Restoring vintage audio gear with the right metal polish

I’ve spent years rebuilding old receivers and amplifiers. The first thing most people notice is the sound. But I always look at the knobs, the faceplate, the metal trim. They tell a story. Aluminum gets cloudy. Brass turns dark. Chrome pits. You can have the best circuit in the world, but if the controls look grimy, the whole machine feels cheap. That’s where a careful hand and the right compound matter.

I’ve tried many polishes over the years, but one that consistently works well is simichrome. It’s a mild abrasive that removes tarnish without scratching. I keep a tube in my toolbox for the final pass on faceplates and knobs. It brings back the original luster without leaving a hazy residue. You don’t need much. A dab on a soft cloth does it.

Brass knobs from the 1970s often have a lacquer coating. That coating can yellow or peel. If you see that, you need to strip it first. I use a gentle solvent and a toothbrush. Then comes the polish. You rub in a tight circular motion. You don’t press hard. You let the compound do the work. Rinse with warm water. Dry immediately. The result is a clean, warm gold color that matches the original look.

What to avoid when polishing faceplates

Faceplates are trickier. They often have silkscreened lettering or painted markings. Aggressive rubbing can erase those in seconds. You want a polish that is fine enough to clean the metal but not harsh enough to lift the paint. I test on a small corner first. If the polish is too gritty, you will see scratches under bright light. Stick to a polish that breaks down as you work it. That way you can control how much abrasion happens. I never use a rotary tool on a faceplate. Hand rubbing gives you feedback. You can feel when the surface is smooth.

Another problem is hidden dirt inside engraved lines. A cotton swab with a tiny bit of polish can reach those spots. Work slowly. Wipe away the polish completely afterward. Any leftover wax can trap dust and attract moisture. That leads to more tarnish later. Clean the entire faceplate with a damp microfiber cloth after polishing. Then dry it with another cloth. Do not let it air dry. Water spots are hard to remove from polished metal.

The right technique for brass knobs

Knobs are easier. They are solid metal most of the time. You can use a bit more pressure. I remove the knobs from the shafts before polishing. That way I avoid getting polish inside the potentiometer. I hold each knob individually. I apply the polish to a folded cloth. I rub the entire surface, including the sides and the top. For knurled edges, I use a toothbrush dipped in the polish. It gets into the grooves. Then I rinse and dry. If the knob has a set screw, I clean that area with a small brush. I reassemble only after everything is bone dry. This process takes time, but the result is consistent.

• Always test the polish on an inconspicuous area first to check for paint damage.
• Use separate cloths for different metals to avoid cross-contamination.
• Polish in a well-ventilated area because the compound can have a mild solvent smell.
• Apply a thin coat of paste wax after polishing to slow down future tarnish.
• Store your polishes in a cool, dry place so they don’t separate or harden.

The work of restoration does not end with the electronics. The metal tells its own history. Clean it with care, and you will hear the full story.