[Richard Knoppow]

At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. While it appears to be still
available its hard to find.
What I did was to dissolve polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old commercial
coil dope.
The result is that the stuff works fine. The solvent
will dissolve an amazing amount of the polyfoam, probably
because its mostly air. After I got the stuff to a good
honey-like consistency I tried it. It dries hard in about
ten minutes. Polyfoam is polystyrene which has excellent
dielectric properties. This is what the commercial coil
dopes were made of.
Both solvents are available from hardware or paint
stores and are cheap. The polyfoam can come from styrofoam
cups but shipping material is the same stuff and is often
just tossed away. All that matters is that its clean.



--
Richard Knoppow
Los Angeles
WB6KBL

[[email protected]]

On Feb 13, 7:41*pm, "Richard Knoppow" wrote:
* * *At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. While it appears to be still
available its hard to find.
* * *What I did was to dissolve polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old commercial
coil dope.
* * *The result is that the stuff works fine. The solvent
will dissolve an amazing amount of the polyfoam, probably
because its mostly air. After I got the stuff to a good
honey-like consistency I tried it. It dries hard in about
ten minutes. Polyfoam is polystyrene which has excellent
dielectric properties. This is what the commercial coil
dopes were made of.
* * *Both solvents are available from hardware or paint
stores and are cheap. The polyfoam can come from styrofoam
cups but shipping material is the same stuff and is often
just tossed away. All that matters is that its clean.

--
Richard Knoppow
Los Angeles
WB6KBL


Dissolve the polyfoam in gasoline and what do you get? Napalm!

Paul, KD7HB

[Richard Knoppow]

" wrote in message
...
On Feb 13, 7:41 pm, "Richard Knoppow"
wrote:
At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. While it appears to be still
available its hard to find.
What I did was to dissolve polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old
commercial
coil dope.
The result is that the stuff works fine. The solvent
will dissolve an amazing amount of the polyfoam, probably
because its mostly air. After I got the stuff to a good
honey-like consistency I tried it. It dries hard in about
ten minutes. Polyfoam is polystyrene which has excellent
dielectric properties. This is what the commercial coil
dopes were made of.
Both solvents are available from hardware or paint
stores and are cheap. The polyfoam can come from styrofoam
cups but shipping material is the same stuff and is often
just tossed away. All that matters is that its clean.

--
Richard Knoppow
Los Angeles
WB6KBL


Dissolve the polyfoam in gasoline and what do you get?
Napalm!

Paul, KD7HB

A helpful hint:-) I thought it was soap but I've never
seriously wanted to make any napalm.



--
Richard Knoppow
Los Angeles
WB6KBL

[Richard Knoppow]

"Richard Knoppow" wrote in message
news

" wrote in message
...
On Feb 13, 7:41 pm, "Richard Knoppow"
wrote:
At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. While it appears to be still
available its hard to find.
What I did was to dissolve polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old
commercial
coil dope.
The result is that the stuff works fine. The solvent
will dissolve an amazing amount of the polyfoam, probably
because its mostly air. After I got the stuff to a good
honey-like consistency I tried it. It dries hard in about
ten minutes. Polyfoam is polystyrene which has excellent
dielectric properties. This is what the commercial coil
dopes were made of.
Both solvents are available from hardware or paint
stores and are cheap. The polyfoam can come from
styrofoam
cups but shipping material is the same stuff and is often
just tossed away. All that matters is that its clean.

--
Richard Knoppow
Los Angeles
WB6KBL


Dissolve the polyfoam in gasoline and what do you get?
Napalm!

Paul, KD7HB

A helpful hint:-) I thought it was soap but I've
never seriously wanted to make any napalm.


Turns out we are both right. Modern napalm has
polystyrene in it, the original used a sort of metallic soap
as the thickening agent. See:

http://en.wikipedia.org/wiki/Napalm

I still have no desire to make any.

--
Richard Knoppow
Los Angeles
WB6KBL

[Avery Comarow]

On Feb 13, 10:41*pm, "Richard Knoppow" wrote:
* * *At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. ...What I did was to dissolve polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old commercial
coil dope.

Richard Knoppow

Proportions, please?

[Scott Dorsey]

Avery Comarow wrote:
On Feb 13, 10:41=A0pm, "Richard Knoppow" wrote:
=A0 =A0 =A0At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. ...What I did was to dissolve polyfoam shippi=
ng material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old commercial
coil dope.

Richard Knoppow

Proportions, please?

When I was a kid, we just added styrofoam to toluene until we got about the
right viscosity. I have coils that I varnished with that stuff thirty years
ago which are still just fine.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Knoppow]

"Avery Comarow" wrote in message
...
On Feb 13, 10:41 pm, "Richard Knoppow"
wrote:
At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. ...What I did was to dissolve
polyfoam shipping material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old
commercial
coil dope.

Richard Knoppow

Proportions, please?

Mostly MEK. I added a little Xylol (AKA Xylene) because
I thought I saw it listed in an MSDS for coil dope. However,
the MSDS for the General Cement product lists only MEK
although the thinner is Toluene. If I do it again I will use
straight MEK. I added the styrofoam until the stuff got to
what seems to be the right consistency, about like honey.
Mine came out a sort of gray color rather than clear but the
pictures of the General Cement Q-Dope also look gray. My
styrofoam was scraps of shipping material from something I
mail ordered. It is amazing how quickly it dissolves, at
least at first. I used a small, wide-mouth, bottle I got
years ago. I would test the cap of any container you plan to
use with a little MEK to make sure it will not be attacked.
MEK is a rather wide spectrum solvent which will dissolve
latex and a number of other substances.
I will make some measurements when I have a little time
to see if my dope affects coil Q. Commercial dope has very
little effect.
MEK is available at any paint or hardware store and
styrofoam abounds. One can use styrofoam cups but I think a
sufficient supply can be found free.
I tried making my own after working on an old
Hewlett-Packard signal generator (606-A) where the high band
coils must be fastened down with it after adjustment. I
found none of my usual local suppliers had the stuff. I have
since found that Action Electronics, in Anaheim CA carries
it but that is a 30 mile drive from here. So, I decided to
make my own.



--
Richard Knoppow
Los Angeles
WB6KBL

[Dave Smirkenberg]

On Feb 15, 10:25*am, (Scott Dorsey) wrote:
Avery Comarow wrote:

On Feb 13, 10:41=A0pm, "Richard Knoppow" wrote:
=A0 =A0 =A0At some time in the recent past there was a discussion
in this or the antique radio group about coil dope. As a
result I tried making some. ...What I did was to dissolve polyfoam shippi=
ng material
in a mixture of MEK and xylol. I chose these two solvents
because both were listed on the lable of some old commercial
coil dope.

Richard Knoppow

Proportions, please?

When I was a kid, we just added styrofoam to toluene until we got about the
right viscosity. *I have coils that I varnished with that stuff thirty years
ago which are still just fine.
--scott

--
"C'est un Nagra. *C'est suisse, et tres, tres precis."

Tolulene runs about 13-15 bucks a gallon at Home Depot, Menards, etc.
You won't ever run out of it if you buy a gallon can!
On top of that, a trick many racers use is to add some to gasoline to
up the octane. In Baja races in Mexico you never know what the octane
of the stuff you are getting may be.

I have digressed, I see...a habit as I age. In any case, I have also
mixed a small amount of tolulene with dried up tubes of plumbers goop
in order to reactivate the stuff. Afterall, drying goop is because of
the evaporation of tolulene in the first place.

[David Griffith]

Richard Knoppow wrote:

Richard Knoppow

Proportions, please?

Mostly MEK. I added a little Xylol (AKA Xylene) because
I thought I saw it listed in an MSDS for coil dope. However,
the MSDS for the General Cement product lists only MEK
although the thinner is Toluene. If I do it again I will use
straight MEK. I added the styrofoam until the stuff got to
what seems to be the right consistency, about like honey.

A word of caution to anyone considering this: when starting this
procedure, fill the container only a third of the way with MEK. All
that polystyrene needed to thicken it up to honey-like consistency will
increase the volume a lot.

I have a half-pint mason jar that started with a third of MEK. I fed it
one and a half letter-sized inch-thick slabs of foam and it's still not
done.

--
David Griffith
--- Put my last name where it belongs

[Richard Knoppow]

"David Griffith" wrote in message
...
Richard Knoppow wrote:

Richard Knoppow

Proportions, please?

Mostly MEK. I added a little Xylol (AKA Xylene)
because
I thought I saw it listed in an MSDS for coil dope.
However,
the MSDS for the General Cement product lists only MEK
although the thinner is Toluene. If I do it again I will
use
straight MEK. I added the styrofoam until the stuff got
to
what seems to be the right consistency, about like honey.

A word of caution to anyone considering this: when
starting this
procedure, fill the container only a third of the way with
MEK. All
that polystyrene needed to thicken it up to honey-like
consistency will
increase the volume a lot.

I have a half-pint mason jar that started with a third of
MEK. I fed it
one and a half letter-sized inch-thick slabs of foam and
it's still not
done.

--
David Griffith
--- Put my last name where it
belongs

I started with about half the jar filled with MEK.
Since I used styrofoam the displacement of the material
before it dissolves is much greater than after because so
much of it is air. The first pieces dissolved very quickly,
in fact it looked like Alka-Seltzer dissolving. Toward the
end it took a few minutes for each additional piece to
dissolve. The total amount is amazing until you remember
that its mostly air. After the first flurry of very quick
solution I added pieces about twice a day and just let it
alone between times. Of course with the cap on, MEK will
evaporate very quickly.


--
Richard Knoppow
Los Angeles
WB6KBL