Personal Trials

(Back to top)

(Back to Pigments No.1)

What did I test?

In the years 1987, 1988, 1989, 1990, 1991, 1994, 1996, 2000 and 2001, I personally tested a lot of colors, mediums and varnishes.

(Back to top)

I. Pigments

A. Method: how I run my pigments trials

1. Painting

I use paper sheets that I specially prepare for oil painting with an universal gesso. Each sheet is divided in numbered squares (see image).

Then I paint the samples with the colors to be tested. I take care of not hiding the numbers.

When testing water colors, I use special paper for water colors in the same manner, but without gesso.

(Back to top)

2. Exposure to light

The samples are cut out of the paper sheet. Each sample is cut in half and the left half is kept in the dark, in a drawer or a cupboard. The right halves are stapled on a piece of cardboard and exposed behind a window during a period of about 8 months (from february to october). The samples must not touch the window-pane.

Then I put together again both halves of each sample and stick them in a sketch book.

(Back to top)

3. How to keep the results of the trials at hand

In spiral notebooks

Here you can see a page of one of my spiral notebooks, in which I keep the results of my trials. These books are ordinary spiral bound sketch or drawing books.

(Back to top)

B. Actual tests

Let’s begin with a very traditional pigment.

1. Vermilion

Here is the result of a test made on 1988 with genuine Vermilion (Mercury Sulfide PR106), pure and mixed with Titanium White or Flake White. (The medium is linseed oil.) You can clearly see the blackening of the pigment after exposure to light.

(Back to top)

2. Alizarine and PY128

This trial was made in 2002. It illustrates an important point of the method.

(Back to top)

3. Alizarine and Dioxazine Violet PV23

This 1994 trial demonstrates that PV23 is not a lightfast pigment.

(Back to Pigments #3)

(Back to top)

4. The “New Permanent” Alizarines

Until 2001, both these so-called “Permanent Alizarines” PR177 and PR264 seemed to be very lightfast. Until now (January 2003), PR264 has never showed any sign of weakness, but in September 2001 some doubt about PR177 was starting (click here for details).

(Back to top)

II. Other trials

For testing mediums and varnishes, there is no question of exposure to light. The samples are not cut from the paper sheet, which is simply put in a drawer.

A. Mediums

Here you have 2 tests of some oil mediums

1. Mediums No.1

This trial was made at the end of 1988 with some mediums for painting in oils. It’s a very interesting one, because it shows the so-called “yellowing” of the linseed oil, which can be extremely different from one medium to the next.

(Back to top)

2. Mediums No.2

This second trial with mediums confirms what was found in the preceding one.

(Back to Painting)

(Back to Mediums)

(Back to Pigments No.2: Transparent Pigments.)

(Back to Chemicals, Refractive Index.)

In any case, concerning mediums, my trials of 1988 and 1989 only hold for the mediums sold at that time. Most manufacturers change regularly the chemical composition of their products, which are getting better and better every year. The trials have thus to be renewed from time to time.

(Back to top)

B. Varnishes

1. Picture Varnishes

Here are the results of some tests made in 1988 and 1989 with picture varnishes. These trials show that the best picture varnishes don’t contain stand oil, which can yellow with the time. (It was already well known that picture varnishes containing linseed oil darken when ageing.)

(Back to top)

2. Retouching Varnishes

Here are the results of some tests made in 1988 and 1989 with retouching varnishes.

Acrylic resin proves to be non-yellowing, compared with ketone resins.

(Back to top)

3. Conclusion about varnishes

Concerning both picture and retouching varnishes, it is safe to limit yourself to products containing acrylic resins only (dissolved in a solvent), and no oil at all.

(Back to Pigments No.1)

Page updated January 20th 2003

Copyright © 2001 Sea Ooh See All Rights Reserved