Q. Why would anyone use locking compound on plastic?
A. Because they think it will lock parts together without the
risk of cracking when overtightening.?? (You advised locking
compound with nylock nuts.)
People generally use too much compound, only a minute amount in
the thread space is needed. If excess runs off onto plastic parts
then they can disintegrate over time. There are a very wide range
of plastics nearly all of which are compounds with various
additives to improve moulding properties, colour, flexibility and
toughness so the reaction to compound solvents is hard to predict.
People may think that Plastics are solids and impermeable however
that's not true for many plastics. Nylons absorb water for example
as do some uncured silicone rubbers which " set" through their
bulk? by exposure to water.
Thread locking compounds set to a plastic mass when squeezed
between metal surfaces, the exclusion of oxygen and the presence
of metal ions trigger the reaction. So the compound cannot work on
plastic parts but the solvents may enter microcracks in plastics
and cause extensive damage to some plastics. Obviously the product
is supplied in a plastic bottle -not all plastics are at risk!
See
A safer option is to use two nuts, the second being used as a
lock-nut.
73, Alan G8LCO.
