Conclusions:

1. Teslin paper is not a good choice. Regular printer paper gives a good color change but

is flimsy and must be attached to a stick so it doesn’t tear. Watercolor paper gives a good color change and is durable and does not require a stick.

Next step: Test to see if color changes in the pH strip are influenced by the

acidity of the paper.

2. Printing is not a good method due to printer failures. Clogged ink heads are the most

common failure and can be cleaned by disassembling the printer and flushing with vinegar. This will most likely not be viable in Kenya because it happens so often. Printers are designed only for original manufactured ink. Each printer is disassembled differently but the most recent model is take apart like this: https://www.youtube.com/watch?v=E0kDN0ccBZg

3. Alternative methods that have been tested are stamps and Fantastix pens. Stamps are

large and do not transfer a solid area to the paper so are less reliable. Fantastix pens work well but may look sloppy if the person manufacturing the strips is not careful.

4. Manufacturing is the best option. Details of the best manufacturers can be found in the

corresponding Excel file. The best deal I’ve found so far is for pH strips priced at 3.2 cents/strip. Alibaba.com is a great resource for finding manufacturers.

5. The N-(1-naphthyl)-ethylenediamine dihydrochloride solution, used in the Nitrite test, is

only stable for one month

pH Testing Picture: