Stupid bakelite question

[atomicomatic]

So I hauled a 1953 Sears Silvertone TV set home today, and began my normal cleaning routine. Knobs, bezels, and finally the chassis.

Low and behold, while painting the numbers on the channel selector knob gold, I got a little paint outside one number. Being picky, I took nail polish remover (I know, dumb idea, but it has worked on brown bakelite for me before) and cleaned that spot. I rinsed it off with water, and there is a white "film" on it now. I can scrape it off with my nail easily, but once it touches water, it comes right back.

I tried crest toothpaste, various polishes, and just cleaning it with a rag. The sheen refuses to come back. I'm hoping I'm just not SOL.

Does anyone have ANY clue how I could fix this? Finding a knob for this is going to be a pain, I would really like to use this one again.

Also, if I can't fix it, does anyone have a spare channel selector knob from a 1953 Sears? Looks like the one in this picture.

http://www.ebay.com/itm/1953-SILVERT...item51a2012d97

Thanks to anyone who replies.

[atomicomatic]

After about 3 coats of wax, and it's gone now. I don't believe this stuff is bakelite, it doesn't really have that nice luster.

[dieseljeep]

Originally Posted by atomicomatic

After about 3 coats of wax, and it's gone now. I don't believe this stuff is bakelite, it doesn't really have that nice luster.

That's the plastic, they used in the day. Some say that it's Soy based, the kind that gets that nasty white crud, on it, after a while.

[earlyfilm]

Originally Posted by atomicomatic

Low and behold, while painting the numbers on the channel selector knob gold, I got a little paint outside one number. Being picky, I took nail polish remover . . . .

Many pre-WWII knobs were Bakelite. After the war, most were common plastic.

Finger nail remover, is basically a weak blend of perfumed lacquer thinner.

I've seen plastic knobs ruined just by applying a lacquer paint.

Except for lacquer base paint on plastic, most paint will wipe off clean with a dry wipe, if done before it has time to set.


The safest cleaner for unknown plastics is Windex.

The next safest is denatured (ie, 30% water) alcohol, but watch out on pre-war (& 1950s custom) wood cabinets as it may soften the finish.

If the item is greasy, just plain soap and water first.

In any case, always test first on a hidden spot!

James

[atomicomatic]

Thanks for the replies, got to be more careful next time! The set is looking presentable now, but the finish is looking weary in spots.

[dieseljeep]

Originally Posted by atomicomatic

Thanks for the replies, got to be more careful next time! The set is looking presentable now, but the finish is looking weary in spots.

I looked up the Sams!
Sears had three different suppliers, that year. Yours is the Arvin-built chassis, which is the best performing one.
It shows, that it has the 21MP4, metal cone CRT. They weren't famous for longevity. Hopefully, yours is good, or at least, usable.

[atomicomatic]

Yes, it is a metal cone CRT. How does one discharge this kind of tube?

[DaveWM]

IHMO the best way to discharge a CRT is with a HV probe. You need one often enough in workign on sets to warrant buying one. Once you have it you can use it to verify the CRT charge status. they are designed to be insulated properly against high voltage. Touch the bell with the HV prob (with the ground attached) and check the voltage or any residual charge. Leave it attached for a min or two as the charge can recover.

With a metal bell crt the CRT does not have the same built in capacitance (internal dag glass bell external dag). But the bell may be attached to an anode lead with a door knob cap in the HV cage OR the the metal bell may have a plastic shell that has a conductive coating on the outside again forming a cap.

[dieseljeep]

Originally Posted by DaveWM

IHMO the best way to discharge a CRT is with a HV probe. You need one often enough in workign on sets to warrant buying one. Once you have it you can use it to verify the CRT charge status. they are designed to be insulated properly against high voltage. Touch the bell with the HV prob (with the ground attached) and check the voltage or any residual charge. Leave it attached for a min or two as the charge can recover.

With a metal bell crt the CRT does not have the same built in capacitance (internal dag glass bell external dag). But the bell may be attached to an anode lead with a door knob cap in the HV cage OR the the metal bell may have a plastic shell that has a conductive coating on the outside again forming a cap.

According to the Sams, it has a 500PF door knob cap.
I hated those CRT's with a passion! Most were easy to install, but hard to substitute.
BTW, they were invented, by an engineer at a Milwaukee metal spinning concern. The round ones are easy to see, how they were formed, but the rectangular ones???
Must have been several operations.

[VintagePC]

Originally Posted by dieseljeep

According to the Sams, it has a 500PF door knob cap.
I hated those CRT's with a passion! Most were easy to install, but hard to substitute.
BTW, they were invented, by an engineer at a Milwaukee metal spinning concern. The round ones are easy to see, how they were formed, but the rectangular ones???
Must have been several operations.

Were there rectangular metal CRTs? yikes, that must have been pretty thick metal to withstand the vacuum pressure since it doesn't have the same natural strength...

[Electronic M]

My guess is that they made the rectangular tubes by warping the round metal bells.

[Jon A.]

Originally Posted by DaveWM

IHMO the best way to discharge a CRT is with a HV probe.

I wouldn't want to do it any other way. A loud SNAP from using a grounded screwdriver would give me quite a start.

[dieseljeep]

Originally Posted by Jon A.

I wouldn't want to do it any other way. A loud SNAP from using a grounded screwdriver would give me quite a start.

Those CRT's didn't seem to hold a charge as long as the glass CRT's. I always used to use a screw driver, propped between the yoke support brackets and the metal cone. Some had a vinyl plastic shield covering the metal cone, so you didn't have to worry about a shock.

[Jon A.]

I've never been inside of anything with a metal cone CRT. I had a bad habit of not trying to discharge CRTs when airing them out back when I was scrapping junk sets. A series of sparks jumped out of a Fony's CRT neck when I cut the evac stem, and a Hitachi console whose CRT I had already aired gave me a spark to the finger hen I reached for a piece of dangling glass. Not nearly enough to knock me over, but I yanked my hand back mighty fast.