Sunday, August 27, 2017

More on Sampling for Grist

After fooling around with trying to spin a specific number of makes in a 1 gram sample, I found I really couldn’t get the grist I wanted consistently.

So I went back to weighing.  Since I don’t have a McMorran balance, which is expensive and single purpose, my first approach was to make a balance to measure relative weight.  I took a short section of dowel rod into the end of which I stuck a sturdy pin. The dowel rod rests on the top of a vase, placed near the edge of a level table, so that the yarn samples hang freely. Then I bent a piece of stainless steel wire.  The center was bent up and this rests on the needle in the dowel rod. It took a bit of messing to get this wire to hang level, but it is important that it does. See the pictures.

Basic parts for the yarn balance - the dowel rests on a vase, glass or mug set at the edge of a level table.  The wire rests on the needle in the dowel.

To use it, I hang on one side a length of yarn that is at the grist I want (in this case a sport weight measuring about 3.36 meters/gram) and on the other side I hang a sample fresh off the wheel that is self plied. I make sure the samples are at least 18 or more inches long. I cut the commercial sample a bit longer so I can snip off bits of it until I achieve balance.  Then I compare their lengths, holding both equally taut.  Actual length doesn’t matter.  If the commercial is longer than my spun yarn then my grist is too dense, if it is short, my grist is too loose and if they are the same length, then the grists are equal.  The balance is easy to make and costs very little.  It is, however, fiddly to use.  It is also subject to my ability to discern level and other factors.  It's better than nothing and a good way to at least get a sense of what one is trying to achieve.

Comparison yarn on the left and my yarn on the right.  Comparison yarn is gets snipped off until the balance is level - in this case, I'm not quite there yet.  Then the lengths are compared.

One of my favorite tools is my weigh scale that measures to the nearest 0.1 grams.  It’s great for all sorts of things – like measuring out the fiber for each single, determining final skein weight, measuring out larger quantities of dye, etc., etc.  It is, however, not fine enough for grist sampling.  Imagine my delight to find that scales measuring in milligrams (0.001 grams) are available and about half the price of a McMorran balance.  For 20$ I bought a 50 gram scale.  It’s about the size of a simple calculator.  I will be able to more precisely measure smaller quantities of dye and chemicals as well as do quick grist measurements.  

Now came the other issue – how do I measure length?  I collected a bunch of commercial yarns from my stash in various weights and from various manufacturers.  I looked at the ball band to determine what the grist is supposed to be.  For example, a Nature Spun sport weight is supposed to measure 168 meters in a 50 gram skein – or 3.36 m/gram.  I cut a length of it and weighed it.  I divided the weight by the m/g to find out how long the sample should be.  Then I measured.  In most cases the length was somewhere between fully stretched and relaxed.  This actually makes sense, since most yarn measuring devices measure length while the yarn is under some tension.

That led me to another question – how is the WPI measured on these commercial yarns?  I prefer to use a control card rather than wrapping, although I sometimes do that, too.  In all cases again, I had to hold the yarn fairly tightly to get the WPI on the control card that yarn should have with respect to grist and Yarn Council norms.  Not at all like what most people describe for measuring WPI.  I now understand what Alden Amos was driving at when he advocated measuring WPI packed to refusal. 
I ended up making a padded box for the scale, which is big enough to include a centimeter tape, the calibration weight and a calculator.  It’s portable and quick and I am hopefully further along in being able to control the grist of my yarns, besides the diameter.  

My milligrams scale, calculator, centimeter tape and calibration weight.  All fit into the box that I padded with closed cell foam.

I’ll let you know how it goes.

Thursday, August 10, 2017

Getting the Gist of Grist

I have been spinning not quite 4 years.  I have spun miles of yarn and enjoyed every inch of it.  I have knit with it and woven some and am pleased how forgiving the yarn seems to be.  All my hiking socks are knit from handspun.  They fit well, breathe well, I get far fewer blisters and they last.

BUT there is one thing that eludes me.  In all my reading and video watching, the following statements are made: handspun is more dense than commercial and if you want to make a specific yarn you have to pay attention to grist.  These statements are contradictory AND no one really seems to address how to really control grist.

Grist is basically yarn density and is usually described in terms of length per weight, such as Yards Per Pound (YPP) or Meters per Kilogram.  Since I have knit decades more than I have spun, I prefer to express grist as meters per gram, because I can then relate that more easily to skeins, which usually come in 25, 50 or 100 gram weights.  (M/Gr = YPP/496.5)

So after I have spun, plied and washed a skein, I measure the length in meters and divide by its weight in grams.  Unfortunately, although it looks and measures perhaps as a fingering weight (16-18 wpi), the grist more often tells me that it’s more a sport or even a DK weight.  Fingering weight usually is somewhere between 3.5-4.5 m/gr, sport weight is more like 3-3.5 m/gr, DK ranges from 2.5 – 3 m/gr and worsted weight is 1.5 to 2.5 m/ gram.  These are approximate and don’t totally jive with the Yarn Council numbers, but they work for me.  The problem comes when knitting with yarn.  The gauge and resulting fabric behaves more according to grist than according to yarn diameter.  Makes sense – you can only compact fiber down so far.  So basically the novice spinner substitutes twist to achieve diameter rather than concentrating on grist.  I have come to the conclusion, if you spin to grist, the diameter takes care of itself.

So how do you achieve desired grist?  The McMorran balance often is mentioned, but that is only a spot sample.  I have done something similar – created a little balance from wire, put a length of a sample yarn of desired grist on one side and the same length of my project yarn on the other.  If they balance, their grists are the same.  But that’s only a spot sample.  Not really useful over the course of a project.

So here what I have been doing.  I haven’t done this enough to know if this consistently works, but it should. First I decide what grist the final yarn is to have.  For example, I want a sport weight of 3m/gr.  It’s to be a 2 ply, so 3*2 means the singles grist should be 6m/gr.  Since I prefer a backward draw – whether short for worsted draft or long for woolen – I can measure a comfortable make – like 45cm (about 18 inches).  If 1 gram of fiber is to measure 6 meters, then 600cm/45 cm per make = 13 to 14 makes. I am aware that final length won’t be what the stretched length while spinning is – I figure at least 10% length reduction.  So I shoot for a slightly higher number of makes to take that into account – 15 makes would probably be better.  If you use a forward draw for worsted, you'd have to measure about how much you draw out each time and go from there.

  I play with this until I understand what this grist looks and feels like.  I repeat this every so often to make sure I am staying more or less at this grist.  I then worry about twist and do ply backs to see if I like what I see.  I adjust pedaling rate and/or whorls if I don’t.  I do not worry about diameter – I figure the grist will take care of that.  

The question is, if this is a reasonable approach or not – feedback most welcome!