All scales have a maximum weighing and accuracy capability. Scales are sold accordingly and are priced on how accurately and over what range they can weigh.

Sample and production colours are usually weighed in the region of 100g - 200g and 1 - 2 kg respectively. The scale must be able to register in at least 0,1g increments up to 2 plus kilograms.

The most useful scale in a colour kitchen that is not too costly is one that measures up to 3 kilograms in 0.1 g increments. The increments that a scale reads or registers are also seen as the permitted deviation or error of the scale. So if the scale’s accuracy is 0.1g then the acceptable deviation when measuring a 1-kg test weight must only be 0.1g, i.e. the scale could read between 999.9 g and 1000.1 g.

Obviously a scale that registers in 0.5 g increments would have a much larger window of latitude - between 999.5 g and 1000.5 g. One could have a scale that measures smaller quantities accurately up to 1.5kgs and another scale to weigh the larger bulk quantities such as 10kgs.

CHECK THE ACCURACY OF THE SCALE

All good scales have a weighing area or pan that should give you the same weight irrespective of where the weight is applied to the pan. If a 1 kilogram weight is placed in the middle or the corners of the weighing pan, the scales should give the same reading.

If the reading differs depending where the weight is placed, then the scale will not record any additions accurately i.e. a differing weight would be shown depending on where the additions are made to the bucket of ink (front, side or middle). One must be able to place additions anywhere in the bucket and still be able to achieve the same accurate reading.

If the deviation is consistently larger than the permittedincrement accuracy of the scale, then it needs servicing and re-calibration by a technician. For example, if the difference in the weight of the 1kg test weight placed in the center or the edges of the weighing pan gives a weight of 999.5g for a 0.1g scale accuracy, the scale is then out by 0.4g consistently and must be re-calibrated.

CHECK THE SCALES ELECTRONIC TRACKING PROGRAM

All electronic scales are programmed to be able to tolerate and not register a small amount of vibration and wind disturbance. This is called the tracking ability of the scale. The more expensive scales can be programmed to accept various degrees of vibration or wind disturbances depending on the environment that they are in. The less expensive scales have a set standard and “crude” tracking mode.

This tracking mode is operative when the scale is in zero or re-zeroed and accommodates small amounts of drafts or vibrations; it does not “see” the influence of these small disturbances to the pan balance. Some scales “see” minute additions of colour as wind and/or vibration disturbances and the scale subtracts or tracks out this small actual weight i.e. it zeros the scale again even though you have put a little bit of ink onto your scale.

The scale will continue to do this, i.e. show a zero value, when in fact you have added an amount in excess of the increment registration value of your scale. This type of “faulty” or crude tracking program can play havoc with trying to add and record touch colours. As soon as the scale “feels” a definite positive weight, it changes over to the weighing mode and will register any, even minute additions of weight to the pan. This is obviously a good thing in an industrial workshop or printshop but it can have disastrous implications for the colourist in that some scales have the tendency to not “see” small sequential additions of weight.

It is therefore very important to see if your scale tracks out small quantities of pigment addition in order to determine if your scale is suitable for measuring small sequential additions to ink.