Last fall, I did some preliminary trials with different types of fabric pretreatments – soy, funori, and konjac. Konjac, a root vegetable, comes from the Okinawan tradition. Funori, a seaweed, is a very common pretreatment for fabric in katazome and its sister, sodum alginate, is often used for pretreatment and thickening in procion mx dye. Soy is used in the Japanese dyeing tradition for both sizing and pigment binding.
Sizing pretreatment is essential for double sided katazome, because it allows the fabric to remain stiff when it’s flipped over. If the fabric is loose and shifty, it’s difficult to place straight on the pasteboard, which means the stencil will be impossible to align on the opposite side. Sizing pretreatment is also essential for geometric designs or designs with straight lines in single sided katazome; if you omit it, you will get curves where straight lines should be because the grain of the fabric was not straight.
None of the katazome books I read discussed sizing of the fabric before laying paste. I don’t know if this is because the fabric supplier applied the sizing, or if it is because sizing is so basic and obvious that it is assumed the reader already knows. This led to some mistakes in my early works.
When I did later find mentions, the books and videos only talked about it as “starch”. Finally, a friend found a youtube video discussing it for yuzen, and they clarified that the sizing they used was made of seaweed. Funori is the traditional seaweed used for sizing in Japan.
For those of you pursuing historical Japanese dyeing, I think soy and funori are both valid choices – funori is mentioned in the engishiki as a textile treatment, and soymilk was readily available and likely used for surizome, though I don’t have any studies showing a molecular analysis of a textile.
The situation with konjac is more complicated because a different root, ヤマゴンニャク (yamagonyaku), wild, not cultivated, was used in Okinawa historically, but cultivated konjac root is the available substitute.
Other substitutes that will likely work: you can substitute sodium alginate for funori. It’s not quite the same, the hand is a little different, it’s slimier and it’s a little harder to wash out, but it does the job and it’s readily available from a lot of dye suppliers. I’m looking forward to investigating Atlantic seaweeds that may also work in place of funori.
My trials were done with 5g/1000ml solution for the konjac powder and funori. For the soy, I followed the instructions on the package – 4 tbsp to 8 oz of water and then diluted it until it was translucent like milk when I stuck my hand in, because it seemed very thick (I diluted it about 2-3x). I don’t think these measurements have to be precise. The few recipes I have found are somewhat imprecise. You can always redip or rinse out if the fabric seems too stiff or too loose, and different fabrics will need different amounts of sizing. Although time consuming, the best way to determine what sizing is best is to make a small swatch and test your process, because different fabrics really benefit from different concentrations of resist. For your reference, I worked with handkerchief weight bast fiber (linen or hemp) in these trials.
Konjac powder and funori both have to be simmered before being applied the fabric, so I did that and then strained the funori because there were undissolved bits of seaweed. The pieces were small I so simply dipped them and squeezed them out, then ironed them.
In the photos below, the spots in the paste are the result of using an old paste, not any issue with the sizing, so please ignore them. Whenever I accidentally ruin a piece, I use it for wash or lightfastness testing so that the fabric isn’t wasted, and that’s exactly what happened here.
Here’s the konjac:
And here’s the funori:
Finally, here’s the soy:
The pieces of fabric on the right hand side were washed once, on high and hot water, in a speed queen front loader washing machine, and the pieces of fabric on the left hand side were washed four times.
Handling them, the funori has the softest and drapiest hand to me, followed by the konjac and then the soy. Full disclosure, I don’t personally find the hand of soy treated fabric very appealing. Soy stiffens and imparts wrinkle resistance, which may or may not be desireable depending on how you are using the cloth.
The soy seems to have taken on the darkest color, but this color also washed out the most and was the most sensitive to abrasion. Because soy is a protein and coats the top of the fabric, binding to indigo in a different way than raw cloth, it makes sense that this is the result. I hypothesize that while more dye is bound with the soy protein, it’s bound more on the surface of the fabric, which makes it more sensitive to abrasion. The funori seems to allow the indigo to penetrate more similarly to raw cloth. Therefore, the fabric doesn’t absorb as much dye as the soy, but it also don’t lose as much in the wash. What I can’t account for is why the konjac lost more color in the wash than the funori. I have to work to a better understanding of why that happened.
Of all the treatments, I personally preferred the funori, because I make garments that are washed. If you were making noren, wall tapestries, or banners, you might prefer the soy.
I dipped these pieces of cloth because they were small, larger items should really be strung up on shinshi and harite and brushed, especially for soy. For funori, konjac, and sodium alginate, larger shops dip and pull longer fabrics through a special set of rollers like in the video above. I’ve adapted a laundry wringer to do this, and it works alright, but brushing is still the best way, even if it is the most time consuming.
Brushing requires a particular motion, and you go back down once you reach the end of the fabric with the same motion, looking for any missed spots. If you’re doing double sided dyeing, brush on both sides of the fabric. If you’re using a particular absorbent fabric, like cottons or bast fibers, apply the sizing twice. Silk only seems to need one application, especially for soy. When your fabric feels taut and stiff, it is well sized. Don’t over or unevenly size – that will create its own resist effect.
I find this brush is the best brush for applying sizing. I think it’s important to keep the soy brush and the funori/sodium alginate brush separate, but this is only because soy can create streaking effects with Procion dyes. If you’re not dyeing with Procion in your studio, you may be able to just wash the brush very thoroughly, but I haven’t tried. Make sure to understand how to properly care for traditional brushes before you purchase them.
If you have to wash your fabric because of a mistake laying paste or multiple applications of dye layers, you will likely have to repeat the sizing process.
In conclusion, sizing fabric before laying it on the pasteboard is an important part of the katazome process, and I hope my humble trials help you pick what sizing is best for your process.
I hope to do future experiments with domestic seaweed, and also with reducing the amount of sizing needed in later steps of hikizome katazome with procion dyes- it is quite tough to wash it all out! I also want to gain a better understanding of the chemistry behind the sizing, and why soy behaves the way it does. I also hope to do experiments with fresh soy, as I think it may give different results.
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