The Thrumdrum Hat Pattern

This is the Thrumdrum Hat, which features on the December page of the 2019 Calendar, Twelve Months of Plant Dyes. 

All the wool was mordanted with alum beforehand. The yarn was first dyed yellow with ivy leaves, then modified to green with copper.

Thrumming is a method for incorporating short strips of wool 'tops' into ordinary knitted stitches.
To avoid felting the fibres, the tops were solar dyed in jars of Coreopsis and Dyers Chamomile flowers, the dye modified with iron by putting a bit of rusty metal in the bottom of one of the jars.  

Tops are unspun, combed wool fibres which can be handspun or felted. Used as thrums, they add texture, pattern and contrast to the fabric surface. On the inside of the knitting, shown here, the tails of the thrums make a thick, puffy layer, forming a loose wool lining which traps air and makes this hat exceptionally warm.

Adult Size Hat Measurements

External circumference of finished hat = 56cm, though the interior circumference is made smaller by the thickness of the thrums. This size fits head circumferences of 55-58cm. 
The hat is designed to sit just over the tops of the ears, so if you prefer a hat that covers your ears, add an extra four or eight rounds of the thrum pattern repeat, remembering you will need a bit more yarn and tops. 

Materials

100m Chunky yarn (typically about 100g)

50g Wool tops
4.5mm circular needle on a 50 or 60cm cord
8 stitch markers
Large darning needle

Tension
10cm squared = 14 stitches and 22 rows in stocking stitch

Yarn suggestions - I have plant dyed and knitted this hat with 100% British Wool Chunky from Woolbothy sold on eBay (yarn described in this post) and also using World of Wool Merino Superwash/Tussah Silk Chunky Weight (yarn described in this post) as well as in handspun 2 ply chunky yarn.

Abbreviations
k = knit
k2tog = knit two stitches together
sl1k1psso = slip 1 stitch as if to knit, knit 1 and then use the left needle to lift the slipped stitch over the knit stitch and off the needle - this occurs in the crown pattern when a reduction includes a thrummed stitch and it ensures that the thrum will end up facing the right way.
st = stitch
thr = thrum

Tops and Thrumming

Choosing Tops 
Undyed natural wool tops are cheap to buy online. You will find wool is available from many different breeds of sheep - the ubiquitous Merino is a safe bet for making thrums with soft puffiness and good felting, for those who prefer a little British character, Blue Faced Leicester is a sound choice on both counts, Shetland sheep's wool also felts well and can be lovely, but its softness may be... variable.

If the yarn you are using has colour changes or is flamboyantly variegated, plain white thrums can draw everything together without making the final effect too busy. I made this hat using remnants of indigo dyed, chunky yarn left over from knitting the Shorelines Shawl Collar Cardigan, which were all in different shades of blue.

If you don't plan to dye your own tops and you do want coloured thrums, you could choose tops from coloured sheep - varieties of rather fuzzy natural Shetland wools are shown on this hat. I love both the high quality and the dyed colour range of the tops sold by John Arbon. For a gorgeous display of thrums, treat yourself to a space dyed, multicoloured braid of tops from an Indie Dyer - my favourite supplier is HillTop Cloud. 

Making Thrums 
Suppose your length of tops weighing 50g was about two metres long. The individual fibres will probably be about 10cm long and the whole length can easily be pulled apart into ten sections each about 20cm long, so long as you leave a gap between your hands of more than 10cm while pulling. The idea is not to break individual fibres, but to let them slip apart against each other. What appears to be a sausage shaped section of fibres can then be teased out into a flatter sheet, which can be separated in half and then half again and so forth. Thrums are made by peeling apart a thin strip of fibres 20cm long, then bending each end to the centre and folding the whole thing in half, so the finished thrum is roughly 5cm long. The thickness of the finished, fourfold thrum should be comparable to the thickness of the yarn, but your thrums can be fatter or thinner, so long as you don't run out of tops. The whole hat will need 320 thrums and 50g should be far more than enough, so in this example of 50g tops being two metres long, you would be aiming to get a minimum of 32 strips out of each 20cm section. Making them all in advance would be a chore, I'd suggest dealing with each section of tops as and when you need more thrums.

Knitting Thrums 
When the pattern says 'thr', make a normal knit stitch with the yarn, but before pulling the new stitch through the loop and off the left needle, take a thrum, lay it on top of the working yarn and bend it round so that you can pinch the two ends together behind the left needle. Use the left needle to complete the stitch as usual, pulling both the yarn and the thrum through the loop together. The following round will be plain knitting and although the thrum and the yarn appear to sit next to each other on the needle, the twist caused by knitting through them both together from right to left in the usual way will cause the thrum to sit in front of the yarn on the right side of the fabric. Each time you come to a thrummed stitch on the left needle, put the right needle through the loop of both yarn and thrum, complete the stitch as usual, then give a little tug to the two ends of the thrum at the back, helping it to sit snugly on the front of the fabric. 

The Thrumdrum Hat Pattern

For instructions on making large and small adult, child and baby sizes, read this post.

BRIM

Cast on 80 stitches - the long tail method is ideal for achieving a firm, elastic edge.

Knit 12 rows back and forth making six garter stitch ridges.

Place a stitch marker and join to work in the round. Purl two rounds. Knit one round.

BODY

Round 1 (k3, thr) repeat to end of round

Round 2 k

Round 3 k1, thr, (k3, thr) repeat to last 2 stitches, k2

Round 4 k

Repeat these four rounds a total of six times.

CROWN

Round 1 (k3, thr) repeat to end of round

Round 2 k
Round 3 k5, thr, (k3, thr) repeat 3 times, *k7, thr, (k3, thr) repeat 3 times* repeat from * to * three times, k2
Round 4 (k2tog, k8, place a stitch marker) repeat to end of round [72 st]
The stitch markers are optional, if you use them, instead of having to count stitches, they will show you when you should be making a reduction in all the following alternate rounds.
Round 5 k2, thr, (k3, thr, k6, thr, k6, thr) repeat 3 times, k3, thr, k6, thr, k4
Round 6 (k2tog, k7) repeat to end of round [64 st]
Round 7 k3, thr, (k3, thr, k5, thr, k5, thr) repeat 3 times, k3, thr, k5, thr, k2
Round 8 (k2tog, k6) repeat to end of round [56 st]
Round 9 thr, (k3, thr, k4, thr, k4, thr) repeat 3 times, k3, thr, k4, thr, k4
Round 10 (sl1k1psso, k5, k2tog, k5) repeat to end of round [48 st]
Round 11 k5, thr, (k3, thr, k7, thr) repeat 3 times, k3, thr, k2
Round 12 (k2tog, k4) repeat to end of round [40 st]
Round 13 (thr, k9) repeat to end of round
Round 14 (sl1k1psso, k3, k2tog, k3) repeat to end of round [32 st]
Round 15 k3, thr, (k7, thr) repeat 3 times, k4
Round 16 (k2tog, k2) repeat to end of round [24 st]
Round 17 (k5, thr) repeat to end of round
Round 18 (k2tog, k1) repeat to end of round removing markers [16 st]

FINISHING
Cut the yarn to 20cm, threading the tail onto a darning needle. Thread the yarn through the remaining 16 st, remove the circular needle, pull tight and fasten off securely. Sew in loose end.
Use the cast on yarn tail to sew the short edges of the brim together to close the circle.
Turn the cast on edge up inside the hat, so that the brim encloses the tails of the lowest 2 rounds of thrums. Tack loosely into position against the inside of the fabric.
Once the hat is washed, the thrums will become felted, which fixes them securely in place.

Phew - a very long blog ends. Next week, I will post instructions for different sizes of Thrumdrum Hat using other yarns and how to make a Thrumdrum Helix Hat.