Moisture and Rubber
Astlett Customer Help Sheet
problems with moisture on natural rubber can be corrected.
External moisture may become trapped under the polyethylene
wrapper and, over time, the rubber becomes bleached
and some of it may decompose (become mouldy).
be trapped on rubber surfaces under the polyethylene wrappers
by condensation or dripping of condensation or rain on
the bales/crates, anytime prior to discovery.
of moisture turns rubber white over time (this is called
bleaching). Removal of moisture (drying) returns the rubber
to its dry condition, with no harm done!
Bleaching is reversible and not usually considered harmful.
The heat of processing will also drive off excess moisture.
If the moisture is not removed, bleached rubber is eventually
denatured and then decomposes (mould or rot).
is a surface phenomena. Longer exposure and/or greater
moisture result in greater penetration. Moisture contamination
could and should be detected on receipt at factory. This
will make it possible to ameliorate or completely avoid
Procedures by Receivers
by cutting windows (4" V shaped cuts) in the polyethylene
wrappers in several places on each unit, a receiver can
check for the possibility of any moisture, bleaching or
is discovered, measures should be taken to promote drying
by cutting numerous windows. This lets any trapped moisture
is discovered, more vigorous drying efforts should be
undertaken. Typically, removing the outer liner, windowing
the affected bales, separating or stripping the bales
to expose to airflow and using a fan or heater to speed
drying of the rubber is suggested. The rubber usually
returns to its original processed colour. The quality
is not affected!
If mould is
discovered, the affected surface can be removed by trimming.
Bleached or mouldy bales or pieces can be used for lesser