Clumping of Non-Granulating Watercolour Paints, Part 2 – It’s not me, it’s you, M. Graham

Several weeks ago, I wrote what turned out to become my most popular blog post yet.  In it, I explored the effect of water hardness and dissolved mineral content in water on watercolour paints on the palette and on paper.

In particular, I was trying to find an explanation for some weird curdling/clumping behaviour I was observing in quinacridone paints from M. Graham.  When I experimented by switching my brushwater from Kitchener-Waterloo tap water (some of the hardest in North America, containing extremely high levels of dissolved calcium and magnesium) to store-bought distilled water, I observed a marked reduction, but not a complete elimination of curdling effects

Original Experiment:  Tap water vs. Distilled, used pans/washed in tap water

At the time of my original post, I attributed the remaining curdling/clumping in the distilled water sheet to mineral buildup in my pans, brushes and palette from previously using tap water.  I theorized that if I switched to distilled water for my painting, over time, this would improve.  I could also reduce the effect of mineral residue on my palettes by wiping them off after washing, and rinsing my brushes in distilled water.  At the time, I was cautiously optimistic that I would be able to all but eliminate this problem with changes to my painting routine.

Over the past few weeks, I have been dilligent about using only distilled water. I no longer think this is a realistic solution, and I now have serious  doubts that this is the only reason for my M. Graham paints curdling.  A few things have changed my mind:

  1.  Despite my dilligence in using only distilled water, all the affected M. Graham paints continue to curdle.  In the case of the quinacridone rose, this effect has reduced enough that it is now no longer as bothersome.  However, the neutral tint still sometimes separates, and the Quinacridone Rust(PO48) still clumps dramatically.  In this case, I have gone as far as to fill a fresh pan, tried using paint straight from the tube, even washed my palettes with distilled water, to no avail.  No matter what I do, if I water this paint down, or try to mix it with another colour, it still clumps. If this is indeed simply a reaction with some minerals, it is reacting with extremely low mineral content, lower than most tap, filtered or bottled water most artists use.
  2. While I am willing, grudgingly, to buy distilled water and haul it to the studio for studio use, I also enjoy carrying around palettes for urban sketching, field studies, etc.  In these cases I will use whatever water is handy – filled from a drinking fountain, lake water, bottled mineral water, etc.  I now find myself concerned not only about whether my paints will unexpectedly clump with the water of the day, but whether I will be messing up my pans by leaving mineral residue in them.  This is ridiculous and unacceptable
  3. In a bizarre mix of frustration and optimism, a couple weeks ago I purchased both a replacement PO48 (Quinacridone Burnt Orange, by Da Vinci) and another supposedly non-granulating M. Graham paint (PG36- Phthalo Green YS).  The Da Vinci paint performs beautifully, a very similar colour to the M. Graham, but not a hint of clumping no matter what water I throw at it – whatever the issue is, it’s clearly not merely pigment related.  The new phthalo from M. Graham, on the other hand, does some bizarre stuff.  It clumps dramatically on the palette, although how much varies day to day, but then the clumping relaxes and all but dissappears as the paint dries on the paper.
  4. Just as I was beginning to really think I was going insane, consistently seeing paint behaviour that nobody else has reported, an amazing Youtuber I follow,  Sadiesavestheday, commented on the same thing in one of her videos (skip to 14:30)

I’m running out of ideas of what could be causing this.  It has occured to me that it could be the honey crystallizing inside the paint due to living in a climate with dramatic temperature swings, but that would also fall under the unnacceptable paint behaviour category.

So where does this leave me?  I’m actually really upset, because, as I’ve raved before, I love the rewettability and saturation of M. Graham paints.  I love their pigment choices and focus on single pigments. Their PY150 Nickel Azo Yellow is hands down my favourite (read: only) yellow. and I love a bunch of their other pigments too.  However,  at this point 4 of the 10 or so M. Graham paints I own display some level of frustrating clumping.  While it is possible to mitigate and work around this in most cases, none of my paints from any other brand have this issue, so I am reaching the conclusion that it will simply be easier to just buy from other brands in the future.

So I guess this is my breakup letter to M. Graham, at least for now.  M. Graham, it’s not me, it’s you.  I just can’t handle your high maintenance needs and mood swings anymore.  I’ll be moving on to more reliable, easygoing paints.

I will reach out to the manufacturer at some point in the near future.   I hear they are very receptive to feedback. I hope that they will be able to track down the root of the issue and fix it, so I can once again enjoy these pretty colours.


Effects of water hardness on watercolour paints

For the past couple of years,  my tap water has been curdling my paints.

It all started with a tube of Quinacridone Rust (PO48)  from M. Graham.   I was attracted to this paint partially because the pigment is listed as non-granulating,  and I fell in love with the colour, but ever since I got it, the paint has had a tendency to clump and curdle when mixed with water in the palette or dropped into a wash, resulting in an incredibly pronounced granulation pattern.  This pattern becomes even more pronounced when Quin. Rust is mixed with another dark valued, non granulating paint such as a phthalo.

Colour mixing experiments with Quin Rust (PO48) and Phthalo Turquoise (PB16)

I searched the internet extensively, and could find no other reports of quinacridone rust granulating like this.  For months I was actually convinced I had received a dud tube, but avoided investigating further, because I really adore the colour and transparency of the tube I own.  Instead, I simply developed strategies for mitigating the crazy clumping and curdling.

Then, a few months ago, I purchased two more quinacridone paints by M. Graham – Quinacridone Rose (PV19)  and Neutral Tint (PV19 + PG7).  Again, all of the pigments are listed as non-granulating, but both of these paints showed the same clumping/curdling behaviour (albeit to a lesser extent).

Now, one dud tube would be easy to explain, but 3 dud tubes purchased at different times would reflect very poorly on the manufacturer.  And yet, still I could find no reports of similar experiences online.  I felt like I was going crazy.

PV19 Quinacridone Rose (M. Graham) on palette with KW water

Finally, I reached out to other botanical artists and asked around.  Someone suggested I should paint with distilled water, as acidity and mineral in tap water can react with some paints.  Suddenly it clicked.   I live in Kitchener-Waterloo, known to have the hardest water in all of North America.

Water hardness refers to the amount of dissolved calcium and magnesium in the water.  Water tends to be harder when drawn as groundwater rather than from lakes or streams.  Water hardness leads to limescale deposits in pipes and fixtures, and premature degradation of water heaters in pipes.  In my area, most households (including my own) have a home water softener, which functions by replacing the dissolved calcium/magnesium with sodium.  We shower and do our dishes with saltwater, which is not drinkable, and have a hard-water tap direct from the city for drinking water. At my art studio, a few blocks away, we do not have a softener.  Thus, my paintings in the past few years have all been done with limewater, and perhaps occasionally saltwater.

In order to test the effects of the tap water on my paints, I purchased a large jug of distilled water at the grocery store, and painted out samples wet-in-wet and wet-on-dry on identical paper using hard water vs. distilled water.


The difference between the two samples was dramatic.  However, there was still a little bit of texture visible in some of the paintouts even when using distilled brushwater.  I attribute this to mineral build-ups in the pans themselves, as well on the brush and the plates I use as palettes, which of course get washed in tap water.  I even tried a sample using fresh tube paints, which was even cleaner, but still contained a little bit of granulation.

So, from now on, I will be painting using distilled water.  My paints are much posher than me, and will get fancier drinking water than I do.  Eventually, I will have a reverse osmosis system installed for the drinking water line at home, although likely not at the studio, which is a rental shared with other artists.  I will however be able to fill up a bottle at home and take it to the studio.  However, I can’t imagine going through the trouble of only washing my palettes and brushes with distilled/RO water, so some hardness effects will still be seen.

I am somewhat torn about manufacturers.  I love the brightness and saturation of M. Graham paints, but they seem to be much more prone to this kind of curdling. Since running this test, I did look through my mixing charts and found a few other paints where some minor unexpected texture, but nothing remotely close to what is seen in these three paints.

My quinacridone pigments from other manufacturers do not show nearly as much clumping.  My PV19 Permanent Rose from Winsor Newton is unfortunately not as bold and red as the M. Graham version, but it shows only the faintest amount of texture even in hard water.  My PR122 Purple Magenta and PV55 Quinacridone Purple from Schmincke and PO49 Quin. Gold from Daniel Smith are also quinacridone pigments, but paint out completely smooth.  Given that in most cases I prefer smooth, non-granulating paint, and that my paint will no doubt continue to come into contact with some dissolved calcium and magnesium, would I be better served switching to different manufacturers for quinacridones (and any other paint that may be similarly affected)?

Does anyone know what the chemical reaction occuring might be in these cases?