Preparation of Binders

 


            In order to prepare a paint that can be used for protective or decorative purposes, a dry pigment must be mixed with some sort of vehicle that holds the pigment in solution so it can be spread evenly over a surface.  This vehicle is called a binder. The binder anchors the pigment to the surface and prevents flaking.  Depending on the binder used, the resulting paint may be transparent or opaque.  Binders must be tough, flexible, durable, and they must dry in a reasonable amount of time.

            In this lab, you will prepare three binders and describe their physical properties.

 

 

Part I. Preparation of binders.

 

Watercolor Binder: Gum Arabic

1.      Place 4 mL of water in a 100-mL beaker.  Add 4 g of sugar and stir to dissolve.

2.      Stir in 6 mL of glycerin and 20 mL of Gum Arabic solution.  Add three to four granules of Alconox (a lab detergent) and mix well.

3.      Pour the prepared binder into a small plastic cup.

4.      Paint a small amount of the Gum Arabic binder under its name in the data table.  Record the viscosity, texture and color of each binder.

5.      Label the lid of the cup with the name of the binder and your name.  Seal tightly.

 

 

Oil Paint binder: Linseed oil and turpentine

1.      Combine 4 mL of linseed oil with 8 mL of turpentine in a small plastic cup.  Mix well.

2.      Paint a small amount of the linseed binder under its name in the data table.  Record the viscosity, texture and color of each binder.

3.      Label the lid of the cup with the name of the binder and your name.  Seal tightly.

 

 

 

Tempera Binder: Glue

1.      Fill a small plastic cup one-third full with Elmer’s Ò glue.

2.      Using a pipette, add water dropwise until the desired consistency is reached.

3.      Paint a small amount of the glue binder under its name in the data table.

4.      Label the lid of the cup with the name of the binder and your name.  Seal tightly.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Data Table

Binder

Viscosity

Texture

Color

Adhesion

(ability to adhere to surface)

Gum Arabic

 

 

 

 

 

 

 

 

Linseed Oil + Turpentine

 

 

 

 

 

 

Glue

 

 

 

 

 

 

 

 

 

 

Conclusion Questions.

1.      Evaluate each binder for the physical properties listed in the table.  You may have to wait until the next day allowing time for the binder to dry in order to evaluate the quality of adhesion.

 

2.      Describe which combination of pigments and binders make the best paints. Is the same binder the best to use for all the pigments?  Explain.

 

 

 

 

Preparation of Binders

 

Setup Sheet

 

For a class of 20 students working in sets of 2.

 

60                2-oz plastic cups with lids

10                100-mL beakers

10                stirring rods

10                25-mL graduated cylinders

10                10-mL graduated cylinders

10                paint brushes

 

balances

markers to label cups

 

Instructor’s Notes

 

Watercolor Binder: Gum Arabic

 

Gum Arabic can be ordered from Kremer Pigments. 1-800-995-5501 to order catalog.

 

Gum Arabic stock solution:

1.      Combine 1 part by volume gum Arabic (25mL) with 2 parts by volume (50mL) boiling distilled water.

Remove from heat and stir to dissolve the gum.

2.      Allow the solution to cool and strain through cheesecloth into a screw-top storage jar.  Store in the

refrigerator.

 

Suggestion: Instead of measuring the linseed oil, turpentine, gum Arabic and glycerin in a graduated cylinder, use disposal pipettes.  Determine the volume that one squeeze of the pipette will deliver and adjust the volumes in procedure to indicate the number of required pipette squeezes that are needed to deliver equal volumes of substances.