Why is Optrols hydrometer float so large?
The etchants to be controlled have many tiny gas bubbles similar to soda pop. These will cling to a float and cause a small bouyancy error. To minimize this error the bouyancy of the float volume must be much larger than the variable bouyancy of the surface bubbles. The volume to surface ratio is proportional to the float diameter. We use a large enough float diameter to easily give the +/- 0.1 degrees Baume precision needed.
