So I had this slightly crazy idea, based on the fact that my son in law (Andy) wanted to prune his small Mulberry tree after it had finished fruiting (apparently the possums are grateful for this years crop).

Figuring the fruiting Red mulberry (Morus rubra) is related to the White mulbery (Morus alba) and in the same family as the Paper mulberry (Broussonetia papyrifera = Kozo). Kozo is known for glorious bast fibers (the inner bark) that is really suited to making fine strong paper. I can hear the experts screaming “don’t go there, it is the wrong plant”, but … meh, time to fuck around and find out.

As a test, I got a single branch, fresh off the tree, took it home and chopped it up into 30cm ish pieces (so they FIT in my pot) and soaked them overnight in water. Next day, using a small sharp knife, I nimbly removed the quills of bark off the sticks, noting how difficult this was, but not damaging myself. (this was not working smart … but I was exploring processes that could be scaled up). I cooked the quills in an old pot on the BBQ with waaaaay too much washing soda (I learned from this) until it was limp and soft, then rinsed, washed, separated the detritus from the inner silky but strong fibers and air-dried the tiny bundle.

I learned a LOT from the proto-twig.

I then proceeded to procrastinate, meaning to message Andy to let him know that when he was ready to prune, I would come over and help then take away the cuttings. Because I left it so long, the pruning happened and i got a call asking if I wanted any of the prunings before they were mulched … this got me off my arse and I collected a lovely mixed bundle of mulberry prunings a day after they were pruned.

When you only have ONE stick, you do not realise how difficult removing the bark was – it was fresh, and I had soaked it overnight but it was still a struggle to get it off. Scaling up, and 2 hand-wounds later I realised I needed to do something different. Remembering my many-readings about making Kozo, I remembered the sticks are STEAMED first before being stripped – doh!

I bought a hotplate, and cooked (boiled) HALF the trimmed bundle for 1/2 hr, dumped the cooked trimmed sticks in cold water and re-used the same water to boil the other half. Sticks that were cooked were so much easier to peel – I just ran the knife along near one end, then I could peel the entire bark off in one quill, it nearly slipped off in some cases – brilliant. On reflection, my test stick took 1 hour to de-bark, but half the bundle was de-barked in the same amount of time. I now have a “knife-safe method of bark stripping – excellent.

Clean water (5L) plus 2 heaped tablespoons of “Lectric” Washing soda and then in with the first half of the liberated bark quills, then caustic cook for 2hrs, gently stirring occasionally. I did this under the house – it is well ventilated “outside’ space. While it was cooking, I stripped the second half of the bundle and left it to dry, along with a rather large collection of nude white sticks that look very cool – I may get arty with them at some stage.

After the 2 hr caustic cook I could tell it was done because quills had gone floppy and I could smoosh them to slide the inner fibers off the goo that was the green layer between fiber and outer black bark. I let it cool in the caustic bath. Later in the same afternoon (gotta love long summer days) I then deep-rinsed the pot 4 times, being careful not to agitate the cooked mess too much – finally the water rinsed clean, I refilled with clean cold water and left it overnight for separation the next day.

When the bark is cooked properly, the inner fibers slide away in thick ropes, leaving the black bark and most of the green mush behind. I had a little “cheese knife” that i used to encouraged any persistent detritus. With whole quills, I could be pretty efficient, removing sheets of black outer bark, sliding any remaining green mush being left with clean fiber pretty easily. This is really tedious, and I am sure professional Kozo manufacturers would be horrified I did not get every speck of black bark or green slime out of the bast, but it looked pretty good to me so I ploughed on.

I kept the nicest sheets of black outer bark to dry and use as inclusions – it’s colour is gorgeous and because it is tissue thin it does not greatly impact the foldability of the finished sheet. I dried it flat on scrap Kraft paper. I massaged and washed the liberated fiber removing more and more of the green and also picking out any black flecks I saw – eventually the water ran clear, so I poured the pot content through a sieve to catch a grapefruit-sized ball of mulberry fiber. I squeezed it dry then spread it out on another scrap of Kraft paper to dry overnight near a window that gets morning sun.

I am amazed by the result. In water, the bast fiber is softer than silk – when dry it is like fine wire and a strong as… a strong thing. The ratio of fiber to waste is excellent – half and half by my estimation. The waste went into the compost.

The fiber extraction is now something i have processes for that are pretty efficient – Dry bark quills can be processed later if I am busy (re-hydrate overnight then caustic cook and continue).

The next step will be beating and sheet formation … excited to have the time to do this, but it will have to wait until after Christmas. I also need some formation/suspension aid to source (perhaps someone grows Okra or Aloe Vera???), and a wooden mallet for the hand-beating. I asked Andy, who is handy, and he is happy to make me one based on my specs – all very exciting.