The pH of Filofax Paper

Well today I sidetracked a little from my Essay book, to do some pH testing on Filofax paper. I had discussed this briefly with Steve from Philofaxy, and decided to try both the cotton cream paper and white paper. For accurate testing, I sampled five sheets of each and am showing my results below.


Cotton Cream
1: 7.6
2: 8.1
3: 7.9
4: 7.7
5: 8.1
Average: 7.9

White Paper
1: 7.2
2: 7.5
3: 7.2
4: 7.0
5: 7.3
Average: 7.2

So in conclusion, both papers are very close to pH neutral which is encouraging. The Cotton Cream is a little more alkali at 7.9 than the white paper.

Neither of them are verging on the acidic side which is good, and the white paper I have used is from 2003, so it has kept acid free for a substantial amount of time.

All in all – very encouraging!


Testing pH

Similarly to the recent post on paste, this is another self indulgent post, designed to remind myself of techniques I have used for the future when my brain starts to forget them!

pH is necessary to test on any number of occasions, for any number of reasons. Our recent washing and bleaching session saw us testing the pH of paper before and after doing experiments on the pages of a book. There are are also various methods of testing pH, though I am only looking at the one here at the moment.

Testing pH using a Probe Meter


Before starting to test the object, the machine must first be calibrated. Once calibrated, it can be used for a day or so, but after leaving for a period of time, it must be calibrated again. The picture shows two pippett jars and two small pots. One jar has an acidic solution with pH of 4, and the second with a neutral pH of 7. A small amount of each solution is put in each small pot and the pippett jars can then be put to one side.


The probe is kept in an airtight pot with a small amount of deionised water to keep it safe. The next step is to remove the probe and dip it into the pH7 pot. At this point the machine should then be altered so that the dial rests on 7. The probe is then washed with deionised water and dipped in the pH4 pot, again the dial should be moved to meet four.


This is repeated until the dial no long needs to be moved. The machine should now be calibrated.


Once calibrated, it is very simple to test the pH. Although one stipulation for this method is that the tested item has to be wet. If testing a dry object, a drop of water can be dropped onto the object and left to soak in. The probe is then rinsed in deionised water and placed on the object, and the reading taken.

Obviously one negative point of this process is that there is the possibility of tidelines, so if it is possible to test whilst humidifying anyway, the risk will be much reduced.