TEST SAMPLES
1 Making the test sample
1: Side by side, I pencilled in a 21/4in square and a 21/4x31/3in rectangle as shown (above). I also made a dark vertical pencil line in the rectangle for the relative transparency/opacity test.
2: To test how the paint behaves in a wet-on-wet application, I wet the total square with clean water so it had an even shine. Then using a 1in flat brush, I brushed paint into the centre with one stroke.
3: To show value range, I made a graded wash in the rectangle by painting a heavy line at the top. Then, quick as lightening, I painted a side V-shape below the band. With horizontal strokes, washed the paint upwards from the base with water to make a graded wash.
4: When the paint was dry, I tested the lifting/staining characteristic. I used a narrow, flat brush and with clear water, I made five strokes up and down and then swiped the area dry with a clean tissue.
5: For the lightfastness test, I cut an inch strip that I placed in a window for at least six months together with a blue-wool fading strip as a light measure.
2 ▲ My procedure
I made ten test samples on a 15x11in quarterImperial sheet of Arches 150lb (300gsm) coldpressed Not watercolour paper
3 ◀ Cinquasia maroon PR206
4 ▼ POTTER’S PINK PR233 COMPLETED TEST
Value range: it’s not dark in mass tone; it’s transparent, granular; manageable in a weton-wet application; lifts readily, so is great for wet-on-wet and graded washes – but not for glazing because it will disturb when overpainted. It is lightfast
5 ► Lightfastness test
I pasted the cut-off lightfastness samples on an acid-free board and placed them in an east window where they were exposed to Texas sunlight for six months. You can use alizarin crimson PR83 as a control in place of the blue-wool strips. If a paint fades as quickly as PR83 then it’s not lightfast