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Measures and records the drying time of surface coating, etc.

The 3-speed Drying Recorders defines stage in the drying process as:

  • The first stage is a pear-shaped impression corresponding to the time taken for evaporation of solvent
  • The second stage is the cutting of a continuous track, corresponding to a sol-gel transition
  • The third stage is an interrupted track corresponding to the surface-dry time
  • A fourth stage is where the needle no longer penetrates the film. Corresponding to the final drying time
  • A typical white enamel would have a drying time expressed as follows:

    1-1/4 __3 -1/2__4 (hours)

    Although all stage recorded are significant it is often sufficient to express a drying time in terms of set-time and hard-dry time, thus: 1-1/4 -4 (hours)
    Brass weights, each weighing 5 g, may be used to apply greater pressure on the needles and thus record the through-drying properties of alkyds, varnishes and paints. The 3-Speed BK Drying Recorder will give useful information about the gelation times of many two component surface coating material and about the properties of such films.


    The drying time is determined by adding the requisite drier and thinning to a viscosity at which the material is normally applied. The finish is allowed to stand at room temperature for 24 hours to mature.

    A test strip measuring 12inch x 1inch ( which may be of plain or ground glass or of other suitable material) is prepared by casting a film upon it by means of a special applicator which is accurately ground at one end to deposit a wet film thickness of .003inch ( 3 mils) and 0.0015inch (1-1/2 mils) at the other.

    The test strips are placed on the table between the brass studs and the instrument is the operated as indicated below.


    The recorder body is robustly constructed from light alloy and the mechanism is mainly stainless steel and brass to avoid corrosion .

    A needle carrier holding six hemispherical ended needle travels the length of the test strip in 6, 12 or 24 hours.

    Other speeds are available to special order.

    The instrument accommodates six test strips 12inch x 1inch. A time scale is mounted on the side cover and is graduated to suit the three different speeds.