Peggy asks:
Karren, I am wondering if we should go out to two decimal places for our measuring of 1% dye stock solution or if you want us to round up or down to one decimal place? I am hoping to FINALLY do my first dye job tomorrow after math tutoring. Measured my water and the pH is approximately 5.3.
The answer has to do with the balance that you have, all of you can weigh to 0.1g and some of you more. To make a 100 mL of 1% stock you will need to weigh one gram of dye powder, that is 1.0g, not 0.9 nor 1.1g. If we weigh 1.0g we only have two significant figures -significant figures are ones that we really measured. No process using that solution will have more than two significant figures-- it is like the bottle neck. So measuring out volume 83mL has two significant figures, pH 4.7 has two, Glauber's salt 10g (not 10.0g). Contary to some perception this is not precsion work. Careful, yes.
pH 5.3 is quiet acid for tap water, but not suprising since you get your water from the mountians. Add maybe a 1/2 tps./L sodium acetate and just a bit of acid. It will be easy to add too much acid so go slow the first time.