[Boatanchors] Water, Water Everywhere.

[Brian]

Hello Robert,

I suspect we agree that bakelite and similar paper-based products are 
hygrophilic. So, they take up water and grow when the humidity is high, and 
they shrink when the humidity is low. Your heating to 150 F clearly drives 
off trapped moisture, allowing shrinkage. If all such items are kept in low 
humidity areas, they will probably shrink, because paper production is a 
very water-intensive process.

My only concern is that 150 F, plus allowance for temperature excursion of 
your thermostat, may be a bit high. You may start to get thermal 
degradation, eg, loss of adhesive, hardening of resins, and possible 
carbonisation.

73 de Brian, VK2GCE.

On Saturday, December 12, 2015 12:02 PM , Robert said:

Brian,

The problem with the bakelite inserts in the WW-II Large Banana Pin style
connectors that Dave alluded to earlier is that they swell, not shrink.  The
increase in diameter 70 years on in about 250 samples that I have here is on
the close order of 0.002" per inch of diameter.  As found, the inserts are
impossible to remove from the cylindrical bodies without at least an arbor
press.  Sometimes the bodies actually split from the swelling.  Dave
discovered experimentally and I have confirmed numerous times that one to 
two hours
at around 150F followed by cooling to ambient was sufficient to allow insert
removal with only ones thumbs.  Otherwise, in order to reassemble a
connector after using a press to remove the insert required reducing the OD 
with a
lathe.

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480