Michael Wendt on wed 11 nov 09
09 (#2009-312)
Daryl,
The main concerns when making glazes is whether the scale is
linear in its behavior, not if it is calibrated to reference
weights and whether it is repeatable in its measuring
function.
To check for linear behavior, accurately weigh out 10
samples one at a time, each the same weight (say 1/10 the
scale capacity) and then add them one at a time to the
scale pan and chart the displayed weight.
If 2 actually weigh double the originally displayed weight
and 3 weigh 3 times the originally displayed weight ... and
so on all the way to capacity, then the scale is performing
linearly and is also demonstrating repeatability.
I use Ohaus D-50 and D-100 electronic scales in the studio.
The bureau of Weights and Measures checks them annually
since they are trade legal. Years ago, I bought 15 LBS of
lead shot and filled different sized plastic jars with some
of our key weights and labeled them. For those key weights,
the check is to place it on the zeroed scale and see what
the reference weight weighs. This approach eliminates
calibration errors if each time you place a known weight on
the scale it displays the same value even if that value is
wrong.
Regards,
Michael Wendt
Daryl wrote:
I made some glazes that did not come out accurately. I think
it might be that my digital scale was moved and was not
recalibrated. Does anyone have experience calibrating them?
Do I need to buy weights to do this? Any help would be
appreciated. Or should I just go buy a triple beam scale????
Daryl
| |
|
