Hi Pop,
You're very perceptive. Yes in-deedy, if a scale is off by 2% then
all readings will exhibit that same degree of inaccuracy which simply
means that your entire recipe will be scaled up or down by the
percentage of inaccuracy. Also, keep in mind, that +/- 2% is the
maximum deviation. In most cases the actual deviation will be
significantly less than that. So in reality, as long as it's within
tolerance it's no big deal.
Before retiring, I worked as an industrial process-control engineer
for 35 years. We were much more interested in repeatability than we
were in accuracy. Repeatability is the ability of a measurement
device to always come back to the same output value each time a given
input value (in this case the input value is weight) is
provided. Simply put, take your scale, place upon it some object
that is below the maximum allowable weight for that particular scale
and record the scale's digital reading. Remove the object (the scale
should go back to zero) then place the object on the scale again and
record the digital reading once more. Do this about 10 times and see
how much deviation there is. I'll betcha there's not one iota of
difference. And if that's the case your scale's good to go.
Happy baking!!
Brett Baker