Archive for May, 2015

Cochineal dye experiments

May 30, 2015

Another dyer and I got together for a day of dye experiments with cochineal.  We had several questions to which we wanted answers.  The first one and the one which we never resolved was an issue with cochineal washing out of silk scarves.  She used a recipe published in Liles book which uses tin and oxalic acid with cochineal.  We tried washing the dyed scarf in orvis paste and hot water.  The dye washed out.  We soaked another dyed scarf in vinegar and the dye washed out in hot water.  My conclusion is that the hot water is breaking the relatively weak bond between the tin, oxalic acid, cochineal, and silk.  We also tried dyeing silks scarves with the one pot recipe from Garcia.  That also washed out.  Subsequently, I consulted with some other natural dyers and it was explained to me that Garcia’s recipe is more along the lines of an acid dye than a traditional mordant dye so that is why it is washing out.  I assume the tin/oxalic acid is similar.  It was suggested that traditional mordant alum based mordant method would work better.  (As an aside, I looked for the recommended % of alum on silk and it ranges from 5 – 100.  Most of the dye books say mordant like other protein fibers.  I haven’t been able to find any studies that compare % of alum on silk.) Second question: cochineal is very sensitive to water and ph.  It is often recommended that you use distilled water.  Garcia suggests adding cream of tartar to tap water when dyeing with cochineal as the cream of tartar acts as a buffer to what is in the water.  We ran an experiment using different water sources and distilled water with and without cream of tartar.  Below is a picture of the sample cards and a picture of one of the sets of jars with and without cream of tartar.  The interesting observation is that all of jars without cream of tartar had the same amount of particulates in the bottom of the jar.  The jars with cream of tartar didn’t have anything in the bottom of the jar.  My conclusion is that cream of tartar does act as a buffer and it is not worth using distilled water unless you have water that will not work with cochineal.  The three instances that I know of where cochineal would not dye with local water was water that was runoff from a mining area. water with iron, and water in which there was sulfur.  The yarn samples are premordanted with 25% alum.  There are some white, grey, brown, and black wools in the samples. The wool cloth sample is unmordanted.       Finally, I wanted to see the results of two other mordants with cochineal; symplocos (premordanted 50% WOF) and titanium (5% WOF) Below are those results on silk and wool.    

Cotton scarves painted with ferrous acetate

May 15, 2015

This is an old project which I finally finished.  Warps were made with scoured organic cotton, mordanted via the methods in Turkey Red Journal, painted with ferrous acetate of various percentages, neutralized in chalk, rinsed, then dyed in madder and lac.  The warps languished until this spring.  The warp was beamed back to front and threaded using the dogwood draft in Strickler’s book.  The weft is also organic cotton dyed in lac.  The warp was very sticky and a lot of threads were broken in the first scarf.  The second scarf was better as I made sure to check behind the heddles every time the warp was brought forward and split out the threads where necessary.  Kind of a pain but the only thing to do short of rebeaming and having the heddles untangle the threads or cutting off the warp.  I like the end result although I need to figure out a different method for cotton warps if I do this again.  
   
   

Cochineal, modifiers, and different types of wool

May 13, 2015

Cream of tartar is often used in dye recipes; particularly in the mordant process.  Various sources say that cream of tartar increases the amount of potassium alum sulphate that is absorbed in the mordant process, improves the hand of wool, and/or brightens red and yellow natural dyes.  In cochineal dyeing, it is important to use if the water contains minerals that make it hard; cream of tartar acts as a buffer and allows the cochineal to bond with the fiber instead of the minerals in the water.  As it is an acid, it will brighten reds and yellows.  It is not clear to me if if the hand of the wool is improved or if it helps with the mordant process.  It seems likely that if you are using hard water, it will act as a buffer and allow more of the potassium alum sulphate to bond with the fiber instead of minerals on the water; similar to the purpose with cochineal.

I usually use rain water when dyeing but decided to experiment a bit with different wools and a different mordant recipe.  For this batch, 20% potassium alum sulphate and 6% cream of tartar was used for the mordant.  The cream of tartar % was not enough to shift the cochineal to red so 10% tartaric acid was added in the dye bath.  The wools were a cormo, a Peruvian wool, and a cashmere wool blend.  The hand was nice on all of the yarns.  The cashmere wool blend (on top) is more orange red than the others but they all seem to have a similar value as far as the color.  No idea why the cashmere blend is a different color.

Acid can be bad for wool (causes it to felt more easily) so I neutralized part of one of the skeins in chalk to see the effect.  I have been told that citric acid, in particular, is bad for wool but am stilling wondering about that as citric acid is routinely used in the chemical dye world with acid dyes.   I don’t care for the effect of the chalk with cochineal (the chalk section is on the left of the skein at the bottom) so will continue to wash the skeins in a neutral soap rather than actually neutralizing the acid.

  

Down the rabbit hole.

May 12, 2015

Sometimes, a book or an article sends me down a natural dye rabbit hole that consumes a lot of time with not much to show for the effort.  But the exploration is interesting.  In this case, I was reading a book called Natural Colorants  for Dyeing and Lake Pigments Practical Recipes and Their Historic Sources.  In it, there are experiments based on historic recipes which include the use of Potash (K2CO3) either in the dye bath or post dyeing.  I had come across this idea before in Boehmer’s book Koekboya, but never really understood the purpose.  The Navajos and Hopis smoke their dyed wool over wood ash which would seem to accomplish the same end (whatever that end is).  I think I finally found an explanation in Application of Dyestuffs by J. Merritt Matthews.  On page 41, there is a discussion of using a concentrated solution of caustic soda on wool at a cold temperature.  It gives the wool more luster and makes it less susceptible to felting so was used on rugs.  The wool cannot be left in the solution for a long time and it will damage the wool so maybe not a good practice for dyeing. This research led me back to the structure of wool and the question of why different breeds of sheep take dye differently.  Dyers can tell you that a long wool sheep such as churro will take dyes easier than a breed like merino or cormo.  I have never understood why.  I came across a statement in The Science and Teaching with Natural Dyes that dye binds only to the amorphous regions of the fiber and not the tightly packed crystalline regions.  So, perhaps this is the reason the different breeds take dye differently.  I have not come across anything that shows the % by breed of the regions.  There is also a question in the natural dye world, if varying the mordant process will increase the amount of dye take up (increasing the amount of alum).  So, another rabbit hole to explore at some point.   I did come across another statement in Textile Science an explanation of fibre properties that confirmed something that had been in the back of my mind; that for a given weight of wool fibre, courser wools will have fewer fibers than finer wools so one would need to use more dye for the finer wool to get the same color.  That would imply that more mordant would also be required.  Some experiments are probably in order. So, no pictures in this post.  Just a documentation of some of my findings for posterity.