[Heathkit] TUBE CEMENT??

[Tom NØJMY - AAR7FV]

Well, as long as the glue question came up...this is what I got from 
Mark, W1EOF, who in turn, got it from Lud Sibley:

"The usual base cement was "No. 6," AKA "C6."  The official recipe for 
this
was:

D3 Durite 7.5 lb.
S15 Shellac    19.5 lb.
R3 Rosin  3.25 lb.
M3 Marble flour     170.0 lb.
A4 Alcohol     9.0 l.
M19 Malachite green 10.0 g.

Makes 200 lb., or enough to base 23,500 Type 50s at 0.0085 lb. each. 
Basic
recipe is in Standardizing Notice 34C-C-6 ("Confidential") of 12-29-48. 
No.
6 was used in transmitting tubes too:  814s, 860s, etc., and CRTs (7BP7,
etc.).  The bills of material for "modern" tubes (post-'30s) didn't 
specify
the type of cement, but I've seen no sign of a change up to the end.

The "Durite" was Durite Resin #275, from Stokes & Smith of Philadelphia, 
not
further defined, bought in 50-lb. pails.

The curing process required a cement temperature of about 150øC.  (This, 
vs.
the blistering temperature of bakelite at about 190øC.)  The heating
schedule varied:

CRTs:  heat 10 min. cool 1.5 min.
813s:  heat 3-« min., cool 1-1/3 min.
8025s:  heat 5-« min., cool 1-« min.

The color change in the malachite was considered only a rough indicator 
of
temperature; it was backed-up with a thermocouple thermometer.

There was a slightly modified cement for top caps, with the same 
ingredients
but using fine and coarse marble flour.

For use in very large tubes like 207s, where excess heat might crack the
seals, there was a low-temperature cement.  It was made of "BR-51 
Resinoid"
(bought commercially), acetone, and marble flour.  It was for only 
purely
cylindrical seals, and cured at 50øC."

Whew!  Aren't you glad you asked?  Personally, I use a tiny amount of 
"Gorilla Glue" (tradename) available at most any hardware store.  Never 
a failure yet.

73,
Tom