Ermine 5

Looking back two years to a project in which I experimented with the thinnest thread I’d tried yet…

A friend asked if I could make a delicate band of ermine spots in silk for a 16th century style bonnet/flat cap. They wanted as fine a weave as possible while still having the ermine be recognisable.

I showed them a possible design, and indicated it would probably be 20mm wide if using 60/2nm silk. I based the width estimate off my experience with no 80 crochet cotton, which I had thought was also supposed to be about 60/2nm thickness. I was wrong…

I prepared the warp on 36 cards. I used a backstrap setup, because I was being cautious about the thin threads. I used the same 60/2nm silk for the weft as well as the warp.

When I worked the first motif, it was around 15mm wide. Luckily this was acceptable, so I continued weaving. Each pattern repeat (including wavy borders) was 60 rows long. Generally, they averaged between 26-28mm in length, depending how hard I beat the weft in. The finished band had 25 repeats (1500 rows) in 70cm, with a couple of cm ‘plain’ before and after.

Thinking back to the width miscalculation – I can’t remember where I got the idea about no 80 crochet cotton and 60/2nm silk being equivalent. They’re not.

Let’s have a think:

  • ‘no 80’ means ‘ticket number 80’ or ‘Tkt 80’. It most often refers to crochet thread size, so ‘size 80’ may be another way you see it written.
  • The higher the Tkt, the finer the thread.
  • 60/1 Nm means 60,000m of single ply thread per kg
  • 60/2 Nm means there is 30,000m of 2 ply thread per kg.
    (You divide the figure you’d get per kg for a single ply thread of the same fibre, by the number of threads plied together in the sample you’re looking at.)

Converting from Nm to Tkt:

Using 60/1 Nm as an example:
Tkt = 60 x 3 = 180
So, a 60/1 Nm thread is Tkt 180

Guess what happens to figure out the Tkt for 60/2 Nm? Yep, that’s right, divide Tkt 180 by 2. So, 60/2 Nm silk is Tkt 90 or thereabouts.

Conclusion: The silk was finer than the cotton.
This result is supported by the narrower width I got on the band.

Putting it all together, the formula I used is:
Tkt = (Nm x 3)/ply

Converting from Tkt to Nm:

Reversing things, the formula to get Nm from Tkt should be:
Nm = (Tkt x ply)/3

So, in theory, the Nm for my preferred no 80 crochet cotton should be:
Nm = (80×6)/3 = 160
So it should be 160/6 Nm.

The final piece of the puzzle – equivalent thread thicknesses:
60/2 Nm is the same thickness as 30/1 Nm.
160/6 Nm is the same thickness as 27/1 Nm (rounding up to the nearest whole number).

Conclusion: 27/1 Nm is thicker than 30/1 Nm, so the cotton was thicker than the silk.

I could have figured this out before. Isn’t hindsight a wonderful thing? 😉


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