Testing, Testing

The past two weeks have been filled with pigment tests. It is easy to see that certain colors take much longer to dry than others. I have consistently taken note of this during the actual painting process of the past many weeks. Waiting for a passage to dry sufficiently to apply the next layer can become very frustrating if prolonged.

This can happen especially in the rainy winter climate in the Northwest. Placing a wet painting near (but not on) a furnace vent will expedite things. This is a trick I employ often.

My drying chart tests were both revealing and surprising. First, Nancy made swatches of all the project colors in use thus far; 33 in all. She used a canvas pad as the surface and linseed oil as the sole medium, attempting all the while to get a uniform paint thickness.

Several pigment groups had more than one color from several different suppliers. An example of this is the yellow ochre category:

Lemon ochre (Rublev), yellow ochre extra pale Cyprus (Sinopia), yellow ochre clear France (Kremer). These colors all vary in hue and opacity slightly, ranging from a rich yellow to an an orangish or dull gold tone. The time was recorded carefully as each swatch was finished. The next step was to simply wait and test the dryness in 12 hour intervals.

It is commonly known that certain colors are excellent driers and some very slow. Umbers, siennas, ochres, generally dry quickly and blacks are notoriously slow, but my results were pretty shocking. The range of drying time in a specific hue category varied enormously. 

We tested four siennas. We expected them all to dry in approximately the same amount of time. But this was not the case at all. They dried anywhere from 23, 45, 62, and 67 hours, a huge difference. We discovered similar results in the ochre and umber categories. Many other colors were found to be dry to the touch but retained a slight tack after as many as 5 days.

On to the blacks, green earths,  and specialty colors next, with final results.