Posament Reconstructions – Eithni's Keep

How to Determine Posament Knot Sizes
Recreations of an Example of Each Posament Knot

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.)

CIMG6767

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.)

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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.

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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.