Catalin : rate of shrinking

[George Pitropakis]

I have been searching this group lately and I found tons of
information about catalin radios. Until now I had never been that
interested in them because I only owned radios of the 20's. All I knew
is that they were expensive, nice looking and fragile sets, at least
their cabinets. These would be condemned to turn to dust shortly… Just
like all of us I guess.

Not a very long time ago my path crossed the one of an extremely nice,
playing, intact Fada Bullet 115 that I bought for a very indecent
price (low, that is), so things changed. I had always considered that
if I found one of them it would directly sell it on Ebay. Now I
changed my mind and I think I will keep it as long as I will enjoy
looking at it more than knowing that there could be some more $$$ on
my bank account instead.

After reading some most interesting discussions, mainly between Peter
Wieck and Mike Schultz, I understand that all agree on the fact that
catalin is shrinking and that is why so many of them are broken. Just
by looking to some pictures there is no doubt about it. Sometimes the
handle can not fall properly into the holes at the top and has to be
left diagonally; the back nearly never fits in the cabinet; only two
screws of the bottom are left in place to avoid any further tension.

I have only one example in front of me so my observations cannot be
considered as rules but I can say that on my radio:

- the back fits in the cabinet, not that there is some space left
though.
- the handle falls very exactly in the holes at the top of the radio.
It is possible that the handle has been shrinking at the same rate as
the cabinet.
- the chassis is very well aligned on the cabinet and the screws can
be easily removed, no pressure on them, no shrinking of the cabinet
compared to the chassis.

So, yes they shrink but not all of them at the same rate, and if all
do shrink it will not be visible in some cases. The storage conditions
could have been an important factor for that difference but I do not
think that it would explain it all. I would imagine that the way the
products were mixed during the making process could be an explanation?

It would be great if someone had the specs of the Fada Bullet 115 and
if we could compare the exact initial size with what we measure today
and point out the differences… Then, is the color making any
difference, year of production ?

Here is the link with the initial discussions.

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=8526-3931D990-23%40storefull-123.iap.bryant.webtv.net&rnum=11&prev=/&frame=on

Thanks to all
George

[Peter Wieck]

>So, yes they shrink but not all of them at the same rate, and if all
>do shrink it will not be visible in some cases. The storage conditions
>could have been an important factor for that difference but I do not
>think that it would explain it all.

You are right. The factors that affect aging of any given catalin radio
include, but are not limited to:

Initial setting process.
Amount of use.
Storage conditions.
Exposure to sunlight, heat, humidity or chemicals.
Initial fit (QC at assembly)
And, of course, Color.

The last issue is important as to whether the pigment is a dye or a solid. Dyes
that bond chemically with the resins will do nothing to lessen shrinkage.
Volatile dyes may even accelerate it. Solids that act as aggregates to the
resins will slow the shrinkage.

The first issue most likely has more to do with the longevity of any particular
example than any other single factor. Catalin is a thermosetting phenolic
resin. The most significant difference between it and bakelite is that Bakelite
(coming from _exactly_ the same chemical precursors)
is first partially set once as a pure phenolic resin, then ground into powder
or fine pellets, then mixed with aggegates (usually sawdust and powdered
pigments), then formed and set again both with heat and pressure. Since it is
not cast in its final form as a liquid (as was catalin), molds can be used over
and over again (typically the catalin mold was destroyed after a single use)
and the finished product can take a much finer level of detail.

Getting back to Catalin: It was typically cast as a liquid in a single-use
mold. The quality of the mold varied, the amount of heat applied during the
setting process might vary, the deburring and prep of the case to receive the
chassis might vary, and the boring of the holes might vary.

So, a case that came from a good mold, got some extra heat in the setting
process for one reason or another, had careful prep, and the bore-holes *just*
right might be much longer-lived than its Monday morning
first-run-from-cold-molds example. And if it were well stored either by
accident or design, even better.

Or, in fewer words: It depends.

http://members.aol.com/pfjw/page1.html

Peter Wieck
Al-Khobar, KSA

[Omer Suleimanagich]

This why wood rules!

A Stradivarius is made out of wood. Wood gives a room warmth with those
vacuum tubes.

I'm sorry that the radio is shrinking, maybe our resident chemist could
recommend an agent to stabilize the catalin body.

Omer

P.S. Perhaps you could find a solution to your problem from the fountain pen
people that are out there
"George Pitropakis" <gpitr...@hotmail.com> wrote in message
news:4345fc2a.04062...@posting.google.com...

> I have been searching this group lately and I found tons of
> information about catalin radios. Until now I had never been that
> interested in them because I only owned radios of the 20's. All I knew
> is that they were expensive, nice looking and fragile sets, at least

> their cabinets. These would be condemned to turn to dust shortly. Just

> and point out the differences. Then, is the color making any

[Sam Byrams]

Maybe someone will do like they do with fender guitars and build a
covert catalin plant and molds and flood the market with
indistinguishable repros, killing the collector value of these usually
shitty old radios.

[Peter Wieck]

Not likely. Catalin is a thermosetting _PHENOLIC_ resin...

Phenol is one of the deadliest precursor chemicals around, not easily handled.
The other ingredients and processes are no backstreet garage operation either.

Well, maybe in China where life is cheap.

[Bruce Mercer]

"Peter Wieck" <pf...@aol.comnopqr> wrote in message ..

> Not likely. Catalin is a thermosetting _PHENOLIC_ resin...
>
> Phenol is one of the deadliest precursor chemicals around, not easily
handled.
> The other ingredients and processes are no backstreet garage operation
either.

One wonders about the dangers people faced when making all of those Diamond
Discs. In Frow's book, he doesn't mention that but does relate the problems
of some pressmen being overcome by the alcohol fumes being given off during
the
pressing of the discs.

Bruce

[Phil Nelson]

To my eyes, Catalin is just a slightly translucent plastic. If I were to
make phonies, I'd use some other plastic that looks the same and can be
manufactured safely. The people likely to buy a phony aren't likely to come
in with a lab kit to confirm that it's really Catalin. Anyhow, the hard
part, in my view, would be economically producing an AA5 chassis.

Selling repros doesn't necessarily kill the value of an original. Grundig
sells modern reproductions of the 960 tabletop, but I would still pay as
much for an orginal 960. You can buy a "replicar" of a Porsche Speedster,
but I'd still pay as much for an original Speedster. And so on.

Just my $0.02 . . . .

Phil Nelson

[maa...@panic.xx.tudelft.nl]

Peter Wieck <pf...@aol.comnopqr> wrote:
> Not likely. Catalin is a thermosetting _PHENOLIC_ resin...
> Phenol is one of the deadliest precursor chemicals around, not easily handled.
> The other ingredients and processes are no backstreet garage operation either.

How did they manufacture it when it was originally used?

---
Met vriendelijke groet,

Maarten Bakker.

[Scott W. Harvey]

On Fri, 09 Jul 2004 20:05:42 GMT, "Phil Nelson"
<philn...@nospam.xyz> wrote:

>To my eyes, Catalin is just a slightly translucent plastic. If I were to
>make phonies, I'd use some other plastic that looks the same and can be
>manufactured safely. The people likely to buy a phony aren't likely to come
>in with a lab kit to confirm that it's really Catalin. Anyhow, the hard
>part, in my view, would be economically producing an AA5 chassis.
>

Check these out:

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010114.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010115.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010116.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010118.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010121.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010123.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010130.jpg

http://techpreservation.dyndns.org/beitman/abpr/newfiles/P1010134.jpg

These are pictures that Daniele recently posted in ABPR. They are all
repros. If these sets look the same in the flesh as they do in the
pictures, then whoever is manufacturing them is doing a stellar job of
imitating the wet-candy look of catalin. Add a matching AA5 chassis
and you have a set that might pass the 10-foot test. Clearly, getting
the look right is not the problem.

-Scott

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[Alan Douglas]

Hi,
Maarten asked:

>How did they manufacture it when it was originally used?

Everything you want to know about Catalin manufacture:

http://www.maarc.org/catalin%20corner/catalin_corner.htm

73, Alan

[Jiri Placek]

Freshly made catalin is a phenolic resin that contains in its matrix
free water and perhaps also salts of neutralizing agents. On a
microscopic scale that may remind somewhat a polyurethane sponge
except the voids that are in this case filled with molecular layers of
water. The catalin resin is not sterically stabilized by a filler
(like bakelite) and behaves as a glass. I am using the word "glass"
in its physical meaning as a description of a material of an extremely
high vicosity that also displays (a) strong dependency of its
viscosity on temperature and (b) a sharp decrease of viscosity at so
call "glass transition temperature". Glass transition temperature is
a physical property that depends on the composition of materialI do
not know what the glass transition temperature of a catalin resin is
but I suspect it will be about 150 deg. C. Viscosity is a measure of
mobility of molecules or aggregates. Systems with high mobility (=
low viscosity) flow easily and vice versa.

Catalin resin is highly viscous at low ambient temperatures so it is
quite stable. With aging there appear small voids in the resin matrix
as the residual water is diffusing out. Surface forces tend to
minimize the surface of voids. The rate of minimizing of these voids
(=shrinking) depends on viscosity. Consequently, a warm catalin resin
will shring faster than a cold catalin resin. Moreover, the rate of
diffusion in polymers is increasing exponentially with temperature.
Hence a catalin resin object will loose water faster at a higher
temperature and it will shrink faster as well. The process is still
quite slow but noticeable within several decades.

I would suspect that another degradation pattern is photooxidation
since in old days there were no antioxidants / free radical scavengers
added to the resin. Hence the discolorization of cabinets with time.

To preserve a catalin radio I would keep it in a cold place with a
high relative humidity an protected from light. A damp basement seems
to an ideal place. :-)

If held in a less inhospitable place I would keep the radio protected
from direct sunlight, apart from heat sources, and with a good
circulation of air if used.

Jiri Placek
Boyertown, PA

gpitr...@hotmail.com (George Pitropakis) wrote in message news:<4345fc2a.04062...@posting.google.com>...

> I have been searching this group lately and I found tons of
> information about catalin radios. Until now I had never been that
> interested in them because I only owned radios of the 20's. All I knew
> is that they were expensive, nice looking and fragile sets, at least

> their cabinets. These would be condemned to turn to dust shortly? Just

> and point out the differences? Then, is the color making any

[Sam Byrams]

Because of the quantity made, there are reasonable stocks of AA5 parts
out there. If I'm not mistaken, at least one parts vendor still sells
a AA5 kit for about $30.