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

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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.

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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.

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

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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.

4 Replies to “Testing pH”

  1. Would it be possible to test some paper samples? Such as standard white Filofax paper and Filofax cotton cream paper, when we asked Filofax they were unable to confirm if the paper was PH neutral or not.

    1. Hi Steve,

      Yes I could certainly test the pH – I think I have some filofax white paper, but no cotton cream – I’ll see if I can get some. The pH testing part should be no problem at all! I’ll get back to you on my results!

      Maudie 🙂

  2. I just read this post, and your pH results post also. Very interesting!

    Are you sure you didn’t effectively test the water penetration of the two paper products? Bright white paper is smoother and can have a coating on it, both of which would slow water penetration and alter your results…

    1. Hi Chris, thanks for the message. Both types of paper were thoroughly humidified prior to pH testing, so when applying additional water for the test, it did not sit on the surface with either sheet.

      Hope that helps and best wishes,
      Maudie

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