Document Authentication Using Security Ink and Chemical Reactant

A method of document authentication, comprising:

• applying a neutralizer security ink to a paper document to be authenticated, the neutralizer security ink neutralizing a reactant in the paper document;
• and
• applying a test solution to at least a first area on the paper document to be authenticated where the neutralizer security ink has been applied;
• wherein the application of the test solution to the first area results in no color change in the first area due to the neutralization of the reactant in the paper document, and application of the test solution to a second area where neutralizer security ink has not been applied results in color change in the second area due to a chemical reaction between the reactant and at least one component of the test solution.

A method of document authentication, comprising:

• applying a color changing security ink to a paper document to be authenticated, the paper document having a coating, and the color changing security ink having a first security color and a second security color;
• applying a test solution to the paper document to be authenticated;
• and
• identifying the paper document as authentic when the application of the test solution to the area where the color changing security ink has been applied causes the color changing security ink to change from the first security color to the second security color.