5 | 524 | 17.5 | loose | 152% | 0.35 | 17.5 | 100% | 1.331 | 46.5 |
P23 | 3 | 561 | 8 | tight | 123% | 0.35 | 8.75 | 109% | 0.471 | 16.5 |
P24 | 5 | 327 | 11 | tight | 160% | 0.4 | 11 | 100% | 1.245 | 35 |
P26 | 4 | 989 | 5 | tight | 125% | 0.35 | 5.5 | 110% | 0.323 | 11.21 |
* Scale examples of P1 and P2 were not attempted because a finer tråd is needed than what is commercially available.
** 0.35 was the only option available for gold plated tråd at the time this table was created. This will soon be attempted with 0.3 gold plated tråd and should be a closer-to-scale reproduction.
Finally, reconstructions in the appropriate size spiral wire were produced. (Note: P1 and P2 were not attempted, because an appropriately fine spiral wire was not available, P23 is slightly too large because the gold plated spiral wire was only available in 0.35 at that time, and P21 is the correct dimensions, but the spiral wire is coarser than the extant example.) While the commercially available tenntråd goes up to a size of 0.6mm, sizes of greater than 0.4mm are not recommended, as they are considerably coarser than the extant posaments. While the spiral width of the extant posaments vary, the wire diameter is usually much less than 0.25 mm.
Recreations of an Example of Each Posament Knot
Please note that these are each based on a specific knot from a specific grave. The same knot in another grave may have very different dimensions. Likewise, different knots found in the same grave will not necessarily have the same gauge of tråd for all the knots! Exemplars are linked when there is an online image available.
P1 – Based on an example from Grave 798 – 0.25 tråd
See Birka III for the exemplar.
Not reproduced to scale because currently available tråd is too thick
P2 – Based on an example from Grave 798
See Birka III for the exemplar
Not reproduced to scale because currently available tråd is too thick
P3 – Based on an example from Grave 886 – 0.3 tråd
Photo forthcoming.
P9 – Based on an example from Grave 643 – 0.25 tråd
See Birka III for the exemplar
P10 – Based on an example from Grave 520 – 0.3 tråd
P11 – Based on an example from Grave 944 (11a) – 0.25 tråd
P12 – Based on an example from Grave 1040 – 0.35 tråd
Photo coming soon!
P13 – Based on an example from Grave 944 – 0.3 tråd
P14 – Based on an example from Grave 524 – 0.3 tråd
Photo coming soon!
P15 – based on an example from Grave 944 – 0.3 tråd
See Birka III for the exemplar
P17 – Based on an example from Grave 561 – 0.35 tråd*
* Please note that 0.3 tråd is probably the more appropriate size, but gold
plated tråd is only available as 0.35.
P18 – Based on an example from Grave 832 – 0.25 tråd
P19 – Based on an example from Grave 1125 – 0.5 tråd
See Birka III for the exemplar
P20 – Based on an example from Grave 520 – 0.35 tråd
P21 – Based on an example from Grave 524 – 0.45 tråd
Please note that while the final SIZE is approximately accurate, the wire is far too coarse
P22 – Based on an example from Grave 524 – 0.35 tråd
P23 – Based on an example from Grave 561 – 0.35 gold plated tråd
P24 – Based on an example from Grave 327 – 0.4 tråd
P26 – Based on an example from Grave 989 – 0.35 tråd