Let’s talk about lac (ครั่ง)!
Today we’re going to go over the steps we take at our studio when using raw stick-lac (Kerria lacca) straight from the jungle to color our silk in a range of natural shades. When using lac in this way we normally go for a deep plum purple color but it’s easy to adjust the steps and get many other shades as well, like coral-orange and pinks. After about a year of playing around with stick-lac as a dye I feel I’ve developed a process that works well for me so I want to share it with you. Hopefully this will be of particular use to other natural dyers out there, and if you’re not a dyer but maybe an enthusiast or just like natural colors then like us you might find the process fascinating and somewhat akin to alchemy.
But first - what is lac anyway?
Lac is a tiny parasitic insect that lives on the branches of particular tree species and secretes resinous tubes in which it lives. This resin is most commonly processed into shellac which is dissolved in alcohol to make sealants, primers and varnishes. It continues to be the choice of sealing wax used by India Post today. The dye itself actually comes from the insects that remain in the resin housing after dying from exposure to sunlight. It is one of the most ancient dyes known to humans.
Lac in particular is a dye I’ve found to be particularly sensitive to water quality and contamination. My biggest hurdle when working with it has been trying to stop it from separating and coagulating into a pigment form. I’ve read somewhere that the word “lake” (referring to a pigment lake - which is liquid dye that has been precipitated into solid pigment most commonly used for making paintings in the past) derives its name from lac due to how easily it was for this dye to separate and become a pigment. In fact it was one of the first dyes to be precipitated in this way.
While pigment lakes certainly have their uses what I want to show you today is something different - we will look at how to extract color out of raw stick-lac, simmer it down to a very concentrated consistency, use that concentrate to paint directly onto fabric (with an option of using pH modifiers) and finally steam set the dye.
While this method is not always superior when using lac and other natural dyes it does have some distinct advantages over the more traditional full-submersion dyeing process carried out in a dye bath:
- Minimized water usage
- Increased depth of shade
- Even dye uptake
- Reduced dye wastage
- Large degree of control allowing for greater creative expression
- No need for large dedicated dyeing vessel
- Easy to add additional shades
Minimized water usage
Because we will not be doing full-submersion dyeing this means that the amount of water which we use is greatly reduced. This is particularly important with lac because from my experience the water has to be as clean as possible and not everyone has ample access to lots of filtered/rain water. We only need a few liters of clean water for this method since we will be simmering it down into a concentrate for direct painting later.
Increased depth of shade
By painting the concentrate directly onto the fabric we force as much dye as possible into the fibers which is much more difficult to do when working with a dye bath. To get the same deep rich color in a dye bath we would have to increase the quantity of dye material used considerably.
Even dye uptake
To get a nice even spread of color across a fabric when doing full-submersion dyeing with natural dyes you either have to use a leveling agent (a chemical that helps to evenly distribute the dye), add more water to ensure that the fabric can float freely in the dye pot or nurse over it like a watchful mother stirring the fabric at regular intervals. With direct painting there’s none of that - just stretch out the cloth, grab a big brush and paint layers until everything looks even.
Reduced dye wastage
With full-submersion dyeing there’s always going to be leftover dye that doesn’t get taken up by the fiber which has to be poured down the drain (or into your flower bed). This is minimised when using a direct painting method.
Larger degree of control
By applying the dye directly to fabric with a brush there are suddenly many new possibilities which aren’t available in the same way when dyeing in a dye pot. You can do all sorts of crazy stuff with brushstrokes, using different colors that overlap, sprinkling salt to create mottled effects or using alcohol/water for gradation effects, etc. It’s also possible to use gutta paste or katazome paste to draw designs and paint within the lines (you would want to treat the fabric with something like raw soy milk first to prevent unwanted color spread in that case and also thicken your dye).
No need for large dedicated dyeing vessel
Especially useful if you’re doing a long piece. Not everyone can invest in a massive pot that sits in the corner 99% of the time eyeing you judgmentally for only using it once a month (next to the sturdy short metal stove which will need to support it). With this method the only large pot you will need is for the steaming step at the end (or no pot at all if you’ve purchased a fabric steamer) and since there is no dyestuff or mordant coming in direct contact with the surface of the pot you can safely use whatever is in the kitchen.
Easy to add additional shades
This one is great. So many times I’ve taken something out of the dye bath, washed and dried it only to discover the color is not what I want. I could put it back in the dye bath but most of the color is exhausted so I would need to boil up a new batch. With direct painting what you see is what you (generally) get. Just paint a layer and let it dry. Don’t like how it looks? Add another one and keep going until you reach your happy place.
Speed - pretty fast (once you’ve made your concentrate)
With a dye pot you often have to leave textiles soaking in the liquid overnight for maximum color. With direct painting on the other hand as long as you do a good job steaming the fabric you can be done in a matter of hours.
It’s incredibly handy to have a jar of natural dye concentrate sitting in the fridge ready to be taken out and used for a project. Rather than spending half a day each time I need to extract color in a dye pot when I want to dye something instead I can do it once and keep the concentrate for later. Easy!
Before we get into the process I should add a little disclaimer - none of this is scientifically accurate/proven/recommended. This is simply the way which I found works best for me after a year of boiling many many failed lac batches and pouring most of them down the drain. Also - while these steps are specific to lac this method can also be used with any other dyestuff.
- Preparing fabric
The first thing you will want to do with your raw stick-lac is to separate the dye from all the impurities (resin, pieces of branches, etc) by grinding and soaking it in water. Marjo Moeyes in her wonderful book “Natural Dyeing in Thailand” provides instructions for grinding the lac in a mortar and pestle with a small amount of boiling water that gets strained and changed periodically until no more dye comes out. I’ve tried this many times. It works but I somehow always manage to spill everything, splatter the walls or both until the studio looks like a crime scene and the neighbors politely avoid eye contact with me until my hands are no longer crimson red. Also, the boiling water heats up the resin turning everything into a sticky mess.
Instead I’ve found that putting the dry material for about 15-20 seconds in a spice blender is a fantastic 21st century alternative. Make sure the container is of high quality as the material really flies around inside at high speed and the whole process is extremely noisy. I wouldn’t blend longer than 20 seconds for two reasons: the first is that blending it for too long creates ultra-fine particles which stubbornly pass through the filtering cloth and the second is that there is a large amount of resin in the material which could heat up causing your blades to start gumming up.
A slightly crumbly consistency of rough sand is perfectly fine.
For my example I will be dyeing one lightweight 2 meter long silk scarf a deep plum purple color and 70 grams of stick-lac gives me enough dye to do that, with a little leftover for future projects.
The dye is water soluble and starts coming out of the material effortlessly. All it needs is one night of soaking in some clean water (either rainwater or reverse-osmosis). In my experience 12 hours works well but leaving it for too long (48 hours) can start causing separation problems.
For my extract I will be soaking the 70 grams of lac in about 7 liters of water.
After about 12 hours of soaking the liquid is strained through a fine muslin cloth to remove the resin and branches and we are left with a vibrant blood-red liquid.
To make sure my color is as pure as possible I have individual filtering cloths for each type of dye I work with - beige for mangosteen, light pink for sappanwood, plum purple for lac and yellow for gourka tree bark
If you are extracting lac for standard full-submersion dyeing then at this point you can use the liquid as a standard dye bath by heating it up (no higher than 80°C/176°F) and putting in your mordanted fabric.
To make the concentrated liquid extract we will need to evaporate out as much water as we can from the dye bath. I’ve found a wider pot works better for this than a deeper one. However, since the dye starts to lose its brilliance past higher temperatures we have to bring it to just before simmer point, turn down the heat to low and keep it there for several hours. The duration depends on how much soaking water you start with and how concentrated you want your final product to be. There’s a trade-off to be made here - too little water and you risk not extracting the maximum amount of dye from the raw material during the soaking stage. Too much water and you will likely have to spend the entire day simmering it down to a concentrated point.
I find that simmering my 7 liters of liquid down to about 300 ml of concentrate gives me enough concentrate to paint 3-4 layers on my silk scarf for a deep color. To gently evaporate excess water from 7 liters to 300 ml usually takes me 6-8 hours of low simmering.
After several hours when there’s only about half an inch of liquid or so left in the pot some special care needs to be taken to avoid burning it. At this point I usually grab the pot and swirl the liquid around in a circular motion for about 20 minutes until the excess water evaporates and the consistency is similar to light syrup. The point when some thickening just barely starts to occur is when I turn off the heat.
5: Filtering (again)
To make sure that the concentrate is as clean as possible I run it through a filtering cloth for a second time. If something went wrong during extraction (unclean water, soaking time too long or temperature too high) then the pigment can coagulate and clog the filtering cloth. The only thing to do then is collect it, dry it, treat is as a pigment for watercolor or wall plaster coloring matter and start again.
If everything went right and the stars are favorably aligned then the resulting liquid should be a very deep velvety red color and drip cleanly through the filter. Here my 7 liters simmered down to just over 300 ml.
At this point the container can be wrapped tightly with plastic wrap and kept in the fridge. I’ve kept some concentrates like this for 3-4 weeks and there was no noticeable degradation in color quality.
6: Preparing fabric
For painting on fabric with natural dyes the material needs to be pre-mordanted (alum or iron is recommended for low toxicity). For silk we use potassium aluminium sulfate together with cream of tartar dissolved in water (20% and 6% weight of fiber respectively) at 80°C/176°F for an hour and left to soak overnight.
Before painting on the concentrate the material needs to be stretched out and slightly dampened - if it’s dry the dye won’t absorb evenly, if it’s too wet the dye will drip off. To stretch it out there are many ways, the most proper and professional of which would be to use Japanese “shinshi” - thin flexible sticks with sharp pins on the ends. One particularly creative way that I’ve seen is to make a frame using blue PVC pipes of a dimension that is about 10 cm larger than your work piece on all sides and stretch out the fabric in the middle by use of rubber bands and safety pins. This is a great and inexpensive option and highly recommended if the paint work will involve delicate shapes and curves as it keeps the fabric stable and perfectly horizontal. The frame can be made out of smaller modular pieces to accommodate fabric of varying sizes.
For our piece because all we want is a solid color (we will be using shibori techniques and over-dyeing with indigo later on) the fabric is simply stretched between a fence and a drying rack using metal clips. It’s very primitive but gets the job done. Also - it is advisable that the space you’re working in is shaded from direct sunlight.
When the fabric is prepared it’s time to paint!
Short hair brushes seem to work far better than synthetic bristle brushes for this. Also, for solid color wider brushes are preferable. Lightly dip your brush in concentrate and start laying down the color using steady even strokes. If excess dye pools up in the middle of the fabric try and redistribute it out towards the rest of the fabric.
Once a layer is applied I usually wait until the fabric is just slightly damp again before putting on the next layer. The silk I’m working with is thin enough for the dye to penetrate through to the back but if your fabric is thicker you will need to flip it and paint both sides.
One of the great things about this technique is that you can very quickly get a good idea of what the final color is going to be and adjust the process accordingly. In my case after the first layer I thought the color was leaning too much towards a pink with coral-orange undertones so I decided to adjust my next layer using an alkali. This is something you can do with most natural dyes - they have a bit of a hue spectrum which you can shift by slightly changing the pH during the dyeing process. In the case of lac pushing the pH towards acidity will produce warmer orange coral tones, while adding an alkali will bring out pinks and purples more. There are many types of pH modifiers used in natural dyeing to achieve this shift and what you use will depend on how far you want the shift to go. Cream of tartar will push acidity a little bit, but not as much as adding straight vinegar. Chalk can push alkalinity, but not as much as slaked lime or soda ash.
Since the lac extract is slightly acidic by itself it naturally tends to move toward the orange-coral spectrum. If that’s the color you want you can use it as it is without any pH adjustments and apply one layer for a light shade, or go over multiple times for a deeper color. Always do a small sample first just in case before painting a larger piece. For my scarf I wanted the color to be plum-purple with an undertone of electric pink so I added a pinch of soda ash to the concentrate. Once the pH is modified the color change of the dye liquid is immediate.
Before adding alkali
After adding alkali
With my newly adjusted lac I painted on another 2 layers, making sure to give the fabric enough time to dry a little bit and soak up the color between each application. If you’re like me and want to hurry things along you can point a fan at the work to help it dry quicker.
After the last layer the fabric is dried completely and prepared for the final step.
Important note - if you’re working with shapes and outlines (like painting within katazome rice paste resist or gutta lines) then the dye needs to be thickened to prevent it from running. A pinch of guar gum stirred into the dye is good for this (make sure the liquid isn’t cool - the gum won’t dissolve properly) but try not to use too much as I’ve found it can act as a color blocker when in excess. I believe there are also ways to pre-treat the fabric to avoid dye running but the only way I know (soaking in fresh raw soy milk) makes the fabric stiff. If anyone knows a better way please let us know in the comments below.
To make the dye permanent it has to be heat-set. Normally this heat application would happen in a hot dye bath but with silk painting it’s necessary to use steam. There are many hobby-size fabric steamers available for sale, both stove-top and electric. In Thailand finding such devices is a bit of a challenge so we made our own (very basic) steamer using a pot with the largest diameter available. The pot only needs to be a little wider than your fabric so if your work is narrow enough you can use a large pot from your kitchen or adjust the width of your work to accommodate your largest vessel.
The basics of a fabric steaming is that the fabric must be suspended in the air and exposed to steam in such a way that also avoids moisture dripping onto the fabric. For our device all that is needed are some ropes suspended securely from the rim so that the work can sit somewhere in the mid-section of the pot (high enough to avoid any contact from the water and low enough to leave space between itself and the lid) without touching the sides of the pot.
To prepare the fabric for steaming in our fancy homemade contraption I roll it sandwiched between layers of newspaper onto a permeable core of rolled up rigid chicken wire-type material and then tightly wrap the entire package in multiple layers of plastic wrap. The plastic wrap is there to make sure no water droplets find their way in - they will leave marks if they do (it’s a good idea to cover the sides of the cylinder also). I then suspend the rolled up fabric in the steaming pot.
The pot opening is covered with a towel to absorb excess moisture and closed with a lid which is weighted down with something heavy. This helps keep too much steam from escaping and also provides something to secure the towel ends with and keep them away from the stove flames.
A proper fabric steamer is less hassle than this and will usually come with a perforated stainless steel core around which you can wrap your fabric and suspend it neatly from the top of the container. It should also come installed with a temperature gauge which is important for silk steaming as you do not want to take the temperature too far past 80°C/176°F. For our gauge we drilled a hole through the lid and put a turkey thermometer held in place with heat-resistant silicone. It works but in hindsight I would recommend going to the BBQ section of a Home Depot and getting one of those thermometers with a screw thread and wing nut to hold it in place. If you’re doing a small project and don’t want to ruin your lid it’s possible to stick a turkey thermometer in between the lid and the pot if it can stay there securely. Otherwise if the heat is just kept on very low then everything should be fine.
When using either the homemade or purchased steamer device care should be taken when rolling the fabric to avoid any wrinkles as those could get steam-set along with the color. If you end up with wrinkles you can put your finished piece in a hot water bath to get them out (this has always worked with my silks).
Once the piece is rolled neatly, plastic wrapped and suspended inside the closed pot the heat is switched on and carefully monitored. Ideally I aim to steam silk for about 3 hours at 80°C/176°F. This gives the steam enough time to penetrate the multiple layers of folds and fix the color to the fabric. After 3 hours I turn off the heat, let everything cool down a little bit, remove the work from the pot and unwrap it.
Any unfixed dye then needs to be washed off. After 4-5 changes of water the excess is gone and the color usually stops running. We finally have our plum-purple-pink silk scarf naturally dyed with lac extract!
Since we used metal clips to stretch the fabric while painting and a funny steaming method there may be some small spots where the color isn’t perfect. This can be avoided by using a proper stretching frame and fabric steamer. However, since I use this method to create a solid background for creating shibori patterns and over-dyeing in indigo these little imperfections don’t matter so much because I can hide them under the blue.
As an example of final products that can be made with this technique - here is a photo of one of our past scarves from our Shibori Scarf Collection which was made using this exact method. The background was dyed in lac extract, then the motifs were stitched and wrapped to resist some of the color and finally the entire piece was dyed in indigo for a deep blue background.
That’s it! Hopefully you found this little guide interesting/inspirational. When reading it all in one go natural dye extraction and silk painting can seem like a daunting task but actually everyone can do something similar at home using the tools they already have available to them, especially if the work piece is smaller. Each plant can give us some kind of color so it’s up to us to experiment and see what sort of interesting shades we can create.