[AMRadio] Paint Filler

Donald Chester k4kyv at charter.net
Mon Jan 6 12:16:46 EST 2014

On Mon, Jan 6, 2014 at 9:16 AM, Jerry wrote:

> ... One comment on the bakelite knobs as my
> wife is an expert bakelite collector.  True bakelite or catalin has no
> "filler" it should be bakelite through and through as I believe 
> Dakaware
> knobs are made.  It would have been a difficult and expensive process 
> to
> apply bakelite over a sawdust filler.  There are lots of bakelite 
> polishes
> available the best (also used for testing if bakelite) is simechrome 
> brand.
> I can take any Dakaware knob and polish it to any grade of luster 
> usually
> with elbow grease sometimes a dremel buffer wheel.   I think one 
> problem is
> that bakelite was replaced for knobs around the 1950-1960's so many 
> later
> knobs were made of a duller non-bakelite plastic and given a paint 
> coat for
> final luster.

"Bakelite, named after Baekeland, its Belgian inventor, has been 
described as one of the most gorgeously tactile materials ever made; it 
is hard and glossy yet capable of being moulded into fine detail. When 
new it carries a lustrous sheen which is difficult to better, even in 
black, which is otherwise a pretty lifeless colour.

... What a shame then that the lustre vanishes all too fast. So many 
artefacts made of bakelite seem to lose their gloss and end up brown and 
porous. It doesn't seem to have anything to do with the age of the item, 
so why does this happen and what can be done about it? First, let's look 
into the technology. Bakelite is a thermoset plastic, that is a plastic 
which starts molten as a liquid but once solidified, does not revert to 
its liquid state when heated. In crude terms it consists of a resin 
(which has the glossy appearance) plus a bulk filler material, usually 
wood flour. The shiny surface you see and admire is the top layer of 
resin but this is often very thin. Once rubbed away through atmospheric 
action, over-enthusiastic polishing or by scorching in the sun's rays, 
it is lost and nothing will bring it back. You are then left with a 
pitted mixture of resin and wood flour (or asbestos powder) and wood 
flour, being very fine sawdust, is not a particularly glossy material. 
It is this wood flour that looks brown and porous once exposed."


Bakelite is a commercial BRAND name. The generic term is "phenolic", of 
which Bakelite is a specific formulation:

"I know bakelite was the predecessor to phenolic resin, or something 
along those lines. Do they perform the same? Is there a big difference 
between them, or is this just a companies way of getting around the 
BCAPL ban on phenolic tips?"

"Bakelite is a type of phenolic compound. In the early 1900's Leo 
Baekeland developed the first artificial plastic. Baekeland's discovery 
was a phenolic resin which he named 'Bakelite'. Bakelite was not 
explosive or flammable, it was easy to work with, and more importantly, 
its playing characteristics were very similar to ivory.

Bakelite is the result of a polymerization process, between phenol and 
formaldehyde heated together. The reactions are complex, but the final 
result is a hard "plastic" made of cross-linked polymer chains. Modern 
phenolic resin is made from thermosetting resins, obtained thru the 
chemical reaction of phenols and simple aldehydes.

Bakelite was the first true synthetic plastic material (having no 
natural analogs). It was used for billiard balls, piano keys and knife 
handles from 1907, and rapidly replaced ivory. From 1920, it was used in 
a wide variety of products. Bakelite quickly became the material of 
choice as a replacement for ivory for billiard balls. It would go on to 
fame as "the material of a thousand uses".


> Jerry
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Donald Chester
> Sent: Monday, January 06, 2014 00:24
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] Paint Filler
> I purchased "Lacquer Sticks" from Antique Electronic Supply in Tempe 
> AZ,
> Tubesandmore.com. They were available in white, gold and maybe some 
> other
> shades. Similar to white wax crayons, including the paper jacket and 
> texture
> of the marking agent, but the stuff smelt more like paint. I think I 
> still
> have mine, but they may have dried out by now.
> I used them to fill in the scales on old Bakelite dials, like the 
> National
> type A and dials from 1920s era TRF receivers, and after more than 20 
> years,
> the paint hasn't flaked out. I would mark over the scale, then 
> carefully
> wipe away the excess with a soft cloth, like an old T-shirt. Sometimes 
> it
> took several passes to completely fill the impressions but completely 
> remove
> excess on the rest of the dial, since wiping off the excess sometimes
> removed some of what was in the grooves.
> Not  sure if they still sell it, but look up their web page to find 
> out.
> A possible substitute would be to pour out a few drops of white 
> oil-based
> paint, and let it sit exposed to the air,  until it thickens to a 
> gummy
> consistency, then use it like the lacquer stick described above.
> A couple of notes of caution, speaking from experience: when renewing 
> those
> old dial scales. NEVER use a sharp metal object like a steel pin or 
> the
> point of a nail to remove the old paint. It will scratch the 
> engravings, and
> that damage is very evident when the new filler paint is applied. Use 
> a
> sharpened toothpick or piece of plastic, something that is softer than 
> the
> Bakelite on the dial. If you are the least in doubt, test on the back 
> side
> of the dial, and if the point leaves a scratch, look for something 
> softer.
> And never use an agent like 409 or Fantastik to clean the dial. It 
> will
> dissolve and wash off the skin from the Bakelite, exposing the filler
> (probably fine sawdust) and permanently remove the shine.
> Don k4kyv
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