Introduction

This project was based on applying various pigments on hand-made paper and fresco. From the beginning of the project, it was assumed that pigments will appear differently on these two surfaces and the aim of the project was to observe, explain, and even measure (with colorimeter tool) the differences. In addition, pigments used for the project were based on six primary colors that form Michael Wilcox's color theory (Blue and Yellow Don't Make Green, p. 31-50, ND 1488.W54 1994). These colors are: two kinds of each red (orange-red and violet-red), blue (green-blue and violet-blue), and yellow (green-yellow and orange-yellow). The pigments were also mixed with each other respectively in order to further explore Wilcox's color theory.

I conducted this project because I liked working with pigments and mixing them, and was interested in how different surfaces react with and accept these pigments. Paper and fresco seemed quite contrasting surfaces and that is why I chose them for the project.

Background

Most of my project was based on Michael Wilcox's color theory that deals with the notion that there are no pure red, blue, or yellow lights. Light never reflects pure red or blue or yellow. In each case, all the colors of spectrum are reflected, just the amount of each reflected light varies. There are two kinds of red, for example. One red leans toward orange because, beside red light, large amount of orange light is reflected. Other red leans toward violet because violet light is also greatly reflected beside red light. The same follows for violet-blue, green-blue, green-yellow, and orange-yellow.

Michael Wilcox uses these six pigments, that represent primary colors, and mixes them respectively in order to get secondary colors. He experiment even further with them in order to explain his theory.

Colorimeter tool and L*a*b* color model were also important for this project. Colorimeter tool measures coordinates of the color offering precise measurements of color's lightness/darkness character, its leaning toward either red, yellow, green, or blue, and its saturation state. The final coordinates were compared with L*a*b* color model from The Color Guide and Glossary, by X-Rite, on page 17.

Procedure

Materials used: 10x12 inches plywood panel topped with stapled metal lath and framed, slaked lime, coarse sand, medium sand, fine white sand, gloves, diamond trowel, water, brush, glass beaker, dry pigments (Cadmium Red, Quinacridone Violet, Lead Tin Yellow, Cadmium Yellow, Cobalt Cerulean Blue, and Ultramarine Blue), glass sheet, muller, palette knife, spoon, small glass jars, paint brushes, mirror sheets,15 min cotton pulp, plastic beaker-100ml, deckle box, mold, wire screen, sizing, felts, pelons, plastic bottle filled with water, drying white board.

I started with grinding the pigments on a glass sheet with water and muller. Water was added to pigments and they were ground with a muller in circular motion. Each ground pigment was placed in a small glass jar and labeled with pigment's name. Then, I made fresco with already prepared material thanks to Anne and Ann Cox. First layer trusilar consisted of mixed coarse sand and hydrated lime in a 2:1 proportion. It took a week for this layer to dry. Second layer or arricio was made of medium grain sand and hydrated lime in a 2:1 proportion. Third layer or intonaco consisted of fine white sand and hydrated lime in a 1:1 proportion. Please see [Anna Bohne's and Ann Cox Steedman's website on how they made these layers]. In addition, two sheets of paper were made from cotton pulp with deckle box. For each paper, 300 ml of cotton pulp and 5 drops of sizing were used.

When sheets of paper dried and when fresco's third layer intonaco was absorbing water, pigments (diluted with water) were applied to these surfaces with small paint brushes. First, reds, blues, and yellows were applied. Then, orange-red and orange-yellow were mixed in order to obtain a secondary color-orange. Violet-red and violet-blue were also mixed and they produced violet. Green-blue and green-yellow produced green. In addition, two kinds of red (orange-red and violet-red) were mixed in hope that they will produce prue red. The same was done with blues and yellows. I further experimented with mixing pigments in order to get different oranges, greens, and violets (just as Wilcox has done in his book). When the pigments dried, colorimeter tool was used to measure their L*a*b* coordinates. The L*a*b* color model was used for comparison and for finding out where the measured coordinates are on this model. Pigments on paper were measured once because paper allowed consistent spreading. With fresco, pigments do not appear evenly spread and a layer of pigment might at the same time be thick and very transparent. That is why pigments on fresco were measured twice, so that one can more accurately know where on The L*a*b* color model these colors are.

Working with pigments: mixing them and applying them on fresco and paper.

Observations and Data

While grinding pigments, I noticed that different pigments react differently with water and under a muller. For example, Ultramarine Blue and Cadmium Red were more difficult to grind and would dry quickly. Quinacridone Violet was also difficult to grind because powder would not accept water and palette knife needed to be used extensively in order to mix water and pigment.

While applying diluted pigments on paper, they would remain on the surface in thick layers. On the other hand, fresco actually absorbed these pigments which started to look transparent and more like watercolors (even though the same quantity of pigments and same method of applying them were employed). When these surfaces dried, pigments on paper started to crack or separate from the paper. Colors, nevertheless, remain darker and shinier than those on/in fresco. Pigments on fresco look more transparent and do not shine. There are exceptions, as always: yellows and greens are darker on fresco than on paper.

After pigments dried, colorimeter tool was used to measure their L*a*b* coordinates. Below are tables with coordinates for each unmixed and mixed pigment. One notices that there is always a difference between same pigment applied on paper and fresco. In most of the cases, pigments appear darker on paper than on fresco, therefore, their L* coordinate is lower. Other two coordinates, a* and b*, do not vary greatly though. With using colorimeter tool, one could learn about many characteristics of a certain color. For example, when measuring the green, we learn that, beside being darker on fresco, it is very saturated and far away from being pure green. Orange, on the other hand, appears quite 'orange' (based on the L*a*b* color model) on both paper and fresco. Violet on paper is very dark but close to real violet. On fresco, violet appears lighter and very saturated though.

What was one of the great interests in this project was to see if the coordinates of red, blue, and yellow are close to the coordinates of 'pure' red, blue, and yellow on the L*a*b* color model. Yellow from this project appears quite pure while blue, for example, still leans toward violet. Red is close to being pure though. Interestingly, both blue and red on fresco are closer to being pure than blue and red on paper.

Beside measuring L*a*b* coordinates of the pigments and comparing their apparances on paper and fresco, mixing pigments was also important. To mix green, for example, two pigments were used - green-yellow and green-blue. The mixed green, however, does not look quite green because too much blue or too little yellow was used. Mixing presented yet another component of the experiment and in some parts it was successful, in others quite unsuccessful. Different oranges, for example, do not look like oranges at all and that probably happened because too much or too little of certain pigment was added.

Below are listed all the pigments - mixed or unmixed - with their L*a*b* coordinates.

Conclusions

The project, for most of the part, succeeded because same pigments indeed appear differently on paper and fresco. The differences could be easily noticed by the eye and also precisely measured by colorimeter tool. By observing pigments and using their L*a*b* coordinates, we can compare and contrast them and draw conclusions about their appearances. In most of the cases, pigments on paper are darker than those on fresco. The a* and b* coordinates, on the other hand, do not manifest any kind of pattern. In some cases, as with yellow, a* and b* coordinates on paper and fresco are quite similar. Other pigments, like violet, have quite different a* and b* coordinates on these two surfaces.

Mixing the pigments with each other was not very successful, on the other hand. Formed green, for example, does not look like regular green and the proportion of green-blue and green-yellow must have been wrong. Oranges also do not look like those from Wilcox's example. They lean toward pink and this is because too much red was used. Mixing of the pigments probably required more knowledge and practice.

Overall, pigments usually appear darker and shinier on the paper, but they do not adhere very well to it when they dry. Fresco, on the other hand, absorbs these pigments but they shine less and look more transparent.

Links

Anna Bohne's and Ann Cox Steedman's website about making frescoes.

Chemistry and Art's websites about fresco and paper making.

Two websites about Michael Wilcox: 1 and 2

Acknowledgements

Many thanks to Anna and Ann Cox, and to Dr. Bordley for recommending Blue and Yellow Don't Make Green by Michael Wilcox, Cincinnati: North Light Books, 1994. The Color Guide and Glossary, by X-Rite was also of good help for this project.