Nick,

Thanks for the clarification. So the "mass" and not "weight" of solubles is included in the denominator. Since we are using only two significant digits, a strength of 1.0 % should be sufficient.

Another question.... The Control Chart seems to use "Coffee TDS" on the ordinate. I reverse calculated the ordinate, and it appears for the ranges we are interested in, Coffee TDS between 840-1680, and NaCl-ppm of 750-1550, are approximately 800-ppm. The NaCl-ppm appears to be similar scale but 100-ppm lower than Coffee TDS. Why not just relabel the TDS ordinate to NaCl or microSimens (previously labeled micromhos) scale? This way, a simple $20 dollar TDS or microSimens conductive meter can be used.

chang00 wrote:Thanks for the clarification. So the "mass" and not "weight" of solubles is included in the denominator. Since we are using only two significant digits, a strength of 1.0 % should be sufficient.

Well, the only thing you were really missing in your equation was that you can't just plug the water mass in. What you'd want to plug in is the gross mass of the solution, which is basically the water + the mass of the solubles. Granted, that results in 1.22% strength vs. your 1.24%, so yeah... significant digits, but you know what I'm sayin'.

To an earlier point, I have never seen evidence of a loss of mass during steeping. I'm interested to see if I can replicate this.

If you haven't yet, pick up the new SCAA Water Quality handbook. Much is built on the Coffee Brewing Handbook, but it's definitely a gem!