Knob polishing on 75A-3

[Ed WA4NJY]

I started to do a light buffing of knobs on my 75A-3.  They never shined up like other knobs that I have done on different rigs.

I use jewelers rouge and a soft cloth.  Rarely have to use a buffing wheel.  Nothing changed with these.

Any ideas?

Thanks,
   Ed WA4NJY

[k4kyv]

Someone may have previously used a cleaner like Fantastik or 409 to clean them. That stuff permanently takes the sheen off bakelite.
 
It dissolves the microscopically thin skin off the phenolic and exposes the filler, which is most probably fine sawdust.  No amount of buffing will bring the shine back.  I ruined a nice pair of National type A Velvet Vernier dials with that  stuff.  Someone else told me they ruined the bezel on their KW-1 the same way.

When I cleaned the dials, I noticed that the water turned brown as it ran off. At first, I thought it was nicotine stain, but actually it was dissolved bakelite. Those cleaners  contain ammonia, and ammonia dissolves the phenolic plastic. Household ammonia and ammonia window cleaner would probably do the same damage.

[Ed WA4NJY]

That is a real possibility.  I did that on some SP-600 knobs.  The A-3 knobs do have a slight gloss and they all look the same.

Oh well,  I will put some new white on the pointer lines.  That will help some.

Thanks you Don.

[Detroit47]

I soak them in Murphys Oil Soap and water over night. I have also used Armorall no abrasives. You got to love it mmmmmmm Phenolic resin aka formaldehyde.

John N8QPC

[w3jn]

Find a 3-4 inch length of 1/4" shaft, chuck it in a drill press.  Attach the knob to the other end of the shaft, and tighten the setscrew.  Wet a rag with Brasso, turn on the drill press and go to town on the knob being careful not to snag the rag.  Let it dry, then turn on the drill press again and buff it with a clean rag.  Make sure you get the dried Brasso out of any grooves and knurls in the knob.

It'll never be as shiny as a knob that hasn't had the bakelite sheen removed, but it's the next best thing.

[WQ9E]

I was lucky enough to read about others' experience with cleaning bakelite before trying to clean it and it sure would have been an easy mistake to make.

I wonder if a really light overspray of a gloss (or maybe matte) clear coat would return the knob to near original?  The cheap approach would be a rattle can of acrylic but some of the wear resistant stuff as used in auto finishing would probably be better.

Or for your classic "shelf queen" a little shoe polish should do until someone touches the knob

[Detroit47]

If you wish to put a coating on the knobs that would last. I would use acrylic urethane. AKA known as water based water based acrylic. It is easy to work with you can just put the knob on a dowel rod and dip it; I would find an old knob to try it on and see if you like the results. I refinish a lot of old wood radios and antique wood furniture. So I have a lot of experience with different finishes. Also due to necessity I have learned to improvise. A friend of mine has a refinishing / antique store, and they have gotten away from Lacquer unless it is specfically requested.

John N8QPC

[Todd, KA1KAQ]

That original coating is almost like a shellac. I'm sure most of us have had he experience of cleaning an old knob and thinking 'wow, look at the nicotine and crud coming off this thing!' only to discover it was supposed to be there.

Brasso is one of the best choices as 'JN has mentioned. Another I haven't tried is something called....Blue Magic? This was recommended to me by WA2PJP but I've yet to find it here locally. It makes the knobs on his rigs look like new. I'm guessing they weren't stripped of their original coating, though.

There's also something out there called NeverDull which is a polishing rag of some sort impregnated with magic ingredients I guess. Looks like it would work well on IF cans, maybe knobs too.

I've never tried the 1/4" shaft in a drill press approach, but I bet that would really make 'em sparkle.

[KM1H]

Brasso aint Brasso any longer thanks to the dips***s at the EPA. I got my last supply from Canada and Ive since heard its been changed up there also.

Carl

[n2bc]

Black shoe polish....   Spin it in your variable speed drill to buff.

[KA1ZGC]

I saw this thread on the front page, but the subject line was truncated to "Knob Polishing on 75...". Wasn't sure I dared to look.

Anyway...

If you wish to put a coating on the knobs that would last. I would use acrylic urethane. AKA known as water based water based acrylic. It is easy to work with you can just put the knob on a dowel rod and dip it; I would find an old knob to try it on and see if you like the results. I refinish a lot of old wood radios and antique wood furniture. So I have a lot of experience with different finishes.

I second that recommendation. I use acrylic as a finish for electric guitars. The stuff is remarkably hard and durable, and mostly color-neutral.

It's often marketed as "acrylic lacquer", but that's a complete misnomer (see below).

In fact, when I was hammering the string cups into the back of my strat after I refinished it, I missed one of them entirely and hit the body full-force with the light clawhammer I was using. After I got done cringing (and swearing), I surveyed the damage. I had to really look close to see the tiniest of dents from the edge of the hammer head.

Also due to necessity I have learned to improvise. A friend of mine has a refinishing / antique store, and they have gotten away from Lacquer unless it is [specifically] requested.

...and even that is probably HVLP (high volume low pressure) spray lacquer. The lacquer that was used in the 50s and 60s on cars and guitars (and other American icons) has been outlawed. Not for the lacquer itself, but for the medium. HVLP is just lacquer-concentrate without the toxic base.

Like John said, you'll want to test it on an area not-normally-visible, just in case there's a chemical reaction to whatever was on your knob (ahem) to start with.

[k4kyv]

That original coating is almost like a shellac. I'm sure most of us have had he experience of cleaning an old knob and thinking 'wow, look at the nicotine and crud coming off this thing!' only to discover it was supposed to be there.

The original skin is part of the moulding process. Electrostatic repulsion forces the particles of the filler away from the mirror-like surface of the mould and  leaves the thin layer of pure phenolic without filler.  If  a good quality mould was used, the sheen is a natural part of the process.

Some kind of clear coating might approximate the original surface, but you will unlikely ever get it exactly the same, and the add-on coating will not be long lasting if the knob is used a lot. The clear-coat will eventually wear back down to the filler, or else will peel of.  Trying to permanently polish bakelite, once the sawdust filler is exposed at the surface, is kind of like trying to polish a turd.

Another product that will restore some semblance of sheen is a furniture polish called Pledge, if they still make it.  You spray it on, let it dry, and then use a soft cloth to wipe off the waxy residue. But it will require periodic re-application.

Some of the remedies mentioned might work ok for a trophy radio that will sit on the display shelf like a museum piece, but if it is a piece you plan to use every day, maybe it would be best to just leave it as is, or look for a replacement set of knobs.  Otherwise, the knobs on the controls that are less frequently used will be nice and shiny, but those that are used the most,  like the tuning knob, will eventually develop a dull surface that won't match the rest. If the receiver is to be mainly a functional unit, I wouldn't worry too much about how shiny the knobs are.

One possibility for a permanent restoration might be some kind of epoxy solution that would soak in to the porous bakelite and actually impregnate the filler before it hardens.  Maybe a good experiment would be to take an old bakelite knob that will not likely be used for anything.  Give it a good cleaning with 409 or Fantastik, until all the shine is clearly washed away.  Let it sit for several days to completely dry.  Mix up a batch of epoxy and add a thinner.  Acetone may work, but commercial epoxy thinner made specially for epoxy wood consolidants is available. Search on line for the website for the Abatron company; they make a number of epoxy wood restoration products, including "consolidants".  The idea is to get the epoxy to almost a water like consistency, rather than the normal molasses-like consistency, so that it will soak into the sawdust or other filler and leave a very thin skin like the original phenolic.  I would think this might work, since from my experience epoxy adheres firmly to bakelite. I have tried to pull cured epoxy off bakelite and when it came off, it took a hunk of bakelite with it.  It would be worthwhile to experiment; if it fails you are only out a junk knob and a few bucks you might have spent for the epoxy and thinner, but if it works, you have discovered a solution to a formidable probem. BTW, I would not necessarily recommend the Abatron epoxy, since it hardens to a soft pliable consistency compatible with that of wood.  I suspect something like Two-Ton Crystal Clear epoxy would work better since it cures to a glass-like hardness. This is assuming that the Abatron thinner would work with other epoxies.

[Detroit47]

Some kind of clear coating might approximate the original surface, but you will unlikely ever get it exactly the same, and the add-on coating will not be long lasting if the knob is used a lot. The clear-coat will eventually wear back down to the filler, or else will peel of. 

I don't belive that you have had experince with acrylic urethane. This product is used on wood floors "Basketball courts", table tops, Stair Banisters. High wear and traffic areas, I don't belive that bakelite would stand up to foot traffic.

73 John

[w3jn]

Brasso aint Brasso any longer thanks to the dips***s at the EPA. I got my last supply from Canada and Ive since heard its been changed up there also.

Carl

Simichrome, or any auto polish/wax will work equally well.  You want a fine abrasive and plenty of friction, which the drill press provides.

Knobs that I've done over 10 years ago this way still have the same shine.

[KA1ZGC]

Some kind of clear coating might approximate the original surface, but you will unlikely ever get it exactly the same, and the add-on coating will not be long lasting if the knob is used a lot. The clear-coat will eventually wear back down to the filler, or else will peel of. 

I don't [believe] that you have had [experience] with acrylic urethane. This product is used on wood floors "Basketball courts", table tops, Stair Banisters. High wear and traffic areas, I don't [believe] that bakelite would stand up to foot traffic.

I'm with John on this one. They use acrylic in bowling alleys (talk about punishment). Just before I refinished my strat, I had the pleasure of sitting at a bar next to this very nice old guy who goes around the country finishing bowling alley floors. He very graciously shared a ton of wisdom on the topic of acrylic on maple. Given the density of maple, I wouldn't have thought that it would be necessary to sanding-seal the wood first. He quickly set me straight on that, and he was right. I gave about 7 coats of sanding seal and 12 coats of acrylic. Like I said, all my might with a light clawhammer made only the tiniest of dents in the finish.

Not to put too fine a point on it, but I'd probably be the only one on this thread still alive by the time an acrylic-finished knob started to lose its finish.

What the old gent told me would also apply to a particle-board bakelite-coated knob: if you're down to the wood, you'll want to apply some sanding sealer. Most home improvement stores should have it. I bought mine from Stewart-MacDonald (www.stewmac.com) along with the acrylic itself, but there's nothing magic about what they stock. I was buying tools for the guitar shop at the time, so it just made sense. Any sealer and acrylic finish will do the trick.

Pigments and dyes are also available for any solid or translucent color you like. A good solid black acrylic on an old-buzzard knob would look quite sexy, and not at all out-of-place.

...for what that's all worth.

[k4kyv]

Brasso aint Brasso any longer thanks to the dips***s at the EPA. I got my last supply from Canada and Ive since heard its been changed up there also.

I wonder what the "bad" stuff is supposed to be in Brasso.  I suppose bicycle helmets are mandatory to do anything these days.

At an auto show about 15 years ago I bought a tube of Wenol metal polish.  It comes in a tube about the same size as a jumbo tube of toothpaste.  It smells and  looks like Brasso, but is in paste form instead of liquid, and they claim it is good for polishing all metals. I find it to work better than Brasso. A tiny drop goes a  long way; I use it all the time and my tube is still 90% full, and it doesn't seem to go bad with age. It was made in UK, so probably not subject to EPA restrictions. But that was 15 years ago. In recent years, EU restrictions make some of the silly stuff over here look like the rules for kindergarten parlour games. For example, they are the ones who initiated that lead-free solder nonsense.

[WD8BIL]

A few coats of High Gloss water based poly should do it!
Great shine............ no fumes!

[WBear2GCR]

Hmmm...

                   _-_-bear

[Detroit47]

I aint sayin nuthin just watchin.

John

[W7TFO]

Somehow a YL fits into this conversation about now....

[Todd, KA1KAQ]

If all else fails and the knobs are pretty well buggered up, a coat of gloss black sprayed over them should at least take away the ugly, dry-brown look.