Bleaching With Cow Dung

MEDIEVAL BLEACHING

(Prior to the advent of bleaching chemicals in the late 18C)

SUMMARY

Linen has been widely used for centuries, white being the preferred colour, but if a colour was desired, the fabric had to be bleached first for the fibres to take the dyes.  So, I have attempted to bleach natural coloured linen (which is a beige or light brown) to white using methods and solutions that were used in the middle ages.  Up front, I would have to say I have failed in that  I did not produce white as we know it, and wondered if whites were really white then as we know them now; I believe not.  I feel somewhat vindicated in this by such comments as: “After weeks of bleaching, the linen turned a milky white.  The snowy whites of today were not available until chlorine was discovered in the 1780s …”[1].

Just to see how much better the modern chemicals were, I also did four experiments with modern products, hydrogen peroxide, Shout, Oxyclean and Javex bleach.  The results are no better than with the medieval processes.  I had read that one should never bleach linen with Javex bleach, I found out why;  the fabric practically disintegrated, granted I used it at 50% strength.

I researched several different ‘recipes’, i.e. different solutions used alone or in conjunction with one or more others, alternating sometimes with each other or with laying out wet on grass in the sun, and beetling or beating the linen.  These solutions include lye in various strengths, cow dung, cow urine, human urine, buttermilk, fermented bran, sour milk, and so on.  Often the process involved alternating an alkaline solution with an acid one, to neutralize it.

Suffice it to say, at the very least the woven linen fabric (also called web) and/or linen clothing was boiled or soaked in a specific liquid, then laid out on mown grass wet, kept wet, and exposed to light, usually the sun.

In the appendices (once I figure out how to insert them) you will find the different recipes I used and the sources of some of them.  Out of curiosity, I also used some different recipes of my own, including each of the solutions on their own.

Preparation

In the fall of 2012, as I was researching, I began gathering some of the materials I would need, such as hard wood ashes, cow dung, sheep dung (which I ended up not using).  I also wanted a space I could use without bringing everything into my kitchen, so I built a ‘mucky kitchen’ outside under my deck to have water, sinks, counter space, etc.  I plumbed the sinks into a drain in the corner, used my Coleman camp stove for boiling and purchased some used saucepans to dedicate to the purpose.

I sieved any remaining charcoal out of my ashes and made several batches of lye.  I did check it to see if it was at the strength of being able to float and egg or a potato in it, as quoted for soap making, and it was not, but I only found reference to that in one place so I considered it not to be important for this purpose.

  

     

  

Fibres and yarns are normally scoured (boiled) by way of finishing.  I have no idea how my commercial fabric was finished so I scoured my one yard of fabric several times, for a total of ten hours before cutting it into 16 pieces for the experiments and marked them with ID numbers.  I could have had a more logical numerical sequence but I felt it was advisable to keep to what I started with.  Several times over the process, other possibilities would present themselves as a result of my research, and some of the samples were cut in half to accommodate.

Over the winter

I undertook the sun on snow (see sample 25) and frost with moonlight (see sample 14) experiments I had read about.  The weather was not wonderfully cooperative so that sometimes the moon was not visible when temperatures were below freezing, other times when it was out, it was not freezing.  I could see a slight difference from month to month, but the lightening with moonlight overall was not significant.  The sun on snow experiments lightened more, but nowhere near white.

Why moonlight?  There is a reference to an old Slav
custom[2].  Further, Robert Mudie (also the author of "the British Naturalist) writes in his “A Popular Guide to the observation of Nature", 1836.

"Now our moonlight really comes from the sun, and is reflected to us from the surface of the moon, just as we can throw light in a dark room by a mirror, or by whitewashing a wall opposite the door on which light can fall. Now the heat of the sun's light, and also the greater part of the red rays, enter into and are absorbed by the moon : and thus moonlight wants the golden brightness of the direct rays of the sun, and is in consequence silvery, and has a little of a bluish tint in it."

            

I found a wonderful essay[3] written in the 1770s by an unnamed author, which described all the processes in great detail, whereas all other references were relatively limited in detail.  Inasmuch as the processes described therein are similar in almost all situations to what I had read about occurring before 1600, and the bleaching chemicals were only just starting to be discovered at this time, I considered this book and its contents to be of great value to the process.  Anything mentioned in this essay that was not mentioned anywhere else was not used, with one exception.  The author believed that it was the action of the evaporation of the water from the fabric that took the colour from it.  He conducted several tests to prove his theory.  I therefore wished to see this for myself, so I put one sample outside, under my deck roof the same amount of time I put one out for the frost and moon sample, wetting it for the same length of time for each (see sample 26).  I also undertook a similar experiment, no direct sunlight, in the spring but without freezing temperatures, for the same number of days/nights (see sample 10a). Both lightened from the original but not as much as those exposed to sun or moon light.

The main work of summer bleaching

The linen is laid out wet, in the sun on ‘freshly mowed grass’ because there is a chemical reaction between the chlorophyll in the grass and the sun.  It is important that it is kept wet, some actually say not to allow it to dry out, and I had found this to be significant.  I had done a very simple experiment a few years ago to use only water and the sun to bleach a piece of fabric.  I found it reached a significantly lighter colour, though creamy white not pure white, in about 15 sunny days when sprinkled several times a day than when it was just put out wet in the morning and not kept wet.  The experiments I have done over the past few months did not achieve quite the same level of lightening in as short a time.  I have two theories as to why this may be the case.

i) The fabric used 3 years ago was hand woven from 75% commercially prepared thread and 25% handspun from commercially prepared fibre.  The fabric used for the experiments this year was commercially prepared fabric upon which various unknown processes may have occurred or sizing used which may require other processes or substances to remove.  Unknown substances may have been applied to the commercial thread I used for the handweaving but my point is that it is a case of comparing apples to oranges, rather than apples to apples.

ii) When I did the original test, it was mid-summer when the days were longest and the sun the strongest.  When I started the experiments this year, while some of the experiments ran from April to October, I started in April when there were fewer hours of sunlight in a day and the grass was pretty sparse.

I made up tracking sheets for each sample so I had an easy guide to follow each day as I was doing different things to different samples, and proceeded to boil, soak, rinse, grass, as indicated.  See Appendix 5 for a completed tracking sample.  Please refer to Appendix II for the various procedures/recipes I used and Appendix I for the most reliable sources and references/bibliography.

On one occasion, I forgot my sample was boiling away, and it boiled dry and burned the fabric.  That was experiment #13.  Go figure!

  

Reconciling what I understood to have taken place in the middle ages with what I was able to do.

What did they do in period?	What I did?	What and why when I did things differently
12-15 hours sunshine	8-10 hrs	That’s all I get
Beating 2-3 hours	2-3 minutes	Because I was working with small pieces of fabric while they were working with miles of yards

 

      

Boiling or soaking in various substances, such as the lye, urine, etc. I have no way of knowing if they reused the solutions over and over again or started fresh each time	I used them over and over
They used various alkaline and/or acid substances, sometimes alone, sometimes combined, sometimes alternating, and always followed by laying out on mown grass wet for weeks or months, and kept wet or sprinkled frequently, several times a day. One common process, known as ‘bucking’ or ‘bowking’ involved laying the linen yardage in a raised wooden barrel folded in a specific way and with sticks laid across at intervals to permit the flow of liquid, then a cloth, likely linen, was laid over the top of the barrel and secured in place around the rim.  Ashes from hard wood were spread over this cloth and boiling water poured over them so as to run through the ashes, through the cloth over the top of the barrel, and trickle down through the layers of linen fabric so as to wet it thoroughly.  This water then became lye (or ley) which was subsequently drained from the barrel by means of a tap or plug at the bottom of the barrel for the liquid to run into another container where it was collected, reheated and poured back again through the ashes and the fabric several times.	I used the same process but not likely in the same containers such as a wooden barrel for bucking with lye. Bucking: because I was only working with small pieces of fabric, it did not make sense to replicate a whole barrel full of yard goods.  Therefore, I made lye by filling a 4L plastic milk jug supported upside down with the bottom cut off and a cloth filter tied over the mouth, and set over another container to catch the lye. Then when I was to apply the lye to the fabric, I brought it to a boil in a pot and added the fabric, then left it to steep in the lye for the prescribed amount of time.	My intent was to immerse the fabric samples in the same solutions in order to attain the whitened effect but not to necessarily replicate all the pieces of equipment used.

Questions I still have

Did they use actual soap of any kind, besides the lye, which I did not find described as having been mixed with animal fat to make soap, in this context.	Although I found the word ‘wash’ here and there, which implies the use of soap in my mind, I did not find reference to soap in relation to the bleaching, so I did not use any soap beyond the washing soda used to scour the fabric before the experiments.
Water	I presumed they would have used rainwater, or stream/river/pond water, so I used unadulterated rainwater for boiling and rinsing.  I think I probably used mains water when scouring.
Did they suspend the linen over grass.	I wondered if the fabric was just laid on the ground/grass or if it was pegged down or suspended somehow.  One of the references I found spoke of loops being made at intervals down the edges of the length of the yardage and sticks being inserted in the loops and stuck into the ground in order to suspend the fabric just over the grass.  I used modern safety pins at each corner and make U-shaped loops with wire to pin them down, some of the time; when it was windy it was sometimes necessary to do something to keep them from blowing around
Did they lift it up daily or when raining	I gave this some thought and felt that picking up what in some cases amounted to miles of yardage just because the sun wasn’t shining (as I did at first with mine), wasn’t very practical.  It not only rains more often in England at least, I cannot speak for the continent, it rains on and off several times a day.  They also had to keep sprinkling it with water regularly by hand anyway (or by some sort of shovel or scoop) if it was drying out. That being said, I did read in more than one place that it was turned over frequently, even daily.  One reference spoke of it being common knowledge that the linen would lighten more on one side if it were left the same side up all the time.  I had found this to be the case when I bleached the first piece several years ago, as it was already hemmed and the lightening did not go into the hem. I turned my samples over every day so they were lightened the same on both sides.

Full sun full day daylight hours	Here I had limitations.  Most farm fields, bleach fields, have full sun all day from dawn to dusk, or as long as the sun is out, without anything impeding the sun.  At my home, when the sun rises at 6 am, it will not be shining on any part of my property, except perhaps the roof of my house, until about 8 am because of trees and hills to the east.  Likewise, at the end of the day it is gone from my property a couple of hours before it officially sets.  Therefore, the hours my experiments could sunbathe were reduced to about 11 from 15 at the longest daylight hours.
6 months	Some references spoke of doing this for 6 or even 8 months of the year.  I had planned to go from mid April to mid October.  April this year was quite cold and not very conducive to playing in water outside, so I did not get most experiments started until April 25th, and the latter part of October it rained almost every day, so I gave up on the remaining four on October 23rd. Also, I planned for the six month samples to be out in the sun for 180 days, but every day they were soaking in something was a day less in the sun; likewise rainy days, or days I was away.  So the process lasted for six months but not 180 days in the sun.
Did they use fresh liquids each time, other than the quoted use of waste ley or lye, which I understand to mean reusing.	I have no way of knowing whether fresh liquids, be it cow dung liquid, urine, lye, etc. were used each time that a second or third etc. immersion was applied, or whether they would have re-used the same liquids used for the first application.  For practical reasons, I reused them and it is possible that while boiling some colour out of the fabric, the colour may have remained in the liquid and even possibly have re-entered it on a subsequent use.

After a few weeks, I discovered that several of the samples had darker threads in them, which appear to have been inherent in the original commercial fabric, especially noticeable when wet, and which I deduced to be a quality control issue.  Those samples that underwent boiling in several different solutions seemed to resolve this problem but in the meantime I decided to add a handspun handwoven piece without these darker threads to the experiments for comparison purposes, and no darker threads developed (see 10b) 

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Some of the samples that were laid out on the grass the longest actually took on a greenish tinge, which rinsed out when boiled in clean water, and the darker threads are more prominent

     

       

Conclusion

So it would appear that experiment #8, which had the highest number of boilings, which combined with alternating sunbathing for the longest period of time, is marginally the lightest.  However, experiment #1, which was plain water only and one month only, came in close behind in fourth place.

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                           Bleachfields/bleaching grounds, Holland, early 17C, Pieter de Hooch

Bucking (pouring hot water through ashes – lye – on linen in barrel)

Two photos of the total experiments taken after presentation

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[1] Christian and Johannes Zinzendorf, The Big Book of Flax, p.116

[2] Linda Heinrich, The Magic of Linen, 48

[3] Multiple contributors, Selected Essays…, (see sources/bibliography for full, very long, title) 88-139