I find all these tests very difficult to read. I am a house painter I match colors and mix colors all the time. What I do right now is look through the vial at the color card. If I can see no color change I figure that is a match. My nitrate card goes from yellow to orange to red in 7 grades, for instance, So if I look through the vial and the patch looks slightly yellow I figure the test reads a bit higher. If I look through the vial and I see red I figure the test reads a bit lower. If I look through the vial and see no color I figure that is about right. I find that holding the vial next to the color gradient and trying to figure out which color is about right to often be misleading.
Actually I find the whole thing quite arbitrary. I have a two part ammonia test that I have never seen read 0. I just know it doesn't read much. So I ignore it.
Actually I find the whole thing quite arbitrary. I have a two part ammonia test that I have never seen read 0. I just know it doesn't read much. So I ignore it.
