Making and Testing Conductive Paints

Making Conductive Paint

Through combining “conductive powders/ pigments or particles with paintable mediums” it is possible to make conductive paints, inks and adhesives that “transmit” or “conduct electricity”. This paintable medium has to be one that “will shrink when it dries rather than expand” as this will bring the “conductive particles closer together, rather than further apart”.

An example of a conductive powder is “carbon graphite powder”. This powder is quite “course” and “finer powders” can allow for “better connections”. The amount of the powder added would depend on the paint’s intended end use and on what material the paint would be applied to.

How to get what you want (n.d). How to get what you want. Retrieved from http://www.kobakant.at/DIY/?p=634.

Method of making conductive paint:

Materials:

· “Latex paint

· Metal particles, like graphite powder

· Paint stirrer

· Conductivity tester”

Instructions:

1.     “Select metal particles to mix into your paint. Some choices include silver powder or powdered graphite. Graphite powder may be too course for some uses, so select the right material for your specific need before mixing it into the paint.

2.     Mix a small sample of latex paint with as much metallic powder as possible until it is clumpy. Test the conductivity of the clumpy paint. Add small amounts of paint and stir the sample until the conductivity falls to the level you want. Maintain measurements of the powder and paint used in your sample for future steps.

3.     Paint a small amount of sample paint on a surface similar to the one you intend to use the conductive paint on. Allow the paint to dry and test its conductivity. Adjust the ratios and retest if needed to be improve the conductivity of the material.

4.     Mix the entire bucket of latex paint with as much metallic powder needed to replicate the proportions of paint and powder found to be most effective in Step 3. Stir thoroughly before testing and painting.”

Michaelson, A. (n.d). eHow. Retrieved from http://www.ehow.com/how_8565295_make-paint-conductive.html#ixzz30ZKd96yT.

Testing conductive paints

Once the ink or paint has been produced, testing of the liquid will display how “well it transmits electrical current”. A “conductivity” test will “indicate the level of impurities in the liquid”. The test “requires the resistance, or ability to limit current flow of the liquid and the dimensions of the container holding the substance”. This testing will prevent time being wasted when sampling. We will be sure that the paint made will conduct electricity before applying it to the paper being used. These tests will also enable us to find errors in our samples more easily as we will be able to eliminate the problem of the paint not conducting the electrical current passing through it.

Materials:

· “Rectangular glass dish

· Digital multimeter

· Tape measure


· Calculator”

Instructions:

1.     “Fill the glass dish with the liquid to be tested. For example, the test might be for tap water.

2.     Turn on the digital multimeter and then turn its measurement dial to the resistance setting. The symbol for resistance on the multimeter is a capital letter "omega." The capital omega stands for the ohm, which is the unit of resistance.

3.     Plug the red and black probes into the positive and negative ports of the multimeter, respectively. Touch the other ends of the probes to the water at opposite ends of the length of the dish. The probes should be at the center of the sides of the dish as well. For example, the resistance might be 500 ohms.

4.     Measure the length, width and depth of the interior of the glass dish in centimeters. Centimeters must be used to get the correct result for the conductivity calculation. For example, assume you have a glass dish with a length 30 cm, a width of 10 cm and depth of 4 cm.

5.     Calculate the area, in square centimeters, of the sides at the ends of the dish's length by multiplying its width times its depth. Continuing the example leads to 10 cm times 4 cm, or an area of 40 square cm.

6.     Multiply the resistance by the area. Call this result "X." Performing this step, for the example, leads to 500 ohms times 40 square cm, or 20,000 ohm times square cm for "X.”

7.     Divide the length by "X" to obtain the conductivity of the liquid in siemens per centimeter. Note that the siemens unit equals one divided by the ohm. Now you have, for the example, 30 cm divided by 20,000 ohm times square cm, or a conductivity of 0.0015 siemens per centimeter.

8.     Multiply the conductivity by 1,000,000 to convert to microsiemens per centimeter, because one million microsiemens equals a single siemens. Completing the exercise leads to 0.0015 times 1,000,000, or a water conductivity of 1,500 microsiemens per centimeter.”

Hirsch, W. (n.d). eHow. Retrieved from http://www.ehow.com/how_8530088_test-conductivity-liquid.html

As a reflection of the information being found, we thought that we might find some of the materials challenging to access and therefore started to research additional methods and other possible replacement materials for these harder to find or more expensive materials.

When using iron filings as the conductive powder, they first need to be “magnetized”. This is achieved by rubbing them on a “magnet” then “forcing them off” and into the paint mixture. It is important to think about how a “water based glue” or paint would react with the iron, causing oxidization.

If unable to access graphite, it can be produced by “crushing up some pencil leads” using a “crucible” to ensure the fineness of the new powder. When mixing the conductive materials into the paintable medium, enough needs to be added to create an “almost clumpy” consistency to the “point of saturation” as this will ensure “conductance”.

Mackaay, S. (2009). Steve's Junk. Retrieved from http://smackaay.com/2009/01/13/making-a-conductive-adhesive/.