The "data" from the colorpHast experiment is in!
What I did:
I solicited colorpHast strips from members of the NB forum and the HBT forum. Only folks from the NB forum actually sent strips. But I still feel that I should post the date here as well:
I then prepared 2 mini mashes by heating 50 ml distilled water to ~60 C (140F) and added 12.5 g pulverized grist. This is a mash thickness of 4:1 (~ 2 qt/lb). After 10 min I cooled these mashes to 25C in an ice bath and tested the pH with a calibrated pH meter. The precision of the pH meter is +/- 0.02. I also took a sample of beer and heated it to 25C for testing.
I then inserted all the strips into this mash, held them in there for about 30s, removed them and blotted the excess liquid before I lined them up on a piece of white pater. On that paper I also placed the color scale. After that I took a picture of that in tungsten light. The pictures were taken in a RAW format and I later color corrected them and adjusted their brightness such that the background in all the pictures has the same color. I made sure that no color adjustments like hue and saturation were active. The final step was using Gimp to assemble pictures that show the strips and the color scale. Those pics are posted below.
What I now like you to do is to look at the pictures and try to match each of the strips to the color scale. Note that there is no number 6. You may use numbers between the numbers shown on the color scale to express cases where the strips may match an intermediate color. I'd also like to to give your match a confidence interval in which you feel. E.g:
1: pH = 5.0 +/- 0.2
Once enough have gone through this exercise I'll collect the data and also reveal the actual pH values measured for the samples.
blank pH strip color:
mash - A:
mash - B:
Let me know if you have more questions about the procedure.