What’s in the water?

I promised in the last post that we’d spend more time talking about various chunks of water chemistry, a very broad overview, as it relates to dye chemistry. In specific, madder dye baths. Well here we are, another post about water. Today we’re going to have a quick look at Total Dissolved Solids, or TDS.

Photo by Snapwire on Pexels.com

I measured the TDS values out of all of my samples with a basic meter (acquired off of Amazon), and gave it a rinse with distilled water between each sample. It was the meter that gave me the least grief throughout the entire experience, so gold star to my little TDS meter.

When we’re discussing things that are dissolved in our water, that is exactly what the TDS measure is. Total Dissolved Solids, which describes the both the inorganic salts and the small amounts of potential organic material present in the water. This could be a while assortment of things, but are usually calcium, magnesium, sodium cations and carbonate, chloride sulfate anions, amongst others. While TDS is often assumed to be a measure of quality, it is less discriminatory than that. It only measures that something is there, not what that something is, nor if that something is harmful, or unpalatable. The WHO has very general guidelines on palatability of drinking water with less than 300 mg/litre being considered excellent, good, between 300 and 600 mg/litre; fair, between 600 and 900 mg/litre; poor, between 900 and 1200 mg/litre; and levels greater than 1200 mg/litre being considered unacceptable.1 In our water survey TDS was measured in ppm (parts per million), which is approximately equivalent to mg/litre. The lowest TDS measured (outside of controls) was sample 37 at 27ppm, which falls in the excellent category and the highest was sample 26 at 559 ppm, which falls in the good category. A copy of my water survey results can be found linked in my google drive.

Inkbird TDS meter

Often, it is assumed that TDS is a measure of hardness, but TDS is too generalized a measure to mean only that. While it includes the minerals that are part of what is referred to as ‘hardness’, primarily calcium and magnesium, that is not all that it includes. The TDS values of the iron samples are a prime example of that (samples 63, 65-68). Those samples are distilled water with the addition of ferrous sulphate, no minerals associated with hard water present and they not only have TDS values, but it is proportionate with the amount of ferrous sulphate added. In our water samples, it is overly simplistic to assume that TDS refers to hardness, but in absence of good detection of other minerals, it is an assumption I am generally willing to make, with caveats. Certainly I do not assume TDS references hardness when the composition of the solution is known (ie the ferrous sulphate solutions). Water in Ontario is extremely variable in hardness, although we do have some of the hardest water in the country, but that is not consistent.2  Madder, as a dye, appreciates hard water, it usually promotes a deeper red colour, although interestingly, we got an exceptional colour from distilled water (sample 60), so clearly no one told my madder bath that day.

Modern dyers, when looking to augment the calcium in their water, tend to add chalk (calcium carbonate) directly, or a crushed up tums tablet or two (which is calcium carbonate, but with handy fruit flavours!), so if you aren’t super happy with the colour you get from your madder pots, give that a try. Calcium carbonate is very mildly basic, so it doesn’t affect the pH of the dye bath to any great extent.

Next up, we’ll have a look at iron, which can be contained in the TDS measure, but is interesting enough to talk about all on it’s own.


  1. Total dissolved solids in Drinking-water; Background document for development of
    WHO Guidelines for Drinking-water Quality
  2. Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Hardness

Water Survey results pt 1

I’m not going to bury the lead on this one, now that I’ve taken my many many skeins of red yarn to show people at last weekend’s Kingdom A&S in Ealdormere, I’m happy sharing it with the blog world too. This is going to be a series of posts over the coming weeks. Starting with the pretty colours today, but then continuing into the water chemistry that affects the dye baths over further weeks. We started that last time with pH, but we’ll also touch on dissolved solids, iron and chlorinated water (and whatever else comes to mind as we go).

I detailed out the premise of the experiment in this blog post, but long story short; in late 2021, I had a hare brained scheme to request water samples from all over the kingdom (and beyond!) to do a selection of dye baths from to illustrate the variation that could be obtained while only changing one variable, the water. Note that photos do not do any of these colours justice, come see my samples at in person events!


With 68 samples to work through, it was clear that a traditional ‘pot on the stove’ style of dyebath for each one was not at all going to be feasible. I have used a water bath method to do batch samples before and it is very effective.

For each water sample the pH, TDS and iron content was measured and noted down. The sample then had 600 ml measured into a clean (rinsed with distilled water) glass jar, if the sample contained less than 600 ml, it was topped up with distilled water to a total volume of 600 ml. Each of these jars had 3 g of madder powder added to them. The water bath was set up to hold 15 jars per batch, and the water temperature was held constant at 65C with a sous vide appliance. The dye liquor was brought up to temperature, and then held at 65C for two hours.

The yarn had been skeined off, weighed dry, mordanted in batches with alum at 10% wof and dried. Before dyeing, the skeins were soaked in distilled water to ensure they were fully wet.

After the dye liquor had steeped for two hours, the wet wool was added and stirred with a disposable bamboo skewer. The wool was held at temperature for an hour (stirred again at 30 minutes for Batch 2-6), and then was removed from the water bath after the hour had passed. The wool remained in the dye bath to cool naturally overnight. After 12 hours of cooling, the wool was removed to a drying rack to dry. The wool was left to dry for approximately 10 days before rinsing with distilled water and being left to dry again.

Everything was recorded in a giant spreadsheet that you are welcome to have a look at here.


We had a quick look at the equipment that I used over in another blog post, go have a look there for all of my meters and strips and the like. The only addition to that list is my newest toy, a Color Muse colour meter. This little gadget is designed for interior designers to be able to match paint to fabric swatches, but also very helpfully provides a standardized reading of colour. The one that I’ve chosen to use is the CIE L*a*b* colourspace, which is specifically designed for comparisons. More on that in a future blog post, I have done little beyond take the readings at this point.


The main form of showing my results is the photo at the top of this post. I embroidered a map of the relevant section of Ealdormere and then tied a loop of wool in the approximate location of its water. (Linen map, outlines in walnut dyed silk, compass point also in silk dyed with indigo, cochineal and mystery yellow.) The sample cards are a little bit easier to look things up and compare numbers and those are arranged by dye batch, shown below.

We’ve started talking about the water chemistry involved, looking at pH first in this post. We’ll move on in future posts to talk about total dissolved solids, iron levels, chlorine in city tap water and ultimately the results of the colour meter, but I’m aiming for this post not to turn into a thesis. When all is said and done, I’ll gather everything up into one document and stick it on my website such that people don’t have to scroll through blog posts to find the information. For the moment, however, stick around for the serialized version. Questions and comments are very welcome!