Substituting yarn for a project can be just like the game Mystery Date. Will it be a dream (sigh) or a dud (groan)?

The gauge can be right, and it can look fine, but sometimes there’s just something that makes a substitution fail in the end.

The reason for this not-quite-rightness may lie in a something that spinners call grist.

Grist is the density of a yarn; the concept factors in both the circumference and weight in a length of yarn. Spinners and weavers talk about grist with the acronym YPP or yards per pound.

It’s kind of a gross word, calling to mind gristle, but once I started paying attention to grist, I became much happier with my yarn subs.

Grist is key to the hand and heft of a finished project. Knowing the grist of a substituted yarn can help you avoid running out, and (my favorite) it can also keep you from making a 12-pound sweater coat. In addition, knowing how to measure grist will give you the power of knowing the yardage in every skein in your stash that is missing its ballband.

What affects grist? All the things I’ve talked about in past posts: the type of fiber in your yarn, whether it is woolen- or worsted-spun, and the number of plies in the yarn.

Spinners and weavers figure out the grist of a yarn by measuring and math. Knitters have it easy: all the info is right there on the ballband, no measuring needed. When I work with knitting yarns, I check my grist with yards per ounce.

All you need to know is how many yards are in an ounce of your yarn. It may just save your knitting day.

Mystery Date Contestant Number One

I have a knitter friend who told me she often runs out of yarn when she subs. I asked about her subbing process. She says she uses a similar weight yarn, swatches, and then subs by weight (I know, bless her heart). Here’s an example of where she was heading into yarn sub dud date territory, but we saved her by checking her grist.

My friend wants to knit a shawl that calls for a skein of Sincere Sheep Cormo Fingering with same weight of Koigu that she had in ancient stash. Both yarns are fingering weight, and knit to the same gauge.

Left: Koigu, our mystery date contestant. Right: Sincere Sheep Cormo Fingering.

Here’s what the labels say:

Sincere Sheep Cormo Fingering: 500 yards, 4 ounces (color: St. Barts).

Koigu Premium Painter’s Palette (100% Merino): 175 yards, 1.76 ounces. (My friend has 2 skeins and a little more, adding up to 4 ounces.)

We know that the Sincere Sheep is 500 yards per 4 ounces (or 125 yards an ounce), so that’s the number the Koigu has to hit for it to be a dreamy sub for the Sincere Sheep.

The Koigu has 175 yards in 1.76 ounces: 99 yards per ounce, or 396 yards in 4 ounces.

Girl, that date is a dud! If friend substitutes 4 ounces of the Koigu for 4 ounces of the Sincere Sheep, she’ll only get three-quarters of the way through the shawl before she runs out of yarn.

If you want to know a big reason why the Koigu is a denser yarn (it has fewer yards per ounce), look closely at the ply twist in the two yarns. The Sincere sheep has a very light ply twist, and the Koigu has a tighter twist. The tighter twist squeezes more fiber into the measurement of yarn, so it’s heavier and has fewer yards per ounce.

Mystery Date Contestant Number Two

The next story is my own tale of woe.

I fell in love with Independence Wool’s Texas Tweed and I decided I wanted to knit a sweater out of it. I found a sweater pattern that calls for 1,600 yards of Sincere Sheep Cormo Sport.

On the LEFT: Sincere Sheep Cormo Sport. On the RIGHT: our Mystery Date, the handsome Texas Tweed.

I swatched my Texas love and it worked as a sub. I knew I would need 11+ skeins of Texas Tweed to get the yardage.

Here are the label stats:

Sincere Sheep Cormo Sport (100% Cormo): 400 yards, 4 oz (color Vitamin C).

Independence Wool, Texas Tweed (60% Rambouillet/40% Mohair): 140 yards, 2.25 ounces.

I paused and did some math. The Sincere Sheep sweater weighs just a pound, which is great for my chosen size. But the Texas Tweed? 11.5 skeins (1,600-ish yards) weigh 1.7 pounds, almost twice the weight.

No, thanks. My Texas Tweed will probably become a shawl.

The why of the extra density in the Texas Tweed is in the fiber. The Cormo in the Sincere Sheep is very fine and light. The Rambouillet in the Texas Tweed is also fine and light, but the mohair, although gorgeously shiny and slick, is a strong and heavy fiber. The mohair is what tips the scale.

In the MDK Shop The Knitter's City Bag has all the minimalist perfection of the Knitter's Tote, now in a trimmed-down shape. Form and function meet. It holds quite a lot, actually! Knitter’s City Bag

The Truly Mysterious Mystery Date

What if you have yarn without a ball band, or leftover yarn with long-forgotten statistics, and want to know the yardage?

Step aside: measuring grist will reveal all!

When measuring for grist, you need to know the weight of a specific length of the yarn.

tangled up in pink. Misunderstood Mystery Date on the left. Measured length of mystery yarn on the right.

I use a digital scale and 10 yards of yarn. I weigh it in ounces. I divide the yardage by the weight, and presto: I have the number of yards in one ounce of that yarn.

I have a mystery tangle of yarn (which I think is cashmere, btw) that weighs .055 ounces for 10 yards.

10 divided by .055 is 181.8 . The grist for my mystery yarn is 181.8 yards per ounce.

My sexy yarn pile weighs .55 ounces, so I have 99.9 yards of it. (181.8 x .55).

Taking the time to check your yarn’s grist as part of the substitution process is quick, and can save you the heartbreak of a dud.

May all your yarn substitutions be a dream.