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close this bookAudio-visual Communication Handbook (Peace Corps; 1989; 134 pages)
View the documentIntroduction
Open this folder and view contentsPlanning instructional materials
Open this folder and view contentsUsing media
Open this folder and view contentsPresentation methods and materials
Open this folder and view contentsBasic production Techniques
Open this folder and view contentsWriting
View the documentAppendix 1 - An example of the four steps in planning
View the documentAppendix 2 - Evaluation procedures
View the documentAppendix 3 - Communication factors in family planning
View the documentAppendix 4 - Formulas
View the documentAppendix 5 - Equipment construction plans
View the documentAppendix 6 - Sample illustrations
View the documentAppendix 7 - Lettering patterns
View the documentAppendix 8 - Media comparison chart
View the documentAppendix 9 - Notes on the use of audio-visual equipment
View the documentAppendix 10 - Sources of information

Appendix 4 - Formulas

Hectograph Formulas

Printing Surface Formulas Ingredients


1 part fish or animal glue
2 parts water
4 parts glycerin


1. Break the glue into small pieces and put them into a can with the water to soak for two hours.

2. Place the can of water in a pan with boiling water (the double boiler principle) to prevent burning. Continue to boil the water and stir the glue constantly until it is totally dissolved.

3. Add the glycerin and continue to heat for 15 minutes, stirring occasionally. Adding an ounce of sugar for each quarter pound of the mixture will give a better consistency.

4. Pour the mixture into a flat, shallow pan made of metal or wood. Straining through a loose-weave cloth will eliminate any dirt particles. After a few hours the printing surface will be ready to use.

Other satisfactory combinations are:


glue, 12 grams
gelatin, 2 grams
water, 7 1/2 grams
sugar, 2 grams
gelatin, 10 grams
sugar, 40 grams
glycerin, 120 grams
barium sulfate, 8 grams

Ink Formulas


alcohol, 22 cc
water, 14 cc
indigo blue, 2 grams
saffron, methyl green, and other colored dyes may also be used.

Making Chalk

If chalk is difficult to find, you may be able to make your own when the right type of soil is handy. You probably won't be able to find it in a pure form, but chalk may be an ingredient of any white to buff colored soil including rocks that are easily crumbled. This is how James Cole, an educational advisor in Haiti, describes the process:

1. Shovel up some likely-looking soil into a bucket or other container, leaving room for about four times as much water as soil.

2. Pour in the water and stir vigorously. Crumble large pieces and dissolve as much soil as possible but do not try to pulverize hard rocks.

3. Allow the soil to settle overnight.

4. Pour the water off the top and skim off the top layer of silt. This is usually several inches thick, and is "chalk" in a liquid state.

5. Put it in a bag made of muslin or similar cloth and let it drip overnight. To speed this process, the water may be squeezed out.

6. Roll the chalk, which now resembles clay or bread dough, into long, snake-like pieces, cut to desired lengths, and let dry.

If your soil is the right kind, you have chalk. Test it. If it does not write well, seek other soil samples, but don't overlook the possibility that you may have discovered something which has other uses.

Making Dyes and Paints

The materials for making many different colored dyes are available in local markets. Laundry bluing is one readily available material.

A wide variety of roots, bark, seeds, and leaves can be used to make dyes and paints. In general, the procedure for making dyes is to boil the vegetable matter in water until the desired color is obtained. Check with the local dyers and chemists to learn what color dyes can be produced from local materials.

Paint similar to poster colors can easily be made from commercial or homemade dyes. Mix the dye with a thin glue solution and powdered clay to give it body. Ground charcoal can be used in place of the dye to make various shades of gray paint. Blackboard paint can be made with:


1 part lamp black
1 part varnish
1 ½ parts of kerosene

Mix thoroughly before using to disperse the lamp black.

Making Rubber Cement

Start with five grams of raw sheet rubber and 250 cc (about a pint) of uncolored gasoline. Use the translucent brown sheet rubber, if available. Put the rubber and gasoline in a jar with a screw top. Let it stand for a few days. Stir thoroughly and the adhesive is ready to use.

It the cement is a bit thin, add more rubber; if too thick, add more gasoline. If uncolored gasoline is not available, filter colored gasoline through a charcoal filter several times to remove the color.

Whether you buy rubber cement or make your own, it should be stored in a brown jar with a tight fitting lid or some reasonable equivalent because light and air can cause it to spoil.

Model Making Materials

Many materials will work well. What to use depends on availability and personal preference. Following are several possible modeling materials.

- Mix equal quantities of flour and salt. Add water and continue mixing until a ball of dough forms. Liquid or powdered colors can be added when mixing.

- Shred newspapers or paper towels. Mix with any starch paste and knead thoroughly.

- Dissolve a half pint of starch paste in water to thin slightly; add three quarters of a pint of plaster; add one pint of sawdust; knead to consistency of tough dough.

- Soak small pieces of newspaper in water overnight; rub wet paper between palms of hands until it is ground to a pulp; mix a quarter teaspoon of glue in half a pint of water; add one pint of plaster; two pints of wet paper pulp, and knead to a doughy consistency.

- Mix a half pint of dry clay powdered and sifted through a screen with one teaspoon of glue in a cup of water; add wet paper pulp and knead to a doughy consistency, adding more water as needed.

- Powder mud from an ant hill and mix with water.


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