A Dyehouse Laboratory Manual – Part 2
Andrew Filarowski, SDC Technical Officer
This article describes some of the principles and practices that are required in a dyeing laboratory, in particular
the measurement and control of temperature and pH. general health and safety guidelines and other general
good housekeeping practices.
During many preparatory, dyeing and finishing processes, temperature control is important. For example
– scouring is carried out at
– dyeing is carried out at
– reduction-clearing is carried out at
Temperature measurement in °C is carried out using either
a. a ‘mercury in glass’ thermometer.
b. an electronic thermometer
A thermometer is a delicate instrument and should never be used as a stirrer. The thermometers typically in use
in a dyeing laboratory are in the range 10–100 °C or 10–250 °C.
It is a good idea to have all thermometers calibrated before use.
Warning: if you break a thermometer, seek advice on cleaning up the mercury as it is hazardous to breathe the
7.2 Temperature control
Good temperature control is important when carrying out preparatory, dyeing or finishing processes.
In an effort to provide accurate control of temperature, the following points should be noted:
– remove or reduce the heat supply to the equipment 5–10 °C before the desired temperature is reached. This
will help to prevent over-shooting.
– keep a check on the temperature once the required temperature has been reached, making adjustments to the
heat supply as necessary to maintain the required temperature.
– if the equipment is being heated indirectly e.g. in a water bath, it is usually necessary to heat the heating
medium (in this case, the water) to a few degrees higher than the required temperature in order to allow for the
temperature difference between the hearing medium and the liquor being heated.
7.3 Methods of Heating
Heating methods can be divided into two types: